Urinalysis may show hematuria and proteinuria, identifying patients with lupus nephritis. Serum blood urea nitrogen and creatinine evaluate renal function. Hypoalbuminemia and hypoproteinemia may be present. Elevation of muscle enzymes may be a clue for the presence of myositis. Elevated cerebrospinal fluid (CSF) protein and an elevated IgG-to-albumin ratio when comparing CSF with serum (IgG index) can indicate antibody production in the CSF and help diagnose SLE affecting the CNS. CNS lupus has a specific pattern on gadolinium-enhanced magnetic resonance imaging.
Because SLE is a multisystem disease, it can be difficult to diagnosis early in the disease course. Suspicion must be high in patients who present with diffuse symptoms, particularly adolescent girls. Many of the clinical manifestations of SLE are found in other inflammatory illnesses and during acute or chronic infection. Criteria have been developed for the diagnosis of SLE (see Table 90-1). The presence of 4 of 11 of these criteria has 98% sensitivity and 97% specificity for SLE.
Corticosteroids have been the mainstay of treatment for SLE for decades. Initial use of pulse methylprednisolone and high-dose oral prednisone (up to 2 mg/kg) frequently is required, followed by cautious tapering to minimize recurrence of symptoms. Nonsteroidal anti-inflammatory drugs have been used to treat the arthralgias and arthritis associated with SLE. Hydroxychloroquine is used not only for the treatment of lupus skin disease, such as discoid lupus, but as maintenance therapy. Hydroxychloroquine treatment results in longer periods of wellness between flares of disease as well as decreased numbers of flares.
Corticosteroids and hydroxychloroquine frequently are not sufficient therapies for lupus nephritis or cerebritis. Cyclophosphamide is effective for the worst forms of lupus nephritis, with significant improvements in outcome and decreased rates of progression to renal failure. CNS lupus responds to cyclophosphamide. For patients who are not able to tolerate the tapering of corticosteroids, the use of steroid-sparing agents, such as azathioprine, methotrexate, or mycophenolate mofetil, may be indicated.
Patients with SLE should be counseled to wear sun block and avoid sun exposure because exposure to the sun precipitates flares of the disease. Because of this prohibition,patients benefit from calcium and vitamin D supplementation to reduce the risk of osteoporosis that may result from prolonged corticosteroid use. Early treatment of hyperlipidemiato decrease long-term cardiovascular complications is alsoindicated.
Long-term complications include avascular necrosis secondary to corticosteroid use, infections, and myocardial infarction. Adult patients with SLE develop accelerated atherosclerosis, not only because of prolonged corticosteroid use but also due to the underlying disease. All patients with SLE should be counseled regarding their weight and maintaining an active lifestyle to reduce other cardiac risk factors.
Outcomes for SLE have improved significantly over the past several decades and depend largely on the organ systems that are involved. Worse prognoses are seen in patients with severe lupus nephritis or cerebritis, with risk of chronic disability or progression to renal failure. With current therapy for the disease and the success of renal transplantation, however, most patients live well into adulthood.
The etiology of juvenile dermatomyositis (JDM) is unknown. It is characterized by activation of T and B lymphocytes, leading to vasculitis affecting small vessels of skeletal muscle, with immune complex deposition and subsequent inflammation of blood vessels and muscle. JDM may follow infections, allergic reactions, or sun exposure, but no causal relationship has been shown.