Quantitative Determination of Thiols and Disulphides in Urine by Means of Ellman's Reagent and Thiolated Sephadex and its Application in Cystinuria

Abstract

A method for quantitative determination of thiols and disulphides in urine by means of Ellman's reagent and thiolated Sephadex is described. The method is suitable as a routine method for the detection of cystinuria. The method was used to study the stability of cysteine in human urines at varying pH. In normal humans an increased excretion of thiols at the expense of disulphides was found in the urine at low pH. In order to inhibit spontaneous oxidation of cysteine, patients with cystinuria were given ammonium chloride to acidify the urine or had urine collected from the renal pelvis directly into hydrochloric acid through ureter catheterization. Despite these precautions the concentration of thiols in cystinuric urines was normal, whereas the concentration of disulphides was greatly increased.