[Parametric methods applied to the standardization of gestational reference intervals for blood renin activity, aldosterone and cortisol using the transversal and longitudinal approach]. / Metodi parametrici applicati alla standardizzazione degli intervalli di normalità gestazionale di attività reninica, aldosterone e cortisolo plasmatici mediante approccio trasversale e longitudinale.

This investigation is devoted to define monthly-qualified gestational reference intervals for plasma renin, aldosterone and cortisol as derived by transverse or longitudinal approaches. Reference intervals refer to 95% confidence interval, 90% tolerance interval, the 95% predictive interval, in addition to the mean plus or minus the standard error and standard deviation. By applying both methodological approaches it has been found that plasma renin and aldosterone exhibit a progressive gestational increase. By contrast, cortisol shows an initial increase and thereafter stays on the same values. Statistical analysis revealed the transversally--and longitudinally--derived reference intervals to be not statistically different. Because of such a similarity, laboratory medicine can interchangeably use both kinds of reference intervals for estimating the normality of plasma renin, aldosterone and cortisol values in a single case of pregnancy. This interchangeability of values leads to simplify the methodology for measuring plasma renin and aldosterone in pregnancy since it is not necessary to standardize the gestational nomograms for renin-sodium and/or aldosterone-sodium relationship. This is a real way to reduce the costs and to optimize the compliance in the monitoring of pregnancy.

Inactive and active renins, aldosterone and cortisol in puerpera and newborn.

Eleven primiparae (aged from 20 to 31 years) have been sampled at the time of partum and throughout the puerperium for simultaneous determinations of plasma levels of inactive (prorenin) and active (PRA) renins, aldosterone (PA) and cortisol (PC). Biodata have been compared to time-qualified values obtained in non-pregnant adult women (aged from 17 to 37 years). Pregnant women show peripartum levels of prorenin, PRA, PA and PC significantly higher than the time-qualified reference intervals. Gestational increment is meanly of 3-4 times for prorenin, of 5-8 times for PRA, of 17-19 times for PA, of 4-5 times for PC. Puerperal levels of PRA, PA and PC show a progressive decline while those of prorenin suddenly fall and then remain quite stable. Neonatal levels of prorenin, PRA, PA and PC are higher than normal. Neonates show levels of prorenin, PRA, PA and PC, respectively equal, increased equal and decreased when compared to mothers. The different equipment of hormonal levels in mother and newborn leads to suggest a selective role of the placenta as a filter.