GENETIC AND ENVIRONMENTAL-FACTORS REGULATING BLOOD-PRESSURE IN CHILDHOOD - PROSPECTIVE-STUDY FROM 0 TO 3 YEARS

Objectives: Blood pressure (BP) regulation depends on the interaction between multiple environmental and genetic factors. Of these, BP sensi tivity to dietary sodium intake has been one that has been investigate d in adults but not in children. The aim of the present study was to i nvestigate, prospectively, the BP profile in relation to different gen etic and hormonal factors, in the first 3 years of life. Population an d methods: Thirty-nine children born at term following normal pregnanc ies, with uncomplicated neonatal periods, were randomly selected to ta ke part in the study. BP, weight and length were evaluated every 3 mon ths from birth to 3 years. At the age of 12 months, haptoglobin phenot ypes and plasma active renin concentration were determined as well as random urine evaluation of aldosterone, cAMP, dopamine and digoxin-lik e immunoreactive substances (DLIS). Family history of cardio-vascular diseases was also recorded. Results: Systolic BP (SEP) demonstrated a gradual increase until the age of 6 months with little variation up to 36 months. Tracking of SEP values was also observed from the first ye ar as infants with high values (above the 75 percentile) maintained th is tendency up to, at least, the age of 36 months. The comparison betw een SEP and diastolic BP (DBP) according haptoglobin phenotypes demons trated that SEP was systematically higher in allele 1, with apparently an increasing tendency with age, although the differences did not hav e statistical significance. The comparative study between haptoglobin phenotypes, with correction for the covariates fractional excretion of sodium and potassium, showed that allele 1 carriers had significantly lower plasma renin and urine aldosterone and cAMP concentrations than allele 2, but dopamine excretion was found to be higher in allele 1 t han in allele 2. There were no differences among variables relating to family history of cardiovascular disease. Conclusions: There was an e arly tracking process of BP values from the first 6 months of life whi ch persists through, at least, to the age of 36 months. Differences in sodium handling between haptoglobin 1 and 2 phenotypes were already p resent in early childhood, although no significant repercussion in BP values could be demonstrated in the 3-year duration of this study.