How is lupus diagnosed?

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How is lupus diagnosed?

As signs and symptoms vary considerably from person to person, there is no single diagnostic test that can confirm lupus. In addition, signs and symptoms tend to change over time and are similar to those of other disorders and diseases. These fluctuations in disease activity make lupus extremely challenging to diagnose.

Currently, doctors use guidelines established by The American College of Rheumatology (ACR) to diagnose lupus (SLE). The guidelines focus on eleven abnormalities that, when combined, suggest that the patient has lupus. To be classified as having SLE, a patient must meet 4 of the following 11 symptoms at any time since the onset of the disease:

Serositis - inflammation of the membrane around the lungs (pleuritis) or the heart (pericarditis)
Mucosal ulcers - small sores found in the lining of the mouth and nose
Arthritis - nonerosive arthritis (tenderness, swelling, pain) of two or more peripheral joints
Photosensitivity - skin rash or other symptoms caused by exposure to ultraviolet light
Blood disorder - hemolytic anemia (low red blood cell count), leucopenia and lymphopenia (low white blood cell count), or thrombocytopenia (low platelet count)
Renal (kidney) disorder - high protein count in urine
Antinuclear antibody test positive
Immunologic disorder - positives on anti-Smith, anti-ds DNA, antiphospholipid antibody tests.
Neurologic disorder - seizures or psychosis
Malar rash - rash on cheeks
Discoid rash - red, scaly patches on skin that cause scarring
In addition to the above tests, doctors will often conduct a variety of blood tests such as:

Complete blood count (CBC) to detect anemia, low platelet count, and low white blood cell count
Erythrocyte sedimentation rate (ESR) to determine the rate at which red blood cells settle to the bottom of a tube in an hour. Rates faster than normal may indicate lupus or another systemic disease, inflammatory condition, or infection.
Kidney and liver assessment to look for certain enzymes and albumin
Urinalysis to measure protein levels or red blood cells in the urine
Syphilis test to determine if anti-phospholipid antibodies are in the blood.