PHILADELPHIA—Levels of fibroblast growth factor 23 (FGF-23) are elevated in acute kidney injury (AKI) and are associated with an increased risk of death or need for renal replacement therapy (RRT), data presented at Kidney Week 2011 suggest.

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FGF-23 is a hormone released by osteocytes that has an important role in phosphate and vitamin D homeostasis. FGF-23 levels are independently associated with increased mortality in chronic kidney disease and end-stage renal disease. FGF-23 has not been studied in AKI, according to investigators.

David E. Leaf, MD, of Columbia University Medical Center in New York, and colleagues studied 30 patients with AKI and 30 controls from the medical intensive care unit and general hospital wards at Columbia. The investigators measured FGF-23 levels at baseline and again five days later.

AKI patients had a median FGF-23 level of 1,471 RU/mL, which was significantly greater than the 263 RU/mL level in the control arm. The proportion of AKI patients progressing to death or need for RRT was about 70% for those in the highest tertile of FGF-23 level compared with about 10% among AKI patients in the lowest tertile. After adjusting for age and baseline serum creatinine levels, FGF-23 remained a significant independent predictor of death or need for RRT, with an adjusted odds ratio of 13.7. In addition, the study showed that FGF-23 correlated positively with phosphate and parathyroid hormone levels and negatively with 1,25-hydoxyvitamin D. 

When asked to comment, Dr. Leaf stated: “This work builds on existing literature suggesting that FGF-23 is an incredibly important hormone in patients with kidney disease. Our study is unique in that it demonstrates the importance of FGF-23 among patients with acute rather than chronic kidney disease, an area in which it has not previously been studied.”