PCOS with thyroid — how to manage both?

Note on the name: in May 2026, polycystic ovary syndrome (PCOS) was formally renamed polyendocrine metabolic ovarian syndrome (PMOS), following a global consensus process. The old name was inaccurate — the condition affects multiple hormone and metabolic systems, not just the ovaries, and "polycystic" wrongly implies ovarian cysts. Nothing about the condition, its diagnosis or its treatment has changed. Both names will be used side by side for the next few years, and we use PCOS below since that is the term most people know.

PCOS and hypothyroidism co-exist more often than chance would predict, and each makes the other harder to manage — both cause irregular cycles, weight difficulty and fertility problems, so symptoms overlap and one can mask the other. The practical approach is to treat the thyroid first and reassess. Correcting hypothyroidism often improves cycle regularity on its own, and it also lowers prolactin, which may itself have been suppressing ovulation. What remains after that is the PCOS to address. Autoimmune thyroid disease is the usual cause where the two occur together, so thyroid antibodies are worth checking. Lifestyle measures help both, and this is one of the genuine advantages of the combination — the same changes work on both fronts. Monitoring: TSH periodically once stable, more frequently if the dose changes or you become pregnant. Thyroid requirements increase in pregnancy and targets are tighter, so tell whoever manages your thyroid as soon as you conceive or start trying. A gynaecologist and endocrinologist communicating with each other is worth arranging rather than managing the two separately.