The diagnosis of systemic lupus erythematosus (SLE)

How is lupus diagnosed?

The symptoms presented by patients are often only indicative.

The diagnosis of lupus first requires:

• an analysis by the doctor of the symptoms presented by the person

• a comprehensive clinical examination analyzing the characteristics of each symptom and looking for associated symptoms

• various biological or complementary tests whose objective will be first to confirm the diagnosis, but also to monitor or search for other conditions related to lupus (including damage to the kidneys, blood cells, lungs and pleura, heart) or associated autoimmune diseases.

  
  

Blood tests:

The specific diagnosis of lupus relies on the detection of autoantibodies. These biological analyses allow for the study of blood cells and the detection of certain abnormalities such as anemia or a decrease in white blood cells or platelets. They also allow for the detection of various autoantibodies.

Antinuclear autoantibodies (ANA)

Their detection is an excellent screening test for lupus, as their absence makes diagnosis unlikely. Antinuclear antibodies (ANA) are very common in people with lupus, but their presence alone is not sufficient for diagnosis; they can also be found in other diseases and sometimes even in people without autoimmune disease.

Anti-native DNA autoantibodies

The presence of anti-native DNA autoantibodies is much more specific for the diagnosis of lupus, even though they are less frequently found than ANA. Thus, if the clinical presentation is suggestive of lupus, the presence of anti-native DNA antibodies combined with a significant level of ANA confirms the diagnosis of lupus.

Other autoantibodies may also be sought depending on the clinical situation, including anti-Sm antibodies and antiphospholipid antibodies (the latter are frequently present in lupus, even in the absence of a thrombosis event).

The doctor may also request the measurement of certain proteins of the complement system (The complement system is a natural defense system, part of the innate immunity and acting non-specifically against infections).

Urine tests and kidney monitoring

Urine analysis allows for the detection of abnormal protein (proteinuria) or blood (hematuria) levels and, along with blood tests (creatinine and glomerular filtration rate measurements), helps monitor kidney function and detect any potential kidney damage related to lupus. These tests are important both during diagnosis and throughout the medical management of lupus.

Additional associated examinations

Depending on the symptoms found in the patient and the organs suspected of being affected, further investigations may be necessary.

These may include imaging tests such as an electrocardiogram, echocardiogram, chest X-ray, or even a pulmonary function test, an ophthalmological examination, or a skin or kidney biopsy. The latter may be necessary to determine the nature and severity of kidney damage and help determine the appropriate treatment.

Key points to remember

The clinical manifestations of lupus are varied and differ from patient to patient in their combination, severity, and progression. There is no single test that can, on its own, confirm or rule out a diagnosis of lupus. Diagnosis relies on a combination of clinical manifestations, autoantibody levels (particularly anti-native DNA antibodies), and, when necessary, other complementary investigations.

The interpretation of these results must always be carried out by a physician. This information sheet is for general information purposes only. It does not replace a consultation or personalized medical advice for diagnosis and follow-up.

Sources: PNDS Systemic Lupus of Adults and Children (2024) — Reference Centres / RAISE / FAI²R Network; Health Insurance.

Content reviewed and validated by Professor Saïd Norou DIOP, specialist in Internal Medicine, medical advisor for TAHIRAH CARE.