Blood Tests

Blood tests are laboratory analyses of a blood sample, used to measure substances in the blood that indicate how organs are functioning, whether disease is present, and how the body is responding to treatment. A wide range of blood tests is used in cardiac care, both during acute hospital admission and in ongoing outpatient management.

Commonly used blood tests in cardiac and post-arrest care include:

– **Full blood count (FBC):** measures red blood cells (including [haematocrit](/glossary/hematocrit/) and haemoglobin), white blood cells, and platelets. Used to detect [anaemia](/glossary/anaemia/), infection, and clotting problems.
– **U&Es (urea and electrolytes):** measures kidney function and electrolyte levels (sodium, potassium, creatinine). Electrolyte imbalances such as low potassium or magnesium can trigger dangerous [arrhythmias](/glossary/cardiac-arrhythmia/) and are closely monitored after [cardiac arrest](/glossary/cardiac-arrest/).
– **Troponin:** a protein released by damaged heart muscle cells. Elevated troponin is the key marker of a [heart attack](/glossary/heart-attack/) and is measured serially to confirm or exclude myocardial injury.
– **[NT-proBNP](/glossary/nt-probnp/):** a marker of cardiac wall stress, used to diagnose and monitor [heart failure](/glossary/heart-failure/).
– **Thyroid function tests (TFTs):** thyroid abnormalities can contribute to [arrhythmia](/glossary/cardiac-arrhythmia/) and are routinely checked in the cardiac arrest workup.
– **Lipid profile:** measures total cholesterol, LDL, HDL, and triglycerides. Important for assessing cardiovascular risk and monitoring [statin therapy](/glossary/statin-therapy/).
– **Blood glucose and HbA1c:** assess for [diabetes](/glossary/diabetes/) and glucose control.
– **Drug levels:** for medications such as [digoxin](/glossary/digoxin/) and [amiodarone](/glossary/amiodarone/), blood levels may be checked to ensure therapeutic dosing and avoid toxicity.
– **Clotting studies (INR):** used to monitor [anticoagulation](/glossary/anticoagulation/) therapy in patients taking warfarin.

Results are interpreted alongside clinical findings and other investigations. Abnormal results prompt treatment adjustments and are an important part of managing cardiac patients safely.