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Relationship Between Bioassayable Growth Hormone, The Insulin‐Like Growth Factor‐I System and Bone Mineral Density in Men and Women
Author(s) -
Nindl Bradley C,
Durkot M J,
Pierce J R,
Tuckow A P,
Kennett M J,
Nieves J W,
Alemany J A,
Cosman F,
Hymer W C
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1421-a
Subject(s) - endocrinology , medicine , bone mineral , insulin like growth factor , chemistry , bone density , hormone , tibia , growth factor , osteoporosis , receptor , anatomy
Bone mineral density (BMD) is influenced by growth factors, such as growth hormone (GH) and insulin‐like growth factor‐I (IGF‐I). The in vivo bioassay for the measurement of GH (BGH) may be more physiologically relevant than in vitro immunoassays, as BGH is quantified on a biological outcome. We determined if BGH and members of the IGF‐I system were associated with BMD in age‐matched (19 y) men (M; n = 41, 70 ± 3 kg, 163 ± 25 cm) and women (W; n =39, 66 ± 3 kg, 141 ± 15 cm). Blood was sampled for hormonal analyses (BGH, immunoreactive GH, IGF‐I and associated binding proteins [BP]), and subjects had BMD measured by pDXA and pQCT. BGH was determined by injecting hypophysectomized, female Sprague‐Dawley rats with a s.c. bolus of each subject’s plasma in 4 daily injections. Subsequently, BGH concentrations were determined by extrapolation of the measured tibia epiphyseal growth plate width. M had greater calcaneal BMD when measured by pDXA (M: 1.27 ± 0.02; W: 1.14 ± 0.02 g/cm 2 ; mean ± SE), but not at the tibia by pQCT (M: 777 ± 16; W: 799 ± 16 g/cm 2 ). BGH was similar between M (16.5 ± 3 μg/L) and W (20.6 ± 3 μg/L) and was not associated with BMD. For W, but not M, the acid labile subunit (ALS) (r = 0.40) and IGFBP‐3 (r = 0.42) significantly correlated with pDXA‐assessed BMD; ALS (r = 0.47) with pQCT‐assessed BMD. Although BGH was not associated with BMD, IGF‐I associated binding proteins (IGFBP‐3 and ALS) emerged as correlates of BMD in W only.