Nine Reasons for False Negative Lyme Blood Test Results

From the Lyme Disease Foundation brochure: Frequently Asked Questions About Lyme Disease

1. Antibodies against Borrelia burgdorferi (Bb) are present, but the laboratory is unable to detect them.

2. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient is currently on, or has recently taken, antibiotics. The antibacterial effect of antibiotics can reduce the body's production of antibodies.

3. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient is currently on or has previously taken anti-inflammatory steroidal drugs. These can suppress a person's immune system, thus reducing or preventing an antibody response.

4. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient's antibodies may be bound with the bacteria with not enough free antibodies available for testing.

For this reason, some of the worst cases of Lyme disease test negative -- too much bacteria for the immune system to handle.

5. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient could be immunosuppressed for a number of other reasons, and the immune system is not reacting to the bacteria.

6. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the bacteria has changed its makeup (antigenic shift) limiting recognition by the patient's immune system.

7. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient's immune response has not been stimulated to produce antibodies, i.e., the blood test is taken too soon after the tick-bite (8-6 weeks).

Please do not interpret this statement as implying that you should wait for a positive test to begin treatment.

8. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the laboratory has raised its cutoff too high.

9. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient is reacting to the Lyme bacteria, but is not producing the "right" bands to be considered positive.