“Micromegaly”: Acromegaly with apparently normal GH, an entity on its own?

Abstract

A small proportion of the patients with acromegaly present with apparently normal basal GH levels and suppressible GH levels despite increased IGF-1 levels, a pattern called micromegaly by some authors. Whether this pattern represents a distinct entity or is just an expression of acromegaly in its early stages is still a matter of debate. Nevertheless, these patients have some peculiar characteristics such as being more likely older and male, mostly harbour microadenomas or small macroadenomas, and have lower IGF-1 and postglucose GH levels. Even though, the frequency and severity of clinical signs and comorbidities are similar to those of patients with classic acromegaly. In conclusion, micromegaly seems to be a distinct clinical entity with a different biological behavior characterized by a low GH output.