May is Lupus Awareness Month, which makes it a good time to cover the basics of one of the most well-known and most variable autoimmune conditions I treat.
What is lupus?
Lupus, or more formally systemic lupus erythematosus (SLE), is a chronic autoimmune disease in which the immune system attacks the body's own tissues. Unlike conditions that target one specific organ or area, lupus can affect almost any part of the body. Joints, skin, kidneys, heart, lungs, brain, and blood cells are all fair game.
That's part of what makes lupus so difficult to diagnose. No two patients look quite the same. Some present with prominent skin and joint symptoms. Others present with kidney involvement and very little else. The variability is the disease's signature.
Who gets lupus?
Lupus disproportionately affects women, with about 9 out of 10 cases occurring in women. It usually develops in early to mid-adulthood, though it can occur at any age.
It also disproportionately affects certain racial and ethnic groups. Black, Hispanic, Asian, and Native American patients have higher rates of lupus and often more severe disease courses than white patients. The reasons for this are not fully understood and likely involve a combination of genetic, environmental, and healthcare-access factors.
If you have a family member with lupus or another autoimmune condition, your risk is somewhat higher, but most patients with lupus don't have a family member with it.
Symptoms
The hallmark symptoms of lupus are broad and often nonspecific, which is part of why it gets missed early. Common features include:
- Fatigue, often profound
- Joint pain and stiffness, sometimes with swelling
- Malar rash, the butterfly-shaped redness across the cheeks and nose
- Photosensitivity, where sun exposure triggers rashes or flares
- Mouth ulcers
- Hair thinning or hair loss
- Raynaud's phenomenon (fingers turning white or blue in the cold)
Beyond those, lupus can involve internal organs:
- Kidney involvement (lupus nephritis), which affects roughly 40 to 50% of patients at some point
- Inflammation around the heart (pericarditis) or lungs (pleuritis)
- Low blood counts
- Neurologic symptoms, including brain fog, headaches, and rarely seizures or strokes
The mix and severity of these symptoms varies enormously from patient to patient. Some people have mild disease primarily affecting joints and skin. Others have life-threatening kidney or brain involvement.
Diagnosis
There's no single test that diagnoses lupus. Like most rheumatic diseases, it's a clinical diagnosis that combines history, physical exam, and lab findings.
The lab tests that matter most:
- ANA (antinuclear antibody) is positive in nearly all lupus patients, but a positive ANA alone doesn't make the diagnosis. About 20% of healthy people also have a positive ANA. I've written more about this in a previous post.
- Anti-dsDNA antibodies are more specific to lupus and often correlate with disease activity.
- Anti-Smith antibodies are less common but highly specific.
- Complement levels (C3 and C4) are often low during active lupus and rise back to normal during remission.
- Routine labs like blood counts, kidney function, and urinalysis are essential for picking up organ involvement.
Diagnosis ultimately comes down to putting the pieces together. The right combination of symptoms, exam findings, and labs.
Management
Lupus is a chronic condition without a cure, but treatment has improved dramatically over the past few decades. The goal is to control disease activity, prevent flares, and protect organs from damage.
A few cornerstones:
- Hydroxychloroquine (Plaquenil) is the foundation of lupus treatment. Nearly every lupus patient should be on it unless there's a specific reason they can't be. It reduces flares, protects against organ damage, and improves long-term outcomes. I'll do a deeper dive on this one next week.
- Immunosuppressive medications like methotrexate, mycophenolate, and azathioprine are used depending on which organs are involved and how severely.
- Newer targeted therapies have expanded options. Belimumab (Benlysta) and anifrolumab (Saphnelo) are biologics that target specific parts of the immune response in SLE. Voclosporin (Lupkynis) is a newer option specifically for lupus nephritis, often used alongside mycophenolate.
- Corticosteroids (prednisone) are useful for acute flares but we try to minimize long-term use because of side effects.
- Sun protection matters a lot. UV light can trigger lupus flares, so broad-spectrum sunscreen, UPF clothing, and avoiding peak sun hours is part of management. More on that in my photosensitivity post.
- Lifestyle factors. Sleep, stress management, exercise, and a generally anti-inflammatory diet aren't replacements for medications, but they meaningfully support the rest of treatment.
Patients with lupus also need regular monitoring. Lab work, urinalysis, and blood pressure checks at every visit, with the frequency depending on disease activity.
Summary
Lupus is variable, complex, and still frequently misunderstood. If you have unexplained fatigue, joint pain, photosensitive rashes, or symptoms that seem to flare and fade without a clear pattern, it's worth bringing up with your doctor. An evaluation by a rheumatologist can help sort out whether lupus might be part of the picture.
The earlier we diagnose lupus, the earlier we can start treatment, and the better the long-term outcomes.