The urine Indican test is also called an Obermeyer test, which is an indicator of intestinal toxemia and overgrowth of anaerobic bacteria. Indican is an indole produced when bacteria in the intestine act on the amino acid, tryptophan. Most indoles are excreted in the feces. The remainder is absorbed, metabolized by the liver, and excreted as indican in the urine.
Normally, only a small amount of indican is found in the urine. The amount of urine indican increases with high protein diets or inefficient protein digestion. If protein is not digested adequately, bacteria act on the protein causing putrefaction in the colon and the production of indoles, which are absorbed and converted in the liver to Indican. Conditions that lead to excess urine Indican include:
Maldigestion and/or malabsorption of protein
Hypochlorhydria (insufficient stomach acid; use of antacids or H2 blockers)
Insufficient digestive enzymes (proteases such as trypsin, pepsin, chymotrypsin)
Malabsorption syndromes (sprue, Hartnup disease, a rare disorder in which amino acids are poorly absorbed from the intestine, etc.)
Bacterial overgrowth in the small and/or large intestine
concurrent intestinal parasitic infections
concurrent intestinal fungal infection
The inability to digest protein can have adverse affects on glycemic control, hormone balance and water balance.
(Obermeyer test – Indoxyl Sulfate)
Following absorption, indole is converted to 3-hydroxy indole (indoxyl potassium sulfate and indoxyl glucuronate), which are termed indicans, in the liver.
Indole (oxidized) ® indoxyl + H2O2 ® indoxyl sulfuric acid K + indoxyl potassium sulfate (indican)
Specimen requirements: No special patient preparation required. If the assay is not run immediately, place sample in labeled plastic tube and freeze.
Detection of indican in the urine depends upon its decomposition and subsequent oxidation of indoxyl to indigo blue and its absorption into a chloroform layer. The resulting color is visually compared to a color chart and graded as follows:
Negative (Normal) = Clear or blue tinge
1+ (Slightly Positive) = Slight blue, yellow, mint green
2+ (Positive) = Dark blue, light green, golden brown
3+ (High Positive) = Violet, indigo, dark brown
4+ (Very High Positive) = Jet black
Todd J: Clinical Diagnosis and Management by Laboratory Methods. WB Saunders, Phil, Pa pp 592-3
Greenberger N, Saegh S, and Ruppert R: Urine indican excretion in malabsorption disorders. Gastroenterol 55:204-11, 1968
Curzon G and Walsh J: Value of measuring urinary indicant excretion. Gut 7:711, 1966
Asatoor A, London D, Craske J, and Milne M: Indole production in Hartnup’s disease. Lancet i:126-8, 1963.