Do Living Kidney Donors Have CKD?
2012; Elsevier BV; Volume: 19; Issue: 4 Linguagem: Inglês
10.1053/j.ackd.2012.05.008
ISSN1548-5609
AutoresTitte R. Srinivas, Emilio D. Poggio,
Tópico(s)Renal and Vascular Pathologies
ResumoLiving kidney donor transplantation is an increasingly used treatment for end-stage renal disease because it both confers excellent outcomes to transplant recipients, and is considered a safe procedure for prospective donors. The short- and long-term safety of prospective donors is paramount to the continued success of living donation. Although the initial experience with living kidney donors mostly included the healthiest donors, increasing need for organs and secular trends in the general population have subtly reshaped prevailing suitability criteria for donation. As the practice of living donation evolved over time, our understanding of kidney disease has also changed as we embraced the framework of the K-DOQI guidelines. It is not uncommon for donors to fit into some of the K-DOQI guidelines paradigms of risk and disease; however, whether there is a true biological consequence or whether it is a merely semantic conundrum remains unclear. Regardless, this is an important issue, and therefore future efforts should aim at addressing this matter. Living kidney donor transplantation is an increasingly used treatment for end-stage renal disease because it both confers excellent outcomes to transplant recipients, and is considered a safe procedure for prospective donors. The short- and long-term safety of prospective donors is paramount to the continued success of living donation. Although the initial experience with living kidney donors mostly included the healthiest donors, increasing need for organs and secular trends in the general population have subtly reshaped prevailing suitability criteria for donation. As the practice of living donation evolved over time, our understanding of kidney disease has also changed as we embraced the framework of the K-DOQI guidelines. It is not uncommon for donors to fit into some of the K-DOQI guidelines paradigms of risk and disease; however, whether there is a true biological consequence or whether it is a merely semantic conundrum remains unclear. Regardless, this is an important issue, and therefore future efforts should aim at addressing this matter. Clinical Summary•Kidney function assessment is a critical aspect of the donor evaluation process, but the obtained information should always be interpreted in the context of other clinical and laboratory data. This is also true when assessing kidney function post-donation.•Kidney donors have an obligate numerical reduction in glomerular filtration rate that rarely progresses to ESRD. In the absence of progressive renal dysfunction, proteinuria or hypertension, this mere reduction in GFR among living kidney donors should not be interpreted as connoting CKD.•Registry data have shown that even among groups at high risk for kidney disease such as African Americans, ESRD rates among former living donors is no higher than that observed in the general population. Unfortunately, outcomes data are obtained from retrospective studies, studies with no appropriate controls, and registry studies.•Future studies of living donor outcomes should include prospective follow up of former donors with capture of biologically relevant measures of cardiovascular, metabolic, and renal parameters. •Kidney function assessment is a critical aspect of the donor evaluation process, but the obtained information should always be interpreted in the context of other clinical and laboratory data. This is also true when assessing kidney function post-donation.•Kidney donors have an obligate numerical reduction in glomerular filtration rate that rarely progresses to ESRD. In the absence of progressive renal dysfunction, proteinuria or hypertension, this mere reduction in GFR among living kidney donors should not be interpreted as connoting CKD.•Registry data have shown that even among groups at high risk for kidney disease such as African Americans, ESRD rates among former living donors is no higher than that observed in the general population. Unfortunately, outcomes data are obtained from retrospective studies, studies with no appropriate controls, and registry studies.