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Different Responses of Bone Alkaline Phosphatase Isoforms During Recombinant Insulin‐like Growth Factor‐I (IGF‐I) and During Growth Hormone Therapy in Adults with Growth Hormone Deficiency
Author(s) -
Magnusson Per,
Degerblad Marie,
Sääf Maria,
Larsson Lasse,
Thorén Marja
Publication year - 1997
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1997.12.2.210
Subject(s) - pyridinoline , endocrinology , medicine , osteocalcin , n terminal telopeptide , bone remodeling , growth hormone deficiency , alkaline phosphatase , insulin like growth factor , type i collagen , growth factor , chemistry , hormone , growth hormone , enzyme , biochemistry , receptor
We studied serum bone alkaline phosphatase (ALP) isoforms and other markers of bone turnover in growth hormone–deficient (GHD) adults ( n = 22). The patients were followed during 1 week of insulin‐like growth factor‐I (IGF‐I) administration, 40 μg/kg of body weight/day ( n = 6), and during 24 months of growth hormone (GH) therapy, 0.125 IU/kg of body weight/week for the first month, and then 0.250 IU/kg of body weight/week ( n = 20). Six ALP isoforms were separated and quantified by high‐performance liquid chromatography: one bone/intestinal, two bone (B1, B2), and three liver ALP isoforms. At baseline, the mean levels of B1, B2, and osteocalcin were higher in GHD adults than in healthy adults. After 1 week of IGF‐I administration and 1 month of GH therapy, only B1 was decreased. We suggest that the initial decrease of B1 during GH therapy could be an effect of endocrine IGF‐I action mediated by GH. After 3 months of GH therapy, both B1 and B2 increased as compared with placebo. Osteocalcin, carboxy‐terminal propeptide of type I procollagen (PICP), cross‐linked carboxy‐terminal telopeptide of type I collagen (ICTP), and urinary pyridinoline cross‐links/creatinine ratio increased during GH therapy. PICP increased significantly before bone ALP and osteocalcin, indicating an early stimulation of type I collagen synthesis as previously demonstrated by in vitro models. Different responses of the bone ALP isoforms during IGF‐I and during GH therapy suggest different regulations in vivo.