Systemic Lupus Erythematosus: An Autoimmune Disease with Many Patterns

Systemic lupus erythematosus, usually called lupus or SLE, is a long term autoimmune disease that can affect many parts of the body. Its pattern varies greatly between people and may change over time. Regular monitoring matters because serious organ inflammation, especially kidney disease, may begin with few obvious symptoms.

What systemic lupus erythematosus is Systemic lupus erythematosus is usually shortened to SLE and commonly called lupus. It is a long term autoimmune disease. The immune system becomes misdirected and causes inflammation or damage within the body's own tissues. The word systemic means that several body systems may be involved. Lupus can affect the skin, joints, blood cells, kidneys, lungs, heart, nervous system and blood vessels. One person may mainly experience rashes, joint pain and fatigue. Another may develop kidney, brain, lung or blood complications. The pattern can also change over time. This variability is central to understanding lupus. Why lupus is called the great imitator Lupus is sometimes called the great imitator because it can resemble many other conditions. Fatigue, fever, joint pain, rashes, hair loss and swollen glands can occur in infections, thyroid disease, other autoimmune conditions and several non inflammatory illnesses. Kidney inflammation may resemble other kidney diseases. Chest pain may arise from inflammation, infection, a blood clot or an unrelated heart condition. The most recognisable features are not present in everyone and may appear months or years apart. The phrase great imitator describes diagnostic difficulty. It does not mean that every unexplained symptom is lupus. Lupus is not one fixed pattern Some people have mild disease affecting the skin and joints. Others develop moderate or severe inflammation affecting internal organs. Symptoms may appear in different combinations. They can be continuous, fluctuate gradually or worsen during a flare. A person may have active inflammation in one organ while another part of the disease remains quiet. Previous inflammation can also leave permanent damage that causes symptoms without current immune activity. Clinicians therefore ask whether a new problem represents active lupus, previous damage, infection, medicine toxicity, thrombosis or an unrelated condition. Who can develop lupus Lupus can begin at any age, including childhood, although it commonly begins in young or middle adulthood. It is more common in women, but men and people of every sex can develop it. Disease frequency and severity differ between populations. People of Black African, Caribbean, South Asian and some other ancestries are more likely to experience severe disease, including kidney involvement. These differences reflect a complex interaction between biology, environment, access to care and wider health inequalities. Ancestry never diagnoses lupus or predicts one person's outcome. Lupus is not contagious and cannot be passed through ordinary contact. What autoimmunity means in lupus The immune system normally recognises infections and damaged cells while avoiding healthy tissue. In lupus, immune tolerance is disrupted. Autoantibodies can bind to the body's own cellular material. These antibodies and other immune components can form immune complexes. They may deposit within tissues and activate inflammation. Complement proteins are part of immune defence. Complement levels can fall when immune activity consumes them during some lupus flares. This explanation is simplified. Lupus involves many immune pathways and no single antibody causes every manifestation. Common constitutional symptoms Fatigue is one of the most common and disabling symptoms of lupus. It may relate to active inflammation, anaemia, pain, poor sleep, low mood, medicine effects or another condition. Severe fatigue does not automatically prove an inflammatory flare. Some people experience low grade fever, reduced appetite, weight loss or swollen glands. Unexplained fever requires careful assessment because infection can resemble a flare and may become more serious during immune suppressing treatment. Joint and muscle symptoms Joint pain and stiffness are common. The hands, wrists, knees and other joints may be affected. Lupus arthritis often affects several joints and can move between sites. Swelling may be mild or more obvious. Unlike rheumatoid arthritis, lupus arthritis is often non erosive, meaning that it does not usually produce the same pattern of bone erosion. Persistent deformity can still occur in a minority of people. Muscle pain and weakness can result from lupus, reduced activity, steroid effects or inflammatory muscle disease. A single suddenly