Urinalysis, Renal Clearance, and Physical Characteristics of Urine (Nursing)

00:01 So now let's look at how we evaluate the kidneys clinically.

00:06 In order to look for signs of disease, we use what's known as a urinalysis, it can also be used to test for illegal substances.

00:17 Assessing renal function is going to require both blood and urine examination.

00:23 For example, renal of function can be assessed by measuring the nitrogenous waste that are found in the blood that should have been excreted.

00:33 To determine renal clearance, we also look at both the blood and the urine.

00:39 Renal clearance is the volume of plasma that kidneys can clear of a particular substance in a given time.

00:47 I'm are renal clearance tests are going to be used to determine our glomerular filtration rate and also help to detect glomerular damage as well as follow the progress of renal diseases.

01:02 We measure the renal clearance rate as the concentration of substance in urine times the flow rate of the urine formation divided by the concentration of substances that remain in the plasma.

01:19 We can use certain substances to measure the glomerular filtration rate.

01:24 So that kidney function can be assessed.

01:27 One of those substances is inulin not to be confused with insulin.

01:32 Inulin is a plant polysaccharide and is a standard used for measuring the glomerular filtration rate.

01:40 It is freely filtered, but neither reabsorbed nor secreted by the kidneys.

01:47 The renal clearance of inulin should be 125 milliliters per minute, which is are pretty much our standard glomerular filtration rate.

02:00 So knowing that the glomerular filtration rate should be around a 125 milliliters per minute, If the clearance rate or the renal clearance is less than a 125 milliliters per minute that we know that the substance must have been reabsorbed.

02:18 If our renal clearance is zero, then that means that the substance was completely reabsorbed and not filtered.

02:27 If the clearance rate is going to be a 125 milliliters per minute.

02:33 Then that means that there was no reabsorption or secretion which is what you see with inulin.

02:39 If the clearance rate is actually a 125 milliliters per minute or more.

02:45 This means that the substance is being secreted.

02:49 This is the case for most drug metabolites.

02:54 So if we look at the chemical composition of the urine we find that is made up of mostly nitrogenous waste like urea, uric acid and creatinine which is going to be a metabolite of creatine phosphate from our muscles.

03:12 Other solutes found includes sodium, potassium, phosphate, sulfate, calcium, magnesium, and bicarbonate.

03:21 Any abnormally h igh concentration of any of these or abnormal components such as blood proteins or white blood cells are bile pigments found in the urine can indicate some type of disease or pathology.

03:39 For example, an abnormal amount of glucose is referred to as glycosuria.

03:46 And a normal amount of proteins can be protonuria and if it is an normal amount of albumin, albuminuria, Ketone bodies can lead to ketonuria.

03:59 The presence of hemoglobin can lead to hemoglobinuria, bio pigments are known as bilirubinuria area the presence of erythrocytes is hematuria.

04:11 And finally the presence of white blood cells or leukocytes is pyuria.

04:18 We can also look at the physical characteristics of our urine in order to assess kidney function.

04:25 Normally the urine can be clear and a cloudy urine is going to indicate some type of urinary tract infection.

04:35 The color is that pale too deep yellow due to the chemical urochrome found in the urine.

04:42 This pigment comes from the breakdown of hemoglobin and the yellow color is to deepen with the increased concentration of the urine.

04:52 So a pale urine is less concentrated and a deep yellow urine is more concentrated.

04:59 And abnormal color of the urine such as a pink urine, a brown urine, or a smoky color can be caused by certain foods.

05:08 The presence of bile pigments, the presence of blood, or can sometimes be changed due to certain drugs.

05:17 The odor of the urine should be slightly aromatic when fresh.

05:22 This develops an ammonia odor over time as the bacteria is able to metabolize the urea.

05:30 The odor can be altered by some drugs and also altered by some vegetables.

05:36 For example, some people have a characteristic urine odor when they eat asparagus.

05:42 Disease can also alter the smell of urine and sometimes patients with diabetes have a lot of acetone in their urine which gives it a fruity smell.

05:55 The pH of the urine is slightly acidic but it actually is different depending on people's diets.

06:02 For example, if you eat a lot of meat and protein you have more of an acidic diet because you have lots of amino acids in your diet.

06:11 This can cause the urine pH to drop and become a little bit more acidic.

06:16 Vegetarians, however, have a very alkaline diet.

06:20 And so this is going to actually cause the pH to go up.

06:24 Also things like prolonged vomiting or certain urinary tract infections can also cause an increase in the pH of the urine.

06:35 Another measure or physical characteristic of our urine is specific gravity.

06:40 This is the ratio of the mass of substance to the mass of equal volume of water.

06:47 This ranges from about 1.001 to 1.035 because urine is made up of both water and solutes.

06:56 Usually a higher specific gravity can indicate that something is wrong.