•Future studies of living donor outcomes should include prospective follow up of former donors with capture of biologically relevant measures of cardiovascular, metabolic, and renal parameters. Living kidney donation allows for a planned transplantation process and provides better clinical outcomes when compared with those of deceased donors. The continuously increasing demand for organs and the changing demographics of the living kidney donor population have been subtly reshaping concepts of donor suitability, with more lenient clinical criteria of acceptance.1Davis C.L. Delmonico F.L. Living-donor kidney transplantation: a review of the current practices for the live donor.J Am Soc Nephrol. 2005; 16: 2098-2110Crossref PubMed Scopus (270) Google Scholar, 2Delmonico F.L. Dew M.A. Living donor kidney transplantation in a global environment.Kidney Int. 2007; 71: 608-614Crossref PubMed Scopus (53) Google Scholar, 3Hariharan S. Johnson C.P. Bresnahan B.A. Taranto S.E. McIntosh M.J. Stablein D. Improved graft survival after renal transplantation in the United States, 1988 to 1996.N Engl J Med. 2000; 342: 605-612Crossref PubMed Scopus (1629) Google Scholar, 4Delmonico F. A report of the Amsterdam forum on the care of the live kidney donor: data and medical guidelines.Transplantation. 2005; 79: S53-S66PubMed Google Scholar Three current issues for living donors are their increasing age at donation, selected acceptance with isolated medical abnormalities, and renal function outcomes and consequences that may include CKD.5Young A. Storsley L. Garg A.X. et al.Health outcomes for living kidney donors with isolated medical abnormalities: a systematic review.Am J Transplant. 2008; 8: 1878-1890Crossref PubMed Scopus (85) Google Scholar Also of note is the increasing rate of living donation among African Americans, who in the general population are known to be at increased risk for hypertension, hypertensive nephrosclerosis, and ESRD.6Cherikh W.S. Young C.J. Kramer B. Taranto S. Randall H. Fan P.Y. Race and gender related differences in the risk of end stage renal disease after living kidney donation.Am J Transplant. 2011; 11: 1650-1655Crossref PubMed Scopus (95) Google Scholar Furthermore, some renal transplantation programs allow selected hypertensive individuals to donate a kidney.7Textor S.C. Taler S.J. Driscoll N. et al.Blood pressure and renal function after kidney donation from hypertensive living donors.Transplantation. 2004; 78: 276-282Crossref PubMed Scopus (147) Google Scholar Given these developments, accurate assessment of kidney function in the living donor is critical, with the need to (1) establish an appropriate threshold for acceptance of a donor and (2) determine long-term functional outcomes. An unintended consequence of living kidney donation could be having a donor being labeled with stage 3 CKD according to current recommendations by the NKF.8National Kidney Foundation K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Kidney Disease Outcome Quality Initiative.Am J Kidney Dis. 2002; 39: S1-S246PubMed Google Scholar, 9Levey A.S. Eckardt K.U. Tsukamoto Y. et al.Definition and classification of chronic kidney disease: a position statement from kidney disease: improving global outcomes (KDIGO).Kidney Int. 2005; 67: 2089-2100Crossref PubMed Scopus (2539) Google Scholar However, the correct interpretation of the direct applicability of this staging among former living donors is debatable, and it is being challenged.10Poggio E.D. Rule A.D. A critical evaluation of chronic kidney disease—should isolated reduced estimated glomerular filtration rate be considered a 'disease'?.Nephrol Dial Transplant. 2009; 24: 698-700Crossref PubMed Scopus (49) Google Scholar, 11Winearls C.G. Glassock R.J. Dissecting and refining the staging of chronic kidney disease.Kidney Int. 2009; 75: 1009-1014Crossref PubMed Scopus (89) Google Scholar, 12Glassock R.J. Winearls C. The global burden of chronic kidney disease: how valid are the estimates?.Nephron Clin Pract. 2008; 110 (discussion c47): c39-c46Crossref PubMed Scopus (50) Google Scholar, 13Glassock R.J. Winearls C. Screening for CKD with eGFR: doubts and dangers.Clin J Am Soc Nephrol. 