One more thing, check with the lab about fasting; we have never had to fast for this test; obviously an ER doesn't make you fast for it if they have to draw your blood, so you may want to question the fasting.
Kidney problems could be a problem. If you were dehydrated on the day the blood was drawn, that would also give you a high reading. talk to your doctor about this.
First of all we need to determine if it was an accurate test. You need to fast prior to the test for 8 hours. No vitamin C, no barbituates, no diuretics. High creatinine is an indicator of the health of one's kidneys, and a high reading indicates they may not be functioning properly. I hope your doctor addressed this with you, if not he needs to.