Lupus, also known as systemic lupus erythematosus (SLE), is a chronic autoimmune disease that can affect many parts of the body. It occurs when the immune system attacks healthy tissue, causing inflammation and damage. While there is no one definitive test for lupus, a combination of medical history, physical examination, blood tests, and other tests can help doctors make a diagnosis.
Symptoms
Lupus can cause a wide variety of symptoms, which can vary in severity from person to person. Some of the most common symptoms include:
- Fatigue
- Fever
- Joint pain and swelling
- Skin rash, particularly a butterfly-shaped rash across the cheeks and nose
- Hair loss
- Chest pain
- Shortness of breath
- Mouth sores
- Dry eyes
- Headaches
- Memory problems
Diagnosis
There is no single test that can definitively diagnose lupus. Instead, we will typically use a combination of the following:
- Medical history: We will ask you about your symptoms, including when they started, how severe they are, and whether they come and go. We will also ask about your family history of lupus or other autoimmune diseases.
- Physical examination: To look for signs of lupus, such as a rash, joint swelling, or mouth sores.
- Blood tests: Several blood tests can be used to help diagnose lupus. These include:
- Antinuclear antibody (ANA) test: This is the most common test used to diagnose lupus. However, a positive ANA test can also occur in people who do not have lupus.
- Anti-double stranded DNA (dsDNA) and Anti-Smith (Sm): Highly specific antibodies for SLE, although not always positive.
- Complement levels (C3 and C4): Help to diagnose and monitor lupus activity.
- Complete blood count (CBC): This test measures the levels of red blood cells, white blood cells, and platelets in your blood. Low levels of red blood cells, platelets or white blood cells can be a sign of lupus.
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): These tests measure inflammation in the body. Elevated levels of ESR and CRP can be a sign of lupus.
Other tests
- Urinalysis: This test can check for protein or blood in the urine, which can be a sign of kidney involvement in lupus.
- Chest X-ray: This test can check for lung involvement in lupus.
- Kidney biopsy: This test involves taking a small sample of tissue from the kidney to look for signs of damage.
- Echocardiogram: This test uses ultrasound to look at the heart and see if it is affected by lupus.
Diagnostic criteria
We will use a set of criteria called the American College of Rheumatology (ACR) criteria to help diagnose lupus. These criteria include 11 different signs and symptoms of lupus. A person must have at least four of these criteria to be diagnosed with lupus.
References
- van Vollenhoven RF, Mosca M, Bertsias G, et al. Treat-to-target in systemic lupus erythematosus: recommendations from an international task force. Ann Rheum Dis 2014; 73:958.
- Bertsias G, Ioannidis JP, Boletis J, et al. EULAR recommendations for the management of systemic lupus erythematosus. Report of a Task Force of the EULAR Standing Committee for International Clinical Studies Including Therapeutics. Ann Rheum Dis 2008; 67:195.
- Wallace DJ. Improving the prognosis of SLE without prescribing lupus drugs and the primary care paradox. Lupus 2008; 17:91.