Wan Nazaimoon WM, Khalid BAK1, Nor Azmi K1, and Tan TT1
Division of Endocrinology, Institute for Medical Research, Jalan Pahang, 50588 Kuala Lumpur, Malaysia
1. Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
CITATION: Wan Nazaimoon WM, Khalid BAK, Nor Azmi K, Tan TT. Plasma insulin-like growth factor-I (IGF-1) in the diagnosis of acromegaly. International Medical Research Journal. 1997 Dec;1(2):127–31.
Insulin-like growth factor-1 (IGF-1} has been suggested to be a good alternative marker for the diagnosis of acromegaly. In this study, 42 samples collected from 25 treated acromegalic patients over 2 years were assayed for fasting growth hormone (CH), IGF-1 and IGF-binding protein-3 (IGFBP-3). 23/42 (54.8%) samples were considered normal based on the normal cut-off value of 10 mlU/L for random GH secretion, but only 9 (21.4%) and 16 (38.1 %) samples were within the age-matched reference values for IGF-1 and IGFBP-3 respectively. Three patients had persistently elevated levels of GH, IGF-1 and IGFBP-3, while 2 patients were diagnosed biochemically cured when these markers remained normal up to 8 months. IGF-1 remained high in 2 other patients despite normalised GH and IGFBP-3, and disease activity subsequently returned when IGFBP-3 also became elevated. Similarly, 2 patients diagnosed normal following OGTT also had high IGF-1, and subsequently, showed increased secretions of GH and IGFBP-3. IGF-1 has a curvilinear relationship with GH,plateauing at higher GH levels. Failure to recognise this relationship caused many investigators to doubt the usefulness of IGP-1. Nevertheless, this study has shown that IGF-1 is indeed a reliable prognostic index for acromegaly, provided results are interpreted with reference to well established, age-matched normal values.
KEYWORDS: acromegaly, insulin-like growth factor-1, growth hormone
