Mycoplasma pneumoniae infection is relatively common in childhood. Its extrapulmonary manifestations have been reported so much, but hepatitis associated with it has not been studied yet until now in Korea.

We performed the prospective study of 19 cases that had AST and ALT>50 IU/L respectively without evidence of hepatitis A, B, C, cytomegalovirus, and Ebstein-Barr virus infections amongst 143 patients with M. pneumoniae pneumonia who were admitted to the Department of Pediatrics, Seoul Red Cross Hospital from Jan. 1999 to Dec. 2000.

1) Hepatitis occurred in 13.3% of Mycoplasma pneumoniae infection, especially in fall and winter times. The average age was 4.86 years and male to female ratio was 2.2 : 1. 2) Vomiting was developed in 21.1%, diarrhea in 36.8%, and hepatomegaly in 21.1%, respectively. And leukocytosis was noted in 21.1%, eosinophilia in 15.4%, anemia in 10.5%, and thrombocytosis in 5.3%, respectively. The average level of C-reactive protein was 6.34±4.82 mg/dl. 3) There was no hyperbilirubinemia, but hypoalbuminemia was detected in 42.1%. The average serum levels of AST and ALT were 214.05±183.22 IU/L and 284.16±286.84 IU/L, respectively. 4) Chest radiology showed lobar or lobular consolidation in 73.7%, bronchial infiltration in 26.3%, and pleural effusion in 31.6%. 5) The average length of hospitalization was 7.9 days, and the average length of normalization of serum transaminases was 8.8 days. All patients recovered within 2 weeks completely.

The prognosis of M. pneumoniae hepatitis is good. However, its incidence is not so low that liver function should be considerately checked in case of M. pneumoniae infection.