This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid Gland, Subject name: Surgery
Most sensitive method to diagnose thyroid function is: 
Select and explain. 
A. T3, B. T4, C. TSH, D. Thyroglobulin
C: TSH
Answer: C: TSH 
Explanation: Ans. (c) TSHRef: Bailey and Love Principles and Practice of Surgery, 26th ed p-743* Most sensitive and specific test to detect hypothyroidism and hyperthyroidism is TSH ASSAY* Total T4: Reflects output from thyroid gland* Total T3: More indicative of peripheral thyroid metabolism, hence not useful for screening