Urinary excretion of renin and angiotensinogen in hypertensive children and adolescents.

INTRODUCTION: In recent years hypertension has become an emerging condition in the young population. It has been proposed that the renin-angiotensin system plays an important role in regulation of blood pressure. We assessed whether activation of the intrarenal renin-angiotensin system occurs in hypertensive children and adolescents and what better reflects its activity: urine angiotensinogen (AGT) or urine renin (REN). MATERIAL AND METHODS: The study was conducted on a sample of 58 subjects with primary hypertension (HT) and 29 normotensive children and adolescents. We measured urine REN and AGT excretion and assessed the values in relation to blood pressure (BP) and other clinical parameters. Both REN and AGT values were calculated by urine creatinine: REN/cr. and AGT/cr., respectively. RESULTS: We observed higher urine REN/cr. values in hypertensive subjects in comparison to the reference group (6.99 vs. 2.93, p = 0.003). Hypertensive participants showed positive correlations between urine REN/cr. and diastolic 24-hour BP (r = 0.42, p = 0.002) as well as between urine REN/cr. and urine AGT/cr. (r = 0.266, p = 0.044, respectively). CONCLUSIONS: Increased urine REN/cr. in hypertensive children and adolescents and its positive correlation with BP may indicate its important role in the pathogenesis of HT. Perhaps urine REN/cr. could be a marker of intrarenal renin-angiotensin system activity. Nevertheless, further research should be undertaken to confirm this observation.

Are low birth weight children predisposed to renal loss of carnitine?

Aim: The plasma homeostasis of both free and esterified carnitines is mostly regulated by renal tubular reabsorption, which may be disturbed in low birth weight children. The aim of study was to check whether disturbances in excretion of l-carnitine (LC) and its main ester, acetyl-carnitine (ALC), may be the result of renal dysfunction in low birth weight children (LBW).Methods: This study included 59 LBW children (2165 g [1490-2440]) and 22 children with normal birth weight as a reference group (3500 g [3275-3650]). Subjects were divided into three groups: 0-3 months, 4-12 months and over 1 year at the time of testing. Urinary levels of carnitine were measured spectrophotometrically.Results: The urine excretion of Free LC, Free LC/cr, Total LC and Total LC/cr. Were significantly higher in 0-3 and 4-12-month old LBW infants study groups when compared to the reference groups. We found statistically significant higher urine excretion of ALC and ALC/cr. in all age groups of LBW infants compared to the reference group. There was a negative correlation between birth weight and free LC/cr. (r= -0.3, p < .05), Total LC/cr. (r= -0.34, p < .05), and ALC/cr. (r= -39, p < .05), and in the children >12-month-old strong negative correlation between eGFR and free LC/cr. (r= -0.6, p < .05), Total LC/cr. (r= -0.61, p < .05), ALC/cr. (r= -0.61, p < .05.)Conclusion: Higher urine excretion of both LC and ALC and its negative correlation with birth weight and eGFR may reflect some degree of renal dysfunction in LBW infants.

The Possible Impact of Hyperuricemia on Serum Soluble Receptor for Advanced Glycation end Products (sRAGE) Levels in Teenagers: A Case Control Study.

BACKGROUND: Dietary advanced glycation end products (AGEs) and their interactions with the soluble receptors for AGEs (RAGE) play a crucial role in the pathogenesis of cardiovascular diseases. OBJECTIVE: This study was set out to assess, whether there was any association between serum sRAGE level and serum uric acid level in children with hyperuricemia. METHODS: This case-control study involved 53 patients (12 girls, 41 boys) with hyperuricemia (defined as serum uric acid >4.8 and >5.5 mg/dl in girls and boys, respectively) aged (median [IQR]) (15.5 [13.5-15.5] years). Thirty-six healthy individuals with normal serum uric acid level were selected as a reference group. Additionally, the study group with hyperuricemia was divided into two groups: HU-HT (hypertensive n=25) and HU-NT (normotensive n=28) teenagers. The serum concentration of human sRAGE was measured using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. RESULTS: We found statistically significant differences in serum sRAGE levels between normotensive subjects with hyperuricemia (median [IQR]) (169.8 [148.3-231.1] pg/ml) and reference group (median [IQR]) (129 [107.4-175.3] pg/ml), p<0.01. Univariate analysis of the data revealed a positive correlation between serum sRAGE and serum uric acid in the study group (r=0.306, p<0.05). CONCLUSION: Our data showed that serum soluble receptors for AGEs are increased in teenagers with hyperuricemia. In contrast, neither hypertension nor increased BMI had a significant influence on serum sRAGE concentration. Further studies are needed to discover the possible mechanism on the influence of uric acid on sRAGE levels and to assess its possible clinical significance.