The effect of 30 min of supine rest on plasma renin concentrations in paediatric patients.

Aim: The aim of this study is to interpret plasma renin concentrations (PRCs) correctly in a clinical setting, it is essential to understand to what extent physical activity influences the concentration. Reference values for different postural positions exist for adults, but data for children are sparse. In this study, the effect of 30 min of rest on plasma renin concentrations in paediatric patients was examined.
Methods: In total, 41 paediatric patients, undergoing either arginine or clonidine provocation tests for growth hormone deficiency, were included. For each stimulation test, two blood samples were drawn. One at time 0 min and one after 30 min of rest. In total, renin concentrations were determined in 86 serum samples.
Results: Renin concentrations decreased from 0 to 30 min with a median value of -20.5% (inter-quartile range: -33.0% to -12.8%). This decrease was not dependent on sex, age, medication or comorbidity, and the variance of renin did not differ between 0 and 30 min.
Conclusion: Renin concentrations in children differ according to postural position, which is comparable to adults. Thus, the clinical interpretation of renin results needs to consider the preanalytical conditions applied in the local reference population.
(© 2024 The Author(s). Acta Paediatrica published by John Wiley & Sons Ltd on behalf of Foundation Acta Paediatrica.)