Hypotension
Overview Definition Hypotension is defined as blood pressure below 90/60 mm Hg. If blood pressure decreases enough, shock may develop. Shock is most commonly defined as the life-threatening failure of adequate oxygen delivery to the tissues and may be due to decreased blood perfusion of vital organs (e.g., brain, heart, kidneys, lungs). Etiology Cardiovascular: Hypovolemia: […]
Renal Potassium Regulation
Overview Introduction Potassium distribution: Mechanisms of K+ balance: Renal processes to regulate water, electrolytes, and waste Nephron anatomy review Nephrons are the functional units of the kidney. Nephron segments (in order through which the filtrate flows): Types of nephrons: Potassium Regulation in the Glomerulus, Proximal Tubule, and Loop of Henle Glomerulus Proximal tubule Cells of […]
Bronchiolitis Obliterans
Definition and Epidemiology Definitions Epidemiology Etiology Small airway injuries that trigger bronchiolitis obliterans can result from inhalation, infections, drug exposure, lung inflammation due to a rheumatic process, or chronic transplant rejection. Pathophysiology and Clinical Presentation Pathogenesis Injury to the distal bronchioles results in inflammation. A dysregulated immune response then leads to fibroproliferation and narrowing of […]
Thyroid Cancer
Overview Definition Thyroid cancer is a malignancy arising from the cells of the thyroid gland, including thyroid follicular cells (thyrocytes), calcitonin-producing C cells, lymphocytes, and/or stromal and vascular elements. Epidemiology In the United States: Thyroid cancer accounts for 1% of new cancer diagnoses annually. Incidence has increased over 30 years, but mortality has not changed. […]
Acute Bronchitis
Overview Definition Acute bronchitis is an acute inflammation of the large airways of the lower respiratory tract wherein the pulmonary parenchyma is not affected. Epidemiology Acute bronchitis is a very common disease. Etiology Acute bronchitis is most commonly caused by a viral infection, although bacterial causes are possible. Pathophysiology Acute bronchitis is characterized by infection […]
Thyrotoxicosis and Hyperthyroidism
Overview Definition Thyrotoxicosis is a condition characterized by the classic physiologic manifestations of excess thyroid hormones regardless of the cause or hormonal source. If the excessive hormones are produced and released by the thyroid gland, the condition is called hyperthyroidism. Epidemiology Thyrotoxicosis due to hyperthyroidism: Thyrotoxicosis without hyperthyroidism: Etiology Table: Thyrotoxicosis due to hyperthyroidism Pathology […]
Thyroiditis
Etiology and Pathophysiology Thyroiditis, or inflammation of the thyroid gland, has multiple etiologies, including autoimmune conditions, infectious agents, and iatrogenic causes. Each causative condition has a specific pathologic mechanism. Table: Etiology and pathophysiology of thyroiditis Category Etiology Pathophysiology Autoimmune Hashimoto’s thyroiditis Associated with HLA-DR3, DR4, and DR5 Thyroid peroxidase (TPO) and thyroglobulin (Tg) antibodies destroy […]
Seborrheic Keratosis
Overview Definition Seborrheic keratosis (SK) is a benign skin tumor consisting of proliferating immature keratinocytes. Epidemiology Etiology Pathophysiology and Clinical Presentation Pathogenesis Morphology Histology Clinical presentation Diagnosis and Management Diagnosis Physical exam: Dermoscopy: Biopsy: Management Differential Diagnosis References
Hypoparathyroidism
Overview Definition Hypoparathyroidism is a condition associated with insufficient secretion of parathyroid hormone (PTH). Hypocalcemia and hyperphosphatemia are the pathognomonic biochemical features of hypoparathyroidism, and result directly from a lack of PTH action on the kidney. Epidemiology Etiology Pathophysiology and Clinical Presentation Pathophysiology Normal physiology of PTH: Effects of hypoparathyroidism: Clinical presentation Acute: Chronic: Diagnosis […]
Hyperparathyroidism
Overview Definition Hyperparathyroidism is a condition associated with elevated blood levels of parathyroid hormone (PTH). Etiology Epidemiology Pathophysiology Normal physiologic effects of PTH Pathophysiology Primary hyperparathyroidism: Secondary hyperparathyroidism: Tertiary hyperparathyroidism: Clinical Presentation Primary hyperparathyroidism (PH) Over 50% of patients are asymptomatic or present with nonspecific symptoms. Mnemonic for PH: Stones, bones, groans, and moans: Other […]