Flares are a major part of having lupus, they can be mild to dangerous. People with SLE often have other illness that flare as well and distinguishing them can be difficult at times. Blood tests are one of the best ways for a Rheumatologist to diagnose a lupus flare; however, these tests are not always accurate when dealing with flares. Sometimes these tests can be normal during rashes and inflammation. If you have any new or troubling symptoms always seek medical attention.