Abstract
Objectives Living kidney donors provide a unique setting to study functional and metabolic consequences after organ donation. Since the lack of data of the homoeostasis of numerous vitamin D metabolites in these healthy subjects, the aim of this study was to assess the vitamin D metabolism before and after kidney donation. Methods We investigated the 25-dihydroxyvitamin D 2 (25[OH]D 2 ), 25-dihydroxyvitamin D 3 (25[OH]D 3 ), 1,25-dihydroxyvitamin D 3 (1,25[OH] 2 D 3 ), 24,25-dihydroxyvitamin D 3 (24,25[OH] 2 D 3 ), 25,26-dihydroxyvitamin D 3 (25,26[OH] 2 D 3 ), and the native vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) in a well characterized study cohort of 32 healthy living kidney donors before and after organ donation. Results Thirty-two healthy subjects after kidney donation had significantly lower median (interquartile range) 1,25(OH) 2 D 3 serum concentrations (88.6 [62.6–118.8] vs. 138.0 [102.6–152.4] pmol/L, p<0.001) and significantly higher median 25(OH)D 2 serum levels (1.80 [1.19–2.19] vs. 1.11 [0.74–1.59] nmol/L, p=0.019) than before donation. Similar serum concentrations of 25(OH)D 3 and 25,26(OH) 2 D 3 were observed before and after donation. The 24,25(OH) 2 D 3 blood levels distinctly decreased after organ donation (4.1 [2.3–5.3] vs. 5.3 [2.2–6.9] nmol/L, p=0.153). Native vitamin D2 (0.10 [0.08–0.14] vs. 0.08 [0.06–0.12] nmol/L, p=0.275) was slightly increased and vitamin D3 (1.6 [0.6–7.2] vs. 2.5 [0.9–8.6] nmol/L, p=0.957) decreased after kidney donation. Conclusions Living kidney donors were found with decreased 1,25(OH) 2 D 3 and 24,25(OH) 2 D 3 , increased 25(OH)D 2 and consistent 25(OH)D 3 and 25,26(OH) 2 D 3 serum concentrations after organ donation. The current study advances the understanding on vitamin D metabolism suggesting that altered hydroxylase-activities after donation is accompanied by compensatory elevated dietary-related 25(OH)D 2 blood concentrations.