2008; 3: 1563-1568Crossref PubMed Scopus (153) Google Scholar, 14Barri Y. Parker 3rd, T. Kaplan B. Glassock R. Primum non nocere: is chronic kidney disease staging appropriate in living kidney transplant donors?.Am J Transplant. 2009; 9: 657-660Crossref PubMed Scopus (24) Google Scholar Unlike any other situation in the practice of medicine, living kidney donors undergo extensive evaluation, with the express and central goal of confirming suspected health instead of suspected disease. Because living donation is an elective procedure, with no direct physical benefit to the donor, it is essential that the evaluation process carefully assess predonation kidney function taking into perspective the factors that may potentially affect postnephrectomy glomerular filtration rate (GFR). Interpreting whether predonation GFR will adequately provide sufficient and acceptable residual postnephrectomy GFR to the donor and sufficient GFR to the recipient is challenging but crucial to a successful transplant procedure. According to current recommendations, living donors should have a GFR of ≥80 mL/min or, alternatively, a kidney function level within 2 standard deviations of normal for age and gender.1Davis C.L. Delmonico F.L. Living-donor kidney transplantation: a review of the current practices for the live donor.J Am Soc Nephrol. 2005; 16: 2098-2110Crossref PubMed Scopus (270) Google Scholar, 2Delmonico F.L. Dew M.A. Living donor kidney transplantation in a global environment.Kidney Int. 2007; 71: 608-614Crossref PubMed Scopus (53) Google Scholar, 4Delmonico F. A report of the Amsterdam forum on the care of the live kidney donor: data and medical guidelines.Transplantation. 2005; 79: S53-S66PubMed Google Scholar Although these recommendations do not clearly specify the method for renal function assessment, most centers perform this critical step using timed urine collections for creatinine clearance. Others rely on more precise and accurate techniques, such as exogenous marker clearances. Nevertheless, no standardized reference values exist for each of the procedures used in clinical practice. Thus, the decision of proceeding (or not) with donation is unfortunately often a matter of subjective interpretation rather than more precise science. Because of the emphasis placed by the NKF on GFR to determine the state of renal health versus disease, renal function assumes an even greater role in understanding living donor outcomes. Traditionally, GFR has been considered the best overall marker of kidney function.15Levey A.S. Measurement of renal function in chronic renal disease.Kidney Int. 1990; 38: 167-184Crossref PubMed Scopus (477) Google Scholar In clinical practice, other than living kidney donor evaluation, GFR is commonly inferred by either the interpretation of serum creatinine levels or by the use of creatinine-based GFR estimation equations.8National Kidney Foundation K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Kidney Disease Outcome Quality Initiative.Am J Kidney Dis. 2002; 39: S1-S246PubMed Google Scholar, 16Levey A.S. Coresh J. Greene T. et al.Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate.Ann Intern Med. 2006; 145: 247-254Crossref PubMed Scopus (4128) Google Scholar, 17Levey A.S. Stevens L.A. Schmid C.H. et al.A new equation to estimate glomerular filtration rate.Ann Intern Med. 2009; 150: 604-612Crossref PubMed Scopus (16177) Google Scholar It is clear that the creatinine-based GFR estimation equations are not acceptable in the setting of living donor evaluation, mostly because a significant percentage of kidney function needs to be lost before there is a corresponding change in serum creatinine level. However, although serum creatinine alone is not a sensitive marker of kidney dysfunction, it is a specific marker of kidney disease.18Rule A.D. Rodeheffer R.J. Larson T.S. et al.Limitations of estimating glomerular filtration rate from serum creatinine in the general population.Mayo Clin Proc. 2006; 81: 1427-1434Abstract Full Text Full Text PDF PubMed Scopus (73) Google Scholar For example, if a prospective donor has a serum creatinine level elevated more than normal values during the evaluation process, he/she is likely to have kidney disease, and therefore the serum creatinine could be