Further Studies on Metabolism of Sulfur Compounds in Cystinuria.*

Abstract

∗Aided by Grant No. 302 from the Committee on Scientific Research of the American Medical Association.Some recent experiments1,2 on sulfur metabolism have been confirmed on another case of cystinuria (16-year-old female from a cystinuric family). Cystine (6.4 gm.), administered orally was almost completely (98%) oxidized to inorganic sulfate and did not increase urinary cystine excretion. Cysteine (3.5 gm.), on the other hand, was largely excreted as extra cystine (45%) and only a part of it was oxidized (38% of the extra sulfur). Methionine (dl, 6 gm.) was also largely excreted as extra cystine (40%) and partly (35%) as undetermined neutral sulfur,† while only a small amount (25% of the extra sulfur) was oxidized.A preliminary experiment with 2.5 gm. of homocystine3 indicates that in cystinuria this amino acid is oxidized (92% of the extra sulfur) and does not give rise to extra cystine in the urine. The implications of this finding will be discussed upon completion of confirmatory experiments now in pro...