Hypophosphatemia induced by intravenous administration of saccharated ferric oxide: another form of FGF23-related hypophosphatemia.
Fibroblast growth factor 23 (FGF23) is a humoral factor that is produced by osteocytes and regulates phosphate and vitamin D metabolism. Several hypophosphatemic diseases including X-linked, autosomal dominant and autosomal recessive hypophosphatemic rickets/osteomalacia and tumor-induced rickets/osteomalacia are caused by excess actions of FGF23. These diseases are characterized by hypophosphatemia associated with impaired proximal tubular phosphate reabsorption and inappropriately low serum 1,25-dihydroxyvitamin D [1,25(OH)(2)D] levels for hypophosphatemia. Saccharated ferric oxide is widely used in Japan for iron-deficiency anemia. While it has been shown that saccharated ferric oxide induces hypophosphatemic osteomalacia, the mechanism of this hypophosphatemia remains to be clarified. We here describe three hypophosphatemic patients caused by intravenous administration of saccharated ferric oxide. Hypophosphatemia in these patients were associated with impaired renal tubular phosphate reabsorption, rather low serum 1,25(OH)(2)D and high FGF23 levels. All these biochemical features improved by the cessation of saccharated ferric oxide. These results indicate that hypophosphatemia caused by saccharated ferric oxide is another form of FGF23-related hypophosphatemia.
Shimizu
Yuichiro
Y
Division of Nephrology and Endocrinology, Department of Medicine, The University of Tokyo Hospital, Tokyo, Japan.
Tada
Yuko
Y
Yamauchi
Mika
M
Okamoto
Takaaki
T
Suzuki
Hisanori
H
Ito
Nobuaki
N
Fukumoto
Seiji
S
Sugimoto
Toshitsugu
T
Fujita
Toshiro
T
D000328:Adult; D000369:Aged, 80 and over; D005260:Female; D005290:Ferric Compounds / Q000008:administration & dosage* / Q000009:adverse effects*; D000077605:Ferric Oxide, Saccharated; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D005937:Glucaric Acid; D006801:Humans; D017674:Hypophosphatemia / Q000139:chemically induced*; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged
C000717427:FGF23 protein, human; D005290:Ferric Compounds; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D000077605:Ferric Oxide, Saccharated; D005937:Glucaric Acid