Differential Diagnosis for an Elevated RPR
The Rapid Plasma Reagin (RPR) test is a screening tool used to detect syphilis, a sexually transmitted infection caused by the bacterium Treponema pallidum. An elevated RPR indicates the presence of antibodies against syphilis, but it is not specific to the disease and can be positive in other conditions. Here is a differential diagnosis for an elevated RPR, categorized for clarity:
Single Most Likely Diagnosis
- Syphilis: This is the most obvious cause of an elevated RPR. Syphilis is a sexually transmitted disease with various stages, including primary, secondary, latent, and tertiary syphilis. The RPR test detects non-treponemal antibodies, which are present in most patients with syphilis.
Other Likely Diagnoses
- Mononucleosis: Infectious mononucleosis, caused by Epstein-Barr virus (EBV), can lead to a false-positive RPR result due to the production of heterophile antibodies.
- Lyme Disease: Lyme disease, caused by Borrelia burgdorferi, can also cause a false-positive RPR due to cross-reacting antibodies.
- Autoimmune Disorders: Certain autoimmune conditions, such as systemic lupus erythematosus (SLE), can produce false-positive results due to the presence of antiphospholipid antibodies.
- Viral Infections: Other viral infections, like hepatitis and HIV, can lead to a false-positive RPR due to the stimulation of non-specific antibody production.
Do Not Miss Diagnoses
- Pregnancy Complications: In pregnant women, untreated syphilis can lead to congenital syphilis, which has severe consequences for the fetus. Therefore, it is crucial to confirm the diagnosis and treat syphilis promptly in pregnant women.
- Neurosyphilis: This condition occurs when syphilis infects the central nervous system. Early detection and treatment are critical to prevent long-term neurological damage.
- Aortic Aneurysm: Tertiary syphilis can cause aortic aneurysms, which are potentially life-threatening if they rupture.
Rare Diagnoses
- Yaws: Caused by Treponema pallidum subspecies pertenue, yaws is a tropical disease that can cause a positive RPR.
- Bejel: Also known as endemic syphilis, bejel is caused by Treponema pallidum subspecies endemicum and can lead to a positive RPR.
- Pinta: Caused by Treponema carateum, pinta is another tropical disease that can result in a false-positive RPR.
- Rat-Bite Fever: This condition, caused by Streptobacillus moniliformis or Spirillum minus, can lead to a false-positive RPR in rare cases.
- Leptospirosis: Infection with Leptospira species can, in rare instances, cause a false-positive RPR result.