Other Urine Tests
There are many other urinary constituents that are measured to establish a diagnosis or to monitor treatment. Many of these tests require a 24-hour sample. Some require a blood sample comparison.
Urine bilirubin: When hemoglobin breaks down, bilirubin is formed in the reticuloendothelial cells of the spleen and bone marrow, and transported to the liver. Urine bilirubin aids in the diagnosis and monitoring of treatment for hepatitis and liver dysfunction. Urine bilirubin is an early sign of hepatocellular disease or biliary obstruction. Urine bilirubin is an important part of a UA because bilirubin may often appear in the urine before other signs of liver dysfunction become apparent. Normal values are negative to 0.02 mg/dl. Even trace amounts of bilirubin are abnormal and warrant further investigation. Increased levels occur in hepatitis and liver disease caused by infections or exposure to toxic agents and obstructive biliary tract disease.
Addis count: The Addis count is a quantitative measurement of red blood cells, white blood cells, and casts in a 12-hour overnight urine specimen. Protein and specific gravity may also be included. Fluids may be restricted before the test so that urine will be concentrated. The Addis test is used to evaluate the course of renal disease by comparing results over time.
Urinary porphyrins: Porphobilinogen, coproporphyrions, and uroporphyrins are produced in the synthesis of heme, which is part of hemoglobin and several enzymes. Abnormalities of porphyrin metabolism may be either genetic or caused by drug intoxication, usually from lead. Because the porphyrins are precursors of the heme pigment, the urine may be burgundy color when exposed to light. Elevations of these tests are used to diagnose one of many forms of acute or chronic porphyria.
Delta-aminolevulinic acid: Used to diagnose lead poisoning. Delta-aminolevulinic acid is an enzyme that is needed for the proper conversion to porphobilinogen in the metabolic formation of heme.
Urinary 5-Hydroxyindoleacetic acid: Used to diagnose carcinoid tumors. Glands in the gastrointestinal tract secrete the hormone serotonin. Serotonin is a vasoconstrictor that is especially useful to small arterioles after tissue injury. It also regulates smooth muscle contraction, such as in peristalsis. The chief metabolite of serotonin, excreted in the urine, is 5-hydroxyindoleacetic acid (5-HIAA). Measuring the serotonin metabolite 5-HIAA in the urine may help in diagnosis of certain gastrointestinal tumors called carcinoid tumors.
Urine hemoglobin: Free hemoglobin in the urine is referred to as hemoglobinuria. This finding is usually related to a condition outside the urinary tract and occurs when there is such extensive or rapid destruction (hemolysis) of red blood cells that the reticuloendothelial system cannot metabolize or store the excess free hemoglobin. Blood may appear in the urine as intact red cells or as free hemoglobin. When intact red cells are present in the urine, the term hematuria is used to indicate bleeding somewhere in the urinary tract.
Hematuria is found in:
Hemoglobinuria is found in:
Urine Bence Jones proteins: Bence Jones proteins are free unattached light protein chains that may be found in either serum or urine. They appear in the urine in multiple myeloma, lymphoma, leukemia, osteogenic sarcoma, and other malignancies.
Urine urobilinogen: Bilirubin is formed from the breakdown of hemoglobin. Bilirubin enters the intestine in the bile where it is transformed through the action of bacterial enzymes into urobilinogen. Some of the urobilinogen formed in the intestine is excreted as part of the feces. Another portion is absorbed into the portal circulation and carried to the liver, where it is metabolized and excreted in the bile. Traces of urobilinogen in the blood that escape removal by the liver are carried to the kidneys and excreted in the urine. Urine urobilinogen is one of the most sensitive tests available to detect liver dysfunction. Urinary urobilinogen is increased by any condition that causes an increase in the production of bilirubin and by any condition that prevents the liver from removing the normally reabsorbed urobilinogen from the portal circulation.
Urine beta-2 Microglobin: Used to diagnose inflammatory conditions and chronic lymphocytic leukemia.
Urine chlorides: Used diagnose dehydration, to guide in adjusting fluid and electrolyte balance, or to help monitor the effects of reduced salt diets.
Urine sodium and potassium: Used to diagnose renal, adrenal, water, and acid-base imbalances.
Uric acid: Used to evaluate uric acid metabolism in gout and renal calculus formation, to diagnose genetic abnormalities, and to evaluate nephrolithiasis.
Urine calcium: Used to assess parathyroid gland dysfunction. The parathyroid glands help maintain balance between body calcium and phosphorus via the secretion of parathyroid hormone.
Urine magnesium: Used to evaluate magnesium metabolism, to investigate electrolyte status, and to evaluate nephrolithiasis.
Urine oxalate: Used to assess the potential for renal stones in patients with surgical loss of the distal small intestine, such as those with Crohn's disease. The incidence of nephrolithiasis in patients with inflammatory bowel disease is approximately 2 to 10%. Increases in urine oxalate and potential formation of renal stones are also an important consideration in morbidly obese patients who have had a jejunoileal bypass.
Urine follicle-stimulating hormone (FSH) and luteinizing hormone (LH): Measure gonadotrophic hormone functioning. Measurement of LSH and LH may help determine whether a gonadal deficiency is of primary origin or due to insufficient stimulation by the pituitary gland. Evaluation of FSH is used along with other endocrine studies to determine the cause of hypothyroidism in women and endocrine dysfunction in men. Urine assays are also used to monitor ovulatory cycles of in-vitro fertilization patients.
Urine pregnanediol: Measures ovarian and placental function.
Urine pregnanetriol: Used to diagnose adrenocortical dysfunction and adrenogenital syndromes.
Urine vanillylmandelic acid: Used to evaluate the presence of pheochromocytoma, a tumor of the adrenal medulla.
Urine 17-Ketosteroids: Used to measure the urinary excretion of steroids and to help diagnose endocrine disorders involving adrenal androgens.
Urine amylase excretion/clearance: Used to differentiate acute pancreatitis from other causes of abdominal pain.
Urine phenylketonuria (PKU): Used, along with blood tests, to detect phenylketonuria (PKU) in newborns. PKU is a genetic disease that if left untreated, leads to mental retardation and brain damage.
Urine tubular phosphate reabsorption: Used to detect hyperparathyroidism.
Urine hydroxyproline: Used to assess the degree of bone and collagen reabsorption in various disorders, and to evaluate the degree of destruction from primary or secondary bone tumors. Also used to measure the severity and response to treatment of Paget's disease of the bone.
Urine lysozymes: Used to differentiate acute myelogenous or monocytic leukemia from acute lymphocytic leukemia.
Urine pregnancy tests: Used to confirm pregnancy.
Urine estrogens: Used to evaluate female menstrual and fertility problems. In males, used to diagnose estrogen-producing tumors.
Urine amino acids: Used as an initial screening test for inborn errors of metabolism in cases of suspected genetic abnormalities, such as mental retardation, reduced growth, etc.
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