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Lupus

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Tests and Diagnosis

Diagnosis of lupus can be challenging, especially because of its wide range of symptoms that may come on slowly and change over time. It is usually made by the clinical evaluation of physical signs and symptoms in combination with tests that can help to confirm the diagnosis or rule out other causes of a person's signs and symptoms.

In 1982, the American College of Rheumatology (ACR) developed classification criteria to aid healthcare practitioners in making a diagnosis, in particular, of SLE. The criteria were last updated in 1997. If someone has four or more of the 11 criteria listed, that person may be diagnosed with lupus.

  1. A rash resembling a butterfly that appears across the nose and cheeks (malar, relating to the cheek)
  2. A red rash consisting of round or oval-shaped patches (discoid rash)
  3. Photosensitivity – rash develops on areas of skin that have been exposed to sunlight
  4. Mouth sores or nose ulcers – usually painless
  5. Arthritis in two or more joints, along with tenderness, swelling, or accumulation of fluid that lasts for a few weeks – arthritis associated with SLE is non-erosive, meaning the bones near affected joints are not damaged
  6. Inflammation of the lining around the heart (pericarditis) and/or lungs (pleuritis)
  7. Neurologic disorder – seizures and/or psychosis without other identifiable causes
  8. Blood (hematologic) disorder – anemia, low white blood cell count, or low platelet count
  9. Kidney problems – such as a high amount of protein in the urine or cellular casts in the urine
  10. Positive blood test for antinuclear antibodies (ANA, see tests below) – high levels are generally more specific to SLE; must be in the absence of medications known to be associated with drug-induced lupus
  11. Positive blood test for anti-double stranded DNA (anti-dsDNA), anti-Sm (Smith) antibody, cardiolipin antibody or lupus anticoagulant (see below), or a false-positive test for syphilis (meaning the person tests positive but does not have the disease)

In 2012, the Systemic Lupus International Collaborating Clinics (SLICC) group revised and validated the ACR's SLE classification criteria. According to the revision, a patient is classified as having SLE if s/he has biopsy-proven kidney involvement (lupus nephritis) with ANA or anti-dsDNA antibodies or if s/he satisfies 4 of the 11 diagnostic criteria, including the presence of at least one sign or symptom and a positive autoantibody test.

The following laboratory tests for autoantibodies may be useful in the diagnosis of lupus:

Other general tests that may be useful for evaluating someone with or suspected of having lupus:

Non-laboratory tests

X-rays or other imaging tests may be ordered to examine organs potentially affected by lupus.

In addition, a kidney biopsy may be performed. This involves taking a piece of kidney tissue for examination to detect any changes in the tissue that could indicate lupus and help guide treatment.

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