Lupus is tricky. Its symptoms come and go and can be mild or severe. Many patients may go through years of red rashes, extreme fatigue, painful or swollen joints, fevers exhibiting some or all of those symptoms without ever noticing a pattern or having a doctor that is able to accurately diagnose the disease.
Some of the difficulty in diagnosis is that there is no one test to determine lupus. Primary care doctors sometimes miss the patterns of lupus due to its rarity some have never seen a case of lupus in their practices before. If lupus is suspected, your doctor will do a physical exam, ask you to relate your medical history (important for flare patterns) and may run tests to rule out other diseases.
Lupus, or systemic lupus erythematosus (SLE) is often diagnosed through an anti-nuclear anitbody blood test (ANA). An ANA test identifies autoantibodies that attack the body's own tissues and cells. A positive ANA does not automatically mean a person has lupus, but rather is one piece of the puzzle of lupus diagnosis that includes a patient's symptoms, a physical examination and other laboratory tests.
Usually in conjunction with the ANA test, your doctor may ask that you take other tests that can help determine the presence of three specific types of antibodies: anti-dsDNA (anti-double-stranded DNA), anti-Sm (anti-Smith antibodies), and anti-RNP antibodies. The anti-dsDNA and anti-RNP tests confirm whether there are antibodies being produced to the genetic material in the cell. The anti-Sm test measures if there are antibodies against a certain protein found in the nucleus of cells.
When either the anti-dsDNA or the anti-Sm antibody test is positive, a person is usually considered to have SLE. Knowing which particular antibody is responsible for the positive ANA test can help determine which autoimmune disease is present.
The American College of Rheumatology also uses a criteria list to help rheumatologists and other doctors make a diagnosis, but blood tests are the gold standard for confirming a lupus diagnosis.
Other criteria include:
- Fever, fatigue, and weight loss
- Arthritis involving multiple joints for several weeks
- Butterfly-shaped rash over the cheeks
- Raised red rashes that scar
- Skin rash appearing in areas exposed to the sun
- Mouth or nose ulcers
- Joint pain with swelling and tenderness
- Heart and lung lining inflammation (pericarditis and/ or pleuritis)
- Seizures or other neurologic disorder
- Kidney problems (blood or protein in the urine detected through urine tests)
- Low blood counts (anemia, low white blood cells or low platelets)