FGF-23 Suppressibility by Calcitonin
FGF-23 Suppressibility by Calcitonin
Introduction:

 Based on our experience with calcitonin as an FGF-23 suppressive agent in a patient with an
 FGF-23 producing tumor we hypothesize that calcitonin may be a physiologically important
 regulator of FGF-23 production and secretion in healthy humans.

 Aim:

 In this study we wish to examine the FGF-23 suppressive effects of calcitonin in healthy men.

 Study Design:

 placebo-controlled, cross-over study

 Method:

 -  All twelve subjects are examined on two occasions, once after exposure to placebo 1 ml
 NaCl 0.9% subcutaneously, and once following calcitonin 200 IU/ml subcutaneously

 -  On both occasions frequent bloodsampling will take place, out an indwelling catheter in
 de forearm vein.

 -  Sampling times: -15, 0, 60, 120, 240, 360, and 480 minutes

 -  Mealtimes: Calcium and Phosphate intake standardized on both occasions

 -  All samples are analyzed for FGF-23, using a C-terminal FGF-23 ELISA kit (Immunotopics,
 San Clemente, USA) that measures intact and C-terminal fragments of FGF-23, and one that
 measures only intact FGF-23

 -  Samples obtained at T-15, T0, T240 and T480 are stored for later analysis of Ca,
 albumin, PO4, PTH, 25-OHD and 1,25-OHD

 Endpoint:

 A change of 25% in de serum FGF-23 levels in response to a single subcutaneous injection of
 calcitonin 200 IU.
Inclusion Criteria:

 -  Healthy man, who are between 20-55 years old, and have a BMI 20-27 kg/m2.

 Exclusion Criteria:

 -  Serum creatinin >100 mmol/L, or glomerular filtration rate <80 ml/min.

 -  Abnormal serum Ca, PO4, albumin, 25-OH vitamin D, or PTH levels.

 -  Any medication.