What are the key hormonal tests to perform in a patient with secondary amenorrhoea?

For a patient presenting with secondary amenorrhoea, the key hormonal tests to perform include:

• Pregnancy test: Pregnancy is a common cause of secondary amenorrhoea and should be excluded ¹.
• Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH): Persistently elevated FSH and LH levels suggest premature ovarian insufficiency in women younger than 40 years of age ¹. For diagnosing premature ovarian insufficiency, elevated FSH levels on two blood samples taken 4 to 6 weeks apart are used ³. Low FSH and LH levels may indicate hypopituitarism or a pituitary tumour ¹. These gonadotrophins should also be measured in women with irregular menstrual cycles ².
• Prolactin: This test should be offered to women who have an ovulatory disorder, galactorrhoea, or a pituitary tumour ². Hyperprolactinaemia is a reason for referral to an endocrinologist ¹.
• Testosterone: An increased testosterone level that is not explained by polycystic ovary syndrome (PCOS) may suggest an androgen-secreting tumour, late-onset congenital adrenal hyperplasia, or Cushing's syndrome ¹.
• Thyroid Function Tests: Hypothyroidism is a recognised cause of secondary amenorrhoea ¹. However, routine measurement of thyroid function should be confined to women with symptoms of thyroid disease ².
• Progesterone: For women with prolonged irregular menstrual cycles, a blood test to measure serum progesterone in the mid-luteal phase of their cycle can be offered to confirm ovulation ². Depending on the timing of menstrual periods, this test may need to be conducted later in the cycle and repeated weekly thereafter until the next menstrual cycle starts ².