Optimizing Evaluation of Split Renal Function in a Living Kidney Donor Using Scintigraphy and Calculation of the Geometric Mean: A Case Report
We report the case of a 28-year-old healthy male applying to donate a kidney to his 61-year-old father. Preliminary assessment showed no contraindications. The computed tomography (CT) angiogram performed showed 2 short renal veins and 2 arteries of the right kidney (fig. ). Due to the complex anatomy and consequently increased risks for the donor and recipient, a living kidney transplantation of the right kidney was not considered by mutual agreement. However, the left kidney had a relative function of 60% in conventional posterior Tc99m-mercaptoacetyltriglycin (MAG3) scintigraphy (fig. ), and MAG3 total clearance was in the lower normal range (242 ml/min/1.73 m2). Considering that the position of the kidney (e.g. malrotation) determines the activity measured, a second scintigraphy using anterior and posterior Tc99m-dimercaptosuccinic acid (DMSA) scans was performed. As expected, the posterior DMSA scan confirmed the results of the posterior MAG3 scan: left kidney 60%. In the additional anterior scan, however, the left kidney now had a relative function of only 46% (fig. ). Calculating the geometric mean (✓ a × p), the adapted relative function of the left kidney was 53%, now meeting the inclusion criteria for living kidney donation. Confirmatory, CT-based renal cortex volume calculation was almost the same on both sides (97.23 and 97.31 ml on the left and right, respectively). After extensive education of the donor and recipient, live donor transplantation was carried out without any intra- or postoperative complications. Postoperative renal function (eGFR) of the donor was 62.59 ml/min/1.73 m2 one week after transplantation (vs. 124.13 ml/min/1.73 m2 preoperatively). Serum creatinine levels of the donor and recipient were normal at the time of discharge. Six months after transplantation, the eGFR of the donor and recipient were 90.75 and 73.64 ml/min/1.73 m2, respectively.