Testing is used to distinguish drug-induced lupus from other forms of lupus such as systemic lupus erythematosus (SLE), from another autoimmune disorder, or from another cause of a person's symptoms. While it is not diagnostic of drug-induced lupus, its presence is consistent with this diagnosis.
If a person is diagnosed with drug-induced lupus, the identified drug may be discontinued upon the recommendation of the health practitioner. One or more histone antibody tests may be used as follow up to monitor antibody levels (titers), if present.
A histone antibody test is ordered when a person has been taking a drug for several weeks to a couple of years and develops signs and symptoms that could be due to drug-induced lupus. This is especially true when the person affected did not have a prior personal or family history of an autoimmune disorder. Symptoms may include:
Arthritis-like pain in one or more joints (but no or little joint inflammation)
Muscle pain (myalgia)
Red rash that frequently resembles a butterfly across the nose and cheek areas (malar rash)
Sensitivity to sunlight
Symptoms and complications involving the central nervous system (CNS) and kidneys occur with SLE but are much rarer with drug-induced lupus.
The histone antibody test may be repeated at intervals after the drug has been discontinued to monitor for decreases in histone antibody levels.
Symptoms that resolve when the drug is discontinued
Histone antibody levels that begin to decrease when the drug is discontinued
A positive histone antibody result by itself does not establish a diagnosis. About 50% of those with SLE will have histone antibodies, though generally not induced by a specific drug. In these cases, it is likely that the anti-dsDNA test will be positive and significantly elevated.
A negative result means that the individual's signs and symptoms may be due to a condition other than drug-induced lupus, such as a drug allergy. A small portion of individuals, 5-10%, may have drug-induced lupus even if they do not have histone antibodies.
An individual with SLE may have a flare-up that is caused or exacerbated by drug therapy without having drug-induced lupus.
SLE tends to affect more women than men and tends to occur in people in their 20s to 40s. Drug-induced lupus affects both sexes equally and can affect anyone but occurs most frequently in those who are older.
This article was last reviewed on November 25, 2013. | This article was last modified on March 31, 2014.
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