Heel pad thickness is an insensitive index of biochemical remission in acromegaly

The value of serial measurements of heel pad thickness as a clinical predictor of biochemical remission in acromegaly was assessed in 25 patients followed for up to 20 years after treatment by interstitial irradiation using yttrium-90 implantation. Growth hormone (GH) levels fell to 50% of baseline values within 12 months of therapy (P less than 0.001) and to 21% at 5 years, reaching normal levels after 10 years, constituting a biochemical cure maintained to the end of the study period. By contrast, heel pad thickness remained relatively stable, falling to 95% of baseline after 5 years (P less than 0.05) and to 87% after 20 years. There was no overall correlation between the measured parameters (r = 0.033, P greater than 0.05) suggesting that heel pad thickness is a poor predictor of biochemical remission in acromegaly.