Different Vitamin D Preparations & FGF23 in Humans
Information source: Massachusetts General Hospital
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Link to the current ClinicalTrials.gov record.
Condition(s) targeted: Vitamin D Deficiency
Intervention: Ergocalciferol (Dietary Supplement); Calcitriol (Dietary Supplement)
Sponsored by: Massachusetts General Hospital
Official(s) and/or principal investigator(s):
Sherri-Ann M Burnett-Bowie, MD, MPH, Principal Investigator, Affiliation: Massachusetts General Hospital
Fibroblast growth factor 23 (FGF23) is a new hormone which controls phosphate and vitamin D
levels in humans. Excess FGF23 is associated with an increased risk of death in patients
with chronic kidney disease. In this study the investigators are investigating the effects
of different forms of vitamin D on FGF23 levels in the blood in order to increase our
understanding of how this important hormone works.
Official title: Effect of Different Vitamin D Preparations on Circulating FGF23 Levels in Vitamin D Deficient Caucasian and African-American Men and Women
Study design: Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label
Primary outcome: Change in FGF23 levels
Change in serum phosphate
Change in urinary phosphate
Change in serum calcium
Fibroblast growth factor 23 (FGF23) is a novel hormone involved in phosphate and vitamin D
physiology. X-linked hypophosphatemia (XLH), autosomal dominant hypophosphatemic rickets
(ADHR), and tumor induced osteomalacia (TIO) are 3 rare diseases characterized by
rickets/osteomalacia, fractures, and hypophosphatemia secondary to renal phosphate wasting
and inappropriately low levels of activated vitamin D (calcitriol), which are caused by
excess amounts of or mutated FGF23. FGF23 excess also occurs in renal failure, where
elevated FGF23 levels predict increased mortality. Thus, abnormal FGF23 appears to be
central to both rare and common diseases. While FGF23 appears to be regulated by vitamin D,
dietary and serum phosphate, much is still unknown. The effects of different forms of
vitamin D on FGF23 stimulation are not well characterized. Similarly, any racial differences
in the regulation of FGF23 by vitamin D have not been investigated.
To address these knowledge deficits, we will randomize 52 vitamin D deficient (25OHD < or =
24 ng/mL by LC/MS) Caucasian and African-American men and women to treatment with either
dietary vitamin D or activated vitamin D for 12 weeks. Our primary endpoint will be the
change in FGF23 with dietary versus activated vitamin D.
Minimum age: 18 Years.
Maximum age: 45 Years.
- Age 18 to 45 yrs
- Serum 25OHD < 24 ng/mL by liquid chromatography/mass spectroscopy
- At least 1 menses in the last 3 months (females) and normal serum testosterone
- African-American or Caucasian race
- Significant cardiac, hepatic, oncologic, or psychiatric disease
- History of malabsorption, kidney stones, or recent alcohol excess/abuse
- Use of medications known to affect serum phosphate levels including phosphate-binding
antacids, sodium etidronate, calcitonin, excessive doses of vitamin D (> 1000 units
per day), excessive doses of vitamin A (> 20,000 units/day), calcitriol, growth
hormone, or anti-convulsants
- Use of thiazide diuretics or cholestyramine
- Serum calcium < 8 or > 11 mg/dL, creatinine > 1. 5 mg/dL, or Hgb < 11 gm/dL
- Serum glucose >140mg/dL
- Liver function tests > 2 times the upper limit of normal
- TSH < 0. 1 or > 7 uU/mL
- WBC < 2,000 or > 15,000/cmm
- Platelet count < 100,000 or > 500,000/cum
- Hormone replacement therapy (however, oral contraceptives are allowed) or
- Urine beta-hCG positive (females)
- Serum phosphate > 4. 6 mg/dL
- Allergy to vitamin D
Locations and Contacts
Massachusetts General Hospital, Boston, Massachusetts 02114, United States
Burnett SM, Gunawardene SC, Bringhurst FR, Jüppner H, Lee H, Finkelstein JS. Regulation of C-terminal and intact FGF-23 by dietary phosphate in men and women. J Bone Miner Res. 2006 Aug;21(8):1187-96.
Bhan I, Shah A, Holmes J, Isakova T, Gutierrez O, Burnett SM, Jüppner H, Wolf M. Post-transplant hypophosphatemia: Tertiary 'Hyper-Phosphatoninism'? Kidney Int. 2006 Oct;70(8):1486-94. Epub 2006 Aug 30.
Burnett-Bowie SM, Mendoza N, Leder BZ. Effects of gonadal steroid withdrawal on serum phosphate and FGF-23 levels in men. Bone. 2007 Apr;40(4):913-8. Epub 2006 Dec 8.
Burnett-Bowie SM, Henao MP, Dere ME, Lee H, Leder BZ. Effects of hPTH(1-34) infusion on circulating serum phosphate, 1,25-dihydroxyvitamin D, and FGF23 levels in healthy men. J Bone Miner Res. 2009 Oct;24(10):1681-5. doi: 10.1359/jbmr.090406.
Starting date: May 2009
Last updated: April 18, 2012