Abstract
Objective: In the medical treatment of acromegaly different factors are influencial; among these the impact on growth hormone binding protein (GHBP) has not been clarified.
Design: Twenty acromegalic patients and nineteen age- and gender-matched normal subjects participated in this study. The patients were treated for 21 months with depot long-acting microsphere-enclosed octreotide (Sandostatin-LAR). Previously, all the patients were treated s.c. with octreotide t.i.d. After a 2-week wash-out period (baseline) the patients received the first i.m. injection of the long-acting octreotide. The first two injections were administered at 60-day intervals; thereafter the injections were at 28-day intervals.
Methods: The levels of GHBP, complexed GHBP, growth hormone (GH) and insulin-like growth factor-I (IGF-I) were determined in fasting serum samples.
Results: In the 2-week wash-out period GHBP levels decreased from 1·13 ± 0·17 to 0·92 ± 0·15 nmol/l (P < 0·05). During the 21-months treatment, GHBP increased again to 1·10 ± 0·16 nmol/l. In the age- and gender-matched control group GHBP levels were significantly higher at all times (1·95 ± 0·21 nmol/l, P(all) < 0·02). Mean levels of 8-h GH decreased from 12·6 ± 2·58 μg/l at baseline to 1·97 ± 0·20 μg/l after 21 months of treatment (P < 0·05). Mean 8-h GH levels were unchanged during long-acting octreotide treatment compared with levels during s.c. treatment (1·97 ± 0·20 μg/l and 1·90 ± 0·20 μg/l respectively). In fasting blood samples GH-complexed GHBP ranged from 13·8 ± 2·4% (9 months) to 25·4 ± 4·5% (baseline) of total GHBP. Serum IGF-I increased from 367 ± 45 to 764 ± 80 μg/l (P < 0·05) during the 2-week wash-out period and decreased to 290 ± 35 μg/l (P < 0·05) after 21 months of treatment with long-acting octreotide. IGF-I levels after 21 months were significantly lower than during s.c. octreotide treatment (P < 0·05).
Conclusion: Serum GHBP levels are similar during treatment with long-acting octreotide as compared with regular octreotide. Furthermore, significant changes in GHBP can occur within 2 weeks. Finally, in addition to the lowering effect on GH levels, the induced increase in GHBP levels may imply a further advantage in octreotide treatment of acromegaly, circulating GH bound to GHBP may less readily reach the tissues.
European Journal of Endocrinology 136 61–66
21 THERAPY OF IDIOPATHIC SHORT STATURE WITH LONG-ACTING GnRH ANALOG; EFFECTS ON GROWTH HORNOE (GH), GROWTH HORMONE-BINDING PROTEIN (GHBP) AND FINAL HEIGHT PREDICTION
