Plasma intact fibroblast growth factor 23 levels in women with anorexia nervosa.
BACKGROUND
Fibroblast growth factor (FGF)23 is a novel phosphaturic factor associated with inorganic phosphate homeostasis. Previous human studies have shown that serum FGF23 levels increase in response to a high phosphate diet. For anorexia nervosa (AN) patients, inorganic phosphate homeostasis is important in the clinical course, such as in refeeding syndrome. The purpose of this study was to determine plasma levels of intact FGF23 (iFGF23) in restricting-type AN (AN-R) patients, binge-eating/purging-type AN (AN-BP) patients, and healthy controls.


METHODS
The subjects consisted of 6 female AN-R patients, 6 female AN-BP patients, and 11 healthy female controls; both inpatients and outpatients were included. Plasma iFGF23, 1,25-dihydroxyvitamin D (1,25-(OH)2D), and 25-hydroxyvitamin D (25-OHD) levels were measured. Data are presented as the median and the range. A two-tailed Mann-Whitney U-test with Bonferroni correction was used to assess differences among the three groups, and a value of p < 0.017 was considered statistically significant.


RESULTS
There were no differences between AN-R patients and controls in the iFGF23 and 1,25-(OH)2D levels. In AN-BP patients, the iFGF23 level (41.3 pg/ml; range, 6.1-155.5 pg/ml) was significantly higher than in controls (3.8 pg/ml; range, not detected-21.3 pg/ml; p = 0.001), and the 1,25-(OH)2D was significantly lower in AN-BP patients (7.0 pg/ml; range, 4.2-33.7 pg/ml) than in controls (39.7 pg/ml; range, 6.3-58.5 pg/ml; p = 0.015). No differences in plasma 25-OHD levels were observed among the groups.


CONCLUSIONS
This preliminary study is the first to show that plasma iFGF23 levels are increased in AN-BP patients, and that these elevated plasma FGF23 levels might be related to the decrease in plasma 1,25-(OH)2D levels.
Otani
Makoto
M
Department of Stress Sciences and Psychosomatic Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. mootani-tky@umin.ac.jp
Takimoto
Yoshiyuki
Y
Moriya
Junko
J
Yoshiuchi
Kazuhiro
K
Akabayashi
Akira
A