Understanding Your Laboratory Blood Test: What to Expect and What Your Results Mean

A laboratory blood test is a common medical procedure in which a small sample of your blood is analyzed to measure cells, substances, and markers that show how your body is working. It gives your healthcare provider important information about your overall health.

This test looks for antibodies produced by your immune system against Borrelia burgdorferi, the bacterium that causes Lyme disease. The test is performed on cerebrospinal fluid (CSF), the clear fluid that surrounds your brain and spinal cord. It detects three types of antibodies: IgM (early infection), IgG (later infection), and IgA (mucosal/early response).

This test is performed to help diagnose medical conditions, monitor an illness you already have or the treatment you are receiving, screen for risk factors before symptoms appear, and guide your doctor in choosing the care plan that is right for you.

This test is primarily used when a patient has symptoms of Lyme disease affecting the nervous system (neuroborreliosis), such as facial palsy, meningitis, radiculoneuritis, or encephalopathy. It helps doctors determine if the Lyme bacteria have spread to the central nervous system.

A trained healthcare professional usually collects the sample from a vein in your arm using a small needle. The site is cleaned first, only a small amount of blood is drawn into tubes, and a bandage is applied afterward. You may feel a brief sting or pinch.

Cerebrospinal fluid is collected through a procedure called a lumbar puncture or spinal tap. A healthcare provider inserts a thin needle into the lower back to withdraw fluid from the space around the spinal cord. This procedure is performed under sterile conditions.

Your results are compared with established reference ranges. Values within the normal range usually suggest typical body function, while results that are higher or lower may point to a condition that needs further evaluation. Your doctor will interpret the numbers together with your symptoms and medical history.

The presence of Lyme disease antibodies in CSF indicates that the bacteria may have entered the central nervous system. IgM antibodies typically appear first (within 1-2 weeks), followed by IgG (within 4-6 weeks). The interpretation considers which antibody types are present, their levels, and the patient's clinical symptoms. A positive result combined with typical symptoms strongly suggests neuroborreliosis.