Hypothyroidism in a Patient with Tuberculosis Suffering from Repeated Side Effects Found by Continuous Pharmacist Outpatient Monitoring

A 79-year-old man with pulmonary tuberculosis was treated with four drugs: isoniazid, rifampicin, ethambutol, and pyrazinamide. The medication was temporarily discontinued and resumed multiple times through desensitization therapy due to adverse drug reactions. Ultimately, treatment was continued with isoniazid, levofloxacin hydrate, and ethionamide. A pharmacist detected the adverse reactions early by proactively monitoring the patient’s progress. On day 670 after starting the abovementioned four drugs, the patient reported anorexia and dysgeusia during an interview with a pharmacist before consulting a physician. Eleven days later, the pharmacist followed up and learned that the patient’s condition had worsened (Grade 3). The pharmacist suspected ethionamide-induced hypothyroidism and consulted a tuberculosis specialist, resulting in an unscheduled medical consultation for the patient. Blood tests showed free T3 < 1.50 pg/mL, free T4 < 0.40 ng/mL, and a thyroid-stimulating hormone level of 339.67 μIU/mL, confirming hypothyroidism. The patient’s symptoms improved with thyroid hormone therapy, allowing him to complete 3 years of treatment without discontinuing the medication.