Are liver function tests required for patients taking isoniazid for latent TB?

Routine liver function test monitoring is not required for all patients on isoniazid therapy for latent tuberculosis (TB) infection (strength of recommendation: B, based on case series). No clinical trials have studied the potential risks and benefits of routinely monitoring liver function tests for all patients taking isoniazid for latent TB infection. Data from 2 case series suggest that routine liver function test monitoring leads to withdrawal of isoniazid prophylaxis from about 6% of patients because of abnormal lab results. This is 10 to 60 times the hepatitis rate found in case series using a symptom-based monitoring strategy. Data are insufficient, however, to conclude that routine liver function test monitoring leads to a lower rate of fatal isoniazid hepatitis compared with a strategy of symptom-based screening. Given that complete recovery from nonfatal hepatitis is the rule, and that patients withdrawn from isoniazid prophylaxis remain at risk for developing active tuberculosis, current evidence does not support routine liver function test monitoring for all patients