Absent Periods
This symptom causes substantial anxiety in the sexually active woman: the first unexpectedly missed period suggests pregnancy; prolonged absence raises the concern that something is seriously amiss. In contrast, management is usually straightforward and helped by acknowledging the anxiety.
Differential diagnosis
Common Diagnoses
- Pregnancy
- Physiological: Rapid Weight (10%–15%) Loss, and Severe Emotional Stress
- Menopause (Including Premature Ovarian Failure)
- Polycystic Ovary Syndrome (PCOS)
- Drugs: Phenothiazines, Metoclopramide, Valproate, Cytotoxics
Occasional Diagnoses
- Hypo- and Hyperthyroidism
- Anorexia Nervosa
- Excessive Exercise/Training
- Severe Systemic Illness of any Kind
- Contraception (Progestogen-only Pill, Long-Acting Reversible Contraception – Common Cause but Rarely Presented as a Symptom)
Rare Diagnoses
- Adrenal Disorders: Addison’s Disease, Cushing’s Disease, Congenital Adrenal Hyperplasia
- Sheehan’s Syndrome
- Arrhenoblastoma, Bilateral Ovarian Tumours
- Prolactinoma, other Pituitary Tumours
- Rare Structural or Chromosomal Abnormalities (Primary Amenorrhoea)
- Anterior Pituitary Failure (Simmonds’s Disease)
Ready reckoner
Key distinguishing features of the most common diagnoses
| Pregnancy | Weight Loss | Menopause | Drugs | PCOS | |
|---|---|---|---|---|---|
| Breast Tenderness | Yes | No | No | No | No |
| Hot Flushes | No | No | Yes | No | No |
| Obesity | No | No | No | No | Possible |
| Galactorrhoea | Yes | No | No | Possible | No |
| Depression | No | Possible | Possible | No | No |
Possible investigations
Likely: Pregnancy test.
Possible: FBC, U&E, TFT, FSH/LH, testosterone, SHBG, prolactin, ultrasound.
Small Print: CT with or without other imaging.
- Pregnancy test whatever contraception is used: Urinary HCG. Remember small false negative rate
- FBC, U&E, TFT: To assess for general severe systemic illness, adrenal disorders and hypo- or hyperthyroidism.
- FSH, LH, testosterone and SHBG: LH and testosterone may be high in PCOS (and SHBG normal or low), FSH very high in menopause.
- Prolactin levels high in prolactinoma and with some drugs (e.g. phenothiazines)
- Ultrasound useful to show multiple ovarian cyst formation and is a reliable check of pregnancy.
- Specialist will arrange CT or similar imaging if prolactinoma suspected.
Top Tips
- Amenorrhoea is common in young women, especially at times of stress; once pregnancy has been excluded and in the absence of any worrying symptoms or signs, only investigate if the problem persists beyond 6 months.
- It is important to confirm a possible diagnosis of premature menopause, as the patient will require hormone-replacement therapy (HRT).
- The same pathologies can cause both amenorrhoea and oligomenorrhoea, therefore take the same clinical approach to both.
Red Flags
- Do not accept too readily the claim that there is ‘no chance of pregnancy’; if in any doubt, arrange a pregnancy test.
- Consider anorexia – an emaciated body may be well hidden under baggy clothing, and the disease often presents with the absence of periods.
- Early morning headache and visual disturbance associated with amenorrhoea suggest possible intracranial pathology – refer urgently
- Before attributing amenorrhoea to weight loss, make sure that the weight loss itself hasn’t been caused by thyrotoxicosis.