20 yrs old young girl, presents with history of rapidly developing hirsutism and amenorrhea with change in voice. To establish a diagnosis you would like to proceed with which of the following tests in blood:

Androgen secreting ovarian neoplasm usually present with rapidly developing hirsutism, amenorrhea, and virilisation. A serum testosterone level of more than 200 ng/dl should be considered evidence of ovarian tumor until proven otherwise. Ref: Shaw's Textbook of Gynaecology, 17th Edition, Page 77 ; Current Obs and Gynae Diagnosis and Treatment, 9th Edition, Page 1005