Plasma Neutrophil Gelatinase-associated Lipoprotein in Living Kidney Donors

Prospective assessment of urinary neutrophil gelatinase-associated lipoprotein in living kidney donors: toward understanding differences between chronic kidney diseases of surgical and medical origin

OBJECTIVES

To evaluate the clinical implications of postoperative urinary neutrophil gelatinase-associated lipoprotein (NGAL) changes and the association between urinary NGAL (uNGAL) and renal function in living kidney donors.

SUBJECTS, PATIENTS AND METHODS

We included 76 healthy adults who underwent donor nephrectomy between December 2013 and November 2014. Perioperative serum creatinine (sCr), uNGAL, serum NGAL (sNGAL), and urinary microalbumin were prospectively measured until 6 months postoperatively. Patients with chronic kidney disease (CKD) due to medical disorders who visited our outpatient clinic during the same period were included for comparison.

RESULTS

The mean (SD) preoperative uNGAL of donors was 5 (5.17) ng/mL. uNGAL (corrected for urinary creatinine) was maximal at 1-2 days postoperatively, decreased on postoperative day 3, and stabilised by 7 days after surgery. Postoperative uNGAL was not associated with sex, age, or preoperative renal function. When corrected for sNGAL to compensate for the systemic increase in NGAL with major surgery, uNGAL on days 1-3 postoperatively was negatively correlated with sCr. Postoperatively, donor uNGAL remained higher than preoperatively for up to 6 months but was significantly lower than in patients with medical CKD with similar glomerular filtration rates.

CONCLUSION

Acute kidney injury due to hyperfiltration of remnant kidney after donor nephrectomy was maximal within 1-2 days postoperatively. The rise in uNGAL during this period in donors was negatively correlated with postoperative sCr levels. Decreased renal function after nephrectomy differs from that of medical CKD.

Clinical Investigation Into Plasma Neutrophil Gelatinase-Associated Lipocalin and Body Adipose Tissue Associated With Remaining Renal Function in Living Kidney Donor

OBJECTIVE

Plasma neutrophil gelatinase-associated lipocalin (pNGAL) is known to increase in proportion to the degree and period of renal damage. This study aimed to evaluate the clinical relevance of pNGAL and body adipose tissue to remaining renal function in living kidney donors.

METHODS

Between July 2013 and February 2015, 75 live kidney donors were enrolled. Visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and VAT/SAT ratio were measured in preoperative CT scan which performed before surgery. We analyzed the correlation among the variables (VAT, SAT, and VAT/SAT ratio), eGFR and pNGAL. ΔpNGAL-max(=Maximum pNGAL-measures), ΔpNGAL-min(=Minimum pNGAL-measures), ΔeGFR-max(=Maximum eGFR-measures) and ΔeGFR-min(=Minimum eGFR-measures) were also analyzed.

RESULTS

The highest value of pNGAL (207.46 ± 76 ng/mL) was observed on postoperative day 7, and the lowest value of eGFR (57.52 ± 11.20 mL/min/1.73 m²) was also measured on postoperative day 7. A significant correlation was found between ΔpNGAL, VAT, and VAT-to-SAT ratio. Moreover, a significant correlation between ΔpNGALmin and ΔeGFRmin was revealed. Also, VAT-to-SAT ratio was correlated with ΔeGFRmin during the all of the follow-up periods, and it was also correlated with ΔpNGALmin until postoperative day 3.

CONCLUSION

There was a correlation between the elevation of pNGAL until postoperative day 5 and the decrease of eGFR after living donor nephrectomy. VAT-to-SAT ratio had a significant correlation with both ΔpNGALmin and eGFRmin. Given the metabolism of pNGAL, the increase of pNGAL seemed to be affected as a consequence of body adipose tissue.

