Laboratory Testing for POTS
All patients with suspected POTS should undergo a core laboratory panel including complete blood count, basic metabolic panel, thyroid function tests, and glycohemoglobin to exclude secondary causes and guide treatment decisions. 1
Essential Core Laboratory Tests
The following tests should be ordered for every patient being evaluated for POTS:
Complete Blood Count (CBC): Essential to evaluate for anemia, which can contribute to orthostatic symptoms or exacerbate POTS 1
Basic Metabolic Panel: Assesses electrolyte abnormalities and renal function that may affect cardiovascular regulation 1
Thyroid Function Tests (TSH): Mandatory in all patients because thyroid disorders (both hyperthyroidism and hypothyroidism) can mimic or exacerbate POTS symptoms 2, 1, 3
Glycohemoglobin (HbA1c): Screens for diabetes mellitus, which can cause autonomic dysfunction 2, 1
Cardiovascular Biomarkers
Additional cardiac-specific testing should include:
Brain Natriuretic Peptide (BNP) or NT-proBNP: Helps identify cardiac causes of symptoms and assess for potential hypovolemic state 2, 1
Serum Electrolytes (including calcium and magnesium): Important for cardiac conduction and muscle function 2, 1
Additional Laboratory Tests Based on Clinical Presentation
Consider these tests when specific clinical features are present:
Fasting transferrin saturation: Screen for hemochromatosis in patients of Northern European descent, as iron overload can affect cardiac function 2
Serum tryptase levels: If mast cell activation syndrome (MCAS) is suspected in patients with episodic multisystem symptoms, collect baseline and 1-4 hours after symptomatic exacerbations (requires 20% increase over baseline plus 2 ng/mL to demonstrate mast cell activation) 4
HIV screening: Reasonable in high-risk patients, though HIV cardiomyopathy typically presents with other HIV signs first 2
Important Clinical Considerations
Target your laboratory testing based on clinical assessment rather than ordering comprehensive panels without specific indications. 1 The American College of Cardiology emphasizes that additional laboratory testing such as D-dimer should only be considered based on the specific clinical presentation 2.
Common Pitfalls to Avoid
Do not order extensive autoimmune or inflammatory panels routinely unless there are specific clinical indicators suggesting these conditions 1
Avoid ordering serum viral antibody titers in patients with recent-onset POTS, as the yield is low and therapeutic implications are uncertain 2
Remember that laboratory testing alone cannot diagnose POTS—the diagnosis requires demonstration of orthostatic tachycardia criteria through active stand testing or tilt-table testing 1, 3
Follow-Up Laboratory Monitoring
Monitor electrolytes if patients are started on medications affecting fluid balance, particularly mineralocorticoids or diuretics 2, 1. Repeat thyroid function tests if symptoms change or do not improve with treatment 2.