hot, red and severely painful joint requires urgent assessment for infection or crystal arthritis. The malar or butterfly rash A malar rash is a red or darker coloured rash across both cheeks and the bridge of the nose. Its shape is sometimes compared with a butterfly. The folds running from the nose towards the corners of the mouth are often relatively spared. The rash may be flat or slightly raised and can be easier to recognise on lighter skin. On brown or black skin, redness may appear purple, grey, darkened or less visually obvious. A malar rash is a recognisable lupus feature but is not present in everyone. Rosacea, sunburn and other skin conditions can produce a similar facial pattern. A photograph taken during an active rash may help a clinician, but it cannot replace examination and appropriate testing. Photosensitivity Photosensitivity means that ultraviolet light triggers or worsens skin disease or wider lupus activity. A rash may develop after sunlight exposure, sometimes after a delay. Ultraviolet A can also pass through some windows. Not every person with lupus is noticeably photosensitive. The absence of sun triggered symptoms does not exclude SLE. High factor broad spectrum sunscreen, protective clothing, shade and avoiding intense midday sun reduce ultraviolet exposure. Vitamin D may need monitoring because strict sun avoidance can contribute to deficiency. Other skin and hair patterns Lupus can cause several rashes rather than one universal appearance. Acute cutaneous lupus includes the malar rash. Subacute cutaneous lupus often produces ring shaped or scaly sun sensitive lesions. Discoid lupus causes well defined inflamed plaques that may heal with scarring and altered pigmentation. Scalp involvement can cause permanent scarring hair loss. Diffuse hair shedding can occur during active disease and may improve when inflammation settles. New scarring lesions, persistent scalp inflammation or uncertain rashes warrant dermatology or rheumatology assessment. Mouth and nose ulcers Painless or painful ulcers can occur inside the mouth or nose. They may be noticed by the person or found during examination. Ulcers have many other causes, including trauma, infection, nutritional deficiency and medicine effects. Persistent, recurrent or unusually severe ulcers should be assessed rather than attributed automatically to lupus. Raynaud phenomenon Raynaud phenomenon causes fingers or toes to change colour in response to cold or stress. They may become pale, then blue or dark, and later red as blood flow returns. The pattern is less visually obvious in some skin tones. Tingling, numbness and pain can occur during an episode. Raynaud phenomenon is common and does not by itself mean that someone has lupus. Persistent ulcers, blackened skin or severe unremitting pain may indicate critically reduced blood flow and require urgent assessment. Blood cell abnormalities Lupus can reduce red blood cells, white blood cells or platelets. Anaemia may cause tiredness, breathlessness, palpitations or pallor. Several different mechanisms can cause anaemia in lupus. Low white cell counts may reflect lupus activity, medicine effects or infection. They can increase infection risk when severe. Low platelets can cause easy bruising, pinpoint bleeding spots, nosebleeds or heavier menstrual bleeding. Blood counts require interpretation alongside symptoms, medicines and other tests. Serositis and chest pain Thin membranes surround the lungs and heart. Lupus can inflame these membranes. Pleuritis causes sharp chest pain that is often worse with deep breathing, coughing or movement. Fluid may collect around the lungs. Pericarditis affects the sac around the heart. Pain may be sharp and can change with position. Chest pain in someone with lupus must not be assumed to be inflammation. Heart attack, pulmonary embolism, pneumonia and other emergencies can produce similar symptoms. Lung involvement Lupus can affect the lungs in several ways. Possible problems include pleuritis, fluid around the lungs, inflammation within lung tissue, pulmonary hypertension and shrinking lung syndrome. Breathlessness can also result from anaemia, infection, heart disease, deconditioning or a blood clot. New or worsening breathlessness requires clinical assessment. Sudden severe breathlessness, chest pain or coughing blood requires emergency care. Heart and cardiovascular health Lupus can inflame the heart lining, heart muscle or heart valves. Long term systemic inflammation also increases cardiovascular risk. Steroids, kidney disease, high blood pressure, diabetes and smoking can add further risk. Regular care therefore includes blood pressure checks and management of cholesterol, diabetes, weight and smoking. New