Determination of urinary cystine for monitoring anticystinuric therapy.
Cystine is assayed in urine by a method adapted from the procedure of Haux and Natelson (Clin Chem 1970;16:366-369) and modifications of the method, which improved its specificity, are presented. Assay imprecision (CV) at four different cystine concentrations (range: 0.042-1.658 mmol/l) varied from 23.1% to 3.7%. Analytical recovery was 94.6 +/- 6.0%. D-Penicillamine, alpha-mercaptopropionylglycine, L-glutamine and metabolites, added to urine, had negligible effect on the results of the cystine assay. Samples were stable for 3 wk when stored at 4 degrees C or frozen. Cystine excretion (mmol/24 h) in apparently healthy persons ranged from 0.041 to 0.170 (mean +/- SD: 0.099 +/- 0.039). Cystine excretions are presented in patients treated with anticystinuric drugs.
D000596:Amino Acids / Q000652:urine; D002855:Chromatography, Thin Layer; D003555:Cystinuria / Q000188:drug therapy / Q000652:urine*; D004355:Drug Stability; D006801:Humans; D008991:Monitoring, Physiologic; D010396:Penicillamine / Q000652:urine
D000596:Amino Acids; D010396:Penicillamine