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SLE (SYSTEMIC LUPUS ERYTHEMATOUSA), WHAT IS IT ?

Posted by dokterhasan on October 1, 2009

What is Systemic lupus erythematosus (SLE) ?
It is a rheumatic multisystem disease of unknown cause that is characterized by the presence of autoantibodies directed against self-antigens. These antibodies cause inflammatory damage to target organs, including the kidneys, blood-forming cells, and the central nervous system (CNS). The natural history of the disease is unpredictable. Untreated or undertreated SLE may be followed by spontaneous remission, years of smoldering disease, or rapid death. Conversely, early diagnosis and appropriate treatment can greatly improve the prognosis.

What is the main cause of SLE death ?
Major causes of death in patients with SLE include nephritis, CNS disease, infections, pulmonary hemorrhage and myocardial infarction.

What is the Hallmark of SLE ?
The hallmark of SLE is autoantibody production against self-antigens, particularly DNA, as well as other nuclear antigens, ribosomes, platelets, coagulation factors, immunoglobulin, erythrocytes, and leukocytes. Elevated levels of immunoglobulin, particularly antidouble-stranded DNA antibodies, are associated with circulating and tissue-bound immune complexes. These lead to complement fixation and recruitment of inflammatory cells, which results in tissue injury. The autoantibodies are synthesized and secreted by activated polyclonal B-lymphocytes. The dysregulation is potentially triggered by exposure to viral elements or drugs. The net result is that circulating self-reactive lymphocytes that normally undergo apoptosis before birth remain active. Other forms of immune dysfunction have also been described in SLE, including defects in macrophage phagocytosis, complement abnormalities, and abnormal complement receptors. Drug-induced lupus has been characterized by the presence of antihistone antibodies and corresponding immunofluorescent staining.
Multiple simultaneous mechanisms lead to end-organ damage in SLE. Vasculitis is a hallmark finding, with fibrinoid deposits in the blood vessel walls of affected organs and parenchymal changes with hematoxylin bodies that most likely represent degenerated cell nuclei. Immune-complex depositions with activated complement, rheumatoid nodules, and even granuloma in affected tissues having been described.

What is Differential Dianosis of SLE ?
Because SLE is a multisystem disease, it can mimic many medical problems. It is considered in the differential diagnosis for a variety of symptoms, including fever of unknown origin, lymphadenitis, arthralgia, nephritis, cytopenias, abdominal pain, dizziness, weight loss, and rashes.

What is 4 of 11 Diagnosis Criteria of SLE ?
Four out of 11 accepted criteria are required to establish the diagnosis of SLE. They are used both in the research setting and by clinicians to better define a disease that presents in such diverse ways and is often difficult to diagnose. The criteria are listed as the followin :
• Hematologic finding (eg, anemia, thrombocytopenia)
• Positive test for ANA
• Serositis (eg, pleural effusion)
• Arthritis
• Malar rash
• Discoid rash
• Immunologic disorder (eg, positive double-stranded DNA)
• Photosensitivity
• Oral ulcers
• Renal disease
• Neurologic disorder

What is the Pathognomic Lab Finding in SLE ?
Antidouble-stranded DNA findings are specific for lupus than the ANA titer. The serum levels of hemolytic complement (CH50), C3, and C4 are decreased in about two-thirds of pediatric SLE patients. Hypergammaglobulinemia is frequently found. The maternal immunoglobulin G (IgG) against Ro, La, and/or U1-ribonucleoprotein can be passively transported across the placenta and result in the heart block condition that is seen in neonatal lupus erythematosus.

Elevated ANA titers should prompt the clinician to screen for SLE, as this finding is present in at least 90% of patients; however, it is not pathognomic and can be associated with rheumatic conditions, such as vasculitic syndromes, chronic autoimmune hepatitis, infectious mononucleosis, scleroderma, and hyperextensibility syndromes.

SOURCE : CME MEDSCAPE.EMEDICINE

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