4. Systemic lupus erythematosus (SLE)

Definition
Systemic lupus erythematosus (SLE) is a chronic, inflammatory autoimmune disorder. It may affect the skin, joints, kidneys, and other organs.

Alternative Names
Disseminated lupus erythematosus; SLE; Lupus; Lupus erythematosus

Causes, incidence, and risk factors
Normally, the immune system controls the body's defenses against infection. In SLE and other autoimmune diseases, these defenses are turned against the body and rogue immune cells attack tissues. Antibodies may be produced that can react against the body's blood cells, organs, and tissues. These lead immune cells to attack the affected systems, producing a chronic (long-term) disease.

The mechanism or cause of autoimmune diseases is not fully known, but many researchers suspect it occurs following infection with an organism that looks similar to particular proteins in the body, which are later mistaken for the organism and wrongly targeted for attack.

The disease affects 9 times as many women as men. It may occur at any age, but appears most often in people between the ages of 10 and 50 years. SLE may also be caused by certain drugs. When this occurs, it is known as drug-induced lupus erythematosus and it is usually reversible when the medication is stopped.

The course of the disease may vary from a mild episodic illness to a severe fatal disease. Symptoms also vary widely in a particular individual over time and are characterized by periods of remission and exacerbation. At its onset, only one organ system may be involved. Additional organs may become involved later. The following organ system manifestations may be seen, but other manifestations are possible.

MUSCLES AND BONES
Almost all people with SLE have joint pain and most develop arthritis. Frequently affected joints are the fingers, hands, wrists, and knees. Death of bone tissue can occur in the hips and shoulders and is frequently a cause of pain in those areas.

SKIN
A "butterfly" rash over the cheeks and bridge of the nose affects about half of those with SLE. The rash is usually worsened by sunlight. A more diffuse rash may appear on other body parts that are exposed to the sun. Other skin lesions or nodules can also occur.

KIDNEYS
Some people with SLE have deposits of antibodies within the cells (glomeruli) of the kidneys. However, less than 50% have lupus nephritis as defined by persistent inflammation (irritation and swelling) in the kidney. These patients may eventually develop kidney failure and require dialysis or kidney transplantation.

NERVOUS SYSTEM
Nerve disorders can affect up to 25% of those with SLE. Mild mental problems are the most common symptom, but any area of the brain, spinal cord, or nervous system can be affected. Seizures, psychosis, organic brain syndrome, and headaches are some of the nervous system disorders that can occur.

BLOOD
Blood disorders can affect up to 85% of those with SLE. Venous or arterial blood clots can form and are associated with strokes and pulmonary embolism, or pregnancy loss. Predisposition to blood clots, or less commonly bleeding, occurs due to antibodies against lipids involved in blood clotting and is referred to as anti-phospholipid antibody syndrome (APS). (See Lupus anticoagulant.) Often platelets are decreased which may cause bleeding or clotting problems. Anemia of chronic disease often develops at some point in the course SLE.

HEART
Inflammation of various parts of the heart may occur as pericarditis, endocarditis, or myocarditis. Chest pain and arrhythmias may result from these conditions.

LUNGS
Pleurisy, an inflammation of the lining of the lung, and pleural effusions, a fluid collection between the lung and its lining, can occur as a result of SLE. Chest pain and shortness of breath are frequently results of these disorders.
African Americans and Asians are affected more often than people from other races.

Symptoms
• fever
• fatigue
• general discomfort, uneasiness or ill feeling (malaise)
• weight loss
• skin rash - a "butterfly" rash, aggravated by sunlight
• sensitivity to sunlight
• joint pain and swelling
• arthritis
• swollen glands
• muscle aches
• nausea and vomiting
• pleuritic chest pain
• seizures
• psychosis

Additional symptoms that may be associated with this disease:
• blood in the urine
• coughing up blood
• nosebleed
• swallowing difficulty
• skin color is patchy
• red spots on skin
• fingers that change color upon pressure or in the cold
• numbness and tingling
• mouth sores
• hair loss
• abdominal pain
• visual disturbance

Signs and tests
The diagnosis of SLE is based upon the presence of at least four out of eleven typical characteristics of the disease.
Tests to determine the presence of these disease manifestations may vary, but will include some of the following:

• antinuclear antibody (ANA) panel including anti-DNA and anti-Smith antibodies, with the latter two tests generally positive in lupus alone
• characteristic skin rash or lesions
• chest x-ray showing pleuritis or pericarditis
• listening to the chest with a stethoscope to reveal heart friction rub or pleural friction rub
• urinalysis to show blood, casts, or protein in the urine
• CBC showing a decrease in some cell types
• kidney biopsy
• neurological examination

This disease may also alter the results of the following tests:
• WBC count
• serum globulin electrophoresis
• rheumatoid factor
• urine protein
• serum protein electrophoresis
• mononucleosis spot test
• ESR
• cryoglobulins
• Coombs' test - direct
• complement component 3 (C3)
• complement
• antithyroid microsomal antibody
• antithyroglobulin antibody
• antimitochondrial antibody
• anti-smooth muscle antibody

Treatment
The disease has multiple symptoms with variable severity, which determines individual treatment. There is no cure for SLE.
Mild disease (rash, headaches, fever, arthritis, pleurisy, pericarditis) requires little therapy. Nonsteroidal anti-inflammatory medications (NSAIDS) are used to treat arthritis and pleurisy. Corticosteroid creams are used to treat skin rashes. Antimalarial drugs (hydroxychloroquine) and low dose corticosteroids are sometimes used for skin and arthritis symptoms.

Sensitivity to light is treated by protective clothing, sunglasses and sunscreen.

Severe or life-threatening manifestations (hemolytic anemia, extensive heart or lung involvement, kidney disease, central nervous system involvement) often requires treatment by both rheumatologists and specialists in the specific area. Corticosteroids or medications to suppress the immune system may be prescribed to control the various symptoms. Some health care professionals use cytotoxic drugs (drugs that block cell growth) to treat people who do not have a good response to corticosteroids or who are dependent on high doses of corticosteroids.

Expectations (prognosis)
The outcome for people with SLE has improved over recent years. Many of those affected have mild illness. Women with SLE who become pregnant are often able to carry the pregnancy safely to term and deliver normal infants, provided severe kidney or heart disease is not present and the SLE is being managed. The presence of anti-phospholipid antibodies may increase the possibility of pregnancy loss.
The 10-year survival rate for lupus patients exceeds 85%. People with severe involvement of the brain, lungs, heart and kidney have the worst prognosis in terms of overall survival and disability.

Complications
• infection
• kidney failure
• thrombocytopenia
• hemolytic anemia
• myocarditis
• seizures

References
Harris ED, Budd RC, Genovese MC, Firestein GS, Sargent JS, Sledge CB. Kelley's Textbook of Rheumatology. 7th ed. St. Louis, Mo: WB Saunders; 2005.
Noble J. Textbook of Primary Care Medicine. 3rd ed. St. Louis, Mo: Mosby; 2001.

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