[Cyanosis as a result of drug-induced methemoglobinemia. A case report].

A 39-old, anaemic woman, admitted to hospital because of a fistula between bladder and bowel, developed a moderate degree of methaemoglobinaemia (19% of total haemoglobin) after prescription of 3 X 200 mg/die phenazopyridine (Pyridium) for 4 weeks. She showed a greyish discoloration of the skin; lips and nailbeds were cyanosed. On the basis of a glucose-6ph-dehydrogenase deficiency (71 mU/10(9) RBCs instead of 131 +/- 13 mU/10(9) RBCs - the normal value for adults) the medication with phenazopyridine induced methaemoglobinaemia. The coincidence of anaemia (8.7 g/dl Hb) and methaemoglobinaemia (19%) caused mild signs of hypoxia (fatigue, headache, feebleness and dyspnoea on exertion).