FGF-23 As a Novel Predictor of Hospital Mortality in Critically Ill Patients

Presentation Number: FRI 347
Date of Presentation: April 1st, 2016

Karin Amrein*1, Verena Schwetz2, Nicolas Verheyen1, Astrid Fahrleitner-Pammer3, Christian Schnedl4, Thomas R Pieber5 and Harald Dobnig6
1Medical University of Graz, Graz, Austria, 2Medical University of Graz, Steiermark, Austria, 3Medical University, Graz, Austria, 4Department of Radiology, Graz, Austria, 5Medical University of Graz, Austria, 6Schilddruesen|Endokrinologie|Institut, Graz, Austria

Abstract

Introduction: Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone and regulator of vitamin D metabolism that seems to be a useful biomarker for the identification of high-risk patients in chronic but also acute disease. It is produced mainly in bone, although the failing heart has recently been suggested to be a source of circulating FGF23via oncostatin M as well. FGF23 rises rapidly in acute and chronic kidney disease and is strongly and independently associated with excess morbidity and mortality. Emerging data suggest that FGF23 is also predictive of poor outcomes in different scenarios of acute illness including cardiogenic shock and cardiac surgery.

Methods: In this posthoc analysis in the placebo group of the VITdAL-ICU study, we analysed FGF23 levels in a subgroup of adult medical/surgical critically ill patients with vitamin D deficiency (25-hydroxyvitamin D equal or lower to 20ng/ml) at baseline (n= 65) and day 7 (n=49). C-terminal FGF-23 was measured in one batch from frozen stored plasma samples by enzyme-linked immunosorbent assay (Immunotopics, San Clemente, CA, USA, upper detection limit after 1:10 dilution 14,000 RU/ml).

Results: Overall, median FGF23 levels were 242 RU/ml at day 0 and 212 RU/ml at day 7 (R=0.67, p<0.01). Patients who died in the hospital (n=19, 29%) had almost 10-fold and significantly higher baseline FGF23 levels than survivors (1500 vs. 170 RU/ml, P<0.01). There was a strong correlation between FGF23 and kidney function, the Simplified Acute Physiology Score II, the Charlson comorbidity index and 1,25-dihydroxyvitamin D (P<0.01), but not with other biochemical markers including phosphate and calcium.

Discussion: FGF23 is an interesting novel biomarker that is a strong independent indicator of poor outcomes in chronic kidney disease. Its role in acute disease is less studied, but appears to be similarly predictive for adverse outcomes which is supported by our data in critical illness. It remains unclear if FGF23 is only a marker or also a contributor of adverse outcomes and if dietary and/or pharmacological interventions to reduce FGF23 concentrations would relate to clinical benefit.

 

Nothing to Disclose: KA, VS, NV, AF, CS, TRP, HD