Procedure Renal Physiology

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Analysis of urine can yield valuable information about the health of the kidney and of the body in general. Various diseases are characterized by abnormal metabolism, which causes abnormal by-products of metabolism to appear in the urine. For example, in individuals with phenylketonuria (PKU), phenylpyruvic acid appears in the urine as a result of an autosomal recessive generic disorder characterize by a deficiency in the enzyme hepatic phenylalanine hydrolase (PAH). This enzyme is necessary to metabolize the amino acid phenylalanine into phenylpyruvate. Left untreated, this disease results in mental retardation. In diabetes mellitus, deficient production of insulin (type one) by the pancreas or insulin insensitivity (type two) results in the appearance of glucose in the urine (glycosuria). The volume of urine produced and its specific gravity give information about the state of hydration or dehydration of the body.

In the following activity, you will analyze your own urine or a provided sample of some for its clinical important constituents.

Specific gravity

- Using the urine from the first activity place enough urine into the urinometer cylinder to fill to just about 1 inch below the lip.

- Holding the urinometer flat by the stem slowly insert it into the cylinder. DO NOT WET THE STEM ABOVE THE WATER LINE, or an inaccurate reading will occur.

- Give the urinometer a slight swirl and read the specific gravity on the stem as it comes to rest. Be sure to capture the reading before the stem comes to rest on the side of the cylinder.

- Remove the urinometer and rinse with water then dry it. Measure the temperature of the urine immediately.

- Return the urine sample to the collection bottle and clean and dry the cylinder and thermometer.

- The urinometer is calibrated to give a correct reading only if the urine is at 15°C. If your urine is at a different temperature correct the specific gravity by adding 0.001 for each 3°C above 15°C or by subtracting 0.001 for each 3°C below 15°C.

The normal range of urine specific gravity is 1.0015 o 1.035. Readings above or below these limits may indicate a pathological condition. For example, a low reading is found in chronic nephritis.

Urinalysis by Urine Dip Test

Advances in urinalysis techniques have made it possible to perform, in a few seconds, tests that previously took hours. The test strips today can measure urinary pH, protein, glucose, ketones, and occult blood. Abnormally low pH, along with a high level of glucose and ketones, indicates diabetes mellitus. Alkaline urine is found in a number of conditions, for example cystitis, in which urine decomposes in the bladder with the production of ammonia. Urinary pH usually is slightly acidic (around pH 6), but the pH may be lowered by a diet rich in proteins or citrus fruits, so pH alone is not very informative. Protein and occult blood in the urine are much more definitive, indicating nephritis, a disease in which the glomeruli are damaged and plasma proteins and erythrocytes leak into the kidney tubules.

- Obtain a test strip and a bottle with reference color indicators. Read the bottle for assistance in correctly determining the test order on the strip.

- When ready dip the test strip into the urine coating all the reagent pads.

- Follow the on bottle instructions for times to read each test.