Endocrine Abstracts

Introduction: The current guidelines state that the goals of growth hormone (GH) therapy should be an appropriate clinical response and avoidance of side effects. The target level for IGF1 is commonly the upper half of the reference range, although no published studies offer specific guidance in this regard. Therefore, the aim of the present study is to investigate associations between IGF1 levels within the reference range and several efficacy and safety measures of GH treatment in substituted GH deficient adults.

Methods: 32 subjects receiving GH therapy for at least a year with a stable IGF1 concentration of −1 to 1 S.D. score (SDS) were included and randomized to receive either a decrease of their regular dose (IGF1 target level of −2 to −1 SDS) or an increase of their dose (IGF1 target level of 1–2 SDS) for a period of 6 months. Measurements of body composition, lipid profile, glucose metabolism, physical performance and quality of life, next to information on tolerability were collected.

Results: Thirty subjects (65.6% male, mean age 46.6 (9.9 S.D.) years) could be analysed. Decreasing the GH dose lead to more experienced fatigue. Increasing the GH dose lead to an improvement of the walking distance (6-min walking test: change 25.5 (29.7 S.D.) meters, P=0.01), and to an overall better feeling (P=0.04). There was a trend of a difference in change between de- and increasing GH dose in waist circumference (P=0.07) in favour of increasing dose. However, increasing GH dose resulted in a higher fasting glucose (0.4 (0.7 S.D.) mmol/l, P=0.05) and subjects experienced more myalgia.

Conclusion: Although increasing GH dose to IGF1 levels of 1 to 2 SDS improved physical performance and subjects reported an overall better feeling, safety is not guaranteed with the demonstrated effect on glucose metabolism and reported adverse events.

Disclosure: This work was partly supported by an investigator-initiated grant from Pfizer bv. C C van Bunderen is supported by an AGIKO grant of The Netherlands Organisation for Health Research and Development (ZonMw) (grant number: 92003591).