Bilirubin is formed in the reticuloendothelial cells of the spleen and bone marrow as a result of the breakdown of hemoglobin; it is then transported to the liver. Urinary bilirubin levels are increased to significant levels in the presence of any disease process that increases the amount of conjugated bilirubin in the bloodstream (see Chapter 6). Elevated amounts appear when the normal degradation cycle is disrupted by obstruction of the bile duct or when the integrity of the liver is damaged.
Urine bilirubin aids in the diagnosis and monitoring of treatment for hepatitis and liver damage. Urine bilirubin is an early sign of hepatocellular disease or intrahepatic or extrahepatic biliary obstruction. It should be a part of every UA because bilirubin often appears in the urine before other signs of liver dysfunction (e.g., jaundice, weakness) become apparent. Not only does the detection of urinary bilirubin provide an early indication of liver disease but also its presence or absence can be used in determining the cause of clinical jaundice.
Examine the urine within 1 hour of collection because urine bilirubin is unstable, especially when exposed to light. If the urine is yellow-green to brown, shake the urine. If a yellow-green foam develops, bilirubin is probably present. Bilirubin alters the surface tension and allows foam to form. The yellow color is the bilirubin.
Chemical strip testing
Dip a chemically reactive dipstick into the urine sample according to the manufacturer’s directions.
Close comparison of color changes on the dipstick with control colors on the color chart is an absolute necessity. Failure to make a close approximation of color may result in failure to recognize urine bilirubin. Good lighting is required.
Interpret results as “negative” to “3+” or as “small,” “moderate,” or “large” amounts of bilirubin.
When it is crucial to detect even very small amounts of bilirubin in the urine, as in the earliest phase of viral hepatitis, Ictotest® reagent tablets are preferred for testing because they are more sensitive to urine bilirubin. When elevated amounts of urine bilirubin are present, a blue to purple color forms on the absorptive mat. The intensity of the color and the rapidity of its development are directly proportional to the amount of bilirubin in the urine.
Even trace amounts of bilirubin are abnormal and warrant further investigation. Normally, there is no detectable bilirubin in the urine.
Increased bilirubin occurs in:
Hepatitis and liver diseases caused by infections or exposure to toxic agents (cirrhosis)
Obstructive biliary tract disease
Liver or biliary tract tumors
Septicemia
Hyperthyroidism
Urine bilirubin is negative in hemolytic disease.
Pretest Patient Care
Explain purpose of test, procedure for urine collection, and interfering factors.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Posttest Patient Care
Review test results; report and record findings. Modify the nursing care plan as needed. Monitor appropriately for liver disease.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.
Drugs may cause false-positive or false-negative results (see Appendix E).
Bilirubin rapidly decomposes when exposed to light; therefore, urine should be tested immediately.
High concentrations of ascorbic acid or nitrate cause decreased sensitivity.
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