Lupus is difficult to diagnose because of the vagueness of the symptoms each person might have. There is no single test that can diagnose lupus. A diagnosis is usually confirmed based on a complete medical history, reported symptoms, and a physical examination that may include the following:
Blood test - To detect for certain antibodies that are present in most people with lupus
Blood and urine tests - To assess kidney function
Complement test - To measure 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)
Erythrocyte sedimentation rate (ESR or sed rate) - 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. Thus, 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) - 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.
Further, the American College of Rheumatology created a set of criteria to assist physicians in making a diagnosis of lupus. The individual must have four of the 11 specific criteria to be diagnosed with lupus. It is important to remember that having some of the following symptoms does not mean that lupus is the diagnosis. The criteria include the following:
Malar rash - A rash shaped like a butterfly that is usually found of the bridge of the nose and the cheeks.
Discoid rash - A raised rash usually found on the head, arms, chest, or back.