[Cyanosis in children caused by inherited methemoglobinemia due to deficiency of NADH-dependent methemoglobin reductase in erythrocytes].

Two cases of the congenital methemoglobinemia in children due to the deficiency of NADH-dependent methemoglobin reductase in erythrocytes. These children were referred to the Cardiological Ward at the Child Health Centre with suspected cyanotic heart defect. Cardiological examinations excluded heart defect but an increased blood methemoglobin level and decreased activity of NADH-dependent methemoglobin reductase were found, that caused methemoglobinemia. Methylene blue and vitamin C diminished cyanosis. These cases advocate inclusion of methemoglobinemia into differential diagnosis of cyanotic disorders especially if there is no evident pathology in cardio-vascular system.