Levels and dynamic changes of serum fibroblast growth factor 23 in hypophosphatemic rickets/osteomalacia.
BACKGROUND
Hypophosphatemic rickets/osteomalacia is a group of diseases characterised by defective mineralization of bone due to hypophosphatemia and low 1,25-dihydroxy vitamin D. To explore the role of fibroblast growth factor 23 (FGF-23) in the regulation of phosphate homeostasis, we measured the circulating concentrations of this growth factor in healthy individuals and in patients with hypophosphatemic rickets/osteomalacia.


METHODS
Nineteen patients with hypophosphatemic rickets/osteomalacia were included in hypophosphatemic group (HP, 12 female and 7 male, mean age was 30 years), and 19 healthy age-matched individuals served as the control group. Full length FGF-23 fragments were measured by two-site enzyme-linked immunosorbent assay.


RESULTS
Mean FGF-23 concentrations were significantly higher in the HP group ((87.4 +/- 43.6) pg/ml) compared with the control group ((19.2 +/- 6.16) pg/ml; P < 0.001). In 1 patient with tumour-induced osteomalacia, serum FGF-23 concentrations were 84.1 pg/ml; these concentrations were normalized 2 hours after a hemangiopericytoma resection (7.8 pg/ml). Subsequently, serum 1,25(OH)(2) vitamin D3 concentrations significantly increased from 21.3 pg/ml to 89.3 pg/ml, and serum phosphorus levels were normalized.


CONCLUSIONS
Serum FGF-23 concentrations were markedly elevated in patients with hypophosphatemic rickets. FGF-23 plays an important role in the pathogenesis of hypophosphatemic rickets/osteomalacia.
Xia
Wei-bo
WB
Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China. xiaweibo@medmail.com.cn
Jiang
Yan
Y
Li
Mei
M
Xing
Xiao-ping
XP
Wang
Ou
O
Hu
Ying-ying
YY
Zhang
Hua-bing
HB
Liu
Huai-cheng
HC
Meng
Xun-wu
XW
Zhou
Xue-ying
XY
D000293:Adolescent; D000328:Adult; D002117:Calcitriol / Q000097:blood; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D053098:Familial Hypophosphatemic Rickets / Q000097:blood*; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010018:Osteomalacia / Q000097:blood*; D010710:Phosphates / Q000097:blood; D055815:Young Adult
C000717427:FGF23 protein, human; D010710:Phosphates; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D002117:Calcitriol