Hypoaldosteronism

Overview

Definition

Hypoaldosteronism is defined as decreased secretion Secretion Coagulation Studies of aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia from the zona glomerulosa Zona Glomerulosa The narrow subcapsular outer zone of the adrenal cortex. This zone produces a series of enzymes that convert pregnenolone to aldosterone. The final steps involve three successive oxidations by cytochrome p-450 cyp11b2. Adrenal Glands: Anatomy of the adrenal cortex Adrenal Cortex The outer layer of the adrenal gland. It is derived from mesoderm and comprised of three zones (outer zona glomerulosa, middle zona fasciculata, and inner zona reticularis) with each producing various steroids preferentially, such as aldosterone; hydrocortisone; dehydroepiandrosterone; and androstenedione. Adrenal cortex function is regulated by pituitary adrenocorticotropin. Adrenal Glands: Anatomy, which may be primary or secondary in nature.

Epidemiology

• Exact incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency is unknown.
• Age at diagnosis: 
  • Generally occurs in older adults (> 50 years of age)
  • May occur in children with underlying disorders (e.g., diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus mellitus, sickle cell anemia Sickle cell anemia A disease characterized by chronic hemolytic anemia, episodic painful crises, and pathologic involvement of many organs. It is the clinical expression of homozygosity for hemoglobin S. Sickle Cell Disease)
• Male = female
• Racial/ethnic bias Bias Epidemiological studies are designed to evaluate a hypothesized relationship between an exposure and an outcome; however, the existence and/or magnitude of these relationships may be erroneously affected by the design and execution of the study itself or by conscious or unconscious errors perpetrated by the investigators or the subjects. These systematic errors are called biases. Types of Biases: more common in Blacks, Native Americans, and Hispanics

