Scripties UMCG - Rijksuniversiteit Groningen
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NT-proBNP rises after living kidney donation: Implications for living kidney donor outcomes

(2018) Afra, M. (Mona)

Introduction. Living kidney donors (LKD) have a small but significant increased risk of long-term cardiovascular disease (CVD) and end-stage renal disease (ESRD). Increased demand for LKDs has led to liberalization of selection criteria, possibly increasing donor risks. Though etiology of increased CVD risk in LKDs is not fully known, donors have shown left ventricular (LV) remodelling and mass increase after nephrectomy. We investigated whether unilateral nephrectomy led to short-term rise of N-terminal pro-brain natriuretic peptide (NT-proBNP), a cardiac marker present in LV remodelling, and whether other known risk factors for cardiovascular and kidney disease are associated with NT-proBNP rise. We also investigated whether short-term rise of NT-proBNP following nephrectomy was associated with long-term hypertension and albuminuria, both risk factors for ESRD and CVD.
Methods. In this longitudinal cohort study 262 donors were included with pre- and early post-donation data, 103 of whom had 5-years post-donation data. We performed a Wilcoxon signed rank test to examine the rise of NT-proBNP pre- and post-donation. To determine whether this rise was nephrectomy-induced or age-related, a Mann-Whitney U test was performed between our donors with 5-years data (n=103) and healthy non-donors from the Prevention of Renal and Vascular End-Stage Disease (PREVEND) cohort (a prospective population–based cohort investigating albuminuria, renal, and cardiovascular diseases). Linear regression was used to determine pre-donation predictors of post-donation NT-proBNP changes. Logistic regression was used to analyse the effect of short-term NT-proBNP changes on long-term development of hypertension and microalbuminuria.
Results. NT-proBNP levels rose in LKDs after unilateral nephrectomy from median 38.0 (IQR 21.8-69.0) to 53.0 (IQR 31.8-101.5). This rise was significantly higher in donors (mean rank=3726, n=103) than in the PREVEND group (mean rank=3288, n=6486), Z = -2.318, p=0.02. Age (st. β=0.158, p=0.02) and smoking (st. β=-0.139, p=0.04 were independent predictors for short-term change in NT-proBNP. A rise of NT-proBNP early post-donation (OR=3.8, p=0.05) and a higher systolic blood pressure pre-donation (OR=1.2, p<0.001) were associated with development of hypertension 5-years post-donation. Short-term changes in NT-proBNP did not predict long-term microalbuminuria outcomes.
Discussion. Unilateral nephrectomy induces a rise in NT-proBNP levels post-donation. Older donors are more likely to have a greater rise in NT-proBNP. The association of a higher rise of NT-proBNP early post-donation, and a higher systolic blood pressure pre-donation with the development of hypertension 5-years post-donation suggests that pre-donation NT-proBNP levels would be a good predictor of long-term hypertension in LKDs. These donors could benefit in the long run from more frequent blood pressure monitoring. Further liberalization of the selection criteria should be done with caution as this could worsen donor outcomes.

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