This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
The best marker for thyroid related disorder is: 
Select and explain. 
A. T3, B. T4, C. TSH, D. Thyroglobulin
C: TSH
Answer: C: TSH 
Explanation: Answer is C (TSH): TSH is the most useful marker for Thyroid Related Disorders. With rare exceptions a normal TSH level excludes a primary abnormality of thyroid function. The enhanced sensitivity and specificity of TSH assays have greatly improved laboratory assessment of thyroid function