You should be concerned about high creatinine levels when your creatinine measurements exceed the normal ranges, which are 0.6 to 1.2 mg/dL for women and 0.7 to 1.3 mg/dL for men. If your creatinine levels are higher than these ranges and you experience symptoms such as fatigue, nausea, vomiting, and swelling, it is advisable to seek medical attention. These symptoms may indicate potential kidney dysfunction or other underlying health issues that need to be addressed.