Testing for lupus involves a combination of medical history review, physical examination, and multiple laboratory tests because no single test can definitively diagnose lupus.

How Lupus is Tested and Diagnosed

1. Medical History and Physical Exam
Doctors start by assessing symptoms and signs that vary widely among individuals and may overlap with other diseases. They also review family history of lupus or other autoimmune diseases and perform a thorough physical examination

. 2. Blood Tests
Several blood tests are used to detect markers associated with lupus:

• Antinuclear Antibody (ANA) Test: This is a sensitive screening test where most people with lupus test positive. However, a positive ANA alone does not confirm lupus because it can be positive in healthy people and other autoimmune diseases

• Anti-double stranded DNA (anti-dsDNA) and Anti-Smith (anti-Sm) Antibodies: These are more specific to lupus and help confirm the diagnosis if ANA is positive

• Complete Blood Count (CBC): Checks for anemia, low white blood cells, or low platelets, which are common in lupus

• Complement Tests: Measure complement proteins that are often low in lupus due to immune system activation

• Other Autoantibodies: Tests for antiphospholipid antibodies and others may be done to assess specific lupus-related antibodies

3. Urine Tests
Urinalysis checks for protein or red blood cells in urine, indicating possible kidney involvement, which is common in lupus

. 4. Imaging and Biopsy
If organ involvement is suspected, doctors may order imaging tests such as X-rays, CT scans, MRI, or echocardiograms to assess heart, lung, brain, or kidney damage. In some cases, a biopsy of skin or kidney tissue may be performed to confirm lupus effects on organs

. 5. Diagnostic Criteria
Doctors use established criteria like the EULAR/ACR or SLICC criteria, which combine clinical symptoms and lab results to make a diagnosis

Summary

• No single test diagnoses lupus.
• Diagnosis is based on a combination of symptoms, physical exam, blood and urine tests, and sometimes imaging or biopsy.
• ANA is a key screening test, but more specific antibody tests and organ assessments are needed to confirm lupus

This comprehensive approach helps differentiate lupus from other conditions and guides appropriate treatment planning.