The diagnosis of lupus is often challenging due to the disease’s wide variety of symptoms and its ability to mimic many other illnesses. Often called “the great imitator,” lupus can resemble conditions like rheumatoid arthritis, fibromyalgia, chronic fatigue syndrome, thyroid disorders, and infections. As a result, achieving a timely and accurate diagnosis requires a careful, step-by-step approach.
Why Lupus Is Hard to Diagnose
Lupus affects people differently. Some may have only mild joint pain, while others experience serious organ involvement. There is no single test for lupus. Instead, diagnosis relies on a combination of symptoms, medical history, physical examination, and lab results.
Patient History and Physical Examination
Doctors start by collecting a detailed medical history. They ask about:
- Fatigue
- Joint pain or swelling
- Skin rashes (especially butterfly-shaped facial rash)
- Mouth ulcers
- Hair loss
- Sensitivity to sunlight
- Fever
- Swollen lymph nodes
They’ll also ask if symptoms come and go or follow a pattern. A family history of lupus or other autoimmune diseases may increase the risk of developing the condition.
During a physical exam, the doctor looks for:
- Skin rashes (especially malar or discoid)
- Signs of inflammation in joints
- Fluid around the heart or lungs
- High blood pressure or leg swelling (may signal kidney problems)
Key Lab Tests in Lupus Diagnosis
1. Antinuclear Antibody (ANA) Test
A positive ANA test is found in nearly all people with systemic lupus erythematosus (SLE). However, a positive ANA alone does not confirm lupus, as it can appear in other conditions — or even in healthy individuals. It is often the first test used to screen for lupus.
2. Autoantibody Tests
If ANA is positive, additional blood tests may follow:
- Anti-dsDNA: Highly specific to lupus, often linked with kidney disease.
- Anti-Smith (anti-Sm): Another marker highly specific to lupus.
- Anti-Ro/SSA and Anti-La/SSB: May be present in cutaneous lupus or Sjögren’s syndrome. These are also associated with neonatal lupus in pregnancy.
- Antiphospholipid antibodies: Increase the risk of blood clots, strokes, and pregnancy complications.
3. Complement Levels (C3 and C4)
Low complement levels often signal active lupus. Doctors use these results to monitor disease flares and treatment response.
4. Blood and Urine Tests
- Complete blood count (CBC) can detect anaemia, low white cells, or low platelets — common in lupus.
- Urinalysis may show protein or blood in the urine, indicating lupus nephritis.
- If kidney involvement is suspected, a kidney biopsy may be needed to determine the severity and guide treatment.
Imaging and Other Diagnostic Tools
If lupus affects major organs, doctors may order imaging such as:
- Chest X-ray or echocardiogram: To detect fluid around the heart or lungs.
- Brain MRI: For neurological symptoms like seizures, confusion, or memory issues.
Classification Criteria for Lupus
To guide diagnosis, doctors may use formal criteria:
American College of Rheumatology (ACR) Criteria
This system includes 11 signs and symptoms. A person meeting 4 or more of these may be diagnosed with lupus.
SLICC Criteria
The Systemic Lupus International Collaborating Clinics (SLICC) classification allows for earlier diagnosis and broader recognition of lupus presentations.
EULAR/ACR 2019 Criteria
These newer guidelines give more weight to key lab tests and allow earlier diagnosis with fewer symptoms, improving accuracy and sensitivity.
When to Refer to a Specialist
Diagnosis can be delayed when symptoms are vague or intermittent. Patients may see several specialists — such as dermatologists, nephrologists, neurologists, or haematologists — before lupus is confirmed. Referral to a rheumatologist is often essential, as they specialise in autoimmune diseases and are best equipped to interpret the full clinical picture.
Types of Lupus
Understanding the specific type of lupus is crucial for diagnosis and treatment:
- Systemic lupus erythematosus (SLE): Affects multiple organs and systems.
- Cutaneous lupus erythematosus (CLE): Limited to the skin.
- Drug-induced lupus: Triggered by certain medications, usually resolves after stopping the drug.
- Neonatal lupus: A temporary condition in newborns caused by maternal antibodies.
Role of Psychological Evaluation
In cases of neuropsychiatric lupus, mental health assessment may be necessary. Lupus can cause depression, anxiety, memory loss, or even psychosis. These issues may be due to the disease itself or the stress of living with a chronic illness.
Summary: Diagnosing Lupus
Diagnosing lupus is a complex process that relies on:
- Patient history
- Physical exam
- Targeted lab testing
- Imaging and biopsies (when needed)
Early diagnosis is crucial for starting treatment and avoiding serious complications. Because lupus can affect many organs and mimic other diseases, a multidisciplinary team approach is often needed for a clear and confident diagnosis.
