538 UNIT VIII RENAL AND UROLOGICAL DISORDERS
Diagnosis Renal function can be evaluated through examination of the urine and blood. Imaging studies can be per- formed to evaluate the anatomy of the kidneys and renal blood flow and visualize renal calculi, tumors, or cysts. Urinalysis Urinalysis is a basic examination of urine that includes a description of the character of the urine, as well as bio- chemical and microscopic analysis. Normally, urine is odorless and clear or slightly hazy with a color ranging from yellow to amber. The color varies according to the concentration of solutes and water content of the urine. For example, a dehydrated person has amber-colored urine, whereas a well-hydrated person has light yellow urine, although urine color can vary with some medica- tions or certain disorders. For example, hepatitis will cause a dark-brown, tea-colored urine caused by bile pigments. Reagent strips, also called dipsticks, are used for analysis of the urine. Urinary pH should be close to a neutral pH of 7, but it does vary from acidic to basic. The specific gravity should be between 1.001 when dilute and 1.030 when highly concentrated. All of the biochemical tests that are measured by reagent strips should be negative in healthy individuals. If any of these tests are positive, they are suggestive of a variety of illness states (see Table 22-1). The presence of glucose and ketones is indicative of diabetic ketoacidosis. Leukocyte esterase measures the amount of enzyme secreted by white blood cells (WBCs); a high amount (positive result) is indicative of either a bladder or kidney infection. Crystals are often seen in the urine of patients with renal calculi. Casts are substances that are secreted into the nephron tubules and retain the shape of the tubules. They are
12th rib
Left kidney
Right kidney
Costovertebral angle
FIGURE 22-4. The kidney is located in the costovertebral angle (CVA) region. In physical examination, the examiner should firmly tap the CVA to assess its pain of kidney disorder. The pain of nephrolithiasis and pyelonephritis is commonly in the CVA region.
Proteinuria, also called microalbuminuria, indi- cates that the urine contains proteins. Normal total protein excretion does not usually exceed more than 150 mg/day. Excess protein in the urine is abnormal and is usually an indication of glomerular injury. The glomerular capillaries should not filter out blood pro- teins; however, when injured, they develop excessive permeability that allows escape of albumin into the nephron tubule. Glomerular injury can occur in such disorders as glomerulonephritis, DM, and HTN.
TABLE 22-1. Urine Analysis Using Reagent Strips
Test
Normal Value
Common Etiology
Glucose
Negative
If positive: hyperglycemia, diabetes
Ketones
Negative
If positive: starvation or diabetic ketoacidosis
Protein
Negative or trace
Minimal: exercise or infection Moderate: polycystic kidney disease (PKD), infection, heart failure, diabetic kidney disease Marked: PKD, glomerulonephritis, diabetic kidney disease, nephrosis, lupus nephritis
Blood
Negative
If positive: infection, kidney stone, or bladder cancer
Bilirubin
Negative
If positive: hemolysis or liver disease
Urobilinogen
Minimal
If high: liver disease
Nitrite
Negative
If positive: urinary tract infection
Leukocyte esterase
Negative
If positive: urinary tract infection
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