Symptom → lab tests
What blood tests are used for heart palpitations?
Short answer
Palpitations that come and go are commonly linked to an overactive thyroid, anemia, and low potassium or magnesium — all checked with TSH and Free T4, a CBC, a metabolic panel and magnesium. Caffeine, stimulants, dehydration and anxiety are the frequent non-lab causes. Palpitations with fainting or chest pain need emergency care.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
When should you see a clinician instead of ordering a test?
- Palpitations with chest pain, fainting, severe shortness of breath or a very fast heart rate that won't slow — call emergency services
- A persistently irregular pulse — see a clinician for an ECG
Why these tests for heart palpitations?
Excess thyroid hormone speeds the heart and causes irregular rhythms; anemia makes the heart work harder; potassium and magnesium govern the heart's electrical stability. Blood tests find these; the rhythm itself is captured by an ECG or wearable monitor, which a clinician can arrange.
Which conditions do these tests help evaluate?
- Thyroid Problems — TSH, Free T4/T3 and antibodies to evaluate an under- or over-active thyroid.
- Anemia — CBC, iron studies, ferritin, B12 and folate to find the cause of fatigue and low energy.
Which tests, and what do they cost?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Complete Thyroid PanelSaves $10.97 vs ordering the tests separately | Panel · 4 tests | $109.99 | No | 3–7 business days |
| General Wellness PanelSaves $6.97 vs ordering the tests separately | Panel · 4 tests | $89.99 | Yes | 1–3 business days |
| TSH (Thyroid Stimulating Hormone) | Test | $26.99 | No | 1–3 business days |
| Free T4 (Thyroxine) | Test | $23.99 | No | 1–3 business days |
| CBC with Differential | Test · 14 biomarkers | $21.99 | No | 1–3 business days |
| Comprehensive Metabolic Panel | Test · 14 biomarkers | $22.99 | Yes | 1–3 business days |
| Magnesium | Test | $19.99 | No | 2–4 business days |
| Ferritin | Test | $24.99 | No | 1–3 business days |
Common questions
Can blood tests show an arrhythmia?
No — a rhythm problem is diagnosed by ECG or a wearable monitor. Blood tests find the metabolic and thyroid causes that provoke palpitations.
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.