Natriuria and calciuria levels in preeclampsia: a cross-sectional study.

Rose Gasnier,Elvino Guardão Barros,Sérgio Hoffmeister Martins-Costa,Edimárlei Gonsales Valério,José Geraldo Lopes Ramos,Janete Vettorazzi

doi:10.1590/s1516-31802013000100021

Rose Gasnier, Elvino Guardão Barros + Show 4 more

Open Access

https://doi.org/10.1590/s1516-31802013000100021

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Abstract

Sodium excretion abnormalities in preeclampsia have been studied in relation to several factors. The objective of this study was to compare natriuria (mEq/24 h) and calciuria levels (mg/24 h) in preeclamptic patients. An analytical cross-sectional study with a control group was conducted in the obstetric center and the high-risk pregnancy outpatient clinic at a university hospital in southern Brazil, and in a primary healthcare unit in the same city, including pregnant women with mild preeclampsia, severe preeclampsia or chronic hypertension, and women with normal pregnancies (14 patients in each group). Natriuria was measured using an ion-selective electrode in an automated clinical chemistry analyzer (Hitache 917, Roche). All the patients collected 24-hour urine, at home or at the hospital, for analysis of proteins, creatinine, calcium, sodium and uric acid. Quantitative variables with asymmetrical distribution were described using the median, minimum and maximum, and were compared using the Kruskal-Wallis test. The results were logarithmically transformed, with one-way analysis of variance (ANOVA) by ranks and then the post-hoc Tukey test, and were analyzed by means of the Spearman correlation and receiver operating characteristic (ROC) curve. The significance level used was 0.05. There were significant differences between the groups in comparing severe preeclampsia with chronic hypertension and severe preeclampsia with controls (P < 0.0001 for both measurements). Natriuria levels may be lower in preeclampsia when associated with calciuria. Natriuria assessment is an additional test for differential diagnosis of hypertensive diseases in pregnancy, but is a poor predictor when used alone.

Highlights

Preeclampsia is one of the major causes of maternal morbidity, preterm birth, intrauterine growth restriction and perinatal mortality.[1,2] Its pathophysiology has been extensively studied, and its etiology is probably multifactorial
In a case-control cross-sectional study, Reis et al demonstrated that aggravation of hypertension in preeclampsia correlates with serum atrial natriuretic peptide (ANP) and brain naturiuretic peptide (BNP) concentrations, BNP values may be influenced by the existence of a prior hypertensive state.[6]
Fetal gestational age was significantly greater in patients with mild preeclampsia than in those with chronic hypertension

Summary

Introduction

Preeclampsia is one of the major causes of maternal morbidity, preterm birth, intrauterine growth restriction and perinatal mortality.[1,2] Its pathophysiology has been extensively studied, and its etiology is probably multifactorial. There is an inverse relationship between the plasma-active renin to prorenin ratio and the clinical severity of preeclampsia.[3]. Natriuretic factors appear to be altered in preeclampsia. Several studies have reported increased atrial natriuretic peptide (ANP) in preeclampsia, but this is not a uniform finding.[4] This event can precede the clinical emergence of the disease. Changes in cell sodium transport are likely to accompany hypertension-induced pregnancy.[5] In a case-control cross-sectional study, Reis et al demonstrated that aggravation of hypertension in preeclampsia correlates with serum atrial natriuretic peptide (ANP) and brain naturiuretic peptide (BNP) concentrations, BNP values may be influenced by the existence of a prior hypertensive state.[6]

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