J Pediatr Endocr Met 2015; 28(7-8): 825–832
Tarah Fatania, Asma Binjaba, Hope Weiler, Atul Sharma and Celia Rodd*
Persistent elevation of fibroblast growth factor 23 concentrations in healthy appropriate-forgestational-age preterm infants Abstract Objective: To explore the temporal evolution of 25-hydroxyvitamin D [25(OH)D], its epimer, parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and minerals in healthy appropriate-for-gestational-age preterms. Patients: A prospective study was undertaken in infants born at 28–32 weeks with monitoring at 1, 3, 5 weeks and term. Methods: Morning plasma and urine calcium; phosphorus; creatinine; PTH, C-terminal and intact FGF23 (iFGF23) and liquid chromatography-tandem mass spectrometry measurements of 25(OH)D were undertaken. Analyses included regression models. Results: Some 11 infants (5 males) were recruited at a median gestational age of 31.2 weeks (interquartile range: 28.1–31.8). Standard chemistries were normal. No infant was vitamin D deficient; 58% achieved 50 nmol/L with a median intake of 540 IU/day. High concentrations of C-3 epimer were detected. iFGF23 and C-terminal concentrations were persistently elevated (double and ten times adult norms, respectively). Tubular resorption of phosphorus was normal (88% ± 8%). Conclusions: Most infants achieved acceptable 25(OH)D3 concentrations. The biologic significance of the elevated FGF23 is unclear. Keywords: calcium; FGF23; phosphorus; premature infant; vitamin D. DOI 10.1515/jpem-2014-0186 Received May 6, 2014; accepted December 8, 2014; previously published online May 13, 2015 a These authors contributed equally to this work. *Corresponding author: Dr. Celia Rodd, Winnipeg Children’s Hospital, FW302-685 William Avenue, Winnipeg, MB, Canada R3E 0Z2, Phone: +204 787 1741, Fax: +204 787 1655, E-mail: [email protected] Tarah Fatani and Asma Binjab: Pediatrics, McGill University, Montreal, Canada H3H 1P3 Hope Weiler: School of Dietetics and Human Nutrition, McGill University, Ste-Anne-de-Bellevue, Canada H9X 3V9 Atul Sharma and Celia Rodd: Pediatrics and Child Health, University of Manitoba, Winnipeg, Canada
Abbreviations: 25(OH)D, 25-hydroxyvitamin D; 24,25 (OH)2D, 24,25-dihydroxyvitamin D; 1,25(OH)2D, 1,25-dihydroxyvitamin D; AGA, appropriate-for-gestational-age; CI, confidence interval; CV%, coefficient of variation; cFGF23, C-terminal FGF23; iFGF23, intact FGF23; FGF23, fibroblast growth factor 23; GA, gestational age; IQR, interquartile range; LC-MS/MS, liquid chromatographytandem mass spectrometry; PTH, parathyroid hormone; TRP, tubular resorption of phosphorus; U ca:cr, urine calcium:creatinine ratio.
Introduction Without the robust third trimester mineral accretion, preterm infants are at risk for diminished bone health (1, 2). Osteopenia is reported in 23% of infants who weigh
Tarah Fatania, Asma Binjaba, Hope Weiler, Atul Sharma and Celia Rodd*
Persistent elevation of fibroblast growth factor 23 concentrations in healthy appropriate-forgestational-age preterm infants Abstract Objective: To explore the temporal evolution of 25-hydroxyvitamin D [25(OH)D], its epimer, parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and minerals in healthy appropriate-for-gestational-age preterms. Patients: A prospective study was undertaken in infants born at 28–32 weeks with monitoring at 1, 3, 5 weeks and term. Methods: Morning plasma and urine calcium; phosphorus; creatinine; PTH, C-terminal and intact FGF23 (iFGF23) and liquid chromatography-tandem mass spectrometry measurements of 25(OH)D were undertaken. Analyses included regression models. Results: Some 11 infants (5 males) were recruited at a median gestational age of 31.2 weeks (interquartile range: 28.1–31.8). Standard chemistries were normal. No infant was vitamin D deficient; 58% achieved 50 nmol/L with a median intake of 540 IU/day. High concentrations of C-3 epimer were detected. iFGF23 and C-terminal concentrations were persistently elevated (double and ten times adult norms, respectively). Tubular resorption of phosphorus was normal (88% ± 8%). Conclusions: Most infants achieved acceptable 25(OH)D3 concentrations. The biologic significance of the elevated FGF23 is unclear. Keywords: calcium; FGF23; phosphorus; premature infant; vitamin D. DOI 10.1515/jpem-2014-0186 Received May 6, 2014; accepted December 8, 2014; previously published online May 13, 2015 a These authors contributed equally to this work. *Corresponding author: Dr. Celia Rodd, Winnipeg Children’s Hospital, FW302-685 William Avenue, Winnipeg, MB, Canada R3E 0Z2, Phone: +204 787 1741, Fax: +204 787 1655, E-mail: [email protected] Tarah Fatani and Asma Binjab: Pediatrics, McGill University, Montreal, Canada H3H 1P3 Hope Weiler: School of Dietetics and Human Nutrition, McGill University, Ste-Anne-de-Bellevue, Canada H9X 3V9 Atul Sharma and Celia Rodd: Pediatrics and Child Health, University of Manitoba, Winnipeg, Canada
Abbreviations: 25(OH)D, 25-hydroxyvitamin D; 24,25 (OH)2D, 24,25-dihydroxyvitamin D; 1,25(OH)2D, 1,25-dihydroxyvitamin D; AGA, appropriate-for-gestational-age; CI, confidence interval; CV%, coefficient of variation; cFGF23, C-terminal FGF23; iFGF23, intact FGF23; FGF23, fibroblast growth factor 23; GA, gestational age; IQR, interquartile range; LC-MS/MS, liquid chromatographytandem mass spectrometry; PTH, parathyroid hormone; TRP, tubular resorption of phosphorus; U ca:cr, urine calcium:creatinine ratio.
Introduction Without the robust third trimester mineral accretion, preterm infants are at risk for diminished bone health (1, 2). Osteopenia is reported in 23% of infants who weigh