used for initial screening of interested prospective donors. The urine creatinine clearance has traditionally been the method of choice to study kidney function in potential donors. Two clearances are usually done to minimize methodological errors. Although the creatinine clearance always overestimates true GFR because of the tubular secretion of creatinine, in conjunction with a comprehensive laboratory and medical evaluation, this method has become the “standard of care” across most transplant centers mostly owing to the lack of a better alternative. This is a good approach as long as the clinician keeps in mind the common potential limitations of this test: (1) it is reliable only when done properly, (2) it overestimates GFR by an unpredictable percentage, and (3) it is not usually interpreted in the context of age- and gender-specific reference values. To exemplify each of these points, consider a potential kidney donor who has 2 urinary creatinine clearance rates (point 1) that average to 87 mL/min and allow donation. This average creatinine clearance may actually reflect a GFR of >80 mL/min/1.73 m2 (point 2). Although this value may be normal for a 55-year-old female donor, it may not be for a 25-year-old male donor (point 3). Therefore, extreme caution should be exercised with this approach. Assessment of GFR by clearances of exogenous markers is the “gold standard” approach. Their use in living kidney donors could be considered one of the most clinically valuable applications of these methods.19Eshima D. Taylor A. Technetium-99m (99mTc) mercaptoacetyltriglycine: update on the new 99mTc renal tubular function agent.Semin Nucl Med. 1992; 22: 61-73Abstract Full Text PDF PubMed Scopus (117) Google Scholar, 20Agarwal R. Ambulatory GFR measurement with cold iothalamate in adults with chronic kidney disease.Am J Kidney Dis. 2003; 41: 752-759Abstract Full Text Full Text PDF PubMed Scopus (34) Google Scholar However, these methods are also not exempt from methodological variability and are expensive, but they are more consistent and reliable. Currently, donor renal function is often evaluated without taking into consideration age- and gender-specific reference values, with the result that any value >80 mL/min/1.73 m2 is generally considered appropriate for proceeding with donation. Although long-term follow-up has demonstrated that former kidney donors have similar or better life expectancy and lower risk of ESRD than the general population,21Fehrman-Ekholm I. Elinder C.G. Stenbeck M. Tyden G. Groth C.G. Kidney donors live longer.Transplantation. 1997; 64: 976-978Crossref PubMed Scopus (329) Google Scholar, 22Fehrman-Ekholm I. Norden G. Lennerling A. et al.Incidence of end-stage renal disease among live kidney donors.Transplantation. 2006; 82: 1646-1648Crossref PubMed Scopus (133) Google Scholar, 23Ibrahim H.N. Foley R. Tan L. et al.Long-term consequences of kidney donation.N Engl J Med. 2009; 360: 459-469Crossref PubMed Scopus (823) Google Scholar a small number of kidney donors have developed the need for renal replacement therapy.24Ellison M.D. McBride M.A. Taranto S.E. Delmonico F.L. Kauffman H.M. Living kidney donors in need of kidney transplants: a report from the organ procurement and transplantation network.Transplantation. 2002; 74: 1349-1351Crossref PubMed Scopus (160) Google Scholar This outcome might be unavoidable in some because of new and unpredictable kidney disease; however, it is not clear whether subjects with prenephrectomy GFR >80 mL/min/1.73 m2, but in the lower percentiles of normal based on age and gender reference values (ie, abnormal or suboptimal), are indeed at higher risk for poor renal outcomes. Donor nephrectomy represents the abrupt loss of approximately 50% of nephron mass, with an immediate and corresponding decrease in GFR. However, the remaining contralateral healthy renal parenchyma has the ability to recover a significant percentage of lost function within a relatively short time. Several investigators have shown that in healthy individuals, unilateral nephrectomy is followed by a compensatory increase in functional capacity of the contralateral kidney by approximately 20% to 40%.25Boner G. Shelp W.D. Newton M. Rieselbach R.E. Factors influencing the increase in glomerular filtration rate in the remaining kidney of transplant donors.Am J Med. 1973; 55: 169-174Abstract Full Text PDF PubMed Scopus (62) Google Scholar, 26Edgren J. Laasonen L. Kock B. Brotherus J.W. Pasternack A. Kuhlback B. Kidney function and compensatory growth of the kidney in living kidney donors.Scand J Urol Nephrol. 