central chest pressure, severe chest pain, sweating or collapse must be assessed as a possible cardiac emergency. Nervous system and cognitive symptoms Lupus can affect the brain, spinal cord or peripheral nerves, although many neurological symptoms have other causes. Possible manifestations include seizures, psychosis, severe headaches, confusion, nerve pain, weakness and movement problems. Some people report problems with attention, memory or processing speed. Fatigue, sleep disturbance, mood disorders and medicines may contribute. A new seizure, sudden confusion, one sided weakness, speech difficulty or loss of consciousness requires emergency assessment. Common headaches alone do not prove neuropsychiatric lupus. Antiphospholipid antibodies and clotting Some people with lupus have antiphospholipid antibodies. These antibodies can be associated with blood clots and pregnancy complications. A positive result alone does not necessarily mean antiphospholipid syndrome. Antiphospholipid syndrome requires a compatible clinical event and persistently positive laboratory tests interpreted by specialists. Possible clot symptoms include a swollen painful leg, sudden breathlessness, chest pain or neurological deficits. The presence of antiphospholipid antibodies influences contraception, pregnancy and thrombosis prevention decisions. Lupus nephritis Lupus nephritis means immune mediated inflammation within the kidneys. It is one of the most important organ threatening manifestations of SLE because untreated inflammation can cause permanent kidney damage, chronic kidney disease or kidney failure. Kidney inflammation may occur near diagnosis or later during the disease. Some people develop swollen ankles, facial puffiness, frothy urine, blood in the urine or high blood pressure. Others feel completely well. Urine abnormalities or rising blood pressure may be the only early signs. Why kidney monitoring cannot rely on symptoms The kidneys can lose protein or leak blood into urine before pain or visible swelling develops. Routine urinalysis looks for blood and protein. A urine protein to creatinine ratio or similar measurement estimates the amount of protein loss. Blood tests assess creatinine and estimated glomerular filtration rate, which reflect kidney function. Blood pressure is checked because kidney inflammation can cause hypertension and hypertension can worsen kidney damage. Current BSR guidance recommends urine testing and blood pressure measurement whenever overall lupus status is assessed. Investigating suspected lupus nephritis New protein, blood or cellular material in the urine prompts further assessment. Clinicians repeat urine testing, quantify protein loss and assess kidney function, blood pressure, complement and anti dsDNA antibodies. Infection, menstruation, stones, diabetes and other kidney diseases can also alter urine tests. A kidney biopsy is usually needed when lupus nephritis is suspected strongly enough to affect treatment. The biopsy identifies the pattern and severity of inflammation, the amount of scarring and features that influence treatment choices. Treating lupus nephritis Lupus nephritis is managed jointly by rheumatology and kidney specialists. Treatment aims to stop inflammation, preserve kidney function, reduce protein loss and prevent relapse. Hydroxychloroquine is usually continued unless contraindicated. Glucocorticoids are combined with one or more immune suppressing medicines. Options can include mycophenolate, cyclophosphamide, calcineurin inhibitors and selected biological medicines. The choice depends on biopsy findings, severity, previous treatment, pregnancy plans and other health factors. Treatment has an initial remission induction phase followed by longer maintenance therapy. Improvement requires regular urine and blood monitoring rather than symptoms alone. Flares and remission A flare means that lupus inflammation has become more active. Possible flare features include worsening rash, joint swelling, mouth ulcers, fever, fatigue, falling blood counts or new organ abnormalities. Remission means that active disease is absent or very limited. Low disease activity is an alternative treatment target when complete remission is not achievable. A rise in anti dsDNA or fall in complement may support concern about a flare in some people. These changes do not prove a clinical flare by themselves. Treatment decisions combine symptoms, examination, urine testing, blood results and organ specific investigations. Infection can mimic a flare Fever, fatigue, aching and abnormal blood tests can occur in both infection and active lupus. Immune suppressing medicines and steroids can increase infection risk or make infection less obvious. Increasing steroids