Etiology and Pathophysiology

Physiology review

• Aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia is stimulated directly by:
  • Angiotensin II Angiotensin II An octapeptide that is a potent but labile vasoconstrictor. It is produced from angiotensin I after the removal of two amino acids at the c-terminal by angiotensin converting enzyme. The amino acid in position 5 varies in different species. To block vasoconstriction and hypertension effect of angiotensin II, patients are often treated with ace inhibitors or with angiotensin II type 1 receptor blockers. Renal Sodium and Water Regulation
  • Hyperkalemia Hyperkalemia Hyperkalemia is defined as a serum potassium (K+) concentration >5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia
• Renin-angiotensin-aldosterone system Renin-angiotensin-aldosterone system A blood pressure regulating system of interacting components that include renin; angiotensinogen; angiotensin converting enzyme; angiotensin i; angiotensin ii; and angiotensinase. Renin, an enzyme produced in the kidney, acts on angiotensinogen, an alpha-2 globulin produced by the liver, forming angiotensin I. Angiotensin-converting enzyme, contained in the lung, acts on angiotensin I in the plasma converting it to angiotensin II, an extremely powerful vasoconstrictor. Angiotensin II causes contraction of the arteriolar and renal vascular smooth muscle, leading to retention of salt and water in the kidney and increased arterial blood pressure. In addition, angiotensin II stimulates the release of aldosterone from the adrenal cortex, which in turn also increases salt and water retention in the kidney. Angiotensin-converting enzyme also breaks down bradykinin, a powerful vasodilator and component of the kallikrein-kinin system. Adrenal Hormones ( RAAS RAAS A blood pressure regulating system of interacting components that include renin; angiotensinogen; angiotensin converting enzyme; angiotensin i; angiotensin ii; and angiotensinase. Renin, an enzyme produced in the kidney, acts on angiotensinogen, an alpha-2 globulin produced by the liver, forming angiotensin I. Angiotensin-converting enzyme, contained in the lung, acts on angiotensin I in the plasma converting it to angiotensin II, an extremely powerful vasoconstrictor. Angiotensin II causes contraction of the arteriolar and renal vascular smooth muscle, leading to retention of salt and water in the kidney and increased arterial blood pressure. In addition, angiotensin II stimulates the release of aldosterone from the adrenal cortex, which in turn also increases salt and water retention in the kidney. Angiotensin-converting enzyme also breaks down bradykinin, a powerful vasodilator and component of the kallikrein-kinin system. Adrenal Hormones):
  • Renin Renin A highly specific (leu-leu) endopeptidase that generates angiotensin I from its precursor angiotensinogen, leading to a cascade of reactions which elevate blood pressure and increase sodium retention by the kidney in the renin-angiotensin system. Renal Sodium and Water Regulation (secreted by the juxtaglomerular (JG) cells within the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy) → converts angiotensinogen (secreted by hepatocytes Hepatocytes The main structural component of the liver. They are specialized epithelial cells that are organized into interconnected plates called lobules. Liver: Anatomy) to angiotensin I
  • ACE (secreted by pulmonary vascular endothelium Endothelium A layer of epithelium that lines the heart, blood vessels (vascular endothelium), lymph vessels (lymphatic endothelium), and the serous cavities of the body. Arteries: Histology) → converts angiotensin I to angiotensin II Angiotensin II An octapeptide that is a potent but labile vasoconstrictor. It is produced from angiotensin I after the removal of two amino acids at the c-terminal by angiotensin converting enzyme. The amino acid in position 5 varies in different species. To block vasoconstriction and hypertension effect of angiotensin II, patients are often treated with ace inhibitors or with angiotensin II type 1 receptor blockers. Renal Sodium and Water Regulation
  • Angiotensin II Angiotensin II An octapeptide that is a potent but labile vasoconstrictor. It is produced from angiotensin I after the removal of two amino acids at the c-terminal by angiotensin converting enzyme. The amino acid in position 5 varies in different species. To block vasoconstriction and hypertension effect of angiotensin II, patients are often treated with ace inhibitors or with angiotensin II type 1 receptor blockers. Renal Sodium and Water Regulation → stimulates release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology of aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia (secreted by the zona glomerulosa Zona Glomerulosa The narrow subcapsular outer zone of the adrenal cortex. This zone produces a series of enzymes that convert pregnenolone to aldosterone. The final steps involve three successive oxidations by cytochrome p-450 cyp11b2. Adrenal Glands: Anatomy in the adrenal cortex Adrenal Cortex The outer layer of the adrenal gland. It is derived from mesoderm and comprised of three zones (outer zona glomerulosa, middle zona fasciculata, and inner zona reticularis) with each producing various steroids preferentially, such as aldosterone; hydrocortisone; dehydroepiandrosterone; and androstenedione. Adrenal cortex function is regulated by pituitary adrenocorticotropin. Adrenal Glands: Anatomy)
• Factors that normally trigger Trigger The type of signal that initiates the inspiratory phase by the ventilator Invasive Mechanical Ventilation RAAS RAAS A blood pressure regulating system of interacting components that include renin; angiotensinogen; angiotensin converting enzyme; angiotensin i; angiotensin ii; and angiotensinase. Renin, an enzyme produced in the kidney, acts on angiotensinogen, an alpha-2 globulin produced by the liver, forming angiotensin I. Angiotensin-converting enzyme, contained in the lung, acts on angiotensin I in the plasma converting it to angiotensin II, an extremely powerful vasoconstrictor. Angiotensin II causes contraction of the arteriolar and renal vascular smooth muscle, leading to retention of salt and water in the kidney and increased arterial blood pressure. In addition, angiotensin II stimulates the release of aldosterone from the adrenal cortex, which in turn also increases salt and water retention in the kidney. Angiotensin-converting enzyme also breaks down bradykinin, a powerful vasodilator and component of the kallikrein-kinin system. Adrenal Hormones (and thus ↑ aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia):
  • ↓ Blood pressure or blood volume
  • ↓ Sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia delivery to the kidney
  • ↑ Sympathetic tone
• Effects of aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia: 
  • Stimulates production of the following proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis within the principle cells in the distal renal tubules:
    • Na⁺/K⁺ ATPase on the basolateral side
    • ENaC ENaC Sodium channels found on salt-reabsorbing epithelial cells that line the distal nephron; the distal colon; salivary ducts; sweat glands; and the lung. They are amiloride-sensitive and play a critical role in the control of sodium balance, blood volume, and blood pressure. Liddle Syndrome (epithelial sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia channels Channels The Cell: Cell Membrane) on the lumen side: allows Na⁺ reabsorption from the lumen into the principal cells Principal cells Tubular System
    • ROMK ( renal outer medullary potassium channel Renal outer medullary potassium channel Renal Potassium Regulation) on the lumen side: allows excretion of K⁺ into the urine
  • Stimulates Na⁺ reabsorption from the renal tubules:
    • Water follows the Na⁺.
    • Creates a negative electrical gradient Electrical gradient Renal Potassium Regulation across the lumen, promoting the secretion Secretion Coagulation Studies of K⁺ and H⁺ into the urine

