Systemic Lupus Erythematosus
Also known as: SLE; LE; Lupus; Disseminated lupus erythematosus; Lupus erythematosus
Tests
Diagnosis is made by the clinical evaluation of physical signs and symptoms and from x-rays. The following laboratory tests are also useful in the diagnosis of SLE:
Diagnosis is made by the clinical evaluation of physical signs and symptoms and from x-rays. The following laboratory tests are also useful in the diagnosis of SLE:
- Autoantibody testing, such as:
- Anti-nuclear antibody (ANA) – is positive in almost all patients with SLE
- Anti-Sm antibody – usually seen only in patients with SLE
- Anti-double stranded DNA – high results are characteristic of active SLE
- Anti-SSA and Anti-SSB – may also be positive
- Urinalysis – may show blood, casts, or protein
- Complete blood count (CBC) – decrease in some cell types, including platelets
- Rheumatoid factor (RF) – may be positive or negative
- Serum protein electrophoresis (SPEP) – increased gamma globulin proteins
- Sed rate (ESR) and C-reactive protein – increased with inflammation
- Cryoglobulin – frequently positive; cryoglobulins are abnormal proteins in the blood that will precipitate when the body temperature drops below normal, causing blockage of the blood vessels. The test involves collecting blood and cooling it in the laboratory, then checking for the presence of the precipitate.
- Complement 3 (C-3) – often decreased; C-3 is one of nine major complement proteins associated with some diseases. Decreased amounts may be associated with lupus, gram-negative septicemia, and shock, as well as malaria.
