Interferon-β treatment associated with a biochemical profile suggestive of acromegaly. A case report of a patient treated for multiple sclerosis.

We describe a 34-year-old female treated with IFN-β for 8 years with a biochemical profile suggestive of acromegaly. The patient presented with elevated serum insulin-like growth factor-I (IGF-I) and insufficient suppression of growth hormone (GH) during oral glucose tolerance test (OGTT). There were no clinical features of acromegaly. A 5-day profile showed higher GH levels on the 3 days following IFN-β injections. Total and bioactive IGF-I were also elevated but did not fluctuate. Four weeks off IFN-β normalized suppression of GH during OGTT but did not reduce serum IGF-I or bioactive IGF-I. In conclusion, IFN-β treatment mimicked acromegaly biochemically. The changes were partially reversible.