Exercise capacity and body composition in living-donor renal transplant recipients over time.

BACKGROUND: Renal transplantation (RTx) restitutes the function of the failing organ and induces convalescence of the entire organism. Our study investigates whether this is accompanied by improvements in cardiovascular function and structural changes.
METHODS: A total of 25 Caucasian patients (14 male, median age 44.2 +/- 9.2 years, BMI 23.7 +/- 4.0 kg/m(2)) were assessed in a prospective trial before, 1, 3 and 12 months after RTx from living donors by clinical examination, cardiopulmonary exercise testing, dual X-ray absorptiometry (DEXA) and analysis of plasma indices.
RESULTS: Creatinine clearance improved from 8.0 +/- 3.1 to 60.9 +/- 18.1 mL/min at 1 month, but declined at 3 (51.6 +/- 16.3 mL/min) and 12 months (53.6 +/- 20.8 mL/min, P = 0.04 versus month 1). Body composition shifted from lean towards fat tissue (25.8 +/- 12.5-31.2 +/- 11.2% body fat content, P = 0.0001). Only baseline lean weight correlated with fat increase over time (r(2) = 0.28, P = 0.008). Patients with fat content above median (n = 13) had a 3-fold increased hazard ratio of infection (CI 1.04-9.41, P = 0.042) and overall hospitalization (hazard ratio 2.95, CI 1.10-7.93, P = 0.03). PeakVO(2) decreased over RTx (23.2 +/- 6.0- 17.6 +/- 5.1 mL/kg/min) and returned to baseline levels not until 1 year later (P < 0.001). After an initial decline, muscle oxidative capacity (peakVO(2)/lean mass) improved from 33.6 +/- 10.1 to 35.0 +/- 8.2 mL/kg/min at 12 months after RTx (P < 0.001).
CONCLUSIONS: After RTx, body composition shifted continuously towards fat tissue, and baseline lean weight significantly correlated with fat increase over time. Both severe infections and hospitalizations are associated with a higher fat content before RTx. Exercise capacity (peakVO(2)) worsened after RTx and restitutes during follow-up, with muscle quality (peakVO(2)/lean) even exceeding baseline levels after 12 months.