Reference ranges for plasma creatinine during the first month of life.

A reference range of plasma creatinine levels for the first month of life derived from 238 babies of 25-42 weeks' gestation is presented. Measurements were performed on a Beckman Creatinine Analyser 2, which uses the Jaffé rate reaction method. There was a decline in plasma creatinine level with increasing postnatal and gestational age. Infants undergoing mechanical ventilation at age 2 days had a significantly increased creatinine level.