This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of pituitary gland, Subject name: Medicine
For galactorrhea and amenorrhea syndromes, what is the investigation in addition to serum prolactin? 
Select and explain. 
A. LH, B. TSH, C. Urinary Keto-steroids, D. HCG
B: TSH
Answer: B: TSH 
Explanation: In patients with Iodine deficiency Low T4/T3 results in TSH || by Feedback mechanism & to ||TSH the TRH is also elevated(||) Now this ||TRH will increase both TSH and Prolactin production. Therefore Hyperprolactinemia resulting in Galactorrhea can also be seen in Patients with thyroid malfunction.