Creatinine level is 1.8 on blood test but no other symptoms, is this a problem?

My husband had his creatinine level checked twice in the last 3 weeks both times at about 1.8. Dr. is concerned and has ordered urine test and other blood tests. He has no other symptoms. He has been on a weight lifting regimen for the last 6 months of at least 2-3 times a week and taking a protein supplement all but last 3 weeks. Could any of this have affected his creatinine levels? Will the urine test show more detail? Thanks!