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.