Approach

Diagnose POTS if a patient has:[1][2][3]

  • Frequent symptoms of orthostatic intolerance when standing that:

    • Interfere with daily living activities

    • Improve rapidly when they return to a supine position

    • Have continued for at least 3 months; AND

  • An increase in heart rate by ≥30 bpm (or ≥40 bpm in patients aged 12 to 19 years old) within 10 minutes of standing from a supine position or head-up tilt (without orthostatic hypotension) that is not due to other causes of sinus tachycardia.[1][2][4]

In addition, identify any comorbidities commonly associated with POTS, and exclude other differentials.[1]

History

Symptoms of orthostatic intolerance include:

  • Palpitations[1][2][3][4]

  • Lightheadedness[1]​​[3][4]

  • Blurred vision[1]

  • Exercise intolerance (which may also be a non-orthostatic feature of POTS)[2][4]

  • Presyncope and syncope[2]

  • Tremor[1][2][4]

  • Generalised weakness[1][2]

  • Fatigue (which may also be a non-orthostatic feature of POTS).​[1][2][3][4]

However, be aware that symptoms of POTS are not limited to changes in posture. Non-orthostatic symptoms include:

  • Dyspnoea[11][32]​​[33]

  • Gastrointestinal symptoms such as bloating, nausea, diarrhoea, constipation, and abdominal pain[1][2][3][4][34]

  • Exercise intolerance[1][2][4]

  • Fatigue[1][2][3][4]

  • Headache[1][2][3][4]

  • Sleep disturbance[2][3][4]

  • Cognitive impairment[1][4]

  • Chest pain[1][4]

  • Bladder disturbance.[35][36]

Determine the duration of the patient’s symptoms; for a diagnosis of POTS, symptoms should have lasted for at least 3 months.[1]

Ask about risk factors for POTS, which include:

  • Recent viral infection (present in around 50% of patients)[4][37]​​

  • Pregnancy[4]

  • Relevant associated comorbidities, such as migraine headaches, irritable bowel syndrome, Ehlers-Danlos syndrome, chronic fatigue syndrome, asthma, fibromyalgia, and autoimmune diseases, particularly Hashimoto’s thyroiditis and coeliac disease.[1][4][13]​​​​[38]​​[39][40]​​​​

Check for features of other conditions that may explain the patient’s symptoms. See Differentials.

Physical examination

Check the patient’s heart rate and blood pressure while they are supine and then standing.[2] This is known as the 10-minute standing test.

  • The patient’s heart rate will typically increase by ≥30 bpm (or ≥40 bpm in patients aged 12 to 19 years old) after changing position from supine to standing, with no orthostatic hypotension (sustained drop in systolic blood pressure by ≥20 mmHg).[1][2][3][4]

  • Allow at least 5 minutes of a supine position and at least 1 minute of standing before checking orthostatic vital signs.[40]​ If there is no significant variation in the patient’s heart rate after 1 minute of standing, repeat the standing heart rate and blood pressure check at 3, 5, and 10 minutes.[40]

  • Note that changes in heart rate are often not apparent after 1 minute of standing in practice. A common mistake is to focus on the changes in heart rate after 1 minute of standing only, rather than the full 10 minutes, which can lead to misdiagnosis.

  • Be aware that some patients have hyperadrenergic POTS, and have increased sympathetic response and excess circulating catecholamine.[1][2]​ Patients with hyperadrenergic POTS will have orthostatic hypertension (increase in systolic blood pressure ≥10 mmHg after standing for 10 minutes).[2]

Undertake a careful cardiac examination to rule out significant structural heart disease.[1]

Examine the patient for other associated comorbidities, which include:[1]

  • Ehlers-Danlos syndrome

  • Autoimmune diseases, particularly Hashimoto’s thyroiditis and coeliac disease.

If the patient has an atypical presentation, examine for neurological diseases that can sometimes be associated with POTS, such as Parkinson’s disease, multiple sclerosis, and peripheral neuropathy, although these are uncommon.[41]

Initial investigations

Electrocardiogram

  • Perform a 12-lead ECG in all patients, to rule out other causes of a patient’s symptoms.[1][2][4]

[Figure caption and citation for the preceding image starts]: ECG showing normal sinus rate and rhythm before the episodeCheema MA et al. BMJ Case Rep. 2019 Apr 20;12(4):e227789; used with permission [Citation ends].com.bmj.content.model.Caption@29c2a81e[Figure caption and citation for the preceding image starts]: ECG showing sinus tachycardia during tilt-table testingCheema MA et al. BMJ Case Rep. 2019 Apr 20;12(4):e227789; used with permission [Citation ends].com.bmj.content.model.Caption@45d26b44

Blood tests

  • Order tests to rule out other causes of the patient’s presentation, which should include thyroid function tests, morning serum cortisol level, and full blood count.[1][2][4][42]

  • In addition, order electrolytes to rule out causes such as adrenal insufficiency.[1][4]​ In practice, electrolytes should also be checked after starting certain pharmacological treatments for POTS, such as fludrocortisone or desmopressin.

Other investigations

Holter monitor

  • Consider a 24-hour Holter monitor, which can help confirm the diagnosis by demonstrating the association between tachycardia and orthostatic changes.​[2]​ A Holter monitor can also rule out supraventricular arrhythmias that may have a similar presentation to POTS.[2]

Organise a tilt-table test if:

  • The diagnosis is unclear after the initial assessment of orthostatic blood pressure and heart rate and you have a high suspicion of POTS.[2] In this scenario, a tilt-table test is helpful because it will provide an assessment of vital signs over a greater time period compared with a simple 10-minute standing test

    OR

  • The patient is not able to perform a 10-minute standing test.[1]

Echocardiogram

  • Organise echocardiogram to exclude heart failure as a differential if you suspect this from the history or there are signs of ventricular dysfunction found on examination (e.g., pitting oedema of the lower extremities, distended jugular veins).​[2][4]

If the patient’s symptoms do not resolve or significantly improve, consider referral to a centre experienced with the autonomic testing of POTS, where available, to organise further investigation of the underlying pathology.[2] However, further investigation should not be performed routinely because the significance for patient management and outcome is unclear.[2] Further investigations include: 

  • Supine and upright plasma adrenaline and noradrenaline level[2]

    • Should be considered if hyperadrenergic POTS is suspected.[43]

  • Thermoregulatory sweat test[2]

    • Detects autonomic neuropathy which is associated with POTS.[2]

  • Quantitative sudomotor axon reflex test[42]

    • Should be considered if neuropathic POTS is suspected.[42]​ Neuropathic POTS is associated with peripheral venous pooling and reduced effective intravascular volume, which is caused by peripheral sympathetic denervation.[1][2]

  • Valsalva manoeuvre and deep breathing test with haemodynamic monitoring[2][4]

    • Can detect autonomic dysfunction.[4]

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