Lupus Health Article

Definition

Lupus, also known as lupus erythematosus, is an autoimmune inflammatory disorder that occurs mostly in women.

Description

Lupus produces widely varying symptoms, although joint pain is reported by most patients and skin lesions are common. Lupus can cause short periods of symptoms alternating with healthy periods, or can progress into a life-threatening disorder affecting the heart, kidneys, and other organs.

Why the disease is termed lupus is unknown, but it has been known as a distinct disorder and called lupus by European physicians since at least the tenth century A.D. The term erythematosus was first attached to the disease in the 1850s, and it refers to the patchy congestion of skin capillaries with blood (erythema) that often accompanies the disease.

Demographics

Between one million and 1.5 million Americans have some form of lupus. The incidence among women is 10–15 times greater than among men, and it is two to three times more common among African Americans, Hispanics, Asians, and Native Americans than among whites. Lupus most often appears for the first time in women between the ages of 15 and 44. Twenty thousand people die of lupus-related causes in the United States annually.

Causes and symptoms

Lupus is an autoimmune disorder, a disease in which the body's immune system turns against the body itself. In a healthy person, the immune system defends against invading organisms but does not, in general, attack the body's own tissues. The cause of lupus is unknown. However, it is known that lupus has a genetic component, which means a predisposition to lupus can be inherited. Approximately 10% of lupus patients have one or more direct relatives with lupus. (Note that this means that 90% of lupus patients have no such relatives; however, it shows a

genetic connection because 10% is a much higher figure for familial lupus than can be attributed to chance alone.) Lupus has been definitely linked to genes on chromosome 1 and less certainly to genes on chromosomes 4 and 6.

Given genetic susceptibility, the disease may either develop spontaneously or be triggered by some environmental factor. Environmental factors known to trigger lupus include infections (e.g., Epstein-Barr virus, which infects 99% of children with lupus, but only 70% of healthy children), antibiotics, ultraviolet light (the rays in sunlight or sunlamp-light that causes sunburn), stress, smoking, certain medications, and hormones (especially estrogen, the female sex hormone).

Lupus manifests as a continuum or spectrum of disorders. However, it is common to divide lupus cases into four categories or groups:

• Systemic lupus erythematosus. This is the most serious form of lupus and affects about 70% of all persons with lupus. It is termed systemic because, in this variety of lupus, the body's immune system attacks one or more essential body systems. Targets may include the brain, kidneys, heart, pancreas, or other organs.
• Discoid or cutaneous lupus erythematosus. This variety of lupus is less severe, in that it attacks the skin only. However, it can be disfiguring, often attacking the skin of the face. The term discoid is derived from the round (disc-shaped) lesions that appear on the skin. About 10–15% of lupus patients have cutaneous lupus.
• Drug-induced or drug-related lupus erythematosus. This term refers to lupus that develops after a patient has taken a medication. Medications that can trigger drug-induced lupus include procainamide or hydralazine. Many of the substances that can potentially trigger lupus fall into the class of aromatic amines, or hydrazines. For example, the aromatic amine paraphenylenediamine is present in certain hair dyes and has been associated with lupus or lupus-like syndrome. Tartrazine (a food coloring, FD&C yellow No. 5), which is present in thousands of foods and medications, has also been associated with lupus. Cocaine abuse can induce lupus and several other connective-tissue diseases, as can exposure to certain metals (e.g., mercury). Between 10,000 and 15,000 people are diagnosed with drug-induced lupus annually in the United States.
• Mixed connective tissue disease. Approximately 10% of patients with lupus also have symptoms of one or more additional connective-tissue diseases.

The symptoms of lupus are quite varied. In discoid lupus, red patches (erythema) appear symmetrically on the cheeks, possibly extending to the face, neck, scalp, and other parts of the body. No organ other than the skin is affected (or the disease is classified as systemic, rather than discoid). Systemic lupus may begin suddenly, signaled by fever, or develop slowly over months or years. Chronic fatigue is a common symptom. Symptoms related to impairment of any organ may occur. The lupus disease process in a given organ is named after that organ; for example, inflammation of the kidneys is termed lupus nephritis, and inflammation of the brain is termed lupus cerebritis. Kidney involvement may be fatal. Over 50% of all systemic lupus patients in the United States presently have some degree of lupus cerebritis; 25–75% have neuropsychiatric symptoms at some time in their illness. Symptoms of lupus cerebritis may include headaches, seizures, stroke, psychosis, dementia, peripheral neuropathy, cerebellar ataxia (failure of muscular coordination, usually on one side of the body), chorea (jerky, involuntary movements), and others. Duration of central nervous system involvement may be transient (as with a migraine headache) or long lasting (as with dementia). Stroke incidence is 3–20% in systemic lupus patients, and is highest in the first five years of the disease. Peripheral neuropathy (carpal tunnel syndrome, for example) occurs in more than 20% of systemic lupus patients and cranial nerve palsies occur in 10–15%.

Exposure to the ultraviolet rays in sunlight can trigger lupus or, in a person who already has the disease, cause it to flare up. Worsening flare-ups of the disease can be life threatening because they can include inflammation and failure of the kidneys. Also, declining memory and mental sharpness with long-term lupus is common.