Absent Periods

Differential Diagnosis

Common Diagnoses

Occasional Diagnoses

  • 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)
  • Hyperthyroidism
  • Hypothyroidism

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

PregnancyWeight LossMenopauseDrugsPCOS
Breast TendernessYesNoNoNoNo
Hot FlushesNoNoYesNoNo

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

  • Advise the patient that a pregnancy test is standard practice even if they don't consider pregnancy a possibility.
  • Consider anorexia – an anorectic 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.
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