Circulating levels of pegvisomant and endogenous GH during prolonged pegvisomant therapy in patients with acromegaly

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  • Michael Madsen, Denmark
  • Sanne Fisker
  • Ulla Feldt-Rasmussen, Ortopædi og Intern Medicin, Denmark
  • Mikkel Andreassen, Ortopædi og Intern Medicin, Denmark
  • Lars Østergaard Kristensen, Ortopædi og Intern Medicin, Denmark
  • Hans Orskov, Denmark
  • Jens Otto L Jørgensen
OBJECTIVE: To investigate if pegvisomant treatment in acromegaly induces gradual elevations in endogenous serum growth hormone (GH) levels and if serum pegvisomant levels predict the therapeutic outcome. PATIENTS AND METHODS: Seventeen patients (6 females), mean age 46.3 years (range: 23.2-76.2), were studied. For each patient, four hospital visits were identified including "active disease" (no treatment) and last follow up. At each visit, 12 blood samples were drawn during 3 hours including an oral glucose tolerance test (OGTT). Eight patients received a somatostatin analogue in addition to pegvisomant on the last visit. RESULTS: Median (range) pegvisomant doses (mg/d) were 10 (10-10), 15 (10-15), and 15 (10-15) at visit 2, 3, and 4, respectively, and the mean duration of pegvisomant treatment was 17.5±3.2 (sem) months. Serum IGF-I changed significantly during the treatment period with the highest level at baseline and lowest levels at visit 3 and 4. GH levels increased in a dose dependent manner during pegvisomant treatment and decreased at visit 4. Changes in IGF-I levels correlated negatively with changes in serum pegvisomant levels between visits. Serum pegvisomant at each visit correlated with baseline growth hormone levels, whereas no associations between serum pegvisomant and either dose, gender, age, or body weight were found. CONCLUSIONS: 1) Serum GH levels increased initially, but remained stable during prolonged pegvisomant treatment in acromegalic patients, 2) Serum pegvisomant levels predicted the reduction in serum IGF-I during treatment, 3) The inter-individual variation in serum pegvisomant levels seems not predicted by either age, gender or body composition. This article is protected by copyright. All rights reserved.
Original languageEnglish
JournalClinical Endocrinology
Pages (from-to)92-100
Number of pages8
Publication statusPublished - 7 May 2013

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