Baseline Na-Li countertransport and risk of hypertension in children: A 10-year prospective study in Hanzhong children

Sodium-lithium countertransport (Na-Li CT) is associated with blood pressure (BP) and in many cross-sectional investigations and some longitudinal studies, essential hypertension has been proposed as a biochemical marker or predictor of hypertension risk in adults. The present study investigated prospectively whether baseline Na-Li CT rate was an index of increased risk of future development of hypertension in children. At baseline visit in 1987 of the Hanzhong Children Hypertension Study comprising 4000 school children aged 5-6 years old, 310 samples were randomly selected for measurement of baseline Na-Li CT rate; we made a 10-year follow-up of them in the same season in 1997. This cohort of children is the sample for analysis in the present report. Baseline Na-Li CT rate was positively correlated to systolic BP (SBP) both in baseline and follow-up (baseline, γ = 0.21, P<0.05; follow-up, γ = 0.32, P<0.01), and positively correlated to diastolic BP (DBP) (γ = 0.20, P<0.05) and body mass index (γ = 0.18, P< 0.05) in follow-up examination. Longitudinal analysis of 10-year BP evolution, children in higher baseline Na-Li CT (ie, > 260 μmol\l RBC/h) had greater BP change than children in lower baseline Na-Li CT (ie, ≤ 260 μmol/l RBC/h) (SBP, 15.8±12.9 vs 19.3± 13.1, DBP 8.8±11.2 and 11.3±10.6, P<0.05). Multiple logistic regression analysis showed that children in the higher Na-Li CT (> 260 μmol/l RBC/h) were associated with approximately 1.5 times greater risk of high BP) in comparison to placement in lower Na-Li CT (≤ 260 μmol/l RBC/h). Elevated baeline RBC Na-Li countertransport could be a risk predictor predisposing to the development of hypertension in children.