From Big Medical Encyclopedia

MELANURIA (melanuria; melas, melanos black, dark + grech, uron wetting) — allocation with urine of a large number of a dark pigment — melanin. Fresh urine most often contains only predecessors of melanin, to-rye on air gradually are oxidized and pass in melanin (see), the dark-brown or black color giving to urine. Darkening of urine can be accelerated by addition of various oxidizers (chromic to - that, ferric chloride), at the same time melanin drops out in a deposit in the form of amorphous glybok.

Predecessors of melanin, reacting with n-dimethylaminobenzaldehyde (Ehrlich's reactant), and also with Sodium nitroprussidum, give specific blue coloring (so-called test of Tormelen).

The m is observed at the malignant tumors developing from pigment cells of skin, and also eye and a soft cover of a head and spinal cord (see. Melanoma ). Predecessors of melanin get to blood and urine from the breaking-up cells of a tumor therefore M. consider the late symptom indicating prevalence of process and damage of a liver. M.'s intensity decreases at treatment by cytostatic means and increases in the conditions of beam impact on a tumor. There are messages that for a melanoma, a coming from choroid of an eye, positive test of Tormelen is characteristic, i.e. M. are caused in this case by the indolcontaining predecessors of melanin.

M.'s identification can be helped by qualitative tests on melanin with hydrated baryta or acetic to - that and the concentrated solution of sodium bicarbonate therefore insoluble in acetic to - those melanin drops out in a deposit. The quantitative research M. is possible during the conducting test with potassium persulphate and methanol.

In a wedge, conditions to avoid false positive results and to achieve high sensitivity of a research, recommend to apply paper chromatography (see) and spektrofotometriya (see).

Darkening of urine on air is observed also at alkaptonurias (see), however in the presence of ammonia such urine gains red-violet color.

Bibliography: Gorzheysha Ya., etc. Fundamentals of clinical biochemistry in clinic of internal diseases, the lane with in., page 577, Prague, 1967; At l of e in and the p B. Analysis of urine, JI., 1945; Pigmental tumors, under the editorship of R. L. Ikonopisov, the lane with bolg., page 127, Sofia, 1977; Duchon J. Pechan Z. The biochemical and clinical significance of melanogenuria, Ann. N. Y. Acad. Sci., y. 100, p. 1048, 1963; Fitzpatrick T.B.a.Lemer A. B. Pigment and pigment tumors, biochemical basis of human melanin pigmentation, Arch. Derm. Syph. (Chic.), v. 69, p. 133, 1954, bibliogr.; R o-d yo I. Die klinischen und strahlenbiologi-schen Eigenschaften des Melanoblastoms, Budapest, 1962, Bibliogr.

S. S. Debov.