Bilirubin in urine

Because only conjugated bihrubin is excreted in urine, its presence indicates conjugated hyperbilirubinemia. The most commonly used method for detecting bilirubin in urine involves the use of a dipstick impregnated with a diazo reagent. Dipstick methods can detect bilirubin concentrations as low as 0.5mg/dL. 

The Chemstrip and Multistix strips for bilirubin in urine are highly specific tests and have a low incidence of falsepositive results. However, medications that color the urine red or that give a red color in an acid medium, such as phenazopyridine, can produce a false-positive reading. Large quantities of ascorbic acid or of nitrite also worsen the detection limit of the test. In practice, bilirubin is rarely measured in urine. 

Bilirubin in urine can be detected by a diazotization reaction (e.g. the Ictotest marketed by Ames) or by its reaction with ferric chloride (Fouchet s test). 

A test for the detection of bilirubin in urine. It is based on the oxidation of bilirubin, by ferric chloride, to produce biliverdin, which can be seen as a green coloration. Various drugs, e.g. chlorpromazine, can interfere by producing a purple colour. 

A test for the detection of bilirubin in urine based on a diazoti-zation reaction... 

The commonest causes of obstructive (posthepatic) jaundice are cancer of the head of the pancreas and a gallstone lodged in the common bile duct. The presence of bilirubin in the urine is sometimes referred to as choluria—therefore, hepatitis and obstruction of the common bile duct cause choluric Jaundice, whereas the Jaundice of hemolytic anemia is referred to as acholuric. The laboratory results in patients with hepatitis are variable, depending on the extent of damage to parenchymal cells and the extent of micro-obstruction to bile ductules. Serum levels of ALT and AST are usually markedly elevated in hepatitis, whereas serum levels of alkaline phosphatase are elevated in obstructive liver disease. 

In jaundice secondary to hemolysis, the increased production of bilirubin leads to increased production of urobilinogen, which appears in the urine in large amounts. Bilirubin is not usually found in the urine in hemolytic jaundice (because unconjugated bihmbin does not pass into the urine), so that the combination of increased urobilinogen and absence of bihmbin is suggestive of hemolytic jaundice. Increased blood destruction from any cause brings about an increase in urine urobilinogen. 

Bilirubin The detection of even trace amounts of bilirubin in the urine is abnormal. 

The use of 3,4-dihydro-2.//-pyrido[l,2-a]pyrimidin-2-one 675 and its alkyl derivatives in test paper strips for the detection of bilirubin in body fluids, especially in urine, has been reported [83JAP(K)83/18168]. 

For many years, phototherapy has been the standard treatment of neonatal hyperbilirubinemia. The effectiveness of this form of therapy is based on the ability of photons of the appropriate wavelength to convert the intramolecularly H-bonded bilirubin IXa with its low solubility into photoisomers of bilirubin in which the normal Z,Z stereochemistry at the 4- and 15-positions is changed, resulting in photoisomers that are more water soluble. In addition, bilirubin can be converted into the cyclic lumirubin, which is soluble and can be excreted in the urine (Fig. 22-2). Photoproducts can also be excreted through the liver pathway without... 

Bilirubin digiucuronide is excreted from the liver via the bile into the intestine. Within the bowel, it is hydrolyzed, and the bilirubin is reduced to urobilinogen and stercobilinogen. These are excreted in urine as urobilin after reabsorption from the bowel, and in feces as stercobilin these pigments give urine and feces their characteristic colors. 

Q3 Signs of jaundice jaundice gives a yellowish colour to the skin and mucous membranes, usually easiest to see in the cornea. The yellow colour is due to the presence of breakdown products of haemoglobin such as bilirubin in tissues, which the liver usually removes from the blood. Jaundice is indicative of liver disease, obstruction of the bile ducts or haemolytic disease. Bilirubin stains not only the tissues but also all body fluids, including plasma and urine, and the patient s urine can become really dark. 

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