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Clinical Summary

Although a urinalysis gives definitive microscopic clues to the presence of disease, gross appearance can provide useful clues prior to formal urinalysis results. Color, clarity, odor, and associated pain give insight to the presence of disease. Normal urine appearance ranges from transparent yellow to dark amber, which is due to urobilin, a bile pigment of hemoglobin. Dark urine (see Fig. 25.50) may be due to dehydration or high concentrations of bilirubin in the blood. Deep red or brown urine may suggest porphyria. Other causes of red urine include myoglobinuria due to hemolysis from brown recluse envenomation (see Fig. 25.51), rhabdomyolysis (see Fig. 25.52), hematuria from cancer (see Fig. 25.53), ureteral stones, clotting disorders, recent genitourinary surgery, urinary tract infection, sexually transmitted infection, or falsely present in females during menses. Blackberries, beets, rhubarb, rifampin, phenazopyridine, and senna can turn urine a red-orange color. Food dyes, methylene blue, indomethacin, and propofol may turn urine blue-green.

FIGURE 25.50

Urinalysis—Dehydration. Dark transparent urine suggests dehydration in the correct clinical context. Dehydration was confirmed with formal urinalysis. (Photo contributor: Lawrence B. Stack, MD.)

FIGURE 25.51

Urine—Hemolysis due to Systemic Loxoscelism. Gross sample of hemoglobinuria as a result of an acute hemolysis seen in systemic loxoscelism after brown recluse spider bite. (Photo contributor: Lawrence B. Stack, MD.)

FIGURE 25.52

Urine—Rhabdomyolysis. Gross sample of cola-colored urine in a patient during resuscitation after rhabdomyolysis due to a crush injury of the leg.

FIGURE 25.53

Urine—Gross Hematuria. Spontaneous gross hematuria after initiation of apixaban. Patient was later found to have bladder cancer. (Photo contributor: Lawrence B. Stack, MD.)

Cloudy or turbid-appearing urine (see Fig. 25.54) is likely due to urinary tract infections or ureteral stones.

FIGURE 25.54

Urine—Urinary Tract Infection. Turbid or cloudy urine suggests infection, dehydration, or hematuria. Microscopic examination of this urine revealed too numerous to count white blood cells suggestive of a urinary tract infection. (Photo contributor: Lawrence B. Stack, MD.)

Management and Disposition

Management varies depending on the cause of the urine discoloration. Intravenous fluids for dehydration, forced diuresis for rhabdomyolysis, ICU admission to observe for ongoing hemolysis in brown recluse envenomations, CT scan to search for ureteral stones or cancer, and cystoscopy may be needed. Antibiotics are needed for urinary tract infections and sexually transmitted infections. An irrigation Foley catheter should be placed if blood clots are present and causing bladder outlet obstruction.

Pearls

  1. Urobilin is the ...

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