during an unrecognised infection can be dangerous. People should follow their specialist flare plan and seek advice for new fever, breathlessness, painful urination, spreading skin infection or significant deterioration. Antibiotics do not treat autoimmune inflammation, and extra steroids do not treat bacterial infection. What triggers flares A flare may follow ultraviolet exposure, infection, treatment interruption, hormonal change or major stress. Sometimes no clear trigger is identified. Taking medicines consistently reduces preventable loss of disease control. Difficulty with adherence should be discussed without blame. Sleep, pacing, physical activity and psychological support may improve wellbeing, but they do not replace disease modifying treatment. How lupus is diagnosed There is no single diagnostic test for SLE. Diagnosis combines a pattern of clinical manifestations with antibody, complement, blood, urine and organ specific findings. Features may accumulate over time, so early disease can be difficult to recognise. Several conditions can mimic lupus, including infections, other connective tissue diseases, blood disorders and medicine reactions. People with strong clinical suspicion should be referred promptly for specialist assessment rather than waiting for every possible criterion to appear. Antinuclear antibody testing The antinuclear antibody test is usually shortened to ANA. ANA is positive at some point in most people with SLE, so a negative result makes new untreated adult SLE less likely. However, ANA has low specificity. Healthy people and people with infections, thyroid disease or other autoimmune conditions may have a positive result. The titre, laboratory method and clinical context all matter. ANA testing should be requested when there is a reasonable clinical suspicion of connective tissue disease, not as a general explanation for isolated fatigue or widespread pain. Anti double stranded DNA antibodies Anti double stranded DNA antibodies are usually shortened to anti dsDNA. They are more supportive of SLE than ANA when the clinical picture is compatible. Levels may change with disease activity, particularly kidney disease, in some people. The relationship is not reliable enough to make treatment decisions alone. A negative anti dsDNA result does not exclude SLE. Low positive results can occasionally be false positives, and different laboratories use different assays. Other antibody and complement tests Anti Smith antibodies are strongly associated with SLE but are present in only a minority of people. Anti Ro, anti La and anti RNP antibodies can help define particular patterns. Anti Ro and anti La are important before pregnancy because they can cross the placenta. Complement C3 and C4 may fall during active immune complex disease. Normal complement does not exclude active lupus. Antiphospholipid antibodies are checked because of their relationship with thrombosis and pregnancy complications. No antibody panel should be interpreted without relevant symptoms and clinical assessment. Classification criteria are not a home test Specialists may use EULAR and American College of Rheumatology classification criteria. These criteria create consistent groups for research and can support clinical reasoning. They are not a simple diagnostic checklist for the public. Someone may need assessment or treatment before every classification item has accumulated. Conversely, collecting points from unrelated symptoms and a positive ANA does not establish lupus. Other investigations A full blood count looks for anaemia, low white cells and low platelets. Kidney and liver tests assess organ function and establish baselines before treatment. Inflammatory markers can support assessment but behave differently in lupus. A normal result does not exclude disease. Urine testing is essential because kidney involvement may be silent. Imaging, heart tests, lung tests, skin biopsy, kidney biopsy or neurological investigations are selected according to the suspected organ involvement. Hydroxychloroquine is a cornerstone treatment Hydroxychloroquine is an antimalarial medicine with immune modifying effects. Current BSR and EULAR guidance recommends it for most people with SLE unless contraindicated. It helps prevent flares and can improve skin, joint and constitutional symptoms. Its benefits extend beyond short term pain relief. The dose is adjusted to body weight, kidney function, flare risk and retinal toxicity risk. It may take several weeks or months to provide its full benefit. Hydroxychloroquine eye monitoring Long term hydroxychloroquine can rarely damage the retina. Risk rises with cumulative exposure, higher weight adjusted doses, kidney impairment, tamoxifen use and