Etiology

The 2 primary mechanisms that cause hypoaldosteronism are reduced aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia production (which can be hyporeninemic or hyperreninemic) and aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing. Medications are often the cause of both mechanisms.

Pathophysiology

• End result of ↓ aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia: 
  • ↑ Serum K⁺ (↓ urinary excretion of K⁺)
  • Metabolic acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis (↓ urinary excretion of H⁺): renal tubular acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis type 4 Type 4 Spinal Muscular Atrophy
  • ↓ Serum Na⁺ (↑ urinary excretion of Na⁺)
  • Volume depletion Volume depletion Volume status is a balance between water and solutes, the majority of which is Na. Volume depletion refers to a loss of both water and Na, whereas dehydration refers only to a loss of water. Volume depletion can be caused by GI losses, renal losses, bleeding, poor oral Na intake, or third spacing of fluids. Volume Depletion and Dehydration and hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension
• Type 4 Type 4 Spinal Muscular Atrophy RTA RTA Renal tubular acidosis (RTA) is an imbalance in physiologic pH caused by the kidney’s inability to acidify urine to maintain blood pH at physiologic levels. Renal tubular acidosis exist in multiple types, including distal RTA (type 1), proximal RTA (type 2), and hyperkalemic RTA (type 4). Renal Tubular Acidosis:
  • ↑ K⁺ → inhibits renal ammonia Ammonia A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as ammonium hydroxide. Acid-Base Balance synthesis Synthesis Polymerase Chain Reaction (PCR) and urinary ammonia Ammonia A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as ammonium hydroxide. Acid-Base Balance excretion
  • ↓ In urinary ammonia Ammonia A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as ammonium hydroxide. Acid-Base Balance excretion → mild metabolic acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis ( type 4 Type 4 Spinal Muscular Atrophy RTA RTA Renal tubular acidosis (RTA) is an imbalance in physiologic pH caused by the kidney’s inability to acidify urine to maintain blood pH at physiologic levels. Renal tubular acidosis exist in multiple types, including distal RTA (type 1), proximal RTA (type 2), and hyperkalemic RTA (type 4). Renal Tubular Acidosis)
• Mechanisms of drug-induced hypoaldosteronism:
  • Drugs that cause a ↓ in aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia synthesis Synthesis Polymerase Chain Reaction (PCR) or release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology:
    • ACE inhibitors ACE inhibitors Truncus Arteriosus/ ARBs ARBs Agents that antagonize angiotensin receptors. Many drugs in this class specifically target the angiotensin type 1 receptor. Heart Failure and Angina Medication
    • Heparin (direct toxic effect on the adrenal zona glomerulosa Zona Glomerulosa The narrow subcapsular outer zone of the adrenal cortex. This zone produces a series of enzymes that convert pregnenolone to aldosterone. The final steps involve three successive oxidations by cytochrome p-450 cyp11b2. Adrenal Glands: Anatomy cells)
    • NSAIDs NSAIDS Primary vs Secondary Headaches/COX-2 inhibitors
    • Beta-blockers Beta-blockers Drugs that bind to but do not activate beta-adrenergic receptors thereby blocking the actions of beta-adrenergic agonists. Adrenergic beta-antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches, and anxiety. Class 2 Antiarrhythmic Drugs (Beta Blockers)
  • Inhibit aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia effects: 
    • Aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia receptor Receptor Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors antagonists: spironolactone Spironolactone A potassium sparing diuretic that acts by antagonism of aldosterone in the distal renal tubules. It is used mainly in the treatment of refractory edema in patients with congestive heart failure, nephrotic syndrome, or hepatic cirrhosis. Its effects on the endocrine system are utilized in the treatments of hirsutism and acne but they can lead to adverse effects. Potassium-sparing Diuretics, eplerenone Eplerenone A spironolactone derivative and selective aldosterone receptor antagonist that is used in the management of hypertension and congestive heart failure, post-myocardial infarction. Potassium-sparing Diuretics
    • ENaC ENaC Sodium channels found on salt-reabsorbing epithelial cells that line the distal nephron; the distal colon; salivary ducts; sweat glands; and the lung. They are amiloride-sensitive and play a critical role in the control of sodium balance, blood volume, and blood pressure. Liddle Syndrome inhibitors: amiloride Amiloride A pyrazine compound inhibiting sodium reabsorption through sodium channels in renal epithelial cells. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with diuretics to spare potassium loss. Liddle Syndrome, trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim, pentamidine
  • Induce aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing:  calcineurin inhibitors Calcineurin Inhibitors Compounds that inhibit or block the phosphatase activity of calcineurin. Immunosuppressants cyclosporine Cyclosporine A cyclic undecapeptide from an extract of soil fungi. It is a powerful immunosupressant with a specific action on T-lymphocytes. It is used for the prophylaxis of graft rejection in organ and tissue transplantation. Immunosuppressants and tacrolimus Tacrolimus A macrolide isolated from the culture broth of a strain of streptomyces tsukubaensis that has strong immunosuppressive activity in vivo and prevents the activation of T-lymphocytes in response to antigenic or mitogenic stimulation in vitro. Immunosuppressants

