A disappearing urban/rural blood pressure difference in Nigerian children: an evaluation of possible determining factors.

Urban Nigerian school children are reported to have a higher systolic blood pressure and diastolic blood pressure than rural community school children until the age of 11-12 years when this difference tends to disappear. We evaluated 874 urban day-school children and 674 rural community school children aged 5-16 (mean 11.9) years in south-eastern Nigeria to confirm this changing pattern, and to assess the contributions of some known factors to the differences as well as the changing pattern. This study confirmed the changing pattern of urban/rural blood pressure of school children. Differences in weight, height and Body Mass Index (BMI), though important, appeared insufficient to explain this pressure difference and the changing pattern. Urban children aged 12-14 years were found to excrete more sodium and (unexpectedly) more potassium in their 24-h urine samples. The observed urban/rural blood pressure difference appears to be sustained by a multiplicity of factors, including differences in weight, BMI, height, electrolytes (especially sodium) consumption, and increased exposure to Western-type education.