urobilin
Noun: 1. A brown bile pigment: Urobilin is a brownish-yellow biological pigment formed in the intestines by the bacterial breakdown of bilirubin. It is a final product in the breakdown of heme from red blood cells. 2. A waste product found in excreta: It is primarily excreted in feces, giving them their characteristic color, and is found in small, trace amounts in normal urine.
Urobilin is a scientific/medical term used specifically in the contexts of physiology, biochemistry, and clinical diagnostics. * The presence of urobilin in urine is a normal finding in small quantities. * An absence of urobilin in feces can indicate a bile duct obstruction. * Laboratory tests can measure urobilin levels to help assess liver function and hemolytic conditions.
- In a physiology textbook: "The characteristic brown color of feces is due to the presence of urobilin."
- In a medical report: "The urinalysis showed a normal trace amount of urobilin."
- In a diagnostic context: "Elevated urobilin in the urine may suggest increased red blood cell destruction."
- Urobilinogen: This is the colorless precursor molecule to urobilin. In clinical tests, urobilinogen is often measured in urine. It is oxidized in air to form urobilin.
- Example: "The test strip checks for the presence of urobilinogen, which converts to urobilin."
- Urobilinogen (noun): The colorless compound produced by the reduction of bilirubin by intestinal bacteria; it is absorbed into the bloodstream and later excreted, with some being converted to urobilin.
- Stercobilin (noun): A chemical very similar to urobilin and often considered the major form found in feces; it is responsible for the brown color.
- Bilirubin (noun): The orange-yellow pigment formed by the breakdown of heme; it is metabolized in the liver and intestines to form urobilinogen and subsequently urobilin.
- Bile pigment: This is a broader category to which urobilin belongs.
- Fecal pigment: A descriptive term highlighting its primary location.
The term "urobilin" specifically refers to the oxidized, colored end-product. Its detection and quantity are important indicators in medicine: 1. Normal Function: Trace amounts in urine and significant amounts in feces indicate normal heme breakdown and biliary excretion. 2. Abnormal Findings: * Increased urine urobilin: Can be a sign of conditions where red blood cells are destroyed faster than normal (hemolysis) or liver damage. * Decreased or absent fecal urobilin: Can indicate a blockage in the bile ducts, preventing bilirubin from reaching the intestines.
- brown bile pigment formed from urobilinogens and found in feces and in small amounts in urine