Hi My name is Dr. Bob Lahita and I am the Chairman of Medicine at Newark Beth Israel Medical Center and I am Professor of Medicine at University of Medicine and Dentistry of New Jersey. And I am going to talk to you about diagnosing Lupus.Lupus erythematosus is an autoimmune disease and it is not an easy disease to diagnose for most physicians. The first and most important thing to making the diagnosis of Lupus is what's called The History. Which is what you the patient give your doctor. 80% of the disease can be diagnosed from the history.There is no specific blood test that's indicative of this disease. There are blood tests such as the anti-nuclear antibody which, if positive, is helpful. But the anti-nuclear antibody is present in about 200 different diseases. And it's even positive in normal people. The other anitbodies, these are proteins that are secreted by cells in your blood that are there to protect you from bacteria and viruses.The other Antibodies are Anti-native DNA, Anti-Smith, Anti-Ribonuclear Protein or RNP for short. Anti-Ro, Anti-LA. And a variety of other antibodies which your doctor may explain to you.Generally these antibodies are obtained by a Rheumatologist who is a specialist in diagnosing lupus. Absence of these antibodies does not mean that you don't have systemic lupus, but their presence is very helpful in clinching the diagnosis. Two other tests that are very helpful are complement determinations C3 and C4 and then finally a total hemolytic complement which is a functional assay which means it tells us how your blood is behaving in response to the presence of what are called immune complexes.Immune complexes are really complexes formed by foreign material which, in the case of lupus, is your own cells and tissues and the antibodies that attach to those cells and tissues. These immune complexes then can activate the complement cascade which is a very complicated amplification system in your blood and it lowers the level of complement components. That's extremely helpful in making the diagnosis of active systemic lupus.Now I say active systemic lupus because there's such a thing as inactive systemic lupus. Inactive Lupus is where most of the tests can be normal but you can still feel pretty bad. Some of the diagnostic clues we look for in the history are a feeling of weakness, tiredness, malaise, hair loss, an unusual rash, sensitivity to the sun, muscle aches, joint pains.I've just given you some information on diagnosing the disease systemic lupus erythematosus, for more information go to the website, About.com.