Uridrosis

URIDROSIS, heavy excretion of urea and uric acid through the skin, encountered sometimes in uremic, respectively renal, patients, in eclampsia, cholera, and other diseases. The greater part of the solid substances of sweat consists of carbamide. With intensive sweating, the excretion of nitrogen plays a significant role in nitrogen metabolism, especially with insufficient kidney function. In untidy subjects who do not care about removing sweat, the urea and uric acid contained in the sweat are precipitated on the skin in the form of fine microscopic crystals, silvery-shining leaflets or grains, easily determined by chemical analysis (formation of nitric acid or oxalic acid urea upon the addition of nitric or oxalic acid). On hairy areas (on the eyebrows, the scalp), the skin becomes covered with a white, frost-like layer. Less frequently, uridrosis is observed on the neck, chest, and extremities, and as a very rare exception, it is also encountered on the mucous membrane of the oral cavity and pharynx. On the hair of the armpit, the deposition of urea crystals gives them a reddish-orange color. According to the studies of Toniyan, the content of urea and uric acid in sweat is especially increased in individuals suffering from pruritus, with a simultaneous decrease of these substances in the urine, whereupon after the healing of the process, the qualitative change of sweat returns to normal. In order to clarify the question of whether sweat glands take part in the excretion of carbamide, Melczer, inducing intensive sweating with the aid of pilocarpine, injected intravenously a 4% solution of carbamide for this purpose. 20 minutes later, he excised a piece of skin in the region of the sole. At the same time, it turned out that part of the injected carbamide, as a result of diffusion from the connective tissue elements of the skin, penetrated into the system of juice channels of the epidermis and from there directly through the excretory ducts of the sweat glands penetrated to the surface of the skin. Histologically, it was possible to establish the presence of carbamide grains in the intercellular clefts of the epidermis and in the epithelium of the sweat glands. The causes of this anomaly are of a twofold nature: internal (uric acid diathesis, abnormal structure of the vascular system) and external (microorganisms, non-observance of cleanliness and hygiene). Treatment is symptomatic: elimination of causative factors, frequent change of linen, soapy washings, dusting powders with disinfecting agents. Lit.: Toniyan V., On the question of the composition of sweat in pruritus cutaneus, Rus. vestn. derm., 1928, № 2; Mayr J., Die Erkrankungen des Schweissdrüsen (Handbuch der Haut- und Geschlechtskrankheiten, herausgegeben v. J. Jadassohn, B. XXX, B., 1932); Melczer N., Untersuchungen über die Ausscheidung der harnsauren Salze durch die Schweissdrüsen, Arch. f. Derm. u. Syph., B. CL, H. 2, 1926.