FGF23 and Marchiafava-Bignami disease: - Median time after donation was 5.3 years - FGF-23 was higher (38.9 vs 29.7 pg/mL) and eGFR was lower in donors compared to controls - Donors had higher urine phosphate and iPTH, but lower serum calcitriol and phosphate levels - iPTH did not correlate with FGF-23 or calcitriol - Unclear if changes impact MBD or fracture rates