Lupus: Why Is It So Hard to Diagnose?

Lupus is hard to diagnose because it is an autoimmune disease that can affect the skin, joints, kidneys, blood, and other organs, and its symptoms overlap with many other conditions. Symptoms can also come and go, so no single visit may capture the full picture. There is no single test that settles it; clinicians combine history, examination, and several lab results over time. This article explains why lupus is easy to miss, what clinicians look at, and which symptoms need urgent care.

Why Lupus Is Hard to Diagnose

Lupus is an autoimmune disease, which means the immune system can attack the body's own healthy tissue. MedlinePlus describes lupus as a disease that can affect many parts of the body, and the most common form is systemic lupus erythematosus (SLE). Several features together make the diagnosis difficult.

• It affects many organ systems. Different people have different combinations of skin, joint, kidney, blood, or nervous system problems, so two people with lupus can look very different.
• Symptoms overlap with other conditions. Fatigue, joint pain, and low-grade fever are common in many illnesses, including other autoimmune diseases, thyroid problems, and infections.
• Symptoms can come and go. Periods of worsening, often called flares, can be followed by quieter periods, so you may feel fine on the day of an appointment.
• Features can appear one at a time. A rash may come first, then joint pain or a lab abnormality months later, and the pattern may only become clear in hindsight.

The mechanisms behind lupus are not fully understood, and several factors are thought to contribute. Because of this variability, the path to a diagnosis can take a while.

Common Early Symptoms That Are Easy to Overlook

Many early symptoms are vague, and each can have an everyday explanation. Having one of them does not establish lupus. Symptoms that are often described include:

• Persistent tiredness that does not improve with rest
• Joint pain, stiffness, or swelling
• A skin rash, including a rash on the face or one that appears or worsens after sun exposure
• Fever without a clear infection
• Mouth sores
• Fingers or toes that turn white or blue in the cold, a pattern described on the MedlinePlus page on Raynaud phenomenon
• Hair thinning

Lupus can also show up in less typical ways. One published case report describes lupus presenting as a rash resembling erythema multiforme, and another describes inflammation of blood vessels in the retina as the first sign. A systematic review of oral manifestations describes mouth lesions in people with SLE. These are reports of unusual presentations, and they illustrate why the disease can be missed rather than how most people first notice it.

Conditions That Can Look Like Lupus

Part of the diagnostic work is considering other explanations. Conditions that can produce overlapping symptoms include:

• Other autoimmune diseases, such as Sjogren's syndrome, rheumatoid arthritis, and multiple sclerosis
• Hypothyroidism, which can cause fatigue and aches
• Other causes of joint pain and swelling, described on the MedlinePlus pages on arthritis and joint disorders
• Viral infections and other illnesses that cause fatigue, fever, and aches

Some autoimmune conditions can also occur together, and having one does not exclude another. MedlinePlus has a general overview of autoimmune diseases if you want the wider context.

How Clinicians Evaluate Possible Lupus

There is no single test that confirms or excludes lupus on its own. Clinicians combine your history, a physical examination, and lab and sometimes imaging or tissue results, then look at how they fit together over time. A positive antinuclear antibody (ANA) test is usually the starting point, and the 2019 EULAR/ACR classification criteria for SLE use it as an entry criterion. These are research classification criteria, not a diagnostic test. Rheumatologists, who specialize in autoimmune and joint conditions, often lead this evaluation.

Your history and examination

Your clinician may ask about the timing of symptoms, sun sensitivity, mouth sores, joint swelling, family history of autoimmune disease, and medicines you take. Keeping a simple symptom diary, with dates, photos of rashes, and notes on what seemed to bring on or ease symptoms, can give them information that a single visit cannot.

Blood and urine tests

Testing commonly includes blood counts, kidney function tests, urine tests, and antibody tests. MedlinePlus lists ANA testing among the tests used when lupus is suspected. A positive ANA result can occur in people who do not have lupus, so it is interpreted alongside symptoms and other findings. The EULAR/ACR criteria also draw on other tests, and anti-dsDNA, anti-Smith, complement levels, and antiphospholipid antibodies may be added depending on what your clinician is looking for.

