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The FGF ‐23/klotho axis and its relationship with phosphorus, calcium, vitamin D, PTH , aldosterone, severity of disease, and outcome in hospitalised foals
Author(s) -
Kamr A. M.,
Dembek K. A.,
Hildreth B. E.,
Morresey P. R.,
Rathgeber R. A.,
Burns T. A.,
Zaghawa A. A.,
Toribio R. E.
Publication year - 2018
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.12946
Subject(s) - klotho , fibroblast growth factor 23 , vitamin d and neurology , calcium , aldosterone , medicine , phosphorus , disease , endocrinology , parathyroid hormone , chemistry , kidney , organic chemistry
Summary Background Fibroblast growth factor‐23 ( FGF ‐23) and klotho are key regulators of vitamin D and parathyroid hormone ( PTH ) synthesis as well as phosphorus and calcium homeostasis; however, information on the FGF ‐23/klotho axis in healthy and hospitalised foals is lacking. Objectives The aims of this study were to measure serum FGF ‐23 and klotho concentrations and determine their association with serum phosphorus, total calcium ( TC a), vitamin D metabolite [25( OH )D, 1,25( OH ) 2 D], PTH , and aldosterone concentrations, disease severity, and mortality in hospitalised foals. Study design Prospective, multicentre, cross‐sectional study. Methods A total of 91 foals ≤72 h old were classified as hospitalised (n = 81; 58 septic; 23 sick non‐septic [ SNS ]) and healthy (n = 10). Blood samples were collected on admission. Hormone concentrations were determined by immunoassays. Results Serum FGF ‐23, PTH , phosphorus, and aldosterone concentrations were higher while klotho, 25( OH )D, 1,25( OH ) 2 D, and TC a concentrations were lower in septic and SNS compared to healthy foals (P<0.05). In hospitalised and septic foals, increased FGF ‐23 and aldosterone concentrations were associated with high phosphorus and PTH but not with TC a and vitamin D metabolite concentrations. Hospitalised foals with the highest FGF ‐23 and lowest klotho concentrations were more likely to die (odds ratio ( OR ): 3.3; 95% confidence interval ( CI ): 1.1–10.3 and OR : 3.1; CI : 1.1–8.0, respectively). Main limitations Blood gas, ionised calcium, blood culture information not being available for many foals, and use of the sepsis score to classify hospitalised foals. Conclusions Imbalances in the FGF ‐23/klotho axis may contribute to mineral dyshomeostasis and disease progression in critically ill foals. Elevated FGF ‐23 and reduced klotho, together with high phosphorus and PTH concentrations suggests FGF ‐23 resistance. FGF ‐23 and klotho are good markers of disease severity and likelihood of mortality in hospitalised foals. Aldosterone may influence phosphorus and PTH dynamics in hospitalised foals. Routine measurement of phosphorus concentrations in sick foals is recommended.