Clinical Presentation

• Usually asymptomatic (discovered on routine lab evaluation)
• Hyperkalemia Hyperkalemia Hyperkalemia is defined as a serum potassium (K+) concentration >5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia (> 5 mEq/L) can present with:
  • Cardiac arrhythmias
  • Muscle weakness
• Hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia (< 135 mEq/L):
  • More common in children and patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with adrenal insufficiency Adrenal Insufficiency Conditions in which the production of adrenal corticosteroids falls below the requirement of the body. Adrenal insufficiency can be caused by defects in the adrenal glands, the pituitary gland, or the hypothalamus. Adrenal Insufficiency and Addison Disease
  • Can present with: 
    • Polyuria Polyuria Urination of a large volume of urine with an increase in urinary frequency, commonly seen in diabetes. Renal Potassium Regulation
    • Dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration
    • Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia
    • Neurologic symptoms: short-term memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment loss, confusion, lethargy Lethargy A general state of sluggishness, listless, or uninterested, with being tired, and having difficulty concentrating and doing simple tasks. It may be related to depression or drug addiction. Hyponatremia, seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures
• Clinical features suggestive of associated conditions (e.g., sickle cell anemia Sickle cell anemia A disease characterized by chronic hemolytic anemia, episodic painful crises, and pathologic involvement of many organs. It is the clinical expression of homozygosity for hemoglobin S. Sickle Cell Disease, SLE SLE Systemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected. Systemic Lupus Erythematosus, adrenal insufficiency Adrenal Insufficiency Conditions in which the production of adrenal corticosteroids falls below the requirement of the body. Adrenal insufficiency can be caused by defects in the adrenal glands, the pituitary gland, or the hypothalamus. Adrenal Insufficiency and Addison Disease)

Diagnosis

The diagnosis of hypoaldosteronism should be considered in any patient with persistent hyperkalemia Hyperkalemia Hyperkalemia is defined as a serum potassium (K+) concentration >5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia without an obvious cause, such as renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome or potassium-sparing diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication.

