# Situation: A 36-year-old woman comes to the Rural Health Unit (RHU), which provides free tuberculosis (TB) care under the National Tuberculosis Program (NTP), because of cough for 3 weeks, afternoon fevers, night sweats, and weight loss. She has type 2 diabetes controlled with metformin. She has no known liver disease and is not pregnant. At her 4-week follow-up she reports nausea and poor appetite for 3 days, without vomiting, abdominal pain, or jaundice. Her urine has been orange since she started treatment. Her alanine aminotransferase (ALT) is 135 U/L (upper limit of normal 40 U/L); it was 28 U/L before treatment. What should the nurse do?

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## 문제

Situation: A 36-year-old woman comes to the Rural Health Unit (RHU), which provides free tuberculosis (TB) care under the National Tuberculosis Program (NTP), because of cough for 3 weeks, afternoon fevers, night sweats, and weight loss. She has type 2 diabetes controlled with metformin. She has no known liver disease and is not pregnant.

At her 4-week follow-up she reports nausea and poor appetite for 3 days, without vomiting, abdominal pain, or jaundice. Her urine has been orange since she started treatment. Her alanine aminotransferase (ALT) is 135 U/L (upper limit of normal 40 U/L); it was 28 U/L before treatment. What should the nurse do?

## 보기

1. Continue the drugs and give an antiemetic before each dose
2. Hold all the drugs and refer her to the physician today **✔ 정답**
3. Continue all the drugs and recheck the liver enzyme in 2 weeks
4. Continue isoniazid and rifampicin, but stop pyrazinamide

**정답: 2**

## 해설

Her ALT is about 3.4 times the upper limit of normal (135 ÷ 40), and she has symptoms of hepatitis (nausea and poor appetite). The rule is to stop the hepatotoxic drugs when ALT is more than 3 times normal with symptoms, or more than 5 times normal without symptoms, so the nurse holds the drugs and refers her to the physician the same day; the physician decides how to reintroduce them one at a time. Orange urine is an expected, harmless effect of rifampicin.

## 심화 해설

Clinical situation The patient is a 36-year-old woman on first-line anti-TB treatment who now has new nausea and poor appetite, with ALT rising from 28 U/L to 135 U/L against an upper limit of normal of 40 U/L. This is approximately 3.4 times the upper limit of normal, and she has gastrointestinal symptoms that suggest drug-induced liver injury (DILI).

Why the answer is “hold all drugs and refer today” The decision rule for anti-tuberculosis drug-induced liver injury (ATB-DILI) is based on two factors: the degree of ALT elevation and whether the patient is symptomatic. When ALT exceeds 3 times the upper limit of normal in a patient with symptoms of hepatitis, or exceeds 5 times the upper limit of normal even without symptoms, all potentially hepatotoxic anti-TB drugs should be stopped immediately and the patient referred for physician evaluation. This patient meets the first criterion because she has both an ALT of 135 U/L and symptoms of nausea with poor appetite.

The rationale for stopping all drugs rather than selectively continuing some is that isoniazid, rifampicin, and pyrazinamide are all potentially hepatotoxic, and the specific offending agent cannot be reliably identified from ALT alone at this point. Key point! The physician, not the nurse, decides which drugs to reintroduce, in what order, and at what dose after the liver enzymes have normalized or significantly improved. The nurse’s immediate responsibility is to recognize the DILI pattern, withhold the drugs, and ensure same-day referral.

Pathophysiology of anti-TB hepatotoxicity The liver is the central site of drug metabolism, and anti-TB medications produce reactive metabolites that can overwhelm hepatocellular detoxification pathways [2]. Isoniazid is metabolized through acetylation to hydrazine intermediates, which are directly hepatotoxic. Rifampicin is a potent inducer of cytochrome P450 enzymes and can enhance the toxicity of isoniazid metabolites when the two are given together. Pyrazinamide has its own dose-related hepatotoxic potential. The combination of these agents explains why first-line anti-TB regimens carry a meaningful risk of DILI, and why early recognition is essential [3].

The spectrum of injury ranges from asymptomatic, transient transaminase elevation—sometimes called hepatic adaptation—to symptomatic hepatocellular injury and, in severe cases, acute liver failure [2][3]. The patient’s nausea and anorexia are important because they suggest that the liver injury is not merely a benign biochemical adaptation but has become clinically significant.

Interpreting the orange urine Orange discoloration of urine is an expected and harmless effect of rifampicin. It is caused by excretion of the drug and its metabolites, not by bilirubin or liver injury. Watch out! Do not confuse orange urine with dark, tea-colored urine from conjugated hyperbilirubinemia. The absence of jaundice and abdominal pain in this patient further supports that the orange urine is rifampicin-related, not a sign of worsening hepatitis.

