Comparison of low-normal and high-normal IGF-1 target levels during growth hormone replacement therapy: A randomized clinical trial in adult growth hormone deficiency

Christa C. van Bunderen, Paul Lips, Mark H. Kramer, Madeleine L. Drent

Research output: Contribution to journalArticleAcademicpeer-review



Current guidelines state that the goals of growth hormone (GH) therapy in adults should be an appropriate clinical response, avoidance of side effects, and an IGF-1 value within the age-adjusted reference range. There are no published studies on the target level for IGF-1 that offer specific guidance in this regard.

To compare low-normal and high-normal target levels of IGF-1 on efficacy and safety of GH treatment.

A randomized, open-label, clinical trial including thirty-two adults from one university hospital receiving GH therapy for at least one year with a stable IGF-1 concentration between − 1 and 1 SD score (SDS). Subjects were randomized to receive either a decrease (IGF-1 target level of − 2 to − 1 SDS) or an increase of their daily GH dose (IGF-1 target level of 1 to 2 SDS) for a period of 24 weeks. The effect on cardiovascular risk factors and physical performance, next to tolerability, was compared.

Thirty subjects (65.6% men, mean age 46.6 (SD 9.9) years) could be analyzed. In subjects with a high-normal IGF-1 target level, waist circumference decreased ( p = 0.05), and overall they felt better ( p = 0.04), compared to subjects with a low-normal IGF-1 target level. However, increasing IGF-1 levels led to more myalgia, and decreasing IGF-1 levels to more fatigue. There was a gender-dependent difference in effect on HDL cholesterol.

Although increasing GH dose to IGF-1 levels between 1 and 2 SDS improved waist circumference and well-being, safety was not guaranteed with the demonstrated effect on HDL cholesterol in men, and reported myalgia.
Original languageEnglish
Pages (from-to)88-93
JournalEuropean Journal of Internal Medicine
Publication statusPublished - Jun 2016

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