Lupus is often called "the great imitator"1 since it can be confused with other ailments. To circumvent this, you have to undergo several tests, as it can be dangerous to be given the wrong diagnosis.
When testing for lupus, antibody tests will help find abnormalities in antibody protein production. Along with these tests, explaining any lupus-specific symptoms to your doctor (such as butterfly rashes) can make the final diagnosis more accurate. Below are several types of tests:
Anti-dsDNA Test2 — This antibody attacks double-stranded DNA found inside the cell nucleus. This test is specifically used when testing for lupus, and test results show that 75 to 90 percent of lupus patients have anti-dsDNA in their system. Presence of anti-dsDNA also indicates a greater risk of lupus nephritis, which is kidney inflammation caused by lupus – something you should watch out for if you test positive for anti-dsDNA.
Antinuclear Antibody (ANA) Test3 — ANA is a type of antibody that attacks cells' nuclei, and is present in 97 percent of patients with active lupus. However, testing positive for this antibody does not necessarily mean you have lupus, because other diseases can have ANA too. It's a good indicator due to the high percentage, but this test must be carefully considered alongside other tests.
Anti-Sm Test4 — Anti-Sm is an antibody that fights against Sm, a protein found in a cell's nucleus. WebMD notes that 30 percent of lupus patients have this protein, so it can be an indicator. Other tests should be taken as well to add more weight to the final diagnosis.
Anti-RNP Test5 — These antibodies target ribonucleoproteins (RNP), which help control cell activities. High quantities of anti-RNP can be found on lupus patients, but can also be found in other diseases as well. For a more accurate diagnosis, this test should be taken with other antibody tests to rule out other diseases.
Antiphospholipid (APL) Antibody Test6 — APLs attack phospholipids, which are integral to the construction of cell membranes.7 These antibodies can constrict your blood vessels, leading to blood clots. Around 60 percent of lupus patients have APL antibodies. Pregnant women need to pay particular attention to this antibody even if the diagnosis for lupus comes out negative, because APLs can cause miscarriage or premature birth.
Complete Blood Cell Count (CBC)8 — This test is administered to count the red and white blood cells for any abnormalities. A decrease in white blood cells (leukopenia), for example, can be found in 50 percent of patients with lupus. The results of a CBC aren't enough to indicate lupus, but it can point to other medical conditions, which is still helpful nonetheless.
Other Laboratory Tests That Can Indicate Lupus
• Urine Test9 — Lupus can attack your kidneys without warning, so a urine test is normally done. Doctors will be on the lookout for proteinuria, which measures the effectiveness of your kidney's ability to filter and eliminate waste.
• Echocardiogram10 — This test looks for any problems in your heart and its surrounding valves, via images made by sound.
• Chest X-ray11 — Your lungs can be affected without any warning, so it's vital to have them checked for any inflammation or fluid.
With the various tests presented, it's important to remember that taking and testing positive for only one test is not an immediate indicator of lupus. You need to take various tests in order to rule out other diseases, and see what abnormal antibodies and proteins remain in your system that can indicate lupus. If other diseases are ruled out, then lupus can be the final diagnosis.