Lupus is a chronic inflammatory autoimmune disorder. Some symptoms of lupus can be transient, such as joint and muscle pain, fatigue, a rash caused or made worse by sunlight, low-grade fevers, hair loss, pleurisy, loss of appetite, sores in the nose or mouth, or painful sensitivity of the fingers in cold environments.
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Lupus can often be misdiagnosed as other diseases, which is why it has often been called the "great imitator." Its symptoms come and go and are analogous to those of other conditions. No single test can tell if a person has lupus, but there are a range of other methods to diagnose it.
Types of lupus
The clinical presentation of lupus can be described as a disease spectrum that centers on the prototypical systemic lupus erythematosus (SLE) but includes three different types of lupus with different pathophysiology, genetics, and clinical features. As a result, each form requires different monitoring and treatment. Accurately defining and differentiating the various types of lupus is central to sound diagnosis and care.
- Systemic Lupus Erythematosus (SLE): The most common type of lupus, also referred to as systemic lupus. SLE can cause a number of symptoms affecting various parts of the body, including joints, skin, kidneys, blood cells (anemia, leukopenia, and thrombocytopenia), brain, heart, and lungs. SLE flares when symptoms appear and disappear when there is remission of symptoms. SLE symptoms can vary in severity, from mild to life-threatening. Regular medical intervention and treatment are necessary in order for each patient to manage the disease.
- Discoid Lupus Erythematosus (DLE): This means your lupus mostly affects your skin. It causes a rash that may become raised and scaly and will likely leave scars, especially on your face, neck, and scalp (this is the most common area affected). This is more visible than what one might expect with an invisible disease. Over time, parts of the rash can become less visible as the body’s natural collagen fills in the gap where the inflammation used to be – we call these areas atrophy. DLE does not usually involve your lungs or kidneys, or other internal organs – unlike SLE. However, if you have DLE, you are roughly 10 times more likely to develop SLE than if you don’t.
- Drug-Induced Lupus (DIL): DIL is characterized by a lupus-like syndrome caused by prescription medications. It produces milder symptoms than SLE that generally resolve upon withdrawal of the medication. While there are myriad drug associations, hydralazine (to treat high blood pressure), procainamide (for abnormal heart rhythms), and certain anti-seizure drugs and antibiotics are the best known. It’s necessary to carefully monitor patients on long-term medications to detect and manage DIL quickly.
- Neonatal Lupus: Unlike other forms of lupus, neonatal lupus is not a true autoimmune disorder but rather a condition that occurs when autoantibodies from a pregnant woman are passed to her fetus. The most common symptoms include skin rashes and, less frequently, a congenital heart block, which can lead to heart rhythm issues. The skin symptoms usually resolve within the first six months of life, but heart-related complications may necessitate lifelong management. It's important for expectant mothers with lupus or a history of lupus-related autoantibodies to be closely monitored during pregnancy.
How is lupus diagnosed?
Medical history
Give your healthcare provider a complete and accurate medical history. This information, along with a physical exam and special tests, helps your healthcare provider to rule out other diseases that can be confused with lupus.
Symptoms
The American College of Rheumatology has outlined the following 11 symptoms that can aid in arriving at a lupus diagnosis. Doctors will expect patients to have four or more of the 11 symptoms of lupus. The symptoms can be those that the patient is currently experiencing or ones that have been experienced since the onset of their illness.
Skin and hair symptoms
- Malar rash - butterfly-shaped rash over the cheeks or other rashes
- Skin rash appearing in areas exposed to the sun (photosensitivity)
- Loss of hair, sometimes in spots or around the hairline
- Discoid rash – red patches of skin due to the scaling of hair follicles
Joint symptoms
- Arthritis lasting for several weeks in multiple joints
Neurological symptoms
- Seizures, strokes, psychosis, balance problems
Hematological symptoms
- Blood clots
- Leukopenia (low white blood cell count)
- Thrombocytopenia (low blood platelet count)
- Hemolytic anemia (reduced red blood cell count)
Renal symptoms
- Blood or protein in the urine or tests that suggest poor kidney function
Oral symptoms
- Sores in the mouth or nose lasting for more than a month
Serositis
Other symptoms
- Fever, fatigue, and weight loss
Lab tests
The Antinuclear antibody (ANA) test is commonly used to diagnose lupus. An antibody is a chemical the body makes to fight off infections. At the same time, autoantibodies are produced when the immune system fails to differentiate between 'self' and 'non-self' and attacks the body's healthy cells in error. This can cause tissue and organ damage.
The anti-dsDNA test targets the DNA found in a cell's nucleus and indicates the presence of autoantibodies in the blood. Most people with lupus test positive for ANA, even though it can be present in patients with a variety of other conditions. Other health problems, like malaria (a disease contracted from a mosquito bite), can also give you a positive test, which is why other tests can be necessary.
Other tests that can be undertaken are chest X-rays for chest infections, urinalysis to monitor the amount of protein or blood in the urine that may indicate kidney problems, and serum creatinine tests, which measure the amount of creatinine in the blood. This waste product forms when creatine in the muscles breaks down, a product that the kidneys usually eliminate. This test determines how well a patient's kidneys are functioning.
Risk factors for lupus
Stress, infection, and trauma can all increase a person's risk of developing lupus. Although it isn't currently known to what degree genes affect lupus incidence, some families have been known to carry genes that increase their risk of developing the condition.
Further Reading
Xist lncRNA identified as key trigger in female-biased autoimmune diseases