[Liver dysfunction during treatment of latent tuberculosis infection]

The indications for treatment for latent tuberculosis infection were revised in 2007 to reflect that any subject with a higher risk of tuberculosis regardless of age should be treated. We worried about the incidence of liver dysfunction due to isoniazid (INH) in patients older than 30 yrs. of age. We evaluated the frequency of liver dysfunction due to INH according to age and discussed the possibility of its prevention.

We reviewed the clinical records of 99 patients younger than 29 yrs. and 229 patients older than 30 yrs. who were treated for latent tuberculosis infection from August 2007 to December 2008 at our clinic. The liver function tests (AST and ALT) were performed before the treatment, one and a half months after the start of the treatment, and almost every month during the treatment. We defined liver dysfunction as an AST and/or ALT greater than 100 IU/L.

Seven out of the 99 younger patients (7.1%) and 42 out of the 229 (18.3%) older patients developed liver dysfunction. The difference between the two age groups was statistically significant according to the chi-square test (p < 0.01). After the occurrence of liver dysfunction, 35 out of 49 patients (71%) completed the treatment by maintaining the same or a decreased dose of INH, while the medication was discontinued in 9 patients who were then followed up by chest X-ray examination. Two of these 49 patients discontinued the medication by themselves.

The frequency of liver damage due to INH was higher in persons older than 30 yrs. In this group, 3 persons developed severe liver damage with ALT and/or AST higher than 1000 IU/L. Early detection is required to avoid serious damage. Thus, we decided to perform liver function tests more often, i.e., at 2 weeks after the onset of treatment and every month thereafter.