A 42-year-old female from Mumbai with newly diagnosed pulmonary TB (sputum smear-positive) is enrolled in RNTCP. She is on standard 4-drug therapy (HRZE) and completes 2 months of intensive phase. At the start of continuation phase, she develops jaundice, elevated transaminases (ALT 280 U/L, AST 320 U/L), and total bilirubin 4.2 mg/dL. Hepatitis A and B serology are negative. What is the most appropriate next step in TB management according to RNTCP guidelines?

Explanation

## Drug-Induced Hepatotoxicity in TB Treatment — RNTCP Protocol ### Clinical Presentation This patient has **drug-induced liver injury (DILI)** secondary to anti-TB therapy: - Jaundice + elevated transaminases (>3× upper limit of normal) - Negative viral hepatitis serology → excludes infectious causes - Timing: onset during continuation phase (when INH and PZA are continued) ### Hepatotoxic Anti-TB Drugs **Key Point:** The **three most hepatotoxic first-line drugs** are: 1. **Isoniazid (INH)** — dose-dependent hepatotoxicity 2. **Pyrazinamide (PZA)** — hyperuricemia and hepatotoxicity 3. **Rifampicin (RIF)** — enzyme inducer, less hepatotoxic but contributory Ethambutol (E) is the least hepatotoxic. ### RNTCP Management Algorithm for TB-DILI ```mermaid flowchart TD A[Anti-TB DILI suspected]:::outcome --> B{Severity of LFT elevation}:::decision B -->|Mild: ALT/AST 1-3× ULN| C[Continue all drugs with monitoring]:::action B -->|Moderate-Severe: ALT/AST > 3× ULN + symptoms| D[Stop hepatotoxic drugs]:::action D --> E[Continue RIF + E only]:::action E --> F[Monitor LFTs weekly]:::action F --> G{LFTs normalize?}:::decision G -->|Yes, after 1-2 weeks| H[Restart INH + PZA sequentially]:::action G -->|No improvement| I[Investigate alternative causes, consider DST]:::action H --> J[Complete TB treatment with modified regimen]:::action ``` ### Rationale for Option C (Correct Answer) **High-Yield:** RNTCP guidelines recommend: 1. **Stop INH and PZA** — the two most hepatotoxic agents 2. **Continue RIF + E** — RIF is essential for TB control; E has minimal hepatotoxicity 3. **Monitor LFTs weekly** — expect improvement within 1–2 weeks 4. **Reintroduce INH and PZA sequentially** once LFTs normalize (usually after 1–2 weeks) 5. **Extend total treatment duration** to compensate for the pause **Clinical Pearl:** Complete cessation of all drugs risks relapse and treatment failure. Continuing RIF + E maintains TB control while allowing hepatotoxic drugs to be metabolized. ### Why NOT Complete Stoppage? - Stopping all drugs increases risk of treatment failure, relapse, and acquired drug resistance - RIF is the most potent anti-TB agent and must be continued - Ethambutol is well-tolerated and has minimal hepatotoxicity ### Monitoring During Modified Regimen - LFTs every 7 days - Clinical assessment for resolution of jaundice and symptoms - Once ALT/AST <100 U/L and bilirubin <2 mg/dL, restart INH first, then PZA after 3–5 days **Mnemonic:** **RIFE** — **R**ifampicin + **I**soniazid + **F**luoroquinolone (if needed) + **E**thambutol are the backbone; stop the **H**epatotoxic **I**soniazid and **P**yrazinamide temporarily.