Introduction
Blood tests do not diagnose every heart condition, but they often provide important context. Depending on your symptoms and history, they may look for anaemia, thyroid disease, electrolyte imbalance, kidney function, inflammation, cholesterol or markers that help assess strain on the heart.
What the result can tell us
An abnormal result is interpreted alongside your symptoms, examination and other tests. For example, thyroid or electrolyte changes can influence the heart rhythm; kidney function may guide medication choices or the safe use of contrast dye for some scans. A normal result is useful too, but it may not remove the need for an ECG or imaging when those answer a different question.
Key points
- The tests requested depend on the clinical question and your current medicines.
- Most samples are taken from a vein in the arm and take only a few minutes.
- We explain which results matter and what, if anything, they change in the plan.
Patient note
“A blood test is most helpful when we are clear about what we are looking for and how the result will guide the next decision.”
Questions about blood tests
Which blood tests are being requested? Do I need to prepare or fast? When will the results be available, and how might they affect my treatment?
FAQ
Can blood tests find the cause of palpitations?
They can identify contributing factors such as thyroid disease, anaemia or electrolyte imbalance, but they do not replace recording the heart rhythm when symptoms occur.
Do I need blood tests before a scan?
Sometimes. Kidney function may be checked before scans that use contrast dye, particularly when there is a history of kidney disease or relevant medication.