Fluid Intake and Blood Pressure in Children. The Spa Project

Background: Sodium intake is known to contribute to the development of hypertension. The reduction of sodium intake is currently a cornerstone in the prevention and management of hypertension. Inducing an increase in renal sodium excretion might represent a further potential preventive and/or therapeutic opportunity .Methods: The SPA Project is a multicenter, observational, cohort study aimed at investigating blood pressure in relation to fluid and sodium intake with the working hypothesis that an increased fluid intake can improve renal sodium handling towards a decreased blood pressure. Children were investigated as to their sodium and fluid intake by means of urinary sodium and creatinine from 4 samples of urine taken in different days in order to characterize them in low/high sodium and low/high fluid intake groups. Both systolic and diastolic blood pressure (by multiple office blood pressure measurements) were used as outcome measures.Findings: Three hundred and thirty-nine healthy, non-overweight children (51.6% boys) with a median age of 5.7 years old (IQR: 5.3-6.2) participated in the study. Among children with higher sodium intake, those introducing more fluids, showed a significantly lower blood pressure (both systolic and diastolic) compared to those with lower fluid intake: systolic 86.0 + 8.5 vs 90.0 + 8.1 mmHg; p: 0.014 and diastolic: 53.8 + 4.9 vs 58.6 + 6.6 mmHg; p