FGF23 and amyotrophic lateral sclerosis: Plasma FGF23 levels were evaluated in 86 ALS patients who had been pre-selected as slower (n = 45) or faster (n = 41) progressors based on a prospectively measured ALSFRS-R decline of less than 0.8 point/month or greater than 1.2 points/month, respectively, as well as in 61 healthy age- and sex-matched controls.