I have a 35-year-old female patient with a 3-year history of polyarthritis who was admitted to the hospital with complaints of fever of a 3-week duration. All investigations leading to an infective pathology, including bloodwork, urine cultures, and chest x-ray, were negative. Her collagen profile: Rh factor-negative, C-reactive protein (CRP)-positive, anti-DNA Abs (double-stranded)-positive. The ECG was negative for vegetations.

Do you think this fever of unknown origin could be a result of systemic lupus erythematosus (SLE) or more likely from another cause? Or could it be from a combination of SLE and an infective etiology? The patient was treated with ceftriaxone and an aminoglycoside for 1 week. After the ANA report, she was started on corticosteroids (60 mg of prednisolone per day). Thank you for your thoughts about this patient.

Prabhakar Rao, MD

Response from Robert Terkeltaub, MD

This young woman with a new, prolonged fever of unknown etiology has a longstanding history of polyarthritis. Blood and other cultures appeared to be negative. We do not have information about her ANA titer and pattern, but she is anti-dsDNA antibody-positive, which indicates she has SLE. Indeed, SLE commonly presents with polyarthralgias and polyarthritis in young women and may present as fever of unknown origin. The primary question is whether the information at hand can tell you if she most likely has fever due to the SLE or due to superimposed infection, a common problem in active SLE. Unfortunately, serologic tests such as anti-dsDNA antibody positivity and low complement cannot give you the answer. However, marked elevation of CRP can point to the possibility of infection in SLE, as there is evidence that the CRP level generally does not become markedly elevated in SLE due to activity of the SLE alone.[1,2]

In this situation, it would be important to know if there is pleuritic pain and evidence of active skin involvement, nephritis, or central nervous system disease. If a thorough infectious disease work-up is negative, and associated with the lack of response to antibiotics and a lack of evidence of malignancy or a drug reaction, then directing treatment to SLE as the likely cause of the fever of unknown origin would be appropriate.


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