[A new equation to predict urine creatinine values using data from Chilean population]

Evaluation of 24-hour collection accuracy is based on urinary creatinine excretion (UCr), usually using wide ranges indexed by weight. Equations that predict the expected UCr are also available.

To generate an equation for estimating UCr in Chilean population and evaluate its performance in comparison to existing formulas.

A total of 464 24-hour urine collections from outpatients aged between 15 and 88 years old were used. Ninety percent of collections (n = 418) were randomly extracted to assess the association between absolute UCr values with sex, age, height and weight of participants. A formula was created to estimate the 24-hour UCr using a multiple linear regression model. In the remaining 10% of urine collections (n = 46), the performance of this formula and others reported in the literature were tested.

Age, sex and weight were significantly associated with 24-hour UCr values. The new equation was able to predict UCr values with a similar accuracy than CKD-EPI and Walser equations and outperformed other equations.

Our equation developed with Chilean values predicts 24-hour UCr values accurately.