Sodium intake and blood pressure in children with clinical conditions: A systematic review with meta-analysis.

Little is known on the effect of sodium intake on BP of children with clinical conditions. Our objective was therefore to review systematically studies that have assessed the association between sodium intake and BP in children with various clinical conditions. A systematic search of several databases was conducted and supplemented by a manual search of bibliographies and unpublished studies. Experimental and observational studies assessing the association between sodium intake and BP and involving children or adolescents between 0 and 18 years of age with any clinical condition were included. Out of the 6861 records identified, 51 full texts were reviewed, and 16 studies (10 experimental and 6 observational), involving overall 2902 children and adolescents, were included. Ten studies were conducted in children with elevated BP without identifiable cause, two in children with familial hypertension, one in children with at least one cardiovascular risk factor, one in children with chronic renal insufficiency, one in children with urolithiasis, and one in premature infants. A positive association between sodium intake and BP was found in all studies, except one. The meta-analysis of six studies among children with elevated BP without identifiable cause revealed a difference of 6.3 mm Hg (95% CI 2.9-9.6) and 3.5 mm Hg (95% CI 1.2-5.7) in systolic and diastolic BP, respectively, for every additional gram of sodium intake per day. In conclusion, our results indicate that the BP response to salt is greater in children with clinical conditions, mainly hypertension, than in those without associated clinical conditions.