TY - JOUR
T1 - Assessment of 24,25(OH) 2 D levels does not support FGF23-mediated catabolism of vitamin D metabolites
AU - Dai, Bing
AU - David, Valentin
AU - Alshayeb, Hala M.
AU - Showkat, Arif
AU - Gyamlani, Geeta
AU - Horst, Ronald L.
AU - Wall, Barry M.
AU - Darryl Quarles, L.
N1 - Funding Information:
This work was supported by the NIH grant RO1-AR45955 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases.
PY - 2012/11/2
Y1 - 2012/11/2
N2 - Progressive elevations of fibroblastic growth factor 23 (FGF23) in chronic kidney disease may reduce serum 25-hydroxyvitamin D (25(OH)) and 1,25-dihydroxyvitamin D (1,25(OH)2 D) levels, via stimulation of 24-hydroxylase (Cyp24a1)-mediated catabolism of these vitamin D metabolites. To test this possibility, we measured serum concentrations of 24,25- dihydroxyvitamin D (24,25(OH)2 D), a product of Cyp24a1 hydroxylation of 25(OH)D, in the Col4a3 knockout mouse, a model of Alport syndrome-derived chronic kidney disease, and in patients with chronic kidney disease of variable severity. There was an inverse correlation between serum FGF23 and both 25(OH)D and 1,25(OH)2 D in the mouse model, but no significant relationship was observed in the cross-sectional patient cohort. The FGF23-dependent increase in Cyp24a1 mRNA expression in the mouse kidneys was consistent with the possibility that FGF23 induces vitamin D catabolism. There was, however, a reduction in serum 24,25(OH)2 D levels, rather than the expected elevation, in both the mice and patients with chronic kidney disease. Low 25(OH)D and elevated FGF23 and parathyroid hormone levels were correlated with the reduced serum 24,25(OH)2 D concentrations of these patients. Thus, we failed to find support for FGF23-mediated catabolism of vitamin D metabolites in chronic kidney disease assessed by 24,25(OH)2 D levels.
AB - Progressive elevations of fibroblastic growth factor 23 (FGF23) in chronic kidney disease may reduce serum 25-hydroxyvitamin D (25(OH)) and 1,25-dihydroxyvitamin D (1,25(OH)2 D) levels, via stimulation of 24-hydroxylase (Cyp24a1)-mediated catabolism of these vitamin D metabolites. To test this possibility, we measured serum concentrations of 24,25- dihydroxyvitamin D (24,25(OH)2 D), a product of Cyp24a1 hydroxylation of 25(OH)D, in the Col4a3 knockout mouse, a model of Alport syndrome-derived chronic kidney disease, and in patients with chronic kidney disease of variable severity. There was an inverse correlation between serum FGF23 and both 25(OH)D and 1,25(OH)2 D in the mouse model, but no significant relationship was observed in the cross-sectional patient cohort. The FGF23-dependent increase in Cyp24a1 mRNA expression in the mouse kidneys was consistent with the possibility that FGF23 induces vitamin D catabolism. There was, however, a reduction in serum 24,25(OH)2 D levels, rather than the expected elevation, in both the mice and patients with chronic kidney disease. Low 25(OH)D and elevated FGF23 and parathyroid hormone levels were correlated with the reduced serum 24,25(OH)2 D concentrations of these patients. Thus, we failed to find support for FGF23-mediated catabolism of vitamin D metabolites in chronic kidney disease assessed by 24,25(OH)2 D levels.
KW - FGF23
KW - chronic kidney disease
KW - parathyroid hormone
KW - vitamin D
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U2 - 10.1038/ki.2012.222
DO - 10.1038/ki.2012.222
M3 - Article
C2 - 22739976
AN - SCOPUS:84868601209
VL - 82
SP - 1061
EP - 1070
JO - Kidney International
JF - Kidney International
SN - 0085-2538
IS - 10
ER -