Metabolism of Various Sulfur Compounds in Cystinuria. ∗ †

Abstract

A cystinuric patient was kept for a period of approximately 4 months on a standard meat free diet and his urine analyzed daily for various nitrogenous and sulfur constituents. In addition the cystine sulfur was determined by both the Folin and the Sullivan methods.

During experimental periods of 3 days each the following compounds were fed in the quantities indicated containing equivalent amounts of sulfur: cystine (6.4 gm.), glutathione (16 gm.), cysteine HCl (8.8 gm., neutralized) and dl-methionine (8 gm.). The experiments were carried out in triplicate except the one with glutathione which was repeated only once.

The results may be summarized as follows:

Cystine experiments showed that 94% of the extra sulfur was excreted as inorganic sulfate and that there was no rise in the excretion of cystine.

Glutathione experiments showed that 80% of the extra sulfur was excreted as inorganic sulfate and that there was a slight rise in the excretion of cystine which amounted to 9% of the extra sulfur.

Cystine experiments showed that only 34% of the extra sulfur were excreted as inorganic sulfate while there was a large increase in the excretion of cystine, continuing for several days after the feeding, which increase in cystine excretion accounted for 66% of the extra sulfur. The analyses also indicated that additional cystine and not cysteine was being excreted.

dl-Methionine experiments showed that only 34% of the extra sulfur was excreted as inorganic sulfate while there was a large increase in the excretion of cystine, continuing for several days after the feeding, which increase in cystine excretion amounted to 47% of the extra sulfur; there was also a definite increase in the excretion of undetermined (non-cystine) neutral sulfur which amounted to 19% of the extra sulfur. The analyses again indicated that additional cystine and not cysteine was being excreted.