Blood Tests for Epilepsy Diagnosis
Reviewed by: HU Medical Review Board | Last reviewed: November 2021
Epilepsy is a neurological (brain) disease that causes people to have seizures. But people may have seizures for many reasons, not just epilepsy. Migraine, stroke, low blood sugar, brain tumors, lead poisoning, and narcolepsy may all cause symptoms that look similar to epilepsy seizures.1-4
It is standard for a hospital to run a drug screening test on people who go to the emergency room after a first seizure.5
Complete blood count
A complete blood count (CBC) measures red blood cells, white blood cells, hemoglobin, and platelets. It also measures the balance among these parts of blood. A CBC can give the doctor an idea of whether you have anemia, an infection, inflammation, or cancer.
CBC results may tell your doctor many things, such as:3
- A low red blood cell count can mean you have anemia, a vitamin deficiency, or abnormal bleeding.
- A high or low white blood cell count may mean you have an infection or an allergy. Certain medicines also affect the white cell count.
- A low platelet count may mean the bone marrow is not making enough platelets or that antibodies are attacking your platelets.
To run a CBC, a nurse or health aide called a phlebotomist will draw blood from your arm.
A glucose test measures the amount of sugar (glucose) in the blood. This test can help your doctor decide if your seizures were caused by low blood sugar levels.
To run a blood glucose test, blood will need to be drawn from the arm. Glucose levels can also be checked from a fingerstick test. The person needs to be fasting for the most accurate results, which means not eating or drinking anything other than water for at least 8 hours before the test.6
A chemistry panel measures the level of sugar (glucose), minerals, proteins, electrolytes, and fluid balance in the blood. These tests give your doctor an idea how well your kidneys, liver, and metabolism are working.7
This test looks for evidence of poisons, illegal drugs, or toxins that may cause seizures.4
Other tests for epilepsy
To diagnose epilepsy, your doctor will also order other tests and conduct a physical exam. The other tests may include:1,2,7
- EEG (electroencephalogram)
- Brain imaging tests
- Neurological exam
- Spinal tap (lumbar puncture)
- Hospital monitoring
- Genetic testing
Once you have been diagnosed with epilepsy and are taking anti-seizure drugs, you may need regular blood work.