Lupus is a chronic autoimmune disease in which the body’s immune system mistakenly attacks its own organs and tissues, causing inflammation and pain, commonly in the skin, joints, and internal organs such as the heart and kidneys, although it can affect any part of the body.
One test used to diagnose lupus is a blood test for antiphospholipid antibodies (lupus anticoagulant [LA], immunoglobulin IgG and IgM anticardiolipin [aCL] antibodies, and IgG and IgM anti-beta2-glycoprotein [GP] 1). About 50% of all people with lupus have these antibodies. One of these antibodies is the lupus anticoagulant.
Causes of lupus anticoagulant may include:
- Genetic changes (mutations)
- Viral infections
- Hepatitis C virus
- Human immunodeficiency virus (HIV)
- Cytomegalovirus
- Varicella zoster
- Epstein-Barr virus
- Adenovirus
- Parvovirus B
If the lupus anticoagulant is positive over a 20-year period of time, 50% of patients will experience a blood clot. Triggers that may cause a blood clot in people who have lupus anticoagulant include:
- Smoking
- Prolonged bed rest
- Pregnancy
- Hormone therapy or birth control pills
- Cancer
- Kidney disease
What Are Symptoms of Lupus?
Symptoms of lupus include:
- Extreme fatigue
- Joint pain or swelling
- Swelling in the hands, feet, or around the eyes
- Fever
- Headache
- Sensitivity to light
- Chest pain when inhaling deeply caused by inflammation in the lining of the lungs
- Butterfly-shaped rash on the cheeks and nose
- Raised red patches on the skin
- Sores in the mouth or nose
- Arthritis in two or more joints, plus swelling or tenderness
- Seizures or other nerve problems
- Hair loss
- Fingers and toes turning white or blue and feeling numb when exposed to cold or stress (Raynaud’s disease)
- Weight loss
- Muscle pain
- Skin lesions
- Blood clots, which can lead to stroke or seizures
- Gastrointestinal problems
- Respiratory problems
- Neurologic and psychiatric problems
- Blood abnormalities
- Swollen lymph nodes
- Eye problems
- Excess protein in the urine
How Is Lupus Diagnosed?
In addition to the antiphospholipid antibodies (lupus anticoagulant [LA], immunoglobulin [Ig] G and IgM anticardiolipin [aCL] antibodies, and IgG and IgM anti-beta2-glycoprotein [GP] 1) blood test, other tests used to help diagnose lupus or rule out other conditions include:
- Blood tests
- ANA
- Anti-double-stranded DNA (anti-dsDNA)
- Antibody tests
- Blood clotting time tests
- C3 and C4 or CH50 complement levels
- C-reactive protein (CRP) levels
- Complement tests
- Complete blood count (CBC)
- Creatine kinase (CK)
- Creatinine
- Erythrocyte sedimentation rate (ESR)
- Protein electrophoresis
- Rheumatoid factor and anti-cyclic citrullinated peptide antibodies
- Serologic studies for infection
- Urine protein-to-creatinine ratio
- Urine tests
- Urinalysis
- 24-hour urine collection
- Tissue or organ biopsies
- Computed tomography (CT) scan
- Magnetic resonance imaging (MRI)
- X-rays
- Electrocardiography
- Ultrasound
- Echocardiography
- Tests to check for pulmonary embolism
- Diffusing capacity for carbon monoxide
What Is the Treatment for Lupus?
Lupus is usually treated with medications to help manage symptoms, such as:
- Anti-inflammatories and steroids
- Antimalarials (to help protect skin from rashes and UV light)
- Biologics
- Immunosuppressives
- Anticoagulants
Home treatment that may help patients manage symptoms of lupus include:
- Sun protection
- Dietary modifications
- Some patients may need increased calories
- Vitamin D supplementation
- Salt restriction for patients with high blood pressure (hypertension) and/or kidney inflammation (nephritis)
- Avoiding smoking
- Regular exercise
- Vaccination as recommended by your doctor
- Management of other medical conditions such as high blood pressure or osteoporosis
From 
https://www.lupus.org/
https://www.uptodate.com/contents/epidemiology-and-pathogenesis-of-systemic-lupus-erythematosus?search=What%20Causes%20Lupus%3F&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H7
https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-systemic-lupus-erythematosus-in-adults?search=Lupus&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H2215760526
https://www.cdc.gov/lupus/basics/women.htm
https://www.hopkinslupus.org/lupus-tests/antiphospholipid-antibodies/
https://pubmed.ncbi.nlm.nih.gov/11836658/
https://www.mountsinai.org/health-library/diseases-conditions/lupus-anticoagulants-and-antiphospholipid-antibodies