Endogenous methemoglobinemia associated with diarrheal disease in infancy.

Infantile diarrhea is sometimes associated with methemoglobinemia. To determine the significance of intestinal bacterial infection or overgrowth and other predisposing factors in this entity, we evaluated prospectively 45 consecutive patients who were admitted for gastroenteritis and methemoglobinemia between March 1980 and September 1992. All the patients were younger than 3 months of age. In 95% of them, methemoglobinemia occurred between the ages of 15 days to 2 months. The peak mean methemoglobin concentration was 9.4% (range, 2.4-57%). Although stool cultures were positive in only 22% of the infants, the epidemiologic data strongly suggested a bacterial or viral etiology in our study population: for 12 years, there was a significant decrease in the annual incidence of methemoglobinemia associated with diarrhea in parallel to the decrease in infantile diarrhea due to known pathogens throughout the country in the same period. There was also a marked seasonal variation in the incidence of the disease, with two peaks in January and the summer months when viral and bacterial infections, respectively, are prevalent. Failure to thrive and low admission-weight percentiles were associated with methemoglobinemia in most of the patients and diarrhea lasting > or = 7 days in 22 (49%) patients. The blood pH and the degree of acidosis did not correlate with the severity of methemoglobinemia. All the patients were formula fed. In the etiology of methemoglobinemia in infants with enteritis, viral and bacterial pathogens appear to play an important role by altering intestinal flora. Breast feeding appears to protect against this entity.