GIGANTISM AND ACROMEGALY



Clinical Manifestations The manifestations of excess growth hormone production are critically dependent on the age of the patient at the time that the abnormality first occurs. If growth hormone is present in excess be­fore the epiphyses close, the increase in linear skeletal growth results in gigantism. After closure of the epiphyses, growth hormone excess results in acromegaly, a disorder characterized by phys’-: ical changes in the bones and soft tissues as well as metabolic abnormalities reflecting the physi­ologic actions of this polypeptide.

In addition to the physical changes that result from excess growth hormone secretion, a variety of metabolic abnormalities may also occur. Im­paired glucose tolerance is present in more than half the cases, but frank diabetes mellitus is not evident unless pancreatic insulin secretion is in­capable of responding to the counter-regulatory effect of growth hormone. An increase in glomer­ular filtration rate and in renal tubular reabsorp-tion of phosphate may also be observed, the latter causing the typical finding of hyperphospha­temia.