Objectives: Kidney transplant is the treatment of choice in patients with end-stage renal disease because it offers improved survival and better quality of life. Although most epidemiologic studies have suggested that living kidney donors have a minimal lifetime risk of developing end-stage renal disease, long-term complications and physiologic and psychologic sequelae resulting from donation remain unclear. Here, we examined the long-term results of living-related kidney donors who donated kidneys at the Başkent University Ankara Hospital over the past 25 years.
Materials and Methods: We were able to examine 607 kidney transplant donors (mean age of 52.03 ± 11.54 years) who were seen at our center from 1986 to 2021 and who agreed to a general health evaluation. Collected data included donor age, sex, blood type, body mass index, duration after donation, blood pressure measurements, biochemical parameters, abdominal ultrasonograph for size, structure, and renal blood flow of the solitary kidney, comorbid conditions, chronic drug use, and surgical procedures after donation.
Results: Mean time after donation was 10.4 ± 3.2 years. Twenty-four donors (3.9%) were diagnosed with diabetes and 21 (3.4%) with thyroid disease, 64 (10.5%) developed hypertension, and 48 (8.8%) developed atherosclerotic cardiovascular disease. Obesity was found to be an increasing problem in our donor population, with 174 (28.6%) developing mild to moderate obesity (body mass index >25 kg/m2). Older age, obesity, smoking, and hyperlipidemia were found to be the major and independent risk factors of both hypertension and atherosclerotic cardiovascular disease in donors. None of our donors developed end-stage renal disease.
Conclusions: Obesity and hypertension were the most common comorbidities that developed in our kidney donor population. Our principle is to avoid unrelated and nondirected donors because of the possible long-term complications. Unrelated donors may be desperate if a family member needs donation in the future.
Key words : Biochemical parameters, Complications, Kidney transplant, Relativeness, Ultrasound
Kidney transplant is the treatment of choice for patients with end-stage renal disease, with an expectancy of improved survival and better quality of life.1 However, the number of deceased donors is inadequate to supply the increasing number of patients with end-stage renal disease. This has resulted in a globally increasing number of living kidney donors.2 Since 2019, due to the COVID 19 pandemic, living donor transplant rates have increased up to 80%. Most epidemiologic studies have suggested that living kidney donors have a minimal lifetime risk of developing end-stage renal disease; however, long-term complications after donation are still unclear because of the lack of optimum follow-up of donors after kidney transplant.3-8 In this study, we aimed to determine the long-term outcomes of living related kidney donors who donated kidneys at the Başkent University Ankara Hospital over the past 25 years.
Materials and Methods
Our team performed the first living related kidney transplant in Turkey in November 1975, the first deceased donor kidney transplant in Turkey in October 1978, and the first local deceased donor kidney transplant in Turkey in July 1979. In May 1992, our team performed a combined liver-kidney transplant procedure from a living related donor, which was the first operation of its kind anywhere in the world. Since 1986, our center at Başkent University has performed 2188 kidney transplants, and 1788 of these were living related kidney transplants.9
Before donation, all donor candidates were evaluated according to the Başkent University donor evaluation criteria. This evaluation criteria allows up to fourth-degree relatives (Table 1), estimated glomerular filtration rate (eGFR) of higher than 100 mL/min, and no coexisting morbidities. Donors undergo 24-hour urine collection to evaluate creatinine clearance and microalbuminuria/proteinuria; viral serologies for hepatitis, cytomegalovirus, and HIV; routine biochemical measurements and lipid profile; and thyroid and abdominal ultrasonography, renal scintography, and renal computerized tomography with renal angiography. Before donation, all donor candidates are evaluated for cardiology and pulmonary diseases, infectious diseases, psychiatry, dentistry, and gynecology (for female donors) conditions.10
For this study, we were able to reach 607 of 2188 donors. A questionnaire was given to all patients who could be reached, and clinical examinations, routine blood tests, and abdominal ultrasonography evaluations were performed for patients who came to the outpatient clinic.
