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: Surgery
TSH acts via : 
Select and explain. 
A. cAMP formation., B. Direct stimulation, C. Receptor stimulation, D. All of the above
A: cAMP formation.
Answer: A: cAMP formation. 
Explanation: When TSH is administered, thyroid function is stimulated, iodide uptake is increased and thyroxin synthesis and secretion is increased. TSH acts via cyclic AMP formation.