But diagnosing lupus can be very challenging, says Stacy Ardoin, MD, a rheumatologist at the Ohio State University Wexner Medical Center in Columbus. Signs can range from a mild rash and arthritis to kidney failure and seizures — “with a whole spectrum in between,” she says. Symptoms can also mimic other diseases, including infections and cancer. Here’s what you need to know about the warning signs, when to see your doc, and tests you can expect that help your healthcare team make a lupus diagnosis. Rashes that develop on the face and upper arms after exposure to sunlight, unexplained fevers, and painful, swollen, or stiff joints are all common lupus symptoms — and are symptoms you should tell your doctor about, says Neil Kramer, MD, a rheumatologist at the Institute for Rheumatic and Autoimmune Diseases at Overlook Medical Center in Summit, New Jersey. Another signal that you may need to undergo further testing for lupus is if a routine urine test (the one you’ll likely do as part of a primary care checkup) shows abnormalities, such as excess protein or red blood cells. Those individuals may need further assessment from a rheumatologist, says Dr. Kramer. The same can be said of unexplained low blood counts. Additionally, a diagnosis of pleuritis (inflammation of the lining surrounding the lungs) or pericarditis (inflammation of the sac around the heart) may also require further investigation. Lupus can cause both conditions, says Kramer. There’s no one test for lupus, so the rheumatologist will typically use a combination of test results and the signs and symptoms you report to make a diagnosis, adds Francis Luk, MD, an assistant professor in the Wake Forest School of Medicine department of internal medicine, section of rheumatology, in Winston-Salem, North Carolina. Symptoms are subjective and include pain levels and how much fatigue a person is experiencing. Signs are measurable and can include rash or swelling of the joints, he says.
Lab Tests the Doctor Might Ru
For lab tests, a blood draw for a complete blood count, which measures levels of the red blood cells, white blood cells, and platelets is standard, says Kramer. Notably, these blood cell levels may be low in people with lupus. (1) A urinalysis, a test of the urine, is also standard for assessing kidney function, says Kramer. Bits of cells called cell casts and large or abnormal amounts of protein in the urine are signs that the kidneys are not doing their job of filtering waste from the blood properly. Inflammation of the kidneys, or lupus nephritis, is a complication of lupus, too; these are all things doctors are on the lookout for. (1) Rheumatologists also look for certain antibodies, or proteins, in your blood to help diagnose lupus, says Kramer. In healthy people, antibodies fight off foreign invaders such as viruses, bacteria, and fungi. People with lupus produce autoantibodies, which are antibodies that attack the body’s own cells and tissues. (2) Laboratory tests check for the following:
Antinuclear Antibodies (ANA) These proteins bind to the cell nucleus, damaging the cell or causing it to die. About 97 percent of people with lupus have these antibodies. (1)Anti-Double-Stranded DNA Antibodies These proteins are a type of anti-nuclear antibody that bind to the DNA, or genetic material, inside the cell nucleus. About half of people with lupus have these antibodies. (3)Antibodies to Sm These antibodies target proteins called Sm in the cell nucleus. This antibody type is present in up to 40 percent of people with lupus. (3)Antiphospholipid Antibodies These antibodies can cause narrowing of the blood vessels. About a third of people with lupus test positive for antiphospholipid antibodies. (3)Complement Proteins These proteins boost the body’s immune response to infections. The inflammation that lupus causes can lead to low complement levels, which is why your rheumatologist might run tests of your levels to help identify lupus. (3)
Other Medical Tests That Help Rheumatologists Diagnose Lupus
Other tests for lupus can depend on the symptoms patients are experiencing, says Stuart Kaplan, MD, a rheumatologist at Mount Sinai South Nassau in Oceanside, New York. For example, chest X-rays and echocardiograms may be necessary to indicate whether a patient has pleuritis or pericarditis if individuals have chest pain or shortness of breath (both symptoms indicate those conditions might be happening). If doctors suspect nephritis is present, the patient may need a kidney biopsy, he says.
The ACR criteria most recently were updated in 1997, though in 2019, the ACR and the European League Against Rheumatism developed updated classification criteria for systemic lupus, meant to be used primarily for research purposes and inclusion in studies rather than diagnosis. (5) Patients are diagnosed with lupus when they have 4 of the 11 total signs or symptoms, says Dr. Luk. Those signs and symptoms include: (6) The newer system, SLICC, published in Arthritis and Rheumatology, may also be a valuable tool, says Dr. Luk. (7) The SLICC criteria include 17 signs and symptoms of lupus that doctors assess, including clinical findings from the patient’s medical history and physical exam, as well as laboratory tests, he explains. Notably, the criteria address a broader range of neurological disorders than the ACR. The SLICC criteria also state that a patient can be diagnosed with lupus when he or she has a symptom based on a clinical finding or exam, along with a positive laboratory finding, such as an antibody positive test, says Luk. Patients may also be diagnosed if a kidney biopsy shows nephritis consistent with lupus. “Sometimes we do see patients who don’t have other symptoms at all but do have nephritis,” he says. The SLICC criteria perform better than the older ACR system but are more complicated, notes Kaplan. And it should be noted that neither system is 100 percent definitive in indicating when someone has lupus and when they don’t, adds Dr. Ardoin. Both systems were developed to help researchers determine which patients should be entered into lupus clinical trials for lupus research, not as diagnostic criteria for the condition, says Ardoin.
