Figure 1. Flow diagram for the laboratory evaluation of amenorrhea. Such a scheme must be considered as an adjunct to the clinical evaluation of the patient. CAH -= congenital adrenal hyperplasia; DHEAS = dehydroepiandrosterone sulfate; FSH = follicle-stimulating hormone; HCA = hypothalamic chronic anovulation; PCO = polycystic ovary syndrome; PRL = prolactin; T = testosterone; TSH = thyroid-stimulating hormone. Originally from Rebar RW, The ovaries. In: Smith LH Jr, ed. Cecil textbook of medicine, ed. 18. Philadelphia. WB Saunders, 1992:1367)