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Background: There is a paucity of literature on the normative levels of plasma renin concentration (PRC) and serum aldosterone (SA) in premature neonates. This study aims to provide normative data on PRC and SA levels in preterm neonates in the first 2 weeks after birth and explore associations with maternal, perinatal, or postnatal factors. Methods: Neonates born at 26- to 34-week gestation were recruited from two neonatal intensive care units in Canada and Australia. The direct renin assay PRC and SA were analyzed on day 1 and days 14–21 after birth to compare across categorical variables and to produce normative values. Results: A total of 262 subjects were enrolled from the Canadian (29%) and Australian (71%) sites. The mean gestational age was 30 weeks, with a mean birth weight of 1457 g. The normative values of PRC and SA for neonates born between 26 + 0 and 29 + 6 weeks and 30 + 0 and 34 + 0 weeks of gestation were produced for day 1 and day 14–21 after birth. Both PRC and SA increased from day 1 to day 14–21. The more premature neonates reached a higher PRC on days 14–21 after birth but exhibited lower SA levels on day 1 after birth. When comparing gender, birth weight, and maternal risk factor categories, no statistical differences in PRC or SA were found. A small but significant decrease in PRC, but not SA, was noted for neonates with placental pathology. Conclusions: This study produced normative values of PRA and SA in clinically stable preterm neonates that can be referenced for use in clinical practice. [ABSTRACT FROM AUTHOR]

Purpose: Primary aldosteronism (PA) is considered the most common form of secondary hypertension, however, its prevalence, particularly in a general population, is still a matter of debate. The aim of our study was to evaluate the prevalence of PA in a randomly selected general population sample. Materials and methods: A total of 1940 individuals (1% population random sample) aged 25–64 years were screened for major cardiovascular risk factors in six districts of the Czech Republic. Hypertension was defined as a mean of two blood pressure readings ≥140/90 mmHg at one visit or taking antihypertensive medication. Within this population, 740 individuals were labelled as hypertensives and 650 of them sampled for the analysis of direct plasma renin and serum aldosterone. The diagnosis of PA was based on elevated serum aldosterone, low plasma renin and high aldosterone/renin (ARR) ratio and was also verified by a confirmatory test with saline infusion. Results: Positive ARR was found in 52 (8%) individuals (64% women, 36% men, however, due to substatntial proportion of reluctatnt participants to undergo a further work-up (27%), we could confirm the diagnosis of PA only in 13 of them (2%). Aldosterone-producing adenoma was found in one case only, seven patients had idiopathic type and five individuals refused potential surgical treatment therefore, adrenal venous sampling was not performed. Conclusion: Elevated serum aldosterone together with low renin and high ARR were found in 52 (8%) of hypertensives selected from a general population sample, however, the diagnosis of PA was confirmed only in 13 of them (2%). This study based on a general population survey highlighted the difficulty of conducting epidemiological studies on primary aldosteronism in a relatively healthy cohort part of whom did not provide the level of collaboration that is necessary to assess the true prevalence of this condition. [ABSTRACT FROM AUTHOR]

Aldosterone is a mineralocorticoid steroid hormone, the measurement of which in the clinical laboratory is principally performed for the investigation of primary hyperaldosteronism. Primary hyperaldosteronism is a specifically treatable and potentially curable form of hypertension, which typically presents as drug-resistant hypertension and, in up to 37 % of cases, hypokalemia. Accurate measurement of aldosterone concentration is essential for correct diagnosis. The serum concentrations of aldosterone are in the picomolar range and therefore sensitive aldosterone assays are required. With the advancement in instrumentation of LC-MS/MS, the picomolar range of aldosterone can be easily measured by the newer models, but for those with a less sensitive instrument, special technique for sample preparation to enhance assay sensitivity is required. This work described the use of charge-tagging for the picomolar measurement of serum aldosterone in a less sensitive LC-MS/MS instrument. The assay was linear up to 3000 pmol/L with lower limit of quantitation at 80 pmol/L. The mean relative recovery was 96.5 % with a range of 89.3-101.6 % for aqueous calibrators and the mean relative recovery was 94.8 % with a range of 87.5-101.4 % for serum calibrators. Intra-assay CVs range from 8.2 % to 11.3 %, and inter-assay CVs ranged from 8.5 % to 13.5 % at concentration range from 229 to 1720 pmol/L. The LC-MS/MS method compared well (y = 1.04x + 8.97) with the in-use radioimmunoassay method. There was no significant difference found ( p = 0.7135) between results determined by LC-MS/MS and radioimmunoassay method. [ABSTRACT FROM AUTHOR]

