Occurrence of Cystine in Sweat of Cystinurics.

Abstract

In 1871, Dewar and Gamgee 1 stated that, in some cases, cystine was present in the sweat of cystinurics, apparently basing their conclusions largely upon the observation that, in cases where cystine was present in the urine, silver coins carried in the pocket were observed rapidly to become blackened. Garrod, 2 however, was unable to obtain evidence of the presence of cystine in the sweat in the one case studied by him.

We have had under observation a cystinuric whose daily cystine excretion (determined by the colorimetric method of Folin and Looney) varied from 1.0 to 1.8 gm., whose urine frequently contained large amounts of cystine crystals, and who occasionally passed cystine calculi. From this patient we collected by the use of pilocarpine and heat, 100 cc. of sweat in 50 minutes. ∗ No cystine could be detected by the colorimetric method of Folin and Looney. 35 cc. of sweat were deproteinized by the use of heat and alumina cream and the filtrate was evaporated to dryness. The residue was extracted with dilute ammonium hydroxide and the extract treated with acetic acid. No cystine crystals were observed microscopically. Wollaston's test (formation of cystine hydrochloride crystals) was also negative.