What tests are done for irregular periods?
Bottom lineIrregular periods are investigated with a pregnancy test, blood tests for thyroid (TSH), prolactin, FSH, LH, estradiol, and androgens such as testosterone, sometimes AMH, and often a pelvic ultrasound to check the ovaries, uterus, and lining; some tests are best drawn on day 2 to 5 of a cycle, and abnormal results, heavy bleeding, or difficulty conceiving usually lead to a gynaecology or endocrinology referral.
The workup for irregular periods is a history, a pregnancy test, a short panel of blood tests, and often a pelvic ultrasound. The aim is to find out whether you are ovulating and, if not, why.
Blood tests
- Pregnancy test (hCG) - always first, whatever the pattern
- Thyroid (TSH) - both an underactive and an overactive thyroid disrupt cycles
- Prolactin - raised levels suppress ovulation; some medications cause this
- FSH and LH - the pituitary signals to the ovaries; the pattern helps separate PCOS, perimenopause, and primary ovarian insufficiency
- Estradiol - usually alongside FSH
- Testosterone and other androgens - when PCOS/PMOS is suspected, especially with acne or excess hair
- AMH - sometimes, as a marker of ovarian reserve or as part of a PCOS assessment
Some of these are best drawn on day 2 to 5 of a cycle. If your cycles are unpredictable, your clinician may take a random sample and repeat it.
Ultrasound
A pelvic ultrasound looks at the ovaries (follicle pattern, cysts), the uterus (fibroids, adenomyosis), and the lining (polyps, thickness). It is routine when bleeding is heavy or prolonged, when there is pain, or when PCOS or a structural cause is suspected.
What comes next
Results point to a cause in most cases, and each has its own treatment. Persistent irregularity while trying to conceive, heavy bleeding, or abnormal results usually mean a referral to gynaecology or endocrinology.
Home hormone kits can preview some of these but do not replace the panel; see at-home hormone tests. Full context in irregular periods: causes, tests, and what helps.
Femora turns your logged cycles into the cycle history your clinician will ask for first.