High urinary homoarginine excretion is associated with low rates of all-cause mortality and graft failure in renal transplant recipients
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Renal transplant recipients (RTR) have an increased cardiovascular risk profile. Low levels of circulating homoarginine (hArg) are a novel risk factor for mortality and the progression of atherosclerosis. The kidney is known as a major source of hArg, suggesting that urinary excretion of hArg (UhArg) might be associated with mortality and graft failure in RTR. hArg was quantified by mass spectrometry in 24-h urine samples of 704 RTR (functioning graft ≥1 year) and 103 healthy subjects. UhArg determinants were identified with multivariable linear regression models. Associations of UhArg with all-cause mortality and graft failure were assessed using multivariable Cox regression analyses. UhArg excretion was significantly lower in RTR compared to healthy controls [1.62 (1.09–2.61) vs. 2.46 (1.65–4.06) µmol/24 h, P < 0.001]. In multivariable linear regression models, body surface area, diastolic blood pressure, eGFR, pre-emptive transplantation, serum albumin, albuminuria, urinary excretion of urea and uric acid and use of sirolimus were positively associated with UhArg, while donor age and serum phosphate were inversely associated (model R 2 = 0.43). During follow-up for 3.1 (2.7–3.9) years, 83 (12 %) patients died and 45 (7 %) developed graft failure. UhArg was inversely associated with all-cause mortality [hazard risk (HR) 0.52 (95 % CI 0.40–0.66), P < 0.001] and graft failure [HR 0.58 (0.42–0.81), P = 0.001]. These associations remained independent of potential confounders. High UhArg levels are associated with reduced all-cause mortality and graft failure in RTR. Kidney-derived hArg is likely to be of particular importance for proper maintenance of cardiovascular and renal systems.
KeywordsCardiovascular risk Transplantation Graft survival Kidney
Body surface area
Diastolic blood pressure
Estimated glomerular filtration rate
Food frequency questionnaire
Human leukocyte antigen
High-sensitivity C-reactive protein
Lower limit of detection
Nitric oxide synthase
N-terminal pro-hormone of brain natriuretic peptide
Renal transplant recipients
This work was supported by Grants from the Dutch Kidney Foundation (NSN C08-2254, P13-114), by COST Action BM1005: ENOG: European Network on Gasotransmitters (www.gasotransmitters.eu), and by the Top Institute Food and Nutrition (A-1003).
Compliance with ethical standards
The Institutional Review Board approved the study protocol (METc 2008/186) which was in adherence to the Declaration of Helsinki.
Conflict of interest
All authors report no conflicts of interest.
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