RACIAL-DIFFERENCES IN ALDOSTERONE EXCRETION - A LONGITUDINAL-STUDY INCHILDREN

Aldosterone production, estimated from urinary excretion of aldosteron e and the plasma aldosterone level was found in a previous cross-secti onal study to be lower in black children than white children. The pres ent study examined aldosterone excretion longitudinally to determine w hether the aldosterone excretion rate changed with time and if the rac ial difference in aldosterone excretion persisted. Urine samples were collected every 6 months for up to 5.5 yr in 351 white and 170 black c hildren for measurements of aldosterone, sodium (Na+), and potassium ( K+) excretion. Results were expressed per mu mol urinary creatinine. M ean values for excretion rates for the total longitudinal period were determined. Na+ excretion was not significantly different in the two g roups, whereas K+ excretion was 18% lower in blacks than whites (P = 0 .0001). Body weight and urinary Na+ and K+ excretion were significantl y related to aldosterone excretion. After adjusting for these variable s, the aldosterone excretion rate was 35% lower in blacks than whites (P = 0.0001), a racial difference that did not change with age. Aldost erone excretion rates showed no longitudinal trend to either increase or decrease. The physiological relevance of the lower aldosterone excr etion rate in black children remains unknown.