Atlas of pathophysiology, 2 Edition

Part II - Disorders

Immunologic Disorders

Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disorder that affects the connective tissues.

SLE is characterized by recurring remissions and exacerbations, which are especially common during the spring and summer. It strikes women 8 times as often as it does men, increasing to 15 times as often during childbearing years. The prognosis improves with early detection and treatment but remains poor for patients who develop cardiovascular, renal, or neurologic complications, or severe bacterial infections.


Direct cause unknown

Predisposing factors

·   Physical or mental stress

·   Streptococcal or viral infections

·   Exposure to sunlight or ultraviolet light

·   Immunization

·   Pregnancy

·   Abnormal estrogen metabolism

·   Drugs, including procainamide, hydralazine, anticonvulsants; less commonly, penicillins, sulfa drugs, oral contraceptives


Autoimmunity is believed to be the prime mechanism in SLE. The body produces antibodies against components of its own cells, such as the antinuclear antibody (ANA), and immune complex disease follows. Patients with SLE may produce antibodies against many different tissue components, such as red blood cells (RBCs), neutrophils, platelets, lymphocytes, or almost any organ or tissue in the body.

Signs and symptoms

·   Joint pain

·   Raynaud's phenomenon

·   Photosensitivity

·   Tachycardia, central cyanosis, and hypotension

·   Altered level of consciousness, weakness of the extremities, and speech disturbances

·   Skin lesions

·   Malar rash

·   Ulcers in the mouth or nose

·   Patchy alopecia (common)

·   Vasculitis

·   Lymph node enlargement (diffuse or local and nontender)

·   Fever

·   Pericardial friction rub

·   Irregular menstruation or amenorrhea, particularly during flare-ups

·   Chest pain and dyspnea

·   Emotional instability, psychosis, organic brain syndrome, headaches, irritability, and depression

·   Oliguria, urinary frequency; dysuria, and bladder spasms

Diagnostic test results

·   Complete blood count with differential reveals anemia and a reduced white blood cell (WBC) count; decreased platelet count; elevated erythrocyte sedimentation rate; and serum electrophoresis showing hypergammaglobulinemia.

·   Positive ANA, DNA, and lupus erythematosus cell test findings in most patients with active SLE, but only slightly useful in diagnosing the disease (the ANA test is sensitive but not specific for SLE).

·   Urine studies showing RBCs, WBCs, urine casts and sediment, and significant protein loss.

·   Blood studies detect decreased serum complement (C3 and C4) levels, indicating active disease; increased C-reactive protein during flare-ups; and positive rheumatoid factor.

·   Chest X-rays reveal pleurisy or lupus pneumonitis.

·   Electrocardiogram reveals a conduction defect with cardiac involvement or pericarditis.

·   Renal biopsy shows the progression of SLE and the extent of renal involvement.

·   Skin biopsy shows immunoglobulin and complement deposition in the dermal-epidermal junction in 90% of patients.


·   Nonsteroidal anti-inflammatory compounds

·   Topical corticosteroid creams

·   Intralesional corticosteroids or antimalarials

·   Systemic corticosteroids

·   High-dose steroids and cytotoxic therapy

·   Dialysis or renal transplant

·   Antihypertensives

·   Dietary changes

·   Sunscreen use





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