In the Southeast United States, African Americans have an estimated incidence of hypertension and end-stage renal disease (ESRD) that is five times greater than Caucasians. Higher rates of low birth weight (LBW) among African Americans is suggested to predispose African Americans to the higher risk, possibly by reducing the number of glomeruli that develop in the kidney. This study investigates the relationships between age, race, gender, total glomerular number (N_glom), mean glomerular volume (V_glom), body surface area (BSA), and birth weight.

Stereologic estimates of N_glom and V_glom were obtained using the physical disector/fractionator combination for autopsy kidneys from 37 African Americans and 19 Caucasians.

N_glom was normally distributed and ranged from 227,327 to 1,825,380, an 8.0-fold difference. A direct linear relationship was observed between N_glom and birth weight (r = 0.423, P = 0.0012) with a regression coefficient that predicted an increase of 257,426 glomeruli per kilogram increase in birth weight (α = 0.050:0.908). Among adults there was a 4.9-fold range in V_glom, and in adults, V_glom was strongly and inversely correlated with N_glom (r =-0.640, P = 0.000002). Adult V_glom showed no significant correlation with BSA for males (r = -0.0150, P = 0.936), although it did for females (r = 0.606, P = 0.022). No racial differences in average N_glom or V_glom were observed.

Birth weight is a strong determinant of N_glom and thereby of glomerular size in the postnatal kidney. The findings support the hypothesis that LBW by impairing nephron development is a risk factor for hypertension and ESRD in adulthood.