Blood and urine tests are used to assess organ involvement, help make the diagnosis of lupus, and to see if the individual is responding to treatment. These laboratory tests include a complete blood count, chemistry panel looking at kidney and liver function, and a urinalysis (examination of the urine) that is another way to assess kidney function. Then, there are specific blood tests for lupus such as anti-nuclear and other antibodies, complement levels, and those that indicate an increased risk of blood clots. Sometimes, x-rays, ultrasound examination and biopsies of organ tissues are needed depending on the symptom and organ involved.

Since the anti-nuclear antibody (ANA) test is so important, a separate but important issue is a positive test in the blood. Normally, the body makes antibodies to fight infection, but in lupus, the body makes antibodies against its own tissues. If you have lupus, you make an antibody directed against the nucleus of a cell that contains important cellular functional components such as DNA. Almost all systemic lupus patients have the ANA test positive, but it is important to note that not all ANA positive tests mean that you have the disease, lupus. It is very important to have a rheumatologist evaluate an ANA test if it is positive, since there may be reasons other than lupus for the test result to be positive, such as if you or a family member already has another autoimmune problem such as lupus or thyroid disease.

There are additional specialized tests that should be checked if the ANA test is positive and the rheumatologist thinks that lupus is a possible diagnosis. Since lupus is characterized by making extra antibodies, blood tests that include a panel of antibodies including double stranded DNA (dsDNA), SSA, SSB, RNP, Sm, and cardiolipin should be performed. When more than one antibody is present, this helps the rheumatologist make the diagnosis of lupus in the setting of appropriate clinical symptoms. In addition, the specific antibodies may help predict prognosis and which symptoms might occur in the future. For example, if the double stranded DNA antibody is present, the patient should be monitored for kidney disease. If the anticardiolipin antibody is present, the patient may have pregnancy problems or an increased risk of blood clots.