Non-urate chromogens in body fluids.

Compoundswhich interfere in the analytic determination of uric acid are referred to as “non-urate chromogens.”Ascorbic acid, when added to serum, causes a significant increase in apparent uric acid levels as determined by a carbonate-phosphotungstate method. The ratio of apparent urate to ascorbicacid is 1:3, a value in close agreement with that obtained for the ratio of labile non-urate chromogensto ascorbic acid in fresh plasma. Ascorbicacid, as well as most of the non-urate chromogens,can be eliminated by mild alkaline treatment prior to adding phosphotungsticacid. These results indicate that the major non-urate chromogenin the average serum is ascorbic acid. The nature of other non-urate chromogensin body fluids is reviewed.