🩺 Secondary Amenorrhoea

Secondary amenorrhoea is the cessation of menstruation for at least 3-6 months in a patient who previously had regular or irregular cycles. It is a symptom of underlying physiological or pathological dysfunction within the hypothalamic-pituitary-ovarian (HPO) axis or the outflow tract. The primary goal of assessment is to exclude pregnancy, identify the level of hormonal disruption, and prevent long-term complications like osteoporosis or endometrial hyperplasia.

Establish the previous menstrual pattern and the duration of absence (usually defined as >6 months of no periods in a previously regular woman, or >12 months if previously irregular). Screen for pregnancy symptoms (nausea, breast tenderness). Inquire about lifestyle factors: weight changes, intensive exercise, and psychological stress. Ask about symptoms of oestrogen deficiency (hot flushes, night sweats, vaginal dryness). Check for galactorrhoea, headaches, or visual changes (pituitary involvement) and features of thyroid dysfunction. Review medications, especially antipsychotics which can cause hyperprolactinaemia.

Record BMI, as both high and low weight can cause amenorrhoea. Assess for clinical signs of hyperandrogenism (hirsutism, acne, male-pattern alopecia) which suggest PCOS. Look for stigmata of Turner syndrome (in cases of delayed primary/early secondary) or features of endocrine disorders, such as thyroid goitre or Cushingoid features. Visual field testing is essential if a pituitary prolactinoma is suspected. Bimanual exam is usually not required unless an anatomical blockage (e.g. cervical stenosis following LLETZ) is suspected.

Polycystic Ovary Syndrome (PCOS) is the leading cause. Hypothalamic causes include stress, excessive exercise, or eating disorders. Pituitary causes include hyperprolactinaemia (often due to prolactinoma or drugs). Ovarian causes include Premature Ovarian Insufficiency (POI). Uterine causes include Asherman’s syndrome (intrauterine adhesions following curettage). Endocrine disorders such as hypothyroidism or Cushing’s syndrome are less common but important to consider.

Headaches and visual field defects (pituitary tumour); sudden onset hirsutism or virilisation (androgen-secreting tumour); rapid weight loss or signs of an eating disorder; symptoms of thyrotoxicosis.

A urinary or serum Beta-hCG is the mandatory first step. Baseline bloods should include FSH, LH, Oestradiol, Prolactin, and TSH. Elevated FSH (>25 IU/L on two occasions) confirms POI. Elevated LH with a high LH:FSH ratio is seen in PCOS, though not diagnostic. High Prolactin necessitates a pituitary MRI. A Pelvic Ultrasound is used to assess for polycystic ovaries and endometrial thickness. A progesterone challenge test (e.g., Medroxyprogesterone) can be used to assess oestrogen status and outflow tract patency.

Always exclude pregnancy first, regardless of the patient's sexual history or stated contraceptive use. PCOS is the most common cause of secondary amenorrhoea but is a diagnosis of exclusion. Premature Ovarian Insufficiency (POI) is defined as menopause before age 40 and requires prompt HRT to prevent osteoporosis. In cases of functional hypothalamic amenorrhoea, excessive exercise or low BMI can suppress the GnRH pulse generator, leading to low FSH/LH and low oestrogen.

Covers Reproductive Health and Endocrinology. Students must be able to interpret hormonal profiles (e.g., high FSH/LH in POI vs. low FSH/LH in hypothalamic causes). Understanding the long-term health implications of amenorrhoea, such as reduced bone mineral density, is critical for MLA-style management questions.