*These are the 1997 revised criteria for diagnosing systemic lupus erythematosus (SLE). A patient must have 4 of the 11 criteria to establish the diagnosis of SLE. These criteria may be present at the same or at different times during the patient’s illness. Additional, less specific diagnostic manifestations are noted in Table 90-2.
proteinuria or hematuria to gross hematuria, nephrotic syndrome, and renal failure. Hypertension or the presence of edema suggests lupus renal disease.
Arthralgias and arthritis are common. The arthritis is rarely deforming and typically involves the small joints of the hands; any joint may be involved. Myalgias or frank myositis, with muscle weakness and muscle fatigability, may occur. SLE can affect the central nervous system (CNS), leading to a myriad of symptoms ranging from poor school performance and difficulty concentrating, to seizures, psychosis, and stroke.
Testing for SLE is performed to establish the diagnosis, determine prognosis, and monitor response to therapy. Althoughnonspecific, a positive antinuclear antibody is found in more than 97% of patients with SLE, usually at high titers.Because of its high sensitivity, a negative antinuclear antibodyhas a high negative predictive value for SLE. The presence of
Myositis, myalgia Arthralgia
Figure 90-1 Malar butterfly rash on teenage boy with systemic lupus erythematosus. Note erythema on cheeks and chin, sparing the nasolabial folds.
antibodies to double-stranded DNA should raise suspicionfor SLE because these antibodies are present in most patientswith SLE and are found almost exclusively in the disease. Titers of anti-double-stranded DNA antibodies are quantifiable and vary with disease activity. Antibodies directed against Sm (Smith) are specific to SLE but are found in onlyapproximately 30% of persons with SLE, limiting its clinical utility. Antibodies to Ro (SSA) and La (SSB) also can befound in patients with SLE, but they also occur in patientswith Sjögren syndrome. Likewise patients with SLE can haveantibodies directed against phospholipids, which also can beseen in other rheumatologic diseases and in primary antiphospholipid syndrome.
These antibodies lead to an increased risk of arterial and venous thrombosis and can be detected by the presence of anticardiolipin antibodies, a false-positive Venereal Disease Research Laboratory (VDRL) test, or a prolonged activated partial thromboplastin time.
Hematologic abnormalities also are prevalent in patients with SLE. Leukopenia, primarily manifest as lymphopenia, is common. Thrombocytopenia and anemia of chronic disease may be found. Rarely patients with SLE develop Coombspositive autoimmune hemolytic anemia. Excessive antibody production can lead to polyclonal hypergammopathy with an elevated globulin fraction in the serum. Excessive circulating antibodies and immune complexes also lead to the consumption of complement proteins, with low levels of C3 and C4 and decreased complement function as measured by CH50. Effective therapy returns the low complement levels to normal. This is one way to monitor therapy except in patients with familial deficiency in complement components, which, itself, predisposes to SLE.