Why the other options are incorrect

| Option | Why it is wrong |
| --- | --- |
| 1. Continue drugs and give an antiemetic | An antiemetic may mask the symptom of nausea without addressing the underlying hepatocellular injury. Continuing all hepatotoxic drugs when ALT is over 3 times normal with symptoms violates the stopping rule and risks progression to severe DILI. |
| 3. Continue drugs and recheck in 2 weeks | Delaying action for 2 weeks while continuing the same regimen is unsafe in symptomatic DILI. The threshold for stopping has already been crossed, and observation alone is not appropriate. |
| 4. Continue isoniazid and rifampicin, stop pyrazinamide | Selectively stopping one drug assumes pyrazinamide is the culprit, but isoniazid and rifampicin are also hepatotoxic. The nurse cannot determine the causative agent at this stage. The correct approach is to stop all potentially hepatotoxic drugs and let the physician plan rechallenge. |

Clinical monitoring and nursing role Before starting anti-TB treatment, baseline liver enzymes should be obtained, especially in patients with risk factors such as diabetes, older age, alcohol use, or pre-existing liver disease [1][3]. This patient’s baseline ALT of 28 U/L was normal, which makes the current elevation clearly treatment-related. During follow-up, nurses should ask specifically about nausea, anorexia, vomiting, abdominal pain, and jaundice, and should check liver enzymes when these symptoms appear.

The management sequence for ATB-DILI is to stop the hepatotoxic drugs, monitor liver function until it improves, and then reintroduce drugs one at a time under physician supervision—typically starting with rifampicin, then isoniazid, with pyrazinamide often avoided if it is suspected. This de-challenge and rechallenge approach is used to identify the offending agent while preserving an effective anti-TB regimen [4]. The nurse’s role in the rural health unit is to recognize the DILI, withhold the medications, document the findings, and refer the patient for same-day physician evaluation.References (research sources)

- [1][Guidelines for diagnosis and management of drug-induced liver injury caused by anti-tuberculosis drugs (2024 version)].GuidelineChinese Medical Association Tuberculosis Branch (2024) · DOI: 10.3760/cma.j.cn112147-20240614-00338

- [2]An official ATS statement: hepatotoxicity of antituberculosis therapy.Research articleSaukkonen JJ, Cohn DL, Jasmer RM, Schenker S, Jereb JA, Nolan CM (2006) · DOI: 10.1164/rccm.200510-1666ST

- [3]Diagnosis, prevention and risk-management of drug-induced liver injury due to medications used to treat mycobacterium tuberculosis.Research articleLewis JH, Korkmaz SY, Rizk CA, Copeland MJ (2024) · DOI: 10.1080/14740338.2024.2399074

- [4]Drug-Induced Liver Injury During First-Line Anti-Tubercular Therapy (Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol): A Case Report with De-challenge and Rechallenge.Case reportChokkakula S, Balasani A, Ammana SR. (2026)

## 임상 시나리오

Anti-TB Drug-Induced Liver Injury: Stop and ReferALT >3x ULN with symptoms is an immediate hold threshold
Stop all hepatotoxic anti-TB drugs when ALT exceeds 3 times the upper limit of normal with symptoms such as nausea, anorexia, or jaundice, or 5 times without symptoms.

This patient's ALT of 135 U/L against a normal limit of 40 U/L is about 3.4x ULN, and she has new nausea with poor appetite, meeting the symptomatic threshold for immediate action.

The nurse should hold all anti-TB drugs and refer to the physician the same day. The physician decides which drugs to reintroduce, in what order, and at what dose after liver enzymes improve.

CautionDo not selectively continue isoniazid, rifampicin, or pyrazinamide, as all are potentially hepatotoxic. Orange urine is an expected, harmless effect of rifampicin and does not indicate liver injury.

## 핵심 개념

- **Drug-induced liver injury (DILI)** — Liver damage caused by medications, detected by rising ALT with or without symptoms such as nausea, anorexia, or jaundice.
- **Alanine aminotransferase (ALT)** — A liver enzyme used to monitor hepatocellular injury; upper limit of normal is typically around 40 U/L.
- **Hepatotoxic anti-TB drugs** — First-line agents isoniazid, rifampicin, and pyrazinamide, all capable of causing liver injury.
- **Rifampicin orange urine** — Expected, harmless discoloration of body fluids caused by rifampicin; not a sign of liver injury.
- **National Tuberculosis Program (NTP)** — Public health program providing free TB diagnosis and treatment, including monitoring for adverse drug reactions.

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