Causes and Diagnoses

Causes and Diagnoses of Systemic Lupus Erythematosus

Lupus is considered to be a multifactorial condition, which means the condition is caused by a number of different factors—usually both genetic and environmental. In lupus, hormones may also contribute to the onset of the disease.


Lupus is difficult to diagnose because there is no test for the disease, and the symptoms vary and are often vague. A diagnosis is usually confirmed based on a complete medical history, reported symptoms and a physical examination that may include:

  • Blood tests: These tests detect certain antibodies present in most people with lupus.
  • Urine tests: These tests assess kidney function.
  • Complement test: This test measures the level of complement, a group of proteins in the blood that help destroy foreign substances. Low levels of complement in the blood are often associated with lupus.
  • X-rays: These are diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones and organs.
  • Erythrocyte sedimentation rate (also called ESR or sed rate): This is a measurement of how quickly red blood cells fall to the bottom of a test tube. When swelling and inflammation are present, the blood's proteins clump together and become heavier than normal which means when measured, they fall and settle faster at the bottom of the test tube. Generally, the faster the blood cells fall, the more severe the inflammation.
  • C-reactive protein (CRP): This is a protein that is elevated when inflammation is found in the body. Although ESR and CRP reflect similar degrees of inflammation, sometimes one will be elevated when the other is not. This test may be repeated to test your response to medication.