METGEMOGLOBINURIYA (methaemoglobinuria; + Greek uron wetting a methemoglobin) — emergence of a methemoglobin in urine. The methemoglobin is formed as a result of oxidation of bivalent iron of prosthetic group hemoglobin (see) and its transformations into trivalent.
The m — a rare symptom, arises more often at acute intravascular hemolysis (see), proceeding with methemoglobinemia (see). The m is observed also at nek-ry hemolitic toxanemias, in particular at poisoning with pharmaceuticals (acetphenetidiene, codeine, phthiocol, etc.) and chemicals, napr, potassium chloride, aniline, nitrobenzene, nek-ry nitrites and nitrates (see. Hemolitic anemia ), at nek-ry forms of an acute intravascular hemolysis with haemoglobinuria (see).
At acid reaction of urine (e.g., at nek-ry poisonings) the methemoglobin is not allocated from an organism and besieged in renal tubules, causing their damage. Normal the methemoglobin in urine is absent; at its emergence urine gains dark color. Definition of concentration of a methemoglobin in urine is made a spectrophotometric method (see. Spektrofotometriya ).
M.'s forecast is defined by weight of a basic disease.
Bibliography: See bibliogr, to St. Methemoglobinemia .
Yu. N. Tokarev.