This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology in Relation to Reproduction, Subject name: Gynaecology & Obstetrics
A 22 years old woman presented with recent onset of hirsutism and voice change. What is the best test to be done? 
Select and explain. 
A. Urine 17 ketosteroids, B. Blood FSH and LH levels, C. Blood testosterone levels, D. Blood thyroxine and TSH levels
C: Blood testosterone levels
Answer: C: Blood testosterone levels 
Explanation: Ans. C. Blood testosterone levelsa. Testosterone is bound to serum hormone binding globulins (SHBG).b. SHBG production in liver is inhibited by androgens and increased by Oestrogen and thyroid hormone.c. Low Oestrogen and thyroid hormone cause fall in SHBG level and this results in some testosterone being released in blood circulation as free T which causes hirsutism.d. Testosterone level >6nmol/l is seen in ovarian tumor and hyperthecosis.e. In PCOD, LH level exceeds 10u/l;T>2.5nmol/L and SHBG<30nmol/l.