Normal kidney function and elevated natriuresis in young men born with lowbirth weight

The aim of our study was to characterize renal function and its relationshi p to blood pressure in healthy young Caucasian men born with a birth weight under 2,500 g (LBW). Urinary protein patterns, N-acetylglucosamine and gam ma -glutamyltransferase activities, fractional sodium and potassium excreti ons, glomerular filtration rate, blood pressure, and erythrocyte Na+/K+-ATP ase activities were determined in 65 subjects, of whom 49 were born with LB W. Signs of glomerular or tubular damage were not detected in the LBW popul ation. However, the blood pressure and the renal sodium excretion were inve rsely correlated to the subjects' birth weight and were higher in LBW subje cts than in controls. In contrast, the erythrocyte Na+/K+-ATPase activities were lower in LBW subjects. An inverse correlation was detected between th e subjects' Na+/K+-ATPase activities and the renal sodium excretion or bloo d pressure. In summary, our results suggest that: (1) in young LBW Caucasia n males signs of early glomerular and tubular impairment are not present; ( 2) the elevated renal sodium excretion may be a result of higher blood pres sure; (3) the alteration of Na+K+-ATPase activity might play a role either in the elevation of blood pressure and/or in the enhanced natriuresis of LB W subjects.