Letters to the Editor Indian Pediatrics 2005; 42:1059-1060 |
Hereditary Methemoglobinemia in an Infant |
Hereditary or congenital forms of methe-moglobinemia are extremely rare(l) and may occur due to NADH-cytochrome b5 reductase deficiency or Hb M disorders. In view of rare reporting of this condition(2-4), we narrate our experience with an infant with congenital methemoglobinemia. A 10-month-old baby girl presented with history of fever, cough and respiratory distress for last five days. In the past five months she had similar attacks of respiratory distress twice, that was treated with oral medication. There was no history of any significant drug intake or exposure to well water. Birth, developmental and dietary history was non-contributory. There was history of consanguinity. Mother was married to her own maternal uncle. The baby had a bluish hue since birth, which used to increase during attack of respiratory distress. On examination she had raised temperature, mild respiratory distress and central cyanosis. She had rhonchi and crepts in both the lung fields but other systems were within normal limits. Her pulse-oximetry reading showed oxygen saturation was 85%, Arterial blood gas analysis showed PH 7.38, PaO2 82, PCO2 34, HCO3-24, SaO2 88%. Colour of blood was dark, which was noted during sampling. She had hemoglobin of 13 gmidL, TLC 16000/cmm, DLC-NeutrophiI 30, Lymphocyte 70, ESR-8 mm, PCV 44, and total erythrocyte count 4.6 × 1012cells/L. Chest X-ray and electrographic tracing and echo-cardiographic finding was normal. Hemoglobin electrophoresis and G6PD assay was also normal. Methemoglobin assayed by spectroscopic method was 38% (normal <1%.). Erythrocyte NADH-dependent methemoglobin reductase level was low with 30% of normal. HbM could not be estimated due to financial constraint. She was managed with oxygen inhalation, bronchodilator nebulisation, and oral antibiotics. The respiratory distress settled down after three days but cyanotic hue persisted even at discharge. She was put on oral ascorbic acid and discharged. Methemoglobin produces detectable cyanosis at concentration. Of 0.5 g/dL(1). In 1948 Horlein and Weber first described a family of hereditary methemoglobinemia in Germany(1). Scott & Griffith in the following year described deficiency of NADH-cytochrome b5 reductase enzyme as the cause of the disease(1). Our case is suffering from hereditary methemoglobinemia (Type l) due to NADH-cytochrome b5 reductase defici-ency. Hereditary methemoglobinemia patient generally maintains levels of methemoglobin between 15-30% of normal (1). Treatment is rarely necessary except for cosmetic purpose or with coexisting G6PD deficiency causing superadded acquired methemoglobinemia(5). R.K. Mondal, |
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