How do I interpret the results of hormonal assays in the assessment of female infertility?

Interpretation of hormonal assays in female infertility assessment:

• Serum progesterone measurement in the mid-luteal phase (day 21 of a 28-day cycle) is used to confirm ovulation, even in women with regular menstrual cycles. A sufficient progesterone level indicates ovulation has occurred.
• For women with prolonged or irregular menstrual cycles, serum progesterone should be measured later in the cycle (e.g., day 28 of a 35-day cycle) and may need to be repeated weekly until menstruation starts to confirm ovulation status.
• Women with irregular menstrual cycles should have serum gonadotrophins measured, specifically follicle-stimulating hormone (FSH) and luteinising hormone (LH), to help classify ovulatory disorders.
• Prolactin testing should not be routinely offered but reserved for women with ovulatory disorders, galactorrhoea, or suspected pituitary tumors.
• Routine thyroid function tests are not recommended unless there are symptoms suggestive of thyroid disease, as thyroid dysfunction is not more common in women with fertility problems than the general population.
• Ovarian reserve testing using FSH, anti-Müllerian hormone (AMH), or antral follicle count can predict ovarian response to stimulation but should not be used alone to predict fertility treatment outcomes.

In summary, hormonal assays should be interpreted in the context of menstrual cycle regularity and clinical presentation, focusing on confirming ovulation (progesterone), assessing ovulatory function (FSH, LH), and excluding specific causes such as hyperprolactinaemia or pituitary disease. Routine prolactin and thyroid testing are not indicated without clinical suspicion. Ovarian reserve markers assist in treatment planning rather than diagnosis of infertility per se.

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