Red blood cell potassium and blood pressure in adolescents: a mixture analysis

Evidence from epidemiological and clinical studies has implicated potassium (K+) depletion in the pathogenesis and maintenance of essential hypertension. In adolescents prone to develop hypertension in the future, several studies have shown an inverse relationship between K+ intake and blood pressure (BP). The aim of this study was to determine whether the variation of red blood cell K+ content (RBCKi) in adolescents could be explained by a single distribution or by a mixture of two or more distributions. If more than one distribution could be identified, we studied whether they differed in BP, parental hypertension and other variables.

Adolescents (n = 100) were recruited from a High School in the city of Valencia, Venezuela. BP, anthropometric measurements and parental history of hypertension were obtained from each subject. Venous blood and urine sample were obtained for RBC, plasma urine electrolyte measurements. Mixture analysis was used to analyze RBCKi distribution. The distribution of RBCKi levels fit significantly better in a bimodal (p < 0.01) than a unimodal or trimodal distribution. Diastolic blood pressure (75 +/- 1 vs 72 +/- 2 mmHg), systolic blood pressure (SBP) (119 +/- 1 vs 113 +/- 2 mmHg) and pulse pressure (PP) (44 +/- 1 vs 41 +/- 2 mmHg) were higher in the subgroup with low-RBCKi, but only SBP and PP values were statistically significant (p < 0.05). The low-RBCKi subgroup had 40% of the hypertensive parents vs 20% in the high-RBCKi subgroup. Adolescents with low RBCKi were three times more likely to have a hypertensive parent than adolescents with high RBCKi (chi 2 = 3, p = 0.04).

K+ depletion in RBC, its bimodal distribution and its strong association with BP and parental hypertension suggest that low RBCKi in adolescents might represent an early sign of K+ depletion that could contribute to the development of future hypertension.