other factors. Current UK guidance recommends retinal screening after five years of treatment and then annually, with earlier annual monitoring for people at higher risk. Routine screening aims to detect toxicity before noticeable visual loss. New visual symptoms still require assessment and should not be ignored between screening appointments. Glucocorticoids Glucocorticoids, often called steroids, suppress inflammation quickly. Creams may be used for some skin disease. Tablets, injections or intravenous treatment may be required for more active or organ threatening lupus. The dose depends on severity and the organ involved. Long term or high dose steroid exposure can cause infection, osteoporosis, diabetes, high blood pressure, cataracts and other harm. Modern treatment aims to use the lowest effective dose and reduce or withdraw steroids when disease control allows. Steroids should not be stopped suddenly after prolonged use unless a clinician provides a safe tapering plan. Other immune modifying medicines Additional medicines are selected according to the organs affected and the severity of disease. Options include methotrexate, azathioprine, mycophenolate, tacrolimus and cyclophosphamide. Biological treatments such as belimumab may be added for selected active autoantibody positive disease despite standard treatment. Newer specialist options for lupus nephritis include voclosporin or obinutuzumab with mycophenolate for eligible adults under current NICE guidance. These medicines have different infection, fertility, pregnancy and organ toxicity risks. Selection and monitoring require specialist care. Pain relief is not disease modification Paracetamol or non steroidal anti inflammatory drugs may reduce musculoskeletal pain. They do not control organ threatening lupus or prevent immune mediated damage. NSAIDs can affect the stomach, kidneys, blood pressure and cardiovascular system. They may be unsuitable in kidney disease, pregnancy or when anticoagulants are used. Persistent pain despite quiet lupus may have several contributors and should not automatically lead to stronger immune suppression. Monitoring treatment safety Immune suppressing medicines can affect blood cells, liver function, kidney function and infection risk. Regular blood tests and clinical reviews are therefore part of treatment. Screening for tuberculosis, hepatitis or other infections may be needed before particular biological medicines. Vaccination is reviewed before substantial immune suppression where possible. Live vaccines may be unsuitable with some treatments. Advice should be obtained from the rheumatology team, GP or vaccination service. Sun protection and skin care Broad spectrum sunscreen should protect against ultraviolet A and ultraviolet B. High SPF products, protective clothing, hats, shade and avoiding intense sunlight can reduce skin activity. Sunscreen needs adequate application and reapplication. Small amounts provide less protection than the labelled SPF. Smoking can worsen cutaneous lupus and cardiovascular risk and may reduce treatment response. Persistent scarring skin disease requires timely specialist treatment to prevent irreversible damage. Exercise, pacing and fatigue Appropriate physical activity supports cardiovascular health, bone strength, muscle function and mood. Activity may need adjustment during active organ disease or a severe flare. Pacing means balancing activity and rest rather than repeatedly exhausting available energy. Fatigue should be assessed for active lupus, anaemia, thyroid disease, infection, sleep problems, depression and medicine effects. Exercise and pacing help function but do not replace lupus treatment. Bone and cardiovascular protection Lupus itself and glucocorticoid treatment can increase osteoporosis risk. Fracture risk assessment may lead to bone density scanning, calcium or vitamin D advice and bone protecting medicine. Blood pressure, cholesterol, diabetes, smoking and physical activity require regular review because cardiovascular risk is increased. Kidney disease and antiphospholipid antibodies may alter prevention strategies further. Pregnancy should be planned with specialist care Many people with lupus have successful pregnancies. Pregnancy is safest when lupus is stable and medicines have been reviewed before conception. Active kidney disease, high blood pressure and antiphospholipid antibodies increase pregnancy risk. Pre pregnancy care should involve rheumatology and specialist maternity services. Kidney specialists, haematology or fetal medicine may also be needed. Unexpected pregnancy should prompt early specialist contact rather than abrupt medicine withdrawal. Medicines and pregnancy Hydroxychloroquine is usually continued