ACQUIRED METHEMOGLOBINEMIA - THE RELATIONSHIP OF CAUSE TO COURSE OF ILLNESS

To better characterize methemoglobinemia in children, we reviewed the charts of 17 patients who were admitted to a children's hospital over the last 10 years. Two distinct groups were identified: (1) The endogenous group (n = 9) included patients with methemoglobinemia associated with an intercurrent illness. (2) The exogenous group (n = 8) included patients with methemoglobinemia secondary to drug exposure. Despite similar initial methemoglobin levels in the endogenous (mean, 29%) and exogenous (mean, 28%) groups, children in the endogenous group had more acidosis (serum bicarbonate levels of 5.9 vs 19.1 mmol/L and arterial pH of 7.01 vs 7.35). All the children in the exogenous group with methemoglobinemia secondary to an accidental ingestion stayed only 1 day in the hospital, while children in the endogenous group were admitted for an average of 19 days. Children with methemoglobinemia secondary to a drug exposure have a more benign illness with a shorter duration than children with methemoglobinemia associated with an intercurrent illness. It appears that the absolute level of methemoglobin is not as important as the underlying cause in determining both the course and severity of illness. © 1990, American Medical Association. All rights reserved.