FGF23 and acute kidney injury: Compared with 8 ICU controls without AKI, FGF23 levels were significantly higher in 12 patients with AKI than in those without (median 1948 RU/mL (IQR), 437–4369) compared to 252 RU/mL (IQR, 65–533) in controls (p = 0.01) and also in nonsurvivors versus survivors with median levels of 4446 RU/mL (IQR, 3455–5443) versus 544 RU/mL (IQR, 390–1948; p = 0.02).