What does a creatinine of 1.24 mean?

Interpretation: Serum creatinine is affected by gender, age, race, muscular build, and renal function. A rising creatinine is always of concern. "normal" on lab tests is generally less than 1.2 mg/dl. Renal function can be estimated with a more complex formula or measured with a 24 h urine collection.

Sounds good: The units are mg/dL, right? Especially if you're a young man with some muscle mass, this is normal.