A comparison of the effects of oral vs. intravenous hydration on subclinical acute kidney injury in living kidney donors: a protocol of a randomised controlled trial

BACKGROUND

Optimal treatment for established renal failure is living donor kidney transplantation. However this pathway exposes healthy individuals to significant reduction in nephron mass via major surgical procedure. Laparoscopic donor nephrectomy is now the most common method for live donor transplantation, reducing both donor post-operative pain and recovery time. However this procedure exposes kidneys to additional haemodynamic stresses. It has been suggested that donor hydration-particularly the use of preoperative intravenous fluids-may counteract these stresses, reducing subclinical acute kidney injury and ultimately improving long-term renal function. This may be important in both preservation of donor renal function and recipient graft longevity.

METHODS/DESIGN

A prospective single-centre single-blinded randomized controlled trial will be carried out to determine the effects of donor preoperative intravenous fluids. The primary outcome is donor subclinical acute kidney injury (defined as plasma NGAL, >153 ng/ml) on day 1 postoperatively. Secondary outcomes include intraoperative haemodynamics, recipient subclinical acute kidney injury, perioperative complications and donor sleep quality. Donors will be randomised into two groups: the intervention group will receive active pre-hydration consisting of three litres of intravenous Hartmann's solution between midnight and 8 am before morning kidney donation, while the control group will not receive this. Both groups will receive unlimited oral fluids until midnight, as is routine. Plasma NGAL will be measured at pre-specified perioperative time points, intraoperative haemodynamic data will be collected using non-invasive cardiac output monitoring and clinical notes will be used to obtain demographic and clinical data. The researcher will be blinded to the donor fluid hydration status. Blinded statistical analysis will be performed on an intention-to-treat basis. A prospective power calculation estimates a required sample size of 86 patients.

DISCUSSION

This study will provide important data, as there is currently little evidence about the use of donor preoperative fluids in laparoscopic nephrectomy. It is hoped that the results obtained will guide future clinical practice.

TRIAL REGISTRATION

This study has been approved by the West of Scotland Research Ethics Committee 3 (reference no. 14/WS/1160, 27 January 2015) and is registered with the International Standard Randomised Controlled Trial Number Register (reference no. ISRCTN10199225 , 20 April 2015).

Neutrophil Gelatinase-Associated Lipocalin, Fibroblast Growth Factor 23, and Soluble Klotho in Long-Term Kidney Donors

Background

The best treatment for end-stage renal disease (ESRD) is kidney transplantation. Twenty-seven percent of transplantations in Norway are from living donors. Recent studies have shown an increased risk of ESRD and increased mortality in donors. The aim of this study was to determine if the levels of the new biomarkers neutrophil gelatinase-associated lipocalin (NGAL), soluble Klotho (sKlotho), and fibroblast growth factor 23 (FGF23) are changed in kidney donors with normal kidney function defined as an estimated glomerular filtration rate (eGFR) >60 ml/min/1.73 m² compared to patients with chronic kidney disease (CKD) stages 3-5 and healthy controls.

Methods

This is a cross-sectional, observational, single-center study including 35 kidney donors with an eGFR ≥60 ml/min/1.73 m² 5 years after donation, 22 patients with CKD stage 3 (eGFR 30-59 ml/min/1.73 m²), 18 patients with CKD stage 4 (eGFR 15-29 ml/min/1.73 m²), 20 patients with CKD stage 5 (eGFR <15 ml/min/1.73 m²), and 35 controls comparing levels of biomarkers in long-term kidney donors with those in CKD patients and healthy controls.

Results

The level of log NGAL was significantly higher in donors than in healthy controls (2.02 ± 0.10 vs. 1.89 ± 0.10 ng/ml; p < 0.001), and the level increased with declining kidney function. The log FGF23 level was nonsignificantly higher in donors than in controls, but it significantly increased with declining kidney function. The log sKlotho levels were significantly lower in patients with CKD stages 4 and 5 than in controls, but no difference was revealed between controls and donors.

Conclusion

Kidney donors have significantly higher levels of NGAL than healthy controls after a median of 15 years (range 5-38). NGAL could be a valuable diagnostic marker in the future. FGF23 and sKlotho were not significantly different between donors and controls.