Differential Diagnosis

Common Diagnoses

Occasional Diagnoses

Rare Diagnoses

  • Carcinoid Tumour
  • Phaeochromocytoma
  • Zollinger–Ellison Syndrome
  • Systemic Mastocytosis
  • ACTH-Secreting Bronchogenic Carcinoma and Cushing’s Syndrome

Ready Reckoner

Key distinguishing features of the most common diagnoses

Weight LossNoPossibleNoNoPossible
Facial PapulesNoNoYesNoNo
Long HistoryPossibleYesPossibleNoPossible

Possible Investigations


Possible:FBC, LFT, TFT, blood sugar, FSH/LH.

Small Print:Echocardiogram, EEG, urinary 5HIAA and VMA, gastrin level, further specialised endocrine tests.

  • FBC: Raised haemoglobin and PCV in polycythaemia (may also be elevated platelets and WCC), raised MCV in chronic alcohol misuse.
  • Biochemistry: LFT and γGT abnormal in alcohol misuse. TFT will reveal hyperthyroidism.
  • Blood sugar: To reveal hypo- or hyperglycaemia.
  • FSH/LH of limited use as does not correlate well with symptoms (useful only if premature menopause suspected).
  • Echocardiography: If mitral stenosis suspected.
  • EEG: For possible epilepsy.
  • Specialist tests might include 24 h urinary 5-HIAA if carcinoid syndrome suspected, 24 h urinary-free catecholamines and VMAs if phaeochromocytoma suspected and further endocrine tests (e.g. for Cushing’s syndrome).

Top Tips

  • Many women complaining of flushing will suspect the cause is the menopause. Address this possibility in the consultation, especially in young women fearing ‘an early change’.
  • A constantly flushed face in older men is likely to be due to alcohol, polycythaemia or rosacea.
  • Anxiety is likely if the circumstances fit – but bear in mind that hyperthyroidism can produce a very similar clinical picture.
  • It can be difficult to distinguish anxiety from menopausal symptoms in a woman of menopausal age. Flushes with sweats waking the woman at night are more likely to be caused by the menopause – but a trial of treatment is the acid test (though beware of an initial placebo response).

Red Flags

  • Diarrhoea and dyspnoea with flushing after alcohol, food and exercise suggest possible carcinoid syndrome.
  • Flushing followed by an episode of altered consciousness points to a significant cause, such as recurrent hypoglycaemia or epilepsy.
  • Do not be tempted to write this symptom off as the hot flushes of emotional blushing. While common, this problem is unlikely to present in daily practice.
  • Recent onset of severe flushing which is not obviously menopausal or anxiety may have a significant cause, especially if the patient has other symptoms. Have a low threshold for investigations or referral in such cases.

Published: 2nd August 2022 Updated: 10th April 2024

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