IMMUNOREACTIVE RENIN CONCENTRATIONS IN HEALTHY-CHILDREN FROM BIRTH TOADOLESCENCE

We establish normative data for immunoreactive renin concentration in serum of healthy children. In a retrospective study, surplus sera of 2 81 healthy children, aged 0-18 years, were collected from the laborato ry. The determinations were performed with a commercially available tw o-site immunoradiometric assay. Functional sensitivity was 4.0 mU/l, i nter-assay and intraassay variance were 7.0-18.3% and 3.8-7.5%, respec tively. In umbilical cord and during the first 4 days of life, renin c oncentrations (geometric mean) were significantly higher (P < 0.05) th an in older infants and children [umbilical cord: 155.2 mU/l; newborn infants (2-4 days of life): 90.9; newborn infants (5-7 days of life): 32.5; 2 weeks-3 months: 40.8; 4 months-1 year: 54.5; 1-3 years: 46.3; 3-5 years: 48.5; 5-7 years: 51.6; 7-11 years: 38.5; 11-15 years: 37.7; 15-18 years: 31.9], Newborn infants delivered by Caesarian section ha d significantly lower renin concentrations in umbilical cord than thos e delivered vaginally (P < 0.02). Considering the methodological advan tages and disadvantages of plasma renin activity and renin concentrati on assays, renin measurement was at least as valuable and accurate as plasma renin activity determination. (C) 1998 Elsevier Science B.V. Al l rights reserved.