The Effect of a 26-Hour Fast in Living Kidney Donors

Background: Living kidney donation is widely practiced, and short- and long-term outcomes are acceptable. Within the living kidney donor population there are unique ethnic groups who practice customs that affect kidney function. In Judaism, Yom Kippur (Day of Atonement) is a 25- to 26-hour fast practiced yearly. There are no studies describing the effect of this fast on LKDs.

Methods: Living kidney donors were approached via e-mail. Exclusion criteria were conditions considered prohibitive of fasting. Control participants were potential living kidney donors approved by the standard medical evaluation but that had not yet donated. Blood and urine samples were obtained at 3 time points: baseline: 3 months before fast; fasting: 1 hour after fast; and follow-up: 14 days after fast.

Results: In total, 85 living kidney donors and 27 control participants were included. Donors were older (42.8 vs 38.8 years) and had a higher baseline creatinine (103 vs 72 umol/L). All other parameters were the same. The percent change between fasting and nonfasting creatinine was smaller in living kidney donors than in control participants (0.12% vs 0.21% change, P = .04). Values of sodium, albumin, and osmolarity were not different between groups. Time from donation did not influence results.

Conclusions: Living kidney donors practicing a day fast showed a different pattern regarding the change in creatinine levels. This pattern cannot be considered hazardous for living kidney donors. The emotional wellbeing of living kidney donors is of utmost importance, and this first report of the safety of a 24-hour fast is reassuring. These findings may be of interest to other religious groups, for example, the Muslim community which observes Ramadan.