Do high creatinine levels mean renal failure?

High creatinine. Serum c is dependent on the person's weight, race and age. You need to have a 24 hour urine collection for a creatinine (c) clearance determination to know what your renal function is. When the urine is returned, blood is taken for a c level. That is the sure way to know how serious your creatinine level is and what your true renal function is.