Brazilian Journal of Medical and Biological Research
versión On-line ISSN 1414-431X
MORAES, R.S.; FUCHS, F.D.; DALLA COSTA, F. y MOREIRA, L.B.. Familial predisposition to hypertension and the association between urinary sodium excretion and blood pressure in a population-based sample of young adults. Braz J Med Biol Res [online]. 2000, vol.33, n.7, pp. 799-803. ISSN 1414-431X. http://dx.doi.org/10.1590/S0100-879X2000000700010.
The reasons for the inconsistent association between salt consumption and blood pressure levels observed in within-society surveys are not known. A total of 157 normotensive subjects aged 18 to 35 years, selected at random in a cross-sectional population-based survey, answered a structured questionnaire. They were classified as strongly predisposed to hypertension when two or more first-degree relatives had a diagnosis of hypertension. Anthropometric parameters were obtained and sitting blood pressure was determined with aneroid sphygmomanometers. Sodium and potassium excretion was measured by flame spectrophotometry in an overnight urine sample. A positive correlation between blood pressure and urinary sodium excretion was detected only in the group of individuals strongly predisposed to hypertension, both for systolic blood pressure (r = 0.51, P<0.01) and diastolic blood pressure (r = 0.50, P<0.01). In a covariance analysis, after controlling for age, skin color and body mass index, individuals strongly predisposed to hypertension who excreted amounts of sodium above the median of the entire sample had higher systolic and diastolic blood pressure than subjects classified into the remaining conditions. The influence of familial predisposition to hypertension on the association between salt intake and blood pressure may be an additional explanation for the weak association between urinary sodium excretion and blood pressure observed in within-population studies, since it can influence the association between salt consumption and blood pressure in some but not all inhabitants.
Palabras llave : hypertension; familial predisposition to hypertension; urinary sodium excretion; salt sensitivity.