before and during pregnancy because maintaining disease control is important. Azathioprine, tacrolimus and some other medicines can be used when clinically appropriate. Mycophenolate, methotrexate and cyclophosphamide can harm a developing pregnancy and require specialist planning before conception. Medicine changes should occur early enough to confirm that disease remains controlled on a pregnancy compatible regimen. Do not stop steroids, hydroxychloroquine or another lupus medicine independently after a positive pregnancy test. Anti Ro, anti La and the baby Anti Ro and anti La antibodies can cross the placenta. They are associated with neonatal lupus, including a small risk of congenital heart block. These antibodies are checked before or early in pregnancy, and fetal heart monitoring may be advised during a defined part of pregnancy. Neonatal lupus is not the baby developing systemic lupus. Many non cardiac features resolve as maternal antibodies disappear. Individual risk and monitoring should be discussed with the specialist team. Antiphospholipid antibodies and pregnancy Antiphospholipid antibodies are associated with miscarriage, pre eclampsia, fetal growth problems and blood clots. Not everyone with a positive antibody test has antiphospholipid syndrome or needs anticoagulation. Low dose aspirin, heparin or other treatment may be recommended according to previous events and antibody profile. Pregnancy treatment must be individualised by the rheumatology, obstetric and haematology teams. Distinguishing flare from pregnancy complications Fatigue, swelling, altered blood counts and changes in kidney tests can occur in lupus flares and pregnancy complications. Lupus nephritis and pre eclampsia can both cause high blood pressure and protein in the urine. The timing, urine findings, complement, anti dsDNA, liver tests, platelets and fetal assessment help specialists distinguish them. Severe headache, visual disturbance, sudden swelling, upper abdominal pain or reduced fetal movement requires urgent maternity assessment. Disease may also flare after birth, so treatment and follow up should continue through the postnatal period. Contraception and reproductive choices Contraception should match personal preference, pregnancy plans, disease activity and clotting risk. Oestrogen containing contraception may be unsuitable for some people with antiphospholipid antibodies, previous thrombosis or particular cardiovascular risks. Long acting reversible methods may be appropriate for many people. Some lupus medicines can harm a pregnancy, making reliable contraception particularly important during treatment. Contraceptive decisions should be made without assuming that lupus prevents pregnancy. Emotional, social and cognitive effects Unpredictable symptoms can affect work, education, relationships and confidence. Fatigue and pain may be invisible to other people, which can contribute to misunderstanding or isolation. Anxiety and depression can coexist with lupus and deserve treatment. Cognitive symptoms may affect concentration and memory, but they require assessment for sleep, mood, medicines and neurological disease. Psychological support and workplace or educational adjustments can be part of appropriate care. Ongoing review Lupus requires long term follow up even during remission. Reviews assess symptoms across all systems, blood pressure, urine, blood counts, kidney function, complement, antibodies and medicine safety as appropriate. Clinicians also review cardiovascular health, bone protection, vaccination, sun protection, pregnancy planning and mental wellbeing. New symptoms are assessed rather than automatically attributed to lupus. People should know how to contact their specialist service for a possible flare or medicine complication. What this lesson should not be used for This lesson cannot diagnose lupus from a facial rash, fatigue or a positive ANA result. It cannot determine whether fever, chest pain, kidney abnormalities or neurological symptoms represent a flare, infection, clot or another emergency. Do not use it to start, stop or change hydroxychloroquine, steroids, immunosuppressants, anticoagulants or pregnancy related treatment. Seek medical assessment for a persistent multi system pattern, and urgent help for severe organ, neurological, clotting or infection symptoms.

Lupus is a highly variable multi system autoimmune disease rather than one fixed symptom pattern. A malar rash and photosensitivity are recognisable but not universal, and antibody tests support rather than independently establish the diagnosis. Hydroxychloroquine is a cornerstone treatment, while regular urine and blood pressure monitoring protects against clinically silent lupus nephritis.