Although low dietary salt intake has beneficial effects on BP (blood pressure), low 24hUNa (24 h urinary sodium excretion), the most accurate estimate of dietary salt intake, is associated with increased mortality in people with diabetes. In the non-diabetic population, low salt intake is associated with increased RAAS (renin-angiotensin-aldosterone system) activity. In this cross-sectional study, we examined the relationship between 24hUNa, PRA (plasma renin activity), serum aldosterone and BNP (brain natriuretic peptide) in patients with diabetes. Clinical characteristics, 24hUNa, PRA, serum aldosterone and BNP were recorded in 222 consecutive patients (77% with Type 2 diabetes) attending a diabetes clinic at a tertiary hospital. The relationship between 24hUNa, serum aldosterone, PRA, BNP, urinary potassium excretion, serum potassium, serum sodium, eGFR (estimated glomerular filtration rate), urinary albumin excretion and HbA1c (glycated haemoglobin) was examined by a multivariable regression model. Levels of 24hUNa significantly predicted serum aldosterone in a linear fashion (R2 =0.20, P=0.002). In the subgroup of patients (n=46) not taking RAAS-modifying agents, this relationship was also observed (R2 =0.10, P=0.03), and the effect of 24hUNa on serum aldosterone was found to be more pronounced than in the whole cohort (coefficient= –0.0014, compared with –0.0008). There was no demonstrable relationship between 24hUNa and PRA or BNP. Low 24hUNa is associated with increased serum aldosterone in people with diabetes, in the presence and absence of RAAS-modifying agents. This raises the possibility that stimulation of the RAAS may be a mechanism that contributes to adverse outcomes observed in patients with low 24hUNa. [ABSTRACT FROM AUTHOR]

Abstract: Measurement of serum aldosterone is clinically important in the diagnosis of hypertension. While isotope dilution gas chromatography–mass spectrometry (ID-GC–MS) provides reliable results, it requires derivatization and is lengthy and time-consuming. Detection by liquid chromatography–mass spectrometry (LC–MS) is a potentially superior method. The analysis utilizes 0.5mL of serum. The samples were extracted with dichloromethane–ether. The extract was evaporated to dryness and aldosterone was analyzed by LC–MS/MS operating in the negative mode ESI after separation on a reversed-phase column. Aldosterone was also measured by RIA. The calibration curves for analysis of serum aldosterone exhibited consistent linearity and reproducibility in the range of 60–3000pmol/L. Interassay CVs were 4.3–7.5% at aldosterone concentrations of 97–993pmol/L. The lower limit of quantitation (LOQ) was 30pmol/L (signal to noise ratio=10). The mean recovery of the analyte added to serum ranged from 95 to 102%. The regression equation by LC–MS/MS (x) and RIA (y) method was: y =1.33x +185 (r =0.95; n =124). Sensitivity and specificity of the LC–MS/MS method for serum aldosterone offer advantages over GC–MS by eliminating derivatization. The novel method is rapid, reliable and simple to perform with a routine LC–MS/MS spectrometer. The sensitivity is adequate for patient samples. Aldosterone concentrations reported by nonextraction RIA were consistently higher than those produced by LC–MS/MS. [Copyright &y& Elsevier]