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Living kidney donation offers a unique setting to study changes in phosphate and vitamin D homeostasis attributable to mild isolated decreases in estimated glomerular filtration rate (eGFR).Cross-sectional study.198 living kidney donors and 98 nondonor controls from 9 transplant centers across 3 countries. For donors, median time after donation was 5.3 years. At assessment, donors had a lower eGFR than controls (73 vs 98 mL/min/1.73 m(2)).Living kidney donation (mildly decreased eGFR).Biochemical markers of chronic kidney disease-mineral and bone disorder.Serum creatinine, total serum calcium, serum and urine inorganic phosphate, plasma intact parathyroid hormone, serum calcidiol and calcitriol, renal fractional excretion of inorganic phosphate, and intact serum fibroblast growth factor 23 (FGF-23).Serum FGF-23 levels were significantly higher in donors (38.1 vs 29.7 pg/mL; P0.001). For every 10-mL/min/1.73 m(2) decrease in eGFR, FGF-23 level was higher by 3.2 (95% CI, 2.0-4.4) pg/mL. Compared with controls, donors showed higher renal tubular fractional excretion of inorganic phosphate (17.8% vs 12.3%; P0.001), lower serum phosphate (0.97 vs 1.02 mmol/L; P = 0.03), and lower serum calcitriol values (63 vs 77 pmol/L; P0.001). Serum calcium levels were not significantly different between the 2 groups. Plasma intact parathyroid hormone levels were significantly higher in donors (5.7 vs 5.0 pmol/L; P = 0.03), but were not correlated with FGF-23 or calcitriol levels.Enrollment of a small proportion of past donors at participating centers; assessment of only postdonation values; unable to assess seasonal variation or other temporal patterns in biochemical markers; assessment of kidney function was based on eGFR, not measured GFR.The FGF-23 pathway may be activated in living kidney donors who show early biochemical changes compatible with chronic kidney disease-mineral and bone disorder. Whether these changes influence bone mineral density and fracture rates warrants consideration.

Background Older dialysis patients have a high burden of mortality and morbidity. Frailty and functional disability are common. One of the main determinants of functional disability in nondialysis populations is acute hospitalization. Such episodes are predictive of increased mortality and a future need for long-term care. Based on the high prevalence of disability in the dialysis population, we undertook a pilot study to determine functional impairment at the time of admission and again at 1 week after discharge. Study Design Prospective cohort study. Setting & Participants Prevalent dialysis patients older than 65 years admitted to a single acute-care institution during a 3-month period. Outcomes The proportion of dialysis patients with difficulty with activities of daily living at baseline and 1 week after discharge. Measurement Basic activities of daily living; Lawton Brody Instrumental Activities of Daily Living score; timed up-and-go and handgrip tests; Trails A & B, and the clock test. Results At the time of admission, only 8 of 35 individuals reported being independent with basic activities of daily living. None of the patients was independent with instrumental activities of daily living. At 1 week after discharge, patients showed deterioration in all aspects of function except the ability to use the telephone and manage their financial affairs. A total of 73.3% of patients (95% confidence interval, 54.1 to 87.7) experienced a decline in personal functional independence in association with hospitalization. Limitations This is a pilot study with a small number of patients who were studied at only 2 times (admission and 1 week after discharge). Conclusions Results of this study suggest that hospitalization is associated with a high rate of disability in elderly dialysis patients. Further study is required to determine whether the functional deterioration seen with hospitalization improves over time.