• Aldosterone-specific tests:
  • Serum aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia:
    • ↓ In all cases of true hypoaldosteronism
    • ↑ In cases of pseudohypoaldosteronism ( aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing)
  • Plasma renin activity Plasma renin activity Renal Artery Stenosis ( PRA PRA Purine and Pyrimidine Metabolism):
    • ↓ In type 4 Type 4 Spinal Muscular Atrophy RTA RTA Renal tubular acidosis (RTA) is an imbalance in physiologic pH caused by the kidney’s inability to acidify urine to maintain blood pH at physiologic levels. Renal tubular acidosis exist in multiple types, including distal RTA (type 1), proximal RTA (type 2), and hyperkalemic RTA (type 4). Renal Tubular Acidosis (hyporeninemic hypoaldosteronism)
    • ↑ In primary adrenal insufficiency Primary adrenal insufficiency An adrenal disease characterized by the progressive destruction of the adrenal cortex, resulting in insufficient production of aldosterone and hydrocortisone. Clinical symptoms include anorexia; nausea; weight loss; muscle weakness; and hyperpigmentation of the skin due to increase in circulating levels of acth precursor hormone which stimulates melanocytes. Adrenal Insufficiency and Addison Disease
  • Transtubular potassium Potassium An element in the alkali group of metals with an atomic symbol k, atomic number 19, and atomic weight 39. 10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance. Hyperkalemia gradient (TTKG): estimates the action of aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia on cortical collecting tubules Collecting tubules Straight tubes commencing in the radiate part of the kidney cortex where they receive the curved ends of the distal convoluted tubules. In the medulla the collecting tubules of each pyramid converge to join a central tube (duct of Bellini) which opens on the summit of the papilla. Kidneys: Anatomy
    • TTKG = [urine K ÷ (urine osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation/serum osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation)] ÷ serum K
    • ↓ TTKG (< 7) in the presence of hyperkalemia Hyperkalemia Hyperkalemia is defined as a serum potassium (K+) concentration >5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia: Hypoaldosteronism is likely.
  • Serum cortisol Cortisol Glucocorticoids: to screen for adrenal insufficiency Adrenal Insufficiency Conditions in which the production of adrenal corticosteroids falls below the requirement of the body. Adrenal insufficiency can be caused by defects in the adrenal glands, the pituitary gland, or the hypothalamus. Adrenal Insufficiency and Addison Disease
    • ↓ In adrenal insufficiency Adrenal Insufficiency Conditions in which the production of adrenal corticosteroids falls below the requirement of the body. Adrenal insufficiency can be caused by defects in the adrenal glands, the pituitary gland, or the hypothalamus. Adrenal Insufficiency and Addison Disease
    • Normal in isolated hypoaldosteronism
• In type 4 Type 4 Spinal Muscular Atrophy RTA RTA Renal tubular acidosis (RTA) is an imbalance in physiologic pH caused by the kidney’s inability to acidify urine to maintain blood pH at physiologic levels. Renal tubular acidosis exist in multiple types, including distal RTA (type 1), proximal RTA (type 2), and hyperkalemic RTA (type 4). Renal Tubular Acidosis (hyporeninemic hypoaldosteronism), laboratory tests will show:
  • Aldosterone-specific test findings:
    • ↓ Serum aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia
    • ↓ PRA PRA Purine and Pyrimidine Metabolism
    • ↓ TTKG
  • Basic metabolic panel Basic Metabolic Panel Primary vs Secondary Headaches ( BMP BMP Primary vs Secondary Headaches) findings:
    • Non-anion gap metabolic acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis
    • ↓ Serum HCO₃ (usually mild, 18–22 mEq/L)
    • ↑ K⁺
    • ↑ Cl^–
    • Markers of ↓ renal function are common (e.g., ↑ creatinine)
  • Urine findings:
    • ↓ Urinary K⁺
    • Normal urinary phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes
    • Normal or ↓ urinary calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes
    • Urine pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance < 5.3‒5.5
• Electrocardiogram Electrocardiogram An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG) (due to ↑ cardiac risks associated with hyperkalemia Hyperkalemia Hyperkalemia is defined as a serum potassium (K+) concentration >5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia)
• Testing to rule out other associated conditions, if suspected:
  • 17-hydroxyprogesterone ( congenital Congenital Chorioretinitis adrenal hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation)
  • HIV HIV Anti-HIV Drugs test

