Epilepsy and Blood Testing

Medically Reviewed by Christopher Melinosky, MD on August 23, 2022
Written by WebMD Editorial Contributors
2 min read

There are a number of blood tests that may be recommended as part of your epilepsy diagnosis and treatment.

As part of your epilepsy treatment, your doctor may order a complete blood count (CBC). A CBC helps the doctor establish a baseline and can identify infections, allergies, and other abnormalities that may affect the choice of appropriate anticonvulsant medication(s) and help to monitor the possible drug-induced side effects in the future. The CBC measures (among other things):

  • The number of red blood cells (which carry oxygen from the lungs throughout the body)
  • The number of white blood cells (which fight infection)
  • Platelets (which help the blood clot in case of a injury or bleeding)
  • Hemoglobin (the substance in red blood cells that carries oxygen)
  • Hematocrit (the percentage of blood that is made up of red blood cells)
  • Mean corpuscular volume (size of the red blood cells)

Another important blood test is known as a chemistry panel. This test includes an evaluation of sodium, potassium, and blood sugar levels. Kidney and liver function tests are also often included, in what is known as a complete metabolic panel. This test will help your doctor identify conditions such as electrolyte (such as sodium) imbalances, kidney or liver damage, and diabetes, which may either be causing your seizures or may affect the choice of the appropriate anticonvulsant medications prescribed for you (including the doses needed).

Your doctor may decide to run various other blood tests, including blood levels of medications you may be taking for seizure control. These tests are most often ordered when seizures continue to occur or when drug-induced side effects are suspected.

The blood is drawn by a nurse or technician. They will place a tourniquet on your arm to restrict the blood flow through the vein (which makes the vein bigger), clean your arm with an antiseptic, and then insert a needle into the vein. The blood is collected in one or two vials and the tourniquet is released. After the needle is removed, the nurse or technician will put a bandage on your arm.

In the case of epilepsy, blood tests such as a CBC and chemistry panel help your doctor assess your overall health and identify conditions such as infections,  iron deficiency anemia, or diabetes that may be triggering the seizures. Blood tests may also help identify conditions such as kidney or liver damage that may affect your treatment and to monitor for the possible occurrence of medication-induced side effects.