Hi Firebabe,
Testing your creatinine levels is used to evaluate your kidney function. I noticed in your signature line that you have lupus nephritis, so this test is important. I've attached a link to the best website for all our questions regarding tests, etc. I hope you get the info you need. Your best resource is your rheumy or family doctor though.
Ginny
http://www.labtestsonline.org/understanding/analytes/creatinine/test.html