This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid, Subject name: Medicine
A 33 year old womau has experienced episodes of fatigue, pleural effusion, pericardial effusion and carpal tunnel syndrome and macrocytic anemia. Best test for diagnosis shall be - 
Select and explain. 
A. Anti-beta 2 phospholipid antibodies, B. Anti-smith antibody, C. Antinulear antibody, D. Assay for thyroid hormones
D: Assay for thyroid hormones
Answer: D: Assay for thyroid hormones 
Explanation: Ans. is 'd' i.e., Assay for thyroid hormones o On the first instance, it appears a case of hypothyroidism.o But, when you look closely it seems a case of hypothyroidism.o Pleural and also pericardial and peritoneal effusions can occur in patients with severe chronic hypothyroidism.o Carpal tunnel syndrome is a common complication of hypothyroidism and is often reversible with thyroid hormone therapy.o Normally hypothyroidism is associated with nonnochromic anemia but may sometimes also cause macrocytic anemia.