Creatinaemia at birth is equal to maternal creatinaemia at delivery: does this paradigm still hold?

Abstract

Objective: The paradigm that creatinaemia at birth is equal to maternal creatinaemia may also depend upon the quantification technique applied. Paired maternal-neonatal creatinaemia samples in whom Jaffe in both or compensated Jaffe (maternal) and enzymatic quantification (neonate) were applied. Methods: Extreme low birth weight infants in two time intervals were included when paired maternal-neonatal creatinaemia samples were available. In cohort 1 (2000–2005), creatinaemia (mothers and neonates) was based on Jaffe assay. In cohort 2 (2007–2010), maternal creatinaemia was based on compensated Jaffe. In neonates, an enzymatic technique was applied. Unpaired Mann Whitney U, paired Wilcoxon and Bland-Altman were used. Results: Based on 80 and 52 paired creatinaemia samples, there was no significant difference between maternal (0.80, 0.41–1.6 mg.dl⁻¹) and neonatal creatinaemia (0.78, 0.31–1.46 mg.dl⁻¹) in cohort 1 while a significant difference (p < 0.001) between maternal (0.6, 0.29–2.24 mg.dl⁻¹) and neonatal creatinaemia (0.67, 0.4–2.2 mg.dl⁻¹) was observed for cohort 2. Using Bland-Altman, the fit was perfect for cohort 1 (mean diff −0.02 mg.dl⁻¹), but not for cohort 2 (−0.08 mg.dl⁻¹). Conclusions: The quantification method affects the paradigm that creatinaemia at birth is similar to maternal creatinaemia. Maternal and neonatal creatinaemia values depend on the method used. Consequently, method-specific reference values are needed.

Keywords::

• Creatinaemia
• enzymatic assessment
• Jaffe
• renal function

Declaration of Interest: Elena Levtchenko and Karel Allegaert are supported by the Fund for Scientific Research, Flanders (Belgium) (F.W.O. Vlaanderen) by a Fundamental Clinical Investigatorship (1801110N and 1800209N).