1976; 10: 134-136Crossref PubMed Scopus (35) Google Scholar, 27Saxena A.B. Myers B.D. Derby G. et al.Adaptive hyperfiltration in the aging kidney after contralateral nephrectomy.Am J Physiol Renal Physiol. 2006; 291: F629-F634Crossref PubMed Scopus (45) Google Scholar, 28Velosa J.A. Offord K.P. Schroeder D.R. Effect of age, sex, and glomerular filtration rate on renal function outcome of living kidney donors.Transplantation. 1995; 60: 1618-1621PubMed Google Scholar, 29Poggio E.D. Braun W.E. Davis C. The science of stewardship: due diligence for kidney donors and kidney function in living kidney donation—evaluation, determinants, and implications for outcomes.Clin J Am Soc Nephrol. 2009; 4: 1677-1684Crossref PubMed Scopus (35) Google Scholar Velosa and colleagues,28Velosa J.A. Offord K.P. Schroeder D.R. Effect of age, sex, and glomerular filtration rate on renal function outcome of living kidney donors.Transplantation. 1995; 60: 1618-1621PubMed Google Scholar among others, showed that as early as 1 week after nephrectomy, renal function has recovered to levels slightly lower than those achieved at 6 months after nephrectomy. Similarly, others showed that the GFR at 1 year after donation was essentially the same or slightly improved from the one achieved as early as 1 week after donation.25Boner G. Shelp W.D. Newton M. Rieselbach R.E. Factors influencing the increase in glomerular filtration rate in the remaining kidney of transplant donors.Am J Med. 1973; 55: 169-174Abstract Full Text PDF PubMed Scopus (62) Google Scholar, 30Bock H.A. Bachofen M. Landmann J. Thiel G. Glomerular hyperfiltration after unilateral nephrectomy in living kidney donors.Transpl Int. 1992; 5: S156-S159PubMed Google Scholar The mechanisms underlying this “adaptive hyperfiltration” are complex and likely determined by several factors.27Saxena A.B. Myers B.D. Derby G. et al.Adaptive hyperfiltration in the aging kidney after contralateral nephrectomy.Am J Physiol Renal Physiol. 2006; 291: F629-F634Crossref PubMed Scopus (45) Google Scholar Demographic and anthropometric factors associated with GFR compensation after nephrectomy include age, gender, race, and body size. The relationship between GFR and aging has been a matter of investigation. Although an invariable decrement in GFR occurs as humans age, when exactly this physiological process becomes a pathological one is debatable.27Saxena A.B. Myers B.D. Derby G. et al.Adaptive hyperfiltration in the aging kidney after contralateral nephrectomy.Am J Physiol Renal Physiol. 2006; 291: F629-F634Crossref PubMed Scopus (45) Google Scholar, 31Davies D.F. Shock N.W. Age changes in glomerular filtration rate, effective renal plasma flow, and tubular excretory capacity in adult males.J Clin Invest. 1950; 29: 496-507Crossref PubMed Scopus (812) Google Scholar, 32Fehrman-Ekholm I. Skeppholm L. Renal function in the elderly (>70 years old) measured by means of iohexol clearance, serum creatinine, serum urea and estimated clearance.Scand J Urol Nephrol. 2004; 38: 73-77Crossref PubMed Scopus (158) Google Scholar, 33Granerus G. Aurell M. Reference values for 51Cr-EDTA clearance as a measure of glomerular filtration rate.Scand J Clin Lab Invest. 1981; 41: 611-616Crossref PubMed Scopus (212) Google Scholar, 34Poggio E.D. Rule A.D. Tanchanco R. et al.Demographic and clinical characteristics associated with glomerular filtration rates in living kidney donors.Kidney Int. 2009; 75: 1079-1087Crossref PubMed Scopus (143) Google Scholar Several investigators hypothesized that kidneys from older donors could have a decreased “renal reserve capacity” that would manifest as impaired kidney function after donation. Studies by Velosa and colleagues as well as by Saxena and colleagues, among others, showed that although aging subjects have a lower baseline GFRs, they do not necessarily lose the adaptive hyperfiltration capability. Furthermore, postnephrectomy GFR appears to depend mostly on the prenephrectomy GFR.27Saxena A.B. Myers B.D. Derby G. et al.Adaptive hyperfiltration in the aging kidney after contralateral nephrectomy.Am J Physiol Renal Physiol. 