Lupus is notoriously difficult to diagnose and often mimics other conditions. While certain symptoms -- such as the classic "butterfly rash" -- may be suggestive of lupus, several laboratory tests must be performed to confirm the diagnosis. Most tests for lupus are simple blood draws, but urine testing may also be performed. Occasionally, a tissue biopsy is also required.
ANA
The antinuclear antibody (ANA) test is usually one of the first blood tests performed when lupus is suspected. According to the Lupus Foundation of America, this test is positive in 97 percent of lupus patients, but many people without lupus also have a positive test result.
Other Antibody Tests
Antiphospholipid antibodies are elevated in about 30 percent of lupus sufferers. Anti-RNP antibodies, anti-Ro/SS-A and La/SS-B antibodies and anti-dsDNA antibodies are also commonly elevated in lupus. Blood tests for the levels of these antibodies are used as evidence for or against the diagnosis of lupus.
ESR
The ESR (erythrocyte sedimentation rate) or "sed rate" test measures levels of a protein in the blood that becomes elevated when systemic inflammation is present. This test is almost always positive in people with lupus, but infections and other conditions can also elevate the ESR.(ESR reader )
Urinalysis
As with other tests for lupus, a urine test cannot determine whether or not a person has the disease, but it can provide supportive evidence. Protein and cell casts are often found in the urine of lupus patients and can indicate kidney damage from the disease.
Biopsy
Rarely, a tissue biopsy may be required to look for antibodies or abnormal cells. A small sample of tissue (usually from the skin or kidneys) is removed and examined microscopically for evidence of lupus.
ANA
The antinuclear antibody (ANA) test is usually one of the first blood tests performed when lupus is suspected. According to the Lupus Foundation of America, this test is positive in 97 percent of lupus patients, but many people without lupus also have a positive test result.
Other Antibody Tests
Antiphospholipid antibodies are elevated in about 30 percent of lupus sufferers. Anti-RNP antibodies, anti-Ro/SS-A and La/SS-B antibodies and anti-dsDNA antibodies are also commonly elevated in lupus. Blood tests for the levels of these antibodies are used as evidence for or against the diagnosis of lupus.
ESR
The ESR (erythrocyte sedimentation rate) or "sed rate" test measures levels of a protein in the blood that becomes elevated when systemic inflammation is present. This test is almost always positive in people with lupus, but infections and other conditions can also elevate the ESR.(ESR reader )
Urinalysis
As with other tests for lupus, a urine test cannot determine whether or not a person has the disease, but it can provide supportive evidence. Protein and cell casts are often found in the urine of lupus patients and can indicate kidney damage from the disease.
Biopsy
Rarely, a tissue biopsy may be required to look for antibodies or abnormal cells. A small sample of tissue (usually from the skin or kidneys) is removed and examined microscopically for evidence of lupus.
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