Management

The management depends on the underlying etiology.

• Medication induced: Adjust/remove medications that may be contributing.
• Type 4 Type 4 Spinal Muscular Atrophy RTA RTA Renal tubular acidosis (RTA) is an imbalance in physiologic pH caused by the kidney’s inability to acidify urine to maintain blood pH at physiologic levels. Renal tubular acidosis exist in multiple types, including distal RTA (type 1), proximal RTA (type 2), and hyperkalemic RTA (type 4). Renal Tubular Acidosis (hyporeninemic hypoaldosteronism):
  • Low-potassium diet
  • Loop or thiazide Thiazide Heterocyclic compounds with sulfur and nitrogen in the ring. This term commonly refers to the benzothiadiazines that inhibit sodium-potassium-chloride symporters and are used as diuretics. Hyponatremia diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication
  • Alkali supplementation (NaHCO₃) if acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis does not improve
  • Mineralocorticoid replacement is not recommended, as many patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship have underlying conditions (e.g., edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema, hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension) that would be exacerbated.
• Primary adrenal insufficiency Primary adrenal insufficiency An adrenal disease characterized by the progressive destruction of the adrenal cortex, resulting in insufficient production of aldosterone and hydrocortisone. Clinical symptoms include anorexia; nausea; weight loss; muscle weakness; and hyperpigmentation of the skin due to increase in circulating levels of acth precursor hormone which stimulates melanocytes. Adrenal Insufficiency and Addison Disease and congenital Congenital Chorioretinitis adrenal hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation:
  • Mineralocorticoid replacement: fludrocortisone Fludrocortisone A synthetic mineralocorticoid with anti-inflammatory activity. Mineralocorticoids
  • Glucocorticoid replacement: hydrocortisone Hydrocortisone The main glucocorticoid secreted by the adrenal cortex. Its synthetic counterpart is used, either as an injection or topically, in the treatment of inflammation, allergy, collagen diseases, asthma, adrenocortical deficiency, shock, and some neoplastic conditions. Immunosuppressants or prednisone Prednisone A synthetic anti-inflammatory glucocorticoid derived from cortisone. It is biologically inert and converted to prednisolone in the liver. Immunosuppressants
• Hyperkalemia Hyperkalemia Hyperkalemia is defined as a serum potassium (K+) concentration >5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia with ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG) changes: emergency management to ↓ K⁺

