Insulin resistance parameters in children born very preterm and adequate for gestational age.

BACKGROUND: Preterm neonates are at risk for metabolic syndrome later in life. Whether prematurity constitutes an independent risk factor for the development of cardiovascular disease and metabolic syndrome remains controversial. OBJECTIVE: To compare anthropometric measures, cardiometabolic risk factors and insulin resistance variables between children who were born very preterm (VPT, <32 gestational weeks) and at term (Term, >37 gestational weeks) and adequate for gestational age (AGA). METHODS: We designed a cross-sectional cohort study, recruiting 120 children (5.0-8.5 years old) from the preterm clinic at Red de Salud UC-Christus and Complejo Asistencial Dr. Sótero del Río, and term children from the community. We excluded children born small for gestational age, based on INTERGROWTH21. Anthropometrics data were classified using WHO reference standards. The homeostasis model assessment insulin resistance (HOMA-IR) index, quantitative insulin sensitivity check index (QUICKI), triglyceride-to-HDL-C ratio (TG/HDL-C) and Pediatric Score Index for Metabolic Syndrome (PsiMS) were calculated. RESULTS: VPT children born AGA had lower HDL cholesterol levels (p = .019) and a higher PsiMS score than those born at term (p = .043). We observed a higher percentage of children with HDL cholesterol ≤40 mg/dl (13.0% vs. 2.3%, p = .026) and BP ≥90th percentile among the VPT children than among the Term children (26.0% vs. 11.6%, p = .031). CONCLUSIONS: At school age, blood pressure was higher, and HDL-C was lower among VPT children born AGA, suggesting a potential metabolic risk; therefore, it is essential to follow this group throughout their lives.

Urinary sodium-to-potassium ratio and plasma renin and aldosterone concentrations in normotensive children: implications for the interpretation of results.

OBJECTIVES: To identify associations among the plasma renin concentration (PRC), plasma aldosterone and urinary sodium (Na)/potassium (K) ratio, and to integrate these variables into a nomogram with the aim of estimating the expected versus observed aldosterone concentration. METHODS: We studied 40 healthy normotensive children (5-8 years old, 57.5% girls) who were born at term and were adequate for their gestational age. Following overnight fasting, the PRC and plasma aldosterone in blood samples were measured, and the Na/K ratio was calculated from a simultaneously obtained urinary spot sample. A mathematical function was defined with these three variables, and a nomogram was built that would return the expected aldosterone concentration from the obtained plasma renin and urinary Na/K ratio values. RESULTS: The PRC (B =  5.9, P < 0.001) and urinary Na/K ratio (B = -98.1, P = 0.003) were significant independent predictors of plasma aldosterone. The correlation between the observed plasma aldosterone and the expected plasma aldosterone, as obtained from the nomogram, was r = 0.88, P < 0.001. The average difference between the observed and expected plasma aldosterone was -0.89, with a standard deviation of ±30%. CONCLUSION: The strong correlation between the urinary Na/K ratio, from urine samples taken at the same as the blood samples, and plasma renin and aldosterone concentrations allowed us to build a nomogram to predict aldosterone levels. This approach may be useful for evaluating the renin-angiotensin-aldosterone system (RAAS) in pediatric patients with hypertension and RAAS dysfunction.