Is increase in bone mineral content caused by increase in skeletal muscle mass/strength in adult patients with GH-treated GH deficiency? A systematic literature analysis

Abstract

Objective: Adult patients with GH deficiency (GHD) are characterized by a reduced muscle mass, but also reduced bone mineral density (BMD) and content (BMC), which have been ascribed to GHD per se.The aim of this study was to investigate if changes in BMD/BMC in adult GHD patients could be due to a muscle modulating effect, and if treatment with GH would primarily increase muscle mass and strength with a secondary increase in BMD/BMC, thus supporting the present physiological concept that mass and strength of bones are mainly determined by dynamic loads from the skeletal muscles. Method: We performed a systematic literature analysis, including 51 clinical trials published between 1996 and 2008, which had studied the development in muscle mass, muscle strength, BMD, and/or BMC in GH-treated adult GHD patients. Results: GH therapy had an anabolic effect on skeletal muscle. The largest increase in muscle mass occurred during the first 12 months of therapy. Most trials measuring BMD/BMC reported significant increases from baseline values. The significant increases in BMD/BMC occurred after 12-18 months of treatment, i.e. usually later than the increases in muscle parameters. Only seven trials studied both muscle and bone variables concomitantly. No trials studied the relationship between the changes in muscle and bone measurements. Conclusion: Although in vitro studies have shown that GH has a direct effect on bone remodeling, present physiological concepts and the results of clinical trials from 1996 to 2008 suggest that the anabolic changes in muscle mass and strength may also contribute to changes in BMD/BMC in GH-treated adult GHD patients.

Can bone loss be reversed by antithyroid drug therapy in premenopausal women with Graves' disease?

“…Measurement of both total and free thyroid hormones will therefore be very method dependant, and in an unpredictable manner, which could invalid results and thus also correlations [45]. Finally, it cannot be excluded that the increase in muscle mass after attainment of euthyroidism can contribute mechanically to an increase in BMD/BMC [reviewed in [46]].…”

Fifteen years of GH replacement increases bone mineral density in hypopituitary patients with adult-onset GH deficiency

“…GH exerts direct effects on bone (2, 11), but it has been questioned whether the direct effects can fully explain the effects of GH on bone. Indirect effects, such as increased muscle performance by GH, could also be of importance (12). Furthermore, the responsiveness to GH replacement is dependent on the group of patients studied.…”

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

“…In acromegalic patients, excess GH does not result in increased muscle mass or strength (21)(22)(23), while the observed increase in muscle strength and endurance experienced by GHD patients following GH treatment appear to be a result of altered metabolic functions as well as a stimulation of protein synthesis, suppression of protein oxidation and increased muscle mass (24)(25)(26)(27). Taken together, it is currently not clear whether GH/IGF1 and skeletal muscle myofibrillar protein synthesis are positively correlated in man, but investigating both acromegalic and GHD patients offers a unique possibility to address this question.…”