Elevated fibroblast growth factor 23 levels in a newborn with secondary hypoparathyroidism.
Fibroblast growth factor 23 (FGF-23) is a recently identified hormone that is of prime importance for phosphate homeostasis in humans. FGF-23 is secreted by osteocytes in response to phosphate-loading. It stimulates renal phosphate excretion and suppresses the formation of 1.25-dihydroxy-vitamin D by inhibiting renal 1α-hydroxylase activity. Knowledge about FGF-23 in early infancy is limited. We report here the case of a newborn with transient secondary hypoparathyroidism caused by maternal primary hyperparathyroidism during pregnancy. FGF-23 levels at birth were extremely high in the child (15.850 kilo-Relative Units per liter, kRU/L) (ie, ∼45 times higher than in the mother) and ∼7 times higher than in healthy newborns. The child's FGF-23 levels declined gradually and reached the normal adult range after ∼7 months. We discuss the potential physiologic significance of FGF-23 in newborns.
Department of Internal Medicine, Rijnstate Hospital, Wagnerlaan 55, 6800 TA Arnhem, The Netherlands.
Anneke
A
Bech
Karin
K
Nabbe
Wim
W
Brussel
Darryl
D
Telting
Hans
H
de Boer
D000328:Adult; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000209:etiology*; D006973:Hypertension / Q000097:blood / Q000150:complications; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000097:blood
C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23