The value of IGF1 estimation in adults with GH deficiency

Abstract

The GH/IGF1 system, like other endocrine systems, is dynamic and its activity changes with age and sexual maturation, and is influenced by body composition and other factors. A normal level of IGF1 does not exclude a diagnosis of GH deficiency (GHD) in adults, and the usefulness of IGF1 in the diagnosis of adult GHD has historically been confusing and contentious. The regulation of IGF1 secretion in adults is complex, and is not solely dependent on GH status with factors recognized to influence IGF1 status in patients with GHD including age, gender, exogenous estrogen therapy, prolactin status, and severity of GHD. The usefulness of IGF1 for monitoring treatment of GH disorders in adulthood is now widely accepted, especially as GH-dosing regimens for GHD have evolved from weight-based dosing (associated with overtreatment and side effects) to individualized dose-titration strategies, which maintain IGF1 within target limits. Sub-optimal replacement therapy may be associated with morbidity and mortality risk from a continuing state of functional GHD. Conversely, avoiding iatrogenic biochemical acromegaly is clearly important and other potential safety issues may be associated with a persistently high IGF1. Analysis and interpretation of IGF1 status therefore represent a useful diagnostic tool especially in the younger adult patients with severe GHD and an essential measurement for monitoring GH replacement in all adults with GHD. High-quality, methodspecific reference ranges for IGF1 and a high degree of methodological consistency in the assay are essential for reliable comparison of results.

Neuroendocrine dysfunction in patients recovering from subarachnoid hemorrhage

“…29 It must be stressed, however, that adult GHD would be strongly predicted by very low IGF-I levels. 23,26,30 In conclusion, neuroendocrine dysfunction following aneurysmal subarachnoid hemorrhage may occur at a much higher prevalence than previously suspected. High incidence of corticotroph and somatotroph dysfunction was observed in this study, with cerebral vasospasm and hydrocephalus emerging as the risk factors for dysfunction of the hypothalamopituitary axes.…”

“…[1][2][3][4][5][6][7][8] The role of IGF-I in the diagnosis of adult GHD has been confusing due to the complexity of the regulation of IGF-I synthesis. 23 A considerable overlap exists in IGF-I levels between normal subjects and patients with GHD. 24 Serum IGF-I levels might be normal even in patients with total anterior hypopituitarism.…”

GH deficiency in patients after cure of acromegaly by surgery alone

“…IGF1 has not been widely used as a reliable marker for the diagnosis of GHD (17). Indeed, Z-scores of IGF1 at the time of follow-up did not significantly correlate with peak GH values from the GHRP2 test, but IGF1 levels and Z-scores themselves were significantly lower in GH-deficient patients than in GH-sufficient patients, similar to a report by Wexler et al (10) which suggests that IGF1 may be of some diagnostic value for sGHD if levels are below the age-and sex-adjusted normal range.…”

GH and IGF1 levels are positively associated with musculotendinous collagen expression: experiments in acromegalic and GH deficiency patients

“…These findings are in accordance with our results and support the view that IGF1, rather than GH, is directly responsible for the elevated collagen expression and protein synthesis seen in the present study. Measuring local IGF1 could prove a relevant diagnostic tool in monitoring the treatment of acromegalic and GHD patients with musculoskeletal disorders, supplementing current monitoring strategies using circulating IGF1 (55). Figure 4 Transmission electron microscopy analysis of tendon.…”