We collected data on donor age, sex, body mass index, smoking status, hypertension after nephrectomy, presence of proteinuria, eGFR according to the Modification of Diet in Renal Disease formula, and duration after donation. Hypertension was defined as systolic blood pressure >140 mm Hg, diastolic blood pressure >90 mm Hg, or the use of antihypertensive medications. Donor proteinuria was established by dipstick test and confirmed by spot urine proteinuria-to-creatinine ratio.
We evaluated the long-term results of 607 patients: 179 (29.4%) of the patients were men and 428 (70.6%) were women. The mean age of the donors was 52.03 ± 11.54 years. Mean time after donation was 10.4 ± 3.2 years.
In our donor group, eGFR was 77 ± 16 mL/min. None of our donors developed end-stage renal disease during follow-up. Twenty-four donors (3.9%) were diagnosed with diabetes, 21 donors (3.4%) were diagnosed with thyroid disease, 64 donors (10.5%) developed hypertension, and 48 donors (8.8%) developed atherosclerotic cardiovascular disease. In our donor group, 174 donors (28.6%) developed mild to moderate obesity with a body mass index higher than 25 kg/m2. Only 5 patients developed a malignancy, and all of these donors were diagnosed with malignancy at least 10 years after donation (Table 2).
We evaluated 607 living related kidney transplant donors with ultrasonography scans, biochemical tests, evaluation of spot urine protein-to-creatinine ratio, and a questionnaire. Complication rates in our donor group seemed to be low. This may be because we have very strict donor criteria in our center. We never accept a donor who has a creatinine clearance lower than 100 mL/min according to 24-hour urine collection. We also do not accept donors who are more than a fourth-degree relative of the recipient. We consider that candidates who are unrelated may be desperate for not being a donor to a family member.10-12
We also do not accept any donor candidate who is diagnosed with hypertension even if the donor has normal blood pressure measurements under antihypertensive drugs.13 Diabetes is also our red line to accept a candidate to be donor. We believe that the strict donor criteria of Başkent University is the main reason for our low complication rates in donors after multiple years of follow-up.
The eGFR of 77 mL/min after donation with no coexisting proteinuria seems to be understandable because we perform a diethylene triamine penta-acetate scintigraphy in all donor candidates prior to transplant. We always prefer a kidney with lower clearance according to scintigraphic measurements.
The most common complication in our donor population was mild to moderate obesity with a body mass index higher than 25 kg/m2. No doubt, weight gain commonly accompanies aging.13 On the other hand, the relief of being a donor may be a risk factor for overt weight gain that may result in obesity. A combined diet and exercise program could be given to kidney donors to prevent obesity similar to that used for our kidney transplant recipients after transplant.14
In the ultrasonographic evaluations of donors, we observed compensatory hypertrophy of the solitary kidney as expected. No other pathology was detected except mild hepato-steatosis in obese donors. None of our donors showed progression to end-stage renal disease, and this is a result that we also attributed to our strict donor criteria.
The definitive treatment of end-stage renal disease is kidney transplant. To increase the donor pool, living related kidney transplant is the most preferred method all over the world. In our study, however, we found that 174 donors (28.6%) developed obesity, which can increase the risk of systemic disease. During our long-term follow-up period, 162 donors (26.6%) developed systemic diseases. We also must keep in mind that unrelated donors may be desperate if a family member needs an organ donation in the future. Therefore, we recommend that deceased donor kidney transplant should be the first choice. If a deceased donor is not available, living related kidney transplant should be preferred.
Volume : 20
Issue : 3
Pages : 17 - 19
DOI : 10.6002/ect.MESOT2021.O4
From the 1Department of Nephrology and the 2Department of General Surgery, Başkent University Faculty of Medicine, Ankara, Turkey
Acknowledgements: The authors have not received any funding or grants in support of the presented research or for the preparation of this work and have no declarations of potential conflicts of interest.
Corresponding author: Burak Sayin, Yukarı Bahçelievler mahallesi 54, Cadde No: 70-72 E Blok Transplantasyon Bölümü E Blok 5, Kat Bahçelievler, Çankaya, Ankara, Turkey
Phone: +90 312 2036868-2006
Table 1. Degree of the Relation Between Living Kidney Donor and Transplant Recipients
Table 2. Demographics of Kidney Donors in Long-Term Follow-Up