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
The best marker to diagnose thyroid related disorder is: 
Select and explain. 
A. T3, B. T4, C. TSH, D. Thyroglobulin
C: TSH
Answer: C: TSH 
Explanation: Ans. (c) TSHRef: Schwartz 10th edition Page 1349* TSH assay is the most sensitive and Specific test for diagnosis of hyper and hypothyroidism for optimizing T4 therapy.