Lab Tests for Lupus

Because many symptoms of systemic lupus erythematosus (SLE) mimic those of other illnesses, lupus can be a difficult disease to diagnose. Diagnosis is usually made by a careful review of three factors:

1. the individual's entire medical history;
2. the individual's current symptoms; and
3. an analysis of the results obtained in routine laboratory tests and some specialized tests related to immune status.

To make a diagnosis of SLE, an individual must show clinical evidence of a multi-system disease (i.e. has shown abnormalities in several different organ systems). The following are typical symptoms or signs that might lead to suspicion of SLE:


1. Skin: Butterfly rash across the cheeks; ulcers in the mouth; hair loss.
2. Joints: Pain; redness, swelling.
3. Kidney: Abnormal urinalysis suggesting kidney disease.
4. Lining membranes: Pleurisy (inflammation of the lining of the lung); pericarditis (inflammation of the heart lining); and/or peritonitis (inflammation around the abdomen). Taken together, these types of inflammation are known as polyserositis.
5. Blood: Hemolytic anemia (the red cells are destroyed by autoantibodies); leukopenia (low white blood cell count); thrombocytopenia (low number of platelets).
Lungs: Infiltrates (shadowy areas seen on a chest x-ray) that come and go
6. Nervous system: Convulsions (seizures); psychosis; nerve abnormalities that cause strange sensations or alter muscular control or strength.

If an individual has several of these symptoms, the physician will then usually order a series of tests to examine the functioning of the individual's immune system. In general, physicians look for evidence of autoantibodies. Although there is no one test that can definitely say whether or not a person has lupus, there are many laboratory tests which aid the physician in making a lupus diagnosis.

First, there are routine clinical tests which suggest that the person has an active systemic disease. These include the sedimentation rate (ESR) and CRP which are frequently elevated in inflammation from any cause. Serum protein electrophoresis may reveal increased gammaglobulin and decreased albumin, and routine blood counts may reveal anemia and low platelet and white cell counts. Finally, routine chemistry panels may reveal kidney involvement by increases in serum blood urea nitrogen and creatinine, abnormalities of liver function tests, and increased muscle enzymes (such as CPK) if muscle involvement is present. These kinds of abnormalities alert the doctor to the presence of a systemic disease with multiple organ involvement.

Commonly used blood tests in the diagnosis of SLE are:

1. The anti-nuclear antibody test (ANA) to determine if autoantibodies to cell nuclei are present in the blood
2. The anti-DNA antibody test to determine if there are antibodies to the genetic material in the cell
3. The anti-Sm antibody test to determine if there are antibodies to Sm, which is a ribonucleoprotein found in the cell nucleus
4.Tests to examine the total level of serum (blood) complement (a group of proteins which can be consumed in immune reactions), and specific levels of complement proteins C3 and C4

In coming posts I will be goin through these Blood tests individualy..