Prorenin and active renin levels in paediatrics: a bioanalytical review

As part of the extended renin-angiotensin-aldosterone system, active renin and its precursor prorenin have been an area of research interest for decades. Although several studies showed a correlation with disease, other studies found no significant association, e.g. attributed to limited sample size or pharmacological effects of antihypertensive drugs. Since the measurement of both proteins has typically been carried out in adult populations, the data in paediatrics is limited. This review aimed to collate the current data on plasma renin and prorenin levels in children and compare the levels of healthy vs. the diseased state. A literature search using Medline resulted in 213 publications of which 15 studies were classified as relevant. In the extant studies in the literature, an age-dependent decline of renin plasma concentration was observed in newborns compared to adolescents. For children with cardiovascular disease, five studies were identified that provide limited insight into the pathophysiological regulation of renin. In general, sample handling is still a crucial step, which might particularly affect measured active renin concentrations due to conformational changes of its precursor prorenin. A reliable assessment for prorenin levels in the maturating population is yet not possible due to the low number of available publications. Three different approaches to quantify prorenin were found and raise the question on the comparability of these methods. The review emphazised several weaknesses and highlights the need for an accurate procedure to determine levels of active renin as well as prorenin in its closed and open form.