[The hepatotoxicity of tuberculosis treatment].

Background: The hepatic toxicity of antituberculous drugs used for the therapy of initial cases was evaluated, assessing the incidence and severity and its relation with each drug, age, other associated hepatic risks and the chronological time of therapy.

Methods: 1235 patients with tuberculosis were prospectively assessed with a protocol including periodical clinical and laboratory controls.

Results: Hepatic toxicity was found in overall 16.5%, with 3.5% of severe forms and need for a definitive change in therapy in 1.5%. Differences in toxicity between the 6-month and the 9-month schedules were not found. The most commonly incriminated drugs was isoniazid followed by pyrazinamide. All severe forms presented with symptoms, although some were nonspecific and insidious. Other associated hepatic risks implied an increased frequency of iatrogenic reactions. Age did not have a determining influence in severe forms, which predominantly developed within the first two months of therapy.

Conclusions: Moderate, transient and asymptomatic increase in transaminase activity not requiring a change a therapy is common. Severe and dangerous forms are uncommon and predominate at the beginning of therapy and in persons with associated hepatic risk factors. Therefore, although the clinical controls should be maintained throughout treatment, laboratory controls should only be carried out during the first two months, except when symptoms are present or in patients with associated hepatic risk factors, where they should be more frequent and carried out throughout treatment.