A 27-year-old man presents for an appointment to establish care. He recently was released from prison. He has felt very fatigued and has had a cough. He has lost roughly 15 pounds over the past 3 weeks. He attributes this to intravenous drug use in prison. His temperature is 99.5°F (37.5°C), blood pressure is 127/68 mmHg, pulse is 100/min, respirations are 18/min, and oxygen saturation is 98% on room air. QuantiFERON gold testing is positive. The patient is started on appropriate treatment. Which of the following is the most likely indication to discontinue this patient's treatment?
Peripheral neuropathy
Red body excretions
Hyperuricemia
Elevated liver enzymes
Elevated liver enzymes
This patient is presenting with weight loss and cough with a positive quantiFERON gold test suggestive of tuberculosis and has been started on treatment. The most likely indication to discontinue tuberculosis therapy is elevation of liver enzymes.

Tuberculosis typically presents with weight loss, cough, and night sweats usually in high-risk patients (prisoners or the immunosuppressed). It can be diagnosed using sputum samples as these organisms will be positive on an acid-fast test. These bacteria are slow to grow so cultures need to be held for an extended period of time. QuantiFERON gold testing can be used to make the diagnosis as well. Treatment for tuberculosis is RIPE therapy: Rifampin, Isoniazid, Pyrazinamide, and Ethambutol. The most common indication to alter or discontinue therapy is an elevation of liver enzymes 5 times greater than baseline.

Tweed et al. review the evidence regarding liver injury in patients with RIPE therapy. They discuss how patients on HIV therapy are at higher risk. They recommend measuring liver enzymes to detect this potential side effect.

Incorrect Answers:
Answer B: Hyperuricemia is a side-effect of pyrazinamide; however, this is not the most common indication for discontinuing RIPE therapy. Patients can be treated with supportive therapy or with uric acid lowering agents in those with arthralgias.

Answer C: Optic neuritis is a side-effect of ethambutol; however, it is not the most common indication for discontinuing RIPE therapy. Treatment is with discontinuation of ethambutol.

Answer D: Peripheral neuropathy is a side-effect of isoniazid; however, it is typically not an indication to discontinue RIPE therapy. Treatment is with supplementation of vitamin B6.

Answer E: Red body excretions are a side-effect of rifampin; however, this is a cosmetic concern rather than an indication to discontinue RIPE therapy. Patients should be counseled regarding this side effect prior to initiation of treatment.

Bullet Summary:
Elevation of liver enzymes 5 times above normal is the most common indication to alter or discontinue RIPE therapy when treating tuberculosis.