Clinical Relevance

• Congenital Congenital Chorioretinitis adrenal hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation ( CAH CAH Congenital adrenal hyperplasia (CAH) consists of a group of autosomal recessive disorders that cause a deficiency of an enzyme needed in cortisol, aldosterone, and androgen synthesis. The most common subform of cah is 21-hydroxylase deficiency, followed by 11β-hydroxylase deficiency. Congenital Adrenal Hyperplasia): consists of a group of autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance disorders involving a genetic mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations that results in an enzyme deficiency required for cortisol Cortisol Glucocorticoids and/or aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia synthesis Synthesis Polymerase Chain Reaction (PCR).
• Primary Addison disease: also called primary adrenal insufficiency Primary adrenal insufficiency An adrenal disease characterized by the progressive destruction of the adrenal cortex, resulting in insufficient production of aldosterone and hydrocortisone. Clinical symptoms include anorexia; nausea; weight loss; muscle weakness; and hyperpigmentation of the skin due to increase in circulating levels of acth precursor hormone which stimulates melanocytes. Adrenal Insufficiency and Addison Disease. Defined as the inadequate production of adrenocortical hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types, including glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids, mineralocorticoids Mineralocorticoids Mineralocorticoids are a drug class within the corticosteroid family and fludrocortisone is the primary medication within this class. Fludrocortisone is a fluorinated analog of cortisone. The fluorine moiety protects the drug from isoenzyme inactivation in the kidney, allowing it to exert its mineralocorticoid effect. Mineralocorticoids, and adrenal androgens Androgens Androgens are naturally occurring steroid hormones responsible for development and maintenance of the male sex characteristics, including penile, scrotal, and clitoral growth, development of sexual hair, deepening of the voice, and musculoskeletal growth. Androgens and Antiandrogens. Primary adrenal insufficiency Primary adrenal insufficiency An adrenal disease characterized by the progressive destruction of the adrenal cortex, resulting in insufficient production of aldosterone and hydrocortisone. Clinical symptoms include anorexia; nausea; weight loss; muscle weakness; and hyperpigmentation of the skin due to increase in circulating levels of acth precursor hormone which stimulates melanocytes. Adrenal Insufficiency and Addison Disease is caused by afflictions in the gland itself. Classic findings include mucosal and cutaneous hyperpigmentation Hyperpigmentation Excessive pigmentation of the skin, usually as a result of increased epidermal or dermal melanin pigmentation, hypermelanosis. Hyperpigmentation can be localized or generalized. The condition may arise from exposure to light, chemicals or other substances, or from a primary metabolic imbalance. Malassezia Fungi, hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension, and GI symptoms.
• Diabetic nephropathy Diabetic nephropathy Kidney injuries associated with diabetes mellitus and affecting kidney glomerulus; arterioles; kidney tubules; and the interstitium. Clinical signs include persistent proteinuria, from microalbuminuria progressing to albuminuria of greater than 300 mg/24 h, leading to reduced glomerular filtration rate and end-stage renal disease. Chronic Diabetic Complications: Diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus mellitus describes a group of metabolic diseases that are characterized by chronic hyperglycemia Hyperglycemia Abnormally high blood glucose level. Diabetes Mellitus and insulin resistance Insulin resistance Diminished effectiveness of insulin in lowering blood sugar levels: requiring the use of 200 units or more of insulin per day to prevent hyperglycemia or ketosis. Diabetes Mellitus. Long-standing diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus mellitus causes vascular changes that eventually result in cardiovascular, renal, retinal, and neurological complications.
• Hyperkalemia Hyperkalemia Hyperkalemia is defined as a serum potassium (K+) concentration >5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia: defined as an elevated serum potassium Potassium An element in the alkali group of metals with an atomic symbol k, atomic number 19, and atomic weight 39. 10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance. Hyperkalemia level (> approximately 5.5mEq/L). The condition is usually an incidental finding in the general population but affects 10% of hospitalized patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship. There are many causes, including transcellular Transcellular The movement of one cell into, through, and out of another cell. Tubular System shifts, tissue breakdown, inadequate excretion, and drug induced. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are usually asymptomatic.
• Hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia: defined as a decreased plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia concentration (< approximately 135 mEq/L). This condition occurs from either loss of sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia or excess water in the extracellular fluid Extracellular fluid The fluid of the body that is outside of cells. It is the external environment for the cells. Body Fluid Compartments.
• RTA RTA Renal tubular acidosis (RTA) is an imbalance in physiologic pH caused by the kidney’s inability to acidify urine to maintain blood pH at physiologic levels. Renal tubular acidosis exist in multiple types, including distal RTA (type 1), proximal RTA (type 2), and hyperkalemic RTA (type 4). Renal Tubular Acidosis: an accumulation of acid in the body due to a failure of the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy to appropriately acidify the urine. The condition is classified into 4 types.