When starting tuberculosis therapy, which laboratory test should be monitored for potential adverse effects?

• A. Hemoglobin
• B. Liver enzymes
• C. Platelet count
• D. Urinalysis

Answer: (B)

TB treatment commonly uses a combination of drugs that can damage the liver, so watching liver function is the key safety check. The most important lab to monitor is liver enzymes (ALT/AST), which reflect hepatocellular injury. Baseline liver tests before starting therapy help establish a point of comparison, and then periodic monitoring during treatment catches rising enzymes early before severe hepatitis develops. If enzymes rise substantially, or if symptoms like fatigue, nausea, vomiting, right upper quadrant pain, or jaundice appear, clinicians reassess and may adjust or stop the offending drugs.

Other labs—like hemoglobin, platelet count, or urinalysis—don’t specifically indicate the common adverse effects of standard TB drugs. They may be relevant in other contexts, but for monitoring potential hepatotoxicity from TB therapy, liver enzymes are the primary concern.