Checking the organs

Lupus can involve the kidneys, sometimes without obvious symptoms early on, so urine protein and blood creatinine tests are checked over time, and a kidney biopsy may be used to guide treatment. Blood count abnormalities are another reason clinicians check blood work, and MedlinePlus has a general page on blood disorders. A skin biopsy may be used when a rash needs further clarification.

Why the Diagnosis Can Take Time

Because symptoms may appear gradually and lab abnormalities may change, clinicians sometimes need to watch the pattern over weeks to months before the picture is clear. The length of that process varies from person to person. A few things can contribute to delays:

• Early symptoms are mild or are attributed to stress, a viral illness, or being busy
• Symptoms involve different organs and are seen by different specialists
• Initial tests are normal or only mildly abnormal
• Rashes or joint swelling have faded by the time of the appointment

If you have been told your tests are normal but symptoms continue, you can tell your clinician that you are still concerned and ask whether a referral to a rheumatologist is appropriate. Photos taken during a rash or swollen-joint episode can help.

Who Is More Likely to Be Affected

MedlinePlus notes that lupus is more common in women, and that it affects people of some racial and ethnic groups more often than others. Genetics, hormones, and environmental factors are thought to contribute, but the exact cause is not fully understood. Lupus can also occur in children, men, and older adults, so being outside the typical group does not rule it out.

Possible Complications Your Care Team May Watch For

Not everyone with lupus develops these problems, and the risk differs from person to person. MedlinePlus notes that lupus can affect organs such as the kidneys, heart, and blood vessels. Your care team may monitor for several of them:

• Kidney involvement (lupus nephritis). Inflammation in the kidneys can occur, sometimes with few early symptoms, which is why urine and blood tests are repeated over time.
• Blood clots. Some people have antiphospholipid antibodies, which are associated with a higher chance of clots in some people. This is one reason clinicians may check for them.
• Heart and blood vessel health. Lupus can affect the heart and blood vessels, so clinicians may discuss cardiovascular health as part of long-term care.
• Pregnancy. Pregnancy can carry added risks when lupus is active, so planning ahead with your rheumatologist and obstetric clinician is often recommended.

What Happens After a Diagnosis

Treatment is individualized and depends on which organs are involved and how active the disease is. Many people are managed by a rheumatologist, sometimes with other specialists such as a kidney specialist or dermatologist. Treatment plans often include hydroxychloroquine, and sometimes corticosteroids or other immune-suppressing medicines, chosen by your rheumatologist according to which organs are involved. Hydroxychloroquine can damage the retina in some people, with risk rising with dose and years of use, so periodic eye screening is usually part of care. Some other lupus medicines, such as mycophenolate and methotrexate, carry boxed warnings about birth defects and pregnancy loss, so discuss your medicines with your rheumatologist before trying to conceive, and ask your prescriber or pharmacist about the label cautions for each one. Do not stop or change a prescribed medicine on your own, including during a period when you feel well. If you may become pregnant or are pregnant, tell your rheumatologist early so your medicines and disease activity can be reviewed together.

Many people can do well with regular follow-up, and outcomes vary. Sun protection, attending monitoring visits, and telling your care team about new symptoms are common parts of long-term care.

How to Prepare for an Appointment

• Write down every symptom, even ones that seem unrelated, with approximate dates
• Take photos of rashes, mouth sores, or swollen joints when they appear
• List all medicines and supplements, since some medicines can cause lupus-like reactions
• Note any relatives with autoimmune conditions
• Bring prior lab results if you have them

Your clinician can then decide which tests and referrals fit your situation.

When to Seek Medical Care for Lupus Symptoms

If you already have lupus or are being evaluated for it, some symptoms can point to serious organ involvement or another urgent problem such as a stroke, blood clot, infection, or bleeding from a low platelet count. Stroke signs, seizures, sudden severe headache, chest pain or sudden trouble breathing, a suddenly swollen leg, serious infection signs, and bleeding that will not stop need 911 or the emergency room, as listed in the box below. Other symptoms need same-day contact with your care team rather than waiting for the next scheduled visit: swelling or foamy or dark urine that may reflect kidney involvement, many new bruises or pinpoint red spots that may reflect a low platelet count, sharp chest pain that worsens with deep breaths, and fever while taking immune-suppressing medicines. If you are unsure which group your symptoms belong to, call your care team or a nurse advice line promptly, and call 911 if any emergency sign above is present.

When to Seek Medical Care