My creatinine is 1.40 mg/dl. the reference values is 0.60-1.44. i am already 37 years old. what does this mean? thank you.

Creatinine of 1.4: Your creatinine (c) of 1.4 mg/dl shows you you are in the normal range. If you are concerned go to a nephrologist for a 24 hour urine collection for creatinine clearance and protein. This will give you an exact idea of your kidney function (k) and if yo have proteinuria. C is a function of muscle mass and k. If you are a small person, you may have a low c with some degree of impaired k function.

I bet you're fine: You're a man near your physical prime and in my experience this is normal. Creatinine varies with muscularity. When i was lifting weights every day, i ran 1.6 to 1.7. The current fad for estimating GFR based on a spot creatinine has turned every strong man into a 'kidney case' to the dismay of nephrologists. Watch your blood pressure and be thankful for overall good health.