This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Adverse Drug Effect, Subject name: Pharmacology
ATT drug causing hypothyroidism: 
Select and explain. 
A. Isoniazid, B. Ethambutol, C. PAS, D. Rifampicin
C: PAS
Answer: C: PAS 
Explanation: Ans. (c) PASRef: 2008 WHO guidelines for programmatic management or drug resistant tuberculosisSecond line ATT like PAS (para amino salicylic acid) and ethionamide can lead to hypothyroidism. Exact mechanism is poorly understood.PAS also causes adverse reactions like GI upset, hepatotoxicity, Hypersensitivity.