Kidney Transplant Recipients Show Limited Lung Diffusion Capacity but Similar Hydrogen Peroxide Exhalation as Healthy Matched Volunteers: A Pilot Study

Abstract

Patients with end-stage chronic kidney disease show higher systemic oxidative stress and exhale more hydrogen peroxide (H₂O₂) than healthy controls. Kidney transplantation reduces oxidative stress and H₂O₂ production by blood polymorphonuclear leukocytes (PMNs). Kidney transplant recipients (KTRs) may be predisposed to an impairment of lung diffusing capacity due to chronic inflammation. Lung function and H₂O₂ concentration in the exhaled breath condensate (EBC) were compared in 20 KTRs with stable allograft function to 20 healthy matched controls. Serum interleukin eight (IL-8) and C-reactive protein (CRP), blood cell counts, and spirometry parameters did not differ between groups. However, KTRs showed lower total lung diffusing capacity for carbon monoxide, corrected for hemoglobin concentration (TLCO_c), in comparison to healthy controls (92.1 ± 11.5% vs. 102.3 ± 11.9% of predicted, p = 0.009), but similar EBC H₂O₂ concentration (1.63 ± 0.52 vs. 1.77 ± 0.50 µmol/L, p = 0.30). The modality of pre-transplant renal replacement therapy had no effect on TLCO_c and EBC H₂O₂. TLCO_c did not correlate with time after transplantation. In this study, TLCO_c was less reduced in KTRs in comparison to previous reports. We suggest this fact and the non-elevated H₂O₂ exhalation exhibited by KTRs, may result perhaps from the evolution of the immunosuppressive therapy.

Keywords: exhaled breath condensate; hydrogen peroxide; kidney transplantation; lung diffusing capacity; pulmonary function.

Figure 1

H₂O₂ levels in exhaled breath condensate of 20 kidney transplant recipients and 20 healthy matched controls. Each dot represents the result of one subject, whereas, each line, represents the mean value. Numerical results are expressed as mean ± SD (median; IQR). No significant differences were found between these groups.