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.