The Relationship between 24-Hour Growth Hormone Secretion and Insulin-Like Growth Factor I in Patients with Successfully Treated Acromegaly: Impact of Surgery or Radiotherapy

Steven R. Peacey, Andrew A. Toogood, Johannes D. Veldhuis, Michael O. Thorner, Stephen M. Shalet
2001 Journal of Clinical Endocrinology and Metabolism  
In patients with treated acromegaly, improved survival is associated with serum GH concentrations below 2 g/L (5 mU/L). A principal aim of therapy in acromegaly is to achieve a GH level less than 2 g/L, as such levels are thought to be "safe." However, such GH levels do not always equate with normalization of plasma insulin-like growth factor I (IGF-I), although epidemiological data linking survival or morbidity to IGF-I levels are at present lacking. The aims of this study were 1) to further
more » ... ere 1) to further define the nature of GH release in those acromegalic patients who achieve mean GH concentrations below 2 g/L post therapy, 2) to examine the effect of different therapeutic interventions on the 24-h GH profile (surgery alone or radiotherapy), and 3) to determine the relationship between the various characteristics of the 24-h GH profile and IGF-I production in acromegalic subjects who have achieved GH below 2 g/L. Spontaneous 24-h GH secretion was measured using both a conventional immunoradiometric assay (limit of detection, 0.4 g/L) and an ultrasensitive assay (limit of detection, 0.002 g/L). The GH data have been analyzed by several methods: 1) the pulse detection algorithm Cluster, 2) a distribution method for detection of peak [the observed concentration 95%, i.e. the threshold at or below which GH concentrations are assessed to be 95% of the time, as calculated by probability analysis (OC 95%)] and trough (OC, 5%) GH activity, 3) deconvolution analysis, and 4) approximate entropy analysis. GH was sampled every 20 min for 24 h, along with basal IGF-I and IGF-binding protein-3, in 21 treated acromegalic patients with a mean GH below 2 g/L [ACR; 9 women and 12 men; median age (range), 49 (31-76) yr] and 16 healthy
doi:10.1210/jcem.86.1.7154 pmid:11232010 fatcat:hrqyok3dhzdwllcdomd3f6ncw4