I'M DAMN SHARP! A synopsis of AFP's "Diagnosis of Systemic Lupus Erythematosus"

Diagnosis of Systemic Lupus Erythematosus
JAMES M. GILL, M.D., M.P.H., Christiana Care Health Services, Wilmington, Delaware, ANNA M. QUISEL, M.D., Newark, Delaware, PETER V. ROCCA, M.D., Wilmington, Delaware, DENE T. WALTERS, M.D., Christiana Care Health Services, Wilmington, Delaware
Am Fam Physician. 2003 Dec 1;68(11):2179-2187.
http://www.aafp.org/afp/2003/1201/p2179.pdf

     SLE is an inflammatory disease that infects many organ systems, including the skin, musculoskeletal, renal, GI, cardiac, pulmonary, hematologic, RES, and neuropsychiatric system. The disease is more common in women, especially african-american women. There is also a familial predisposition. SLE patients are at high risk of CAD, respiratory and urinary infections. The most common signs in children include fever, arthritis, renal involvement, and alopecia. 
     The diagnosis of SLE requires at least four of the following 11 criteria (the mnemonic IM DAMN SHARP);
Immunoglobulins (Anti-dsDNA, Anti-Sm, Anti-phospholipid), 
Malar Rash, 
Discoid Rash, 
Antinuclear Antibody, 
Mucositis (Oropharyngeal Ulcers), 
Neurological Disorders, 
Serositis (Pleuritis, Pericarditis), 
Hematologic Disorders, 
Arthritis, 
Renal Disease, and
Photosensitivity
     The diagnosis algorithm goes like this. If the patient has manifestations in two or more organ systems, then an ANA test is done. If the titer is less than 1:40, then it is most likely NOT SLE. If an alternative explanation can not be found, then the patient should be referred to a rheumatologist. If the titer is greater than 1:40, then the above 11 criteria should be investigated. Lab studies, including CBC, UA, serum creatinine, ANA, and the immunologic antibodies, should be drawn. 
     Even though the ANA is very sensitive, many patients may have a false negative test early in the course of the disease. ANA can also be false positive due toother connective tissue diseases, including sjogren's syndrome, scleroderma  RA, and juvenile RA. This is why the ANA should be drawn only after the patient presents with at least two clinical manifestations. The other antibodies (Anti-dsDNA, Anti-Sm, Anti-phospholipid) are helpful in patients with a high ANA titer, but who have not met the other clinical criteria.