The data cited have been intended to show that renal functional abnormalities are commonly associated with reflux. Tubular abnormalities, particularly concentrating defects, probably occur early, and glomerular dysfunction is a late manifestation. Problems with acid-base balance are uncommonly examined but may be more relevant clinically, because such abnormalities could affect bone growth. Fractional excretion studies are less sensitive than concentrating ability in indicating dysfunction. Associated pyelonephritis hastens renal damage and exacerbates any functional abnormality. Renal functional abnormalities are more common in patients with renal scarring and indeed may be predictive of a process that is not yet apparent pathologically.