POSTEXERCISE PROTEINURIA IN CHILDHOOD AND ADOLESCENCE

Postexercise proteinuria has been observed in healthy adults but there was a need for information in young individuals. Boys and girls (n = 170) from 6 to 18 years of age were submitted to maximal exercise by t he 20-meter shuttle run test. Urine collection was made prior to and 3 0 min after completion of the run. Total protein, albumin, beta(2)-mic roglobulin (beta(2)-m), retinol-binding protein (RBP) and creatinine w ere determined on each sample. Resting values for total protein, album in, beta(2)-m and RBP excretion rates were within the normal range for each component with a progressive increase for total protein and albu min. The effect of exercise increased with age. Between the 6 and 9 ye ar olds there was a gender difference in postexercise proteinuria, boy s enhanced the excretion of macromolecules while girls did not show an y increase by maximal exercise. The excretion rates of all protein com ponents were related to the absolute intensity of exercise expressed a s maximal speed (R between 0.86 and 0.90, p < 0.001). High- and low-mo lecular weight protein excretion gave evidence of increasing disturban ces from the age of 9 to 18 years in boys and girls, These data clearl y demonstrate that 1) postexercise proteinuria is present at maximal e xercise from chidhood to adolescence; 2) the magnitude of protein excr etion is strictly related to the absolute intensity of exercise; 3) th e glomerulus permeability and the tubular reabsorption process are bot h different in pre- and postpubertal children and adolescents.