A test for bile salts in urine.

Abstract

A search through the text books of physiological chemistry reveals two tests that are used for the detection of bile salts in urine. One is the Pettenkofer reaction which depends on the production of a red coloration when a strong acid, furfural, and bile salts are mixed. The other, the Hay test, depends on surface tension change due to the bile salts. Because of difficulty in eliminating the urinary pigments, the Pettenkofer test has not been adapted for use as a quantitative test. Recently Meyer 1 has devised a method for quantitating the bile salts in urine dependent on surface tension changes.

The following method can be used as a qualitative test with relatively simple apparatus. (For the quantitation of the bile salts a nephelometer is needed.) It is as follows: Thirty cc. of urine to be tested is mixed with thirty cc. of 95 per cent alcohol. One cc. of 25 per cent trichloracetic acid is added together with a small quantity of charcoal. This mixture is boiled and then filtered. The charcoal remaining on the filter paper is washed with hot alcohol. The combined filtrate is made alkaline with sodium hydroxide and then evaporated to a volume of less than 15 cc. After cooling, the volume is made up to exactly 15 cc. and the fluid is then filtered. To five cc. of this slightly alkaline filtrate is added five cc. of normal sulfuric acid. To another five cc. is added five cc. of distilled water. After standing five minutes the tubes are compared in a beam of strong light. A cloudiness in the tube to which acid has been added indicates the presence of bile salts.