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Continuation of GH therapy confers metabolic benefits in Prader-Willi syndrome
Young adults with Prader-Willi syndrome who continued previous growth hormone therapy for 1 year after attaining adult height saw no adverse effects on metabolic parameters, according to findings from a randomized crossover study.
“In our cohort of patients who were GH-treated during childhood for many years, none had [metabolic syndrome] at attainment of [adult height] and none developed [metabolic syndrome] during GH therapy after [adult height], while one developed [metabolic syndrome] during placebo treatment,” Renske J. Kuppens, MD, of Erasmus University Medical Center in the Netherlands, and colleagues wrote. “Elaborating on this, it might be that the role of body composition, and subsequently GH treatment, is even larger. Continuation of GH prevents deterioration of body composition and, thus, favorably affects metabolic health.”
In a 2-year, randomized, double blind, placebo-controlled crossover study, Kuppens and colleagues analyzed data from 27 young adults (eight males) with Prader-Willi syndrome treated with GH therapy during childhood who had attained adult height (mean age, 17 years). Within the cohort, GH therapy was initiated at a mean age of 8.5 years and continued for a mean of 8.7 years. Researchers assigned patients 1 year of subcutaneous injections once daily at bedtime of either 0.67 mg/m² GH (Genotropin, Pfizer) or 1 year of identical placebo, after which patients crossed over to the alternative treatment for 1 year. Researchers assessed height, weight, waist circumference, blood pressure, fasting glucose, and insulin and lipid parameters at baseline and 6, 12, 18 and 24 months. Patients also underwent a 75-g oral glucose tolerance test.
Metabolic syndrome was defined as having three or more of the following: abdominal obesity (waist circumference > 102 cm in men; > 88 cm in women); triglycerides greater than 1.7 mmol/L; HDL cholesterol in men less than 1.03 mmol/L and women less than 1.3 mmol/L; BP of at least 130/85 mm Hg; fasting glucose of at least 5.6 mmol/L.
Researchers found that 1 year of continued GH therapy did not result in metabolic syndrome vs. 1 year of placebo. After 1 year of GH, four patients had obesity, three had low LDL levels and five had high BP. After 1 year of placebo, five had central obesity, one had high triglyceride levels, six had low LDL levels, four had high BP and one had high fasting glucose. One woman developed metabolic syndrome after 1 year of placebo treatment.
Fasting glucose and insulin levels were similar at 30, 60, 90 and 120 minutes after glucose load after both GH treatment and placebo. Fasting glucose and insulin levels were higher after GH treatment vs. placebo, but both remained in the normal range in both phases (glucose, 4.7 mmol/L vs. 4.5 mmol/L; P = .012; insulin, 65.8 pmol/L vs. 47.4 pmol/L, P = .037). BP and lipid profiles were not significantly different after GH vs. placebo, according to researchers.
“Our 2-year, randomized, double blind, placebo-controlled crossover study shows that GH treatment has no adverse effects on glucose homeostasis, with similar glucose-stimulated glucose and insulin levels during the OGTT, [area under the curve] of glucose and insulin, and insulin/glucose ratios during GH and placebo treatments,” Kuppens told Endocrine Today. “Fasting glucose and insulin levels remained within the normal ranges and were only slightly higher during GH treatment vs. placebo. BP and lipid profile remained similar in both phases. None of the patients developed metabolic syndrome during GH treatment, while one developed metabolic syndrome during placebo. Thus, GH-treated young adults with Prader-Willi syndrome who have attained [adult height] benefit from continuation of GH treatment without safety concerns regarding their metabolic health profile.”
Kuppens said although the findings are reassuring, additional studies are needed to confirm longer-term results, as patients are still young and received only 1 year of GH treatment. – by Regina Schaffer
Disclosure: One of the researchers reports receiving an independent research grant from Pfizer. Pfizer provided Genotropin.