Red flag symptoms: Hyperhidrosis

Anxiety is a common reason for sweating but more serious causes should not be missed.

Thyrotoxic goitre: thyrotoxicosis may cause excessive sweating
Thyrotoxic goitre: thyrotoxicosis may cause excessive sweating

Excessive sweating, also known as hyperhidrosis, is a non- specific symptom and has a range of underlying causes.

Patients presenting with hyperhidrosis usually have associated symptoms which will indicate the likely cause, but it is important to enquire about the red flag symptoms listed above to exclude serious underlying pathology.

Red flag symptoms
  • Systemically unwell
  • Night sweats
  • Weight loss
  • Palpitations
  • Chest pain

History
It is useful to note the duration and distribution of the sweating. An acute presentation may suggest infection or a cardiac cause. A chronic history would support a diagnosis of anxiety.

Anxiety is a common cause of sweating in primary care but other causes must be considered first and it should be noted that night sweats would be unusual in cases of anxiety.

If the sweating is focal (in palms, soles or axillae) and has persisted for more than six months, consider a diagnosis of primary localised (focal) hyperhidrosis if at least two of the following features are present:

  • bilateral and symmetrical sweating
  • excessive sweating at least once a week
  • disruption of daily activities
  • cessation during sleep
  • positive family history.

The patient should be asked about recent travel, occupation and other risk factors for infection. A full drug and alcohol history should be taken.

Examination
A thorough physical examination should be undertaken, checking for lymphadenopathy, hepatomegaly and splenomegaly. Pulse and BP should be recorded. Thyrotoxicosis and a phaeochromocytoma can cause tachycardias and AF. The temperature should be taken if there is any concern about infection.

Investigations
First-line blood tests would include an FBC to check for infection and malignancy and TFTs for thyrotoxicosis.

Consider inflammatory markers to look for evidence of infection or malignancy. Hypoglycaemia can be a cause of sweating so a blood glucose, ideally at the time of sweating, would be useful, however if the patient is acutely unwell a finger prick test to check instant blood glucose should be undertaken.

If the diagnosis of menopause is being considered, an FSH and LH may be helpful. An ECG should be performed if indicated by examination findings and a chest X-ray requested if infection, especially TB, or malignancy is suspected.

Phaeochromocytomas are rare but if under consideration 24-hour urinary catecholamines can be done. It is important to ensure the urine collection is performed according to local laboratory protocols, as the result may otherwise be misleading. If the index of suspicion is high, a referral to an endocrinologist for investigation is appropriate.

  • Dr Porter is a salaried GP in Rochford, Essex
Possible causes
  • Anxiety
  • Drug-induced - alcohol, drug withdrawal, venlafaxine
  • Infection - HIV, TB, infective endocarditis
  • Menopause
  • Thyrotoxicosis
  • Phaeochromocytoma
  • Hypoglycaemia
  • Acromegaly
  • Malignancy
  • Syncope
  • Acute coronary syndrome
  • Primary localised hyperhidrosis

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