Insulin-Like Growth Factor I and Growth Responses during the First Year of Growth Hormone Treatment in KIGS Patients with Idiopathic Growth Hormone Deficiency, Acquired Growth Hormone Deficiency, Turner Syndrome and Born Small for Gestational Age

Abstract

Background and Methods: We assessed the value of in- sulin-like growth factor I (IGF-I) monitoring during growth hormone (GH) treatment by retrospectively examining the relationships between (1) GH dose and IGF-I response, (2) baseline serum IGF-I concentration and growth response and (3) serum IGF-I response and growth response after 1 year of GH treatment among patients in the Pfizer International Growth Study database (KIGS). KIGS patients were eligible for the study if they were classified as having idiopathic GH deficiency, acquired GH deficiency, Turner syndrome or were born small for gestational age. Results: Correlations between GH dose and IGF-I response and between pretreatment IGF-I values and first-year growth response were weak across all groups. Correlations between the IGF-I response and growth response after 1 year of treatment were greater than those between baseline serum IGF-I values and first-year growth response. Pre- and posttreatment clinical characteristics were consistently different across all groups, but the numerous technical factors affecting these relationships are remediable. Conclusions: IGF-I monitoring during GH therapy is a valuable tool to monitor compliance and ensure that IGF-I levels do not exceed the normal range for extended periods. IGF-I monitoring may help clinicians increase GH doses as needed during puberty to achieve normal serum IGF-I values and normal or enhanced growth.