2006; 291: F629-F634Crossref PubMed Scopus (45) Google Scholar, 28Velosa J.A. Offord K.P. Schroeder D.R. Effect of age, sex, and glomerular filtration rate on renal function outcome of living kidney donors.Transplantation. 1995; 60: 1618-1621PubMed Google Scholar Using a different approach, Rook and colleagues35Rook M. Bosma R.J. van Son W.J. et al.Nephrectomy elicits impact of age and BMI on renal hemodynamics: lower postdonation reserve capacity in older or overweight kidney donors.Am J Transplant. 2008; 8: 2077-2085Crossref PubMed Scopus (71) Google Scholar, 36ter Wee P.M. Tegzess A.M. Donker A.J. Pair-tested renal reserve filtration capacity in kidney recipients and their donors.J Am Soc Nephrol. 1994; 4: 1798-1808PubMed Google Scholar reported that although the postnephrectomy GFR may not be affected by age, the postnephrectomy “reserve capacity” of the remaining kidney was significantly impaired in older and heavier donors. Reported ranges of induced renal hyperfiltration in non-nephrectomized healthy subjects vary between 20% and 35% of basal values.29Poggio E.D. Braun W.E. Davis C. The science of stewardship: due diligence for kidney donors and kidney function in living kidney donation—evaluation, determinants, and implications for outcomes.Clin J Am Soc Nephrol. 2009; 4: 1677-1684Crossref PubMed Scopus (35) Google Scholar Humans may lose renal reserve as they age because of nephron loss possibly secondary to glomerulosclerosis and/or renal microvascular disease.37Fuiano G. Sund S. Mazza G. et al.Renal hemodynamic response to maximal vasodilating stimulus in healthy older subjects.Kidney Int. 2001; 59: 1052-1058Crossref PubMed Scopus (128) Google Scholar Rule and colleagues38Rule A.D. Amer H. Cornell L.D. et al.The association between age and nephrosclerosis on renal biopsy among healthy adults.Ann Intern Med. 2010; 152: 561-567Crossref PubMed Scopus (329) Google Scholar showed that glomerulosclerosis prevalence increases with age from approximately 2.7% for donors younger than 30 years to up to 58% for donors aged 60 years; however, these findings were not associated with declining GFR in the entire cohort. Finally, because of the wider acceptance of living donation among various races and cultures, the current living donor population is also becoming more multiracial.6Cherikh W.S. Young C.J. Kramer B. Taranto S. Randall H. Fan P.Y. Race and gender related differences in the risk of end stage renal disease after living kidney donation.Am J Transplant. 2011; 11: 1650-1655Crossref PubMed Scopus (95) Google Scholar The effects of race on GFR are not very clear because most reports described Caucasian populations. In our own experience, African Americans have comparable levels of GFR and age-associated rates of GFR decline when compared with non–African Americans.34Poggio E.D. Rule A.D. Tanchanco R. et al.Demographic and clinical characteristics associated with glomerular filtration rates in living kidney donors.Kidney Int. 2009; 75: 1079-1087Crossref PubMed Scopus (143) Google Scholar Donors of Asian Indian background have lower levels of GFR, but they maintain induced hyperfiltration rates similar to those observed in Caucasians.39Barai S. Bandopadhayaya G.P. Patel C.D. et al.Do healthy potential kidney donors in India have an average glomerular filtration rate of 81.4 mL/min?.Nephron. 2005; 101: p21-p26Crossref PubMed Scopus (42) Google Scholar, 40Barai S. Gambhir S. Prasad N. et al.Levels of GFR and protein-induced hyperfiltration in kidney donors: a single-center experience in India.Am J Kidney Dis. 2008; 51: 407-414Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar, 41Mahajan S. Mukhiya G.K. Singh R. et al.Assessing glomerular filtration rate in healthy Indian adults: a comparison of various prediction equations.J Nephrol. 