Understanding Lab Tests for False Positive Result in Certain Conditions
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
False positive results occur when a laboratory test indicates the presence of a condition, infection, or substance that is not actually present in the patient. This phenomenon is particularly relevant in patients with autoimmune disorders, where the immune system's overactivity can interfere with certain blood test interpretations.
Recommended Test
Hep B Core Antibody, IgM
This test can produce false positive results in patients with autoimmune disorders such as rheumatoid arthritis or systemic lupus erythematosus. The false positivity occurs due to nonspecific polyclonal activation of B cells, which can mimic the antibody response seen in actual Hepatitis B infection. Healthcare providers should consider the patient's clinical history and autoimmune status when interpreting positive results.
2907 reviews
Why False Positives Occur
In autoimmune conditions such as rheumatoid arthritis and systemic lupus erythematosus, the immune system produces antibodies that can cross-react with test components or cause nonspecific activation of immune cells. This can lead to positive results on tests designed to detect specific infections or conditions, even when those conditions are not present.
Clinical Significance and Follow-up
When false positive results are suspected, healthcare providers may recommend confirmatory testing using different methodologies or additional clinical correlation. It's essential to interpret test results within the context of the patient's overall health status, symptoms, and medical history.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for proper interpretation of laboratory results and clinical correlation.