2005; 18: 257-261PubMed Google Scholar Further studies of kidney function in prospective kidney donors of other minorities and races are needed. During the past decade, the NKF has provided the framework for a new approach to the diagnosis, staging, and management of kidney disease. Estimation of GFR plays a pivotal role in not only defining but also staging kidney disease. However, the definition of kidney disease does not take into consideration either the underlying pathological process or the clinical context in which the GFR estimate is being obtained. Therefore, evidence of parenchymal kidney damage is not required to establish the diagnosis of stage 3 CKD as long as the eGFR is >60 mL/min/1.72 m2—a level that could commonly be found in former donors.42Ibrahim H.N. Rogers T. Tello A. Matas A. The performance of three serum creatinine-based formulas in estimating GFR in former kidney donors.Am J Transplant. 2006; 6: 1479-1485Crossref PubMed Scopus (63) Google Scholar, 43Barri YM, Parker T 3rd, Daoud Y, Glassock RJ. Definition of chronic kidney disease after uninephrectomy in living donors: what are the implications? Transplantation. 15; 90: 575–580.Google Scholar, 44Tent H. Rook M. Stevens L.A. et al.Renal function equations before and after living kidney donation: a within-individual comparison of performance at different levels of renal function.Clin J Am Soc Nephrol. 2010; 5: 1960-1968Crossref PubMed Scopus (70) Google Scholar Justification for using this cutoff value as the driver in establishing CKD is extracted from epidemiological data associating low GFR with increased cardiovascular and overall mortality.45Go A.S. Chertow G.M. Fan D. McCulloch C.E. Hsu C.Y. Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization.N Engl J Med. 2004; 351: 1296-1305Crossref PubMed Scopus (9047) Google Scholar Whether an isolated decreased GFR in an otherwise healthy subject (eg, former kidney donors) should be considered “chronic disease” remains a matter of debate.10Poggio E.D. Rule A.D. A critical evaluation of chronic kidney disease—should isolated reduced estimated glomerular filtration rate be considered a 'disease'?.Nephrol Dial Transplant. 2009; 24: 698-700Crossref PubMed Scopus (49) Google Scholar The question that the transplant community now faces is whether the current approach to CKD is applicable to living kidney donors. Prospective studies to specifically address this matter are not available yet, although single-center experiences with long-term follow-up indirectly provide reassuring results. The current diagnosis and classification of CKD require that GFR be estimated.16Levey A.S. Coresh J. Greene T. et al.Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate.Ann Intern Med. 2006; 145: 247-254Crossref PubMed Scopus (4128) Google Scholar Available models to estimate GFR (like the Modification of Diet in Renal Disease [MDRD] equation) have been developed from patients with established CKD, that is, subjects with an underlying renal pathological process. Kidney donors specifically evaluated to exclude any such pathologic process but now having just a single kidney could have eGFR levels >60 mL/min/1.73 m2. Based on GFR estimations, studies that used the MDRD equation found that the prevalence of CKD was common in kidney donors; however, the GFR was indeed higher when measured by an endogenous marker.42Ibrahim H.N. Rogers T. Tello A. Matas A. The performance of three serum creatinine-based formulas in estimating GFR in former kidney donors.Am J Transplant. 2006; 6: 1479-1485Crossref PubMed Scopus (63) Google Scholar, 43Barri YM, Parker T 3rd, Daoud Y, Glassock RJ. Definition of chronic kidney disease after uninephrectomy in living donors: what are the implications? Transplantation. 15; 90: 575–580.Google Scholar, 46Louvar D.W. Rogers T.B. Bailey R.F. Matas A.J. Ibrahim H.N. Cystatin C is not superior to creatinine-based models in estimating glomerular filtration rate in former kidney donors.Transplantation. 2007; 84: 1112-1117Crossref PubMed Scopus (14) Google Scholar In a recent study that used the CKD-EPI (EPI, epidemiology) equation, although better than the MDRD equation, this approach still showed that equations are suboptimal to estimate kidney function in this setting.44Tent H. Rook M. Stevens L.A. et al.Renal function equations before and after living kidney donation: a within-individual comparison of performance at different levels of renal function.Clin J Am Soc Nephrol. 2010; 5: 1960-1968Crossref PubMed Scopu
Referência(s)