Renal function studies after nephrectomy in renal donors

Surgical intervention and long-term renal outcomes of congenital ureteropelvic junction obstruction in a young adult cohort

PURPOSE

To evaluate the impact of surgical intervention on long-term renal outcomes for adult patients with congenital ureteropelvic junction obstruction (UPJO).

METHODS

We queried service members diagnosed with UPJO from the United States Military Health System electronic health records from 2005 to 2020. We assessed demographic, laboratory, radiology, surgical intervention, and outcome data. We evaluated the impact of surgical intervention on renal function based on the estimated glomerular filtration rate (eGFR), hypertension (HTN, defined as any prescription for blood pressure [BP] medication and/or average of two BP readings ≥ 130/80 mmHg more than 2 weeks apart), and changes in renal excretory function on radionuclide scans.

RESULTS

We identified 108 individuals diagnosed with congenital UPJO; mean follow-up of 7 years. Mean age at diagnosis was 25 years; 95% male; 69% White, 15% Black. At diagnosis, median BP was 130/78 mmHg and mean eGFR 93 ml/min/1.73m2. Subsequently, 85% had pyeloplasty and 23% had stent placement. There were no significant differences in mean eGFR pre- and post-intervention (94 vs. 93 ml/min/1.73m2, respectively; p = 0.15) and prevalence of defined HTN (59% vs. 61%, respectively; p = 0.20). Surgical intervention for right-sided UPJO significantly reduced the proportion of patients with delayed cortical excretion (54% pre vs. 35% post, p = 0.01) and T½ emptying time (35 min vs. 19 min, p = 0.009). Similar trends occurred with left-sided UPJO but were not significant.

CONCLUSION

Surgical intervention was not associated with significant differences in the long-term outcomes of kidney function and HTN prevalence in our young adult cohort. However, renal excretory function improved on radionuclide scans.

The Minnesota attributable risk of kidney donation (MARKD) study: a retrospective cohort study of long-term (> 50 year) outcomes after kidney donation compared to well-matched healthy controls

BACKGROUND

There is uncertainty about the long-term risks of living kidney donation. Well-designed studies with controls well-matched on risk factors for kidney disease are needed to understand the attributable risks of kidney donation.

METHODS

The goal of the Minnesota Attributable Risk of Kidney Donation (MARKD) study is to compare the long-term (> 50 years) outcomes of living donors (LDs) to contemporary and geographically similar controls that are well-matched on health status. University of Minnesota (n = 4022; 1st transplant: 1963) and Mayo Clinic LDs (n = 3035; 1st transplant: 1963) will be matched to Rochester Epidemiology Project (REP) controls (approximately 4 controls to 1 donor) on the basis of age, sex, and race/ethnicity. The REP controls are a well-defined population, with detailed medical record data linked between all providers in Olmsted and surrounding counties, that come from the same geographic region and era (early 1960s to present) as the donors. Controls will be carefully selected to have health status acceptable for donation on the index date (date their matched donor donated). Further refinement of the control group will include confirmed kidney health (e.g., normal serum creatinine and/or no proteinuria) and matching (on index date) of body mass index, smoking history, family history of chronic kidney disease, and blood pressure. Outcomes will be ascertained from national registries (National Death Index and United States Renal Data System) and a new survey administered to both donors and controls; the data will be supplemented by prior surveys and medical record review of donors and REP controls. The outcomes to be compared are all-cause mortality, end-stage kidney disease, cardiovascular disease and mortality, estimated glomerular filtration rate (eGFR) trajectory and chronic kidney disease, pregnancy risks, and development of diseases that frequently lead to chronic kidney disease (e.g. hypertension, diabetes, and obesity). We will additionally evaluate whether the risk of donation differs based on baseline characteristics.

DISCUSSION

Our study will provide a comprehensive assessment of long-term living donor risk to inform candidate living donors, and to inform the follow-up and care of current living donors.

Vitamin A metabolism is changed in donors after living-kidney transplantation: an observational study

Background

The kidneys are essential for the metabolism of vitamin A (retinol) and its transport proteins retinol-binding protein 4 (RBP4) and transthyretin. Little is known about changes in serum concentration after living donor kidney transplantation (LDKT) as a consequence of unilateral nephrectomy; although an association of these parameters with the risk of cardiovascular diseases and insulin resistance has been suggested. Therefore we analyzed the concentration of retinol, RBP4, apoRBP4 and transthyretin in serum of 20 living-kidney donors and respective recipients at baseline as well as 6 weeks and 6 months after LDKT.

Results

As a consequence of LDKT, the kidney function of recipients was improved while the kidney function of donors was moderately reduced within 6 weeks after LDKT. With regard to vitamin A metabolism, the recipients revealed higher levels of retinol, RBP4, transthyretin and apoRBP4 before LDKT in comparison to donors. After LDKT, the levels of all four parameters decreased in serum of the recipients, while retinol, RBP4 as well as apoRBP4 serum levels of donors increased and remained increased during the follow-up period of 6 months.

Conclusion

LDKT is generally regarded as beneficial for allograft recipients and not particularly detrimental for the donors. However, it could be demonstrated in this study that a moderate reduction of kidney function by unilateral nephrectomy, resulted in an imbalance of components of vitamin A metabolism with a significant increase of retinol and RBP4 and apoRBP4 concentration in serum of donors.

Nephropathy in remnant kidneys: pathological proteinuria after unilateral nephrectomy

It is a matter of dispute as to whether and to what extent hyperfiltrative nephropathy occurs in a contralateral remnant kidney after unilateral nephrectomy. This question was investigated in a retrospective progress observation using urinary electrophoresis among other methods. Of 106 patients who underwent nephrectomy between 1963 and 1984 because of unilateral kidney diseases, only 39 fulfilled all of the requisite criteria for a followup examination 2 to 23 years later. Whereas there was arterial hypertension or decreased kidney function in 4 cases (10.3%), pathological proteinuria was found in 32 of the remnant kidneys (82.1%): tubular in 13 (40.6%) and glomerular in 19 (59.4%). In contrast to that of arterial hypertension or decreased kidney function, this incidence is far greater than the expected risk in the normal population, which in our opinion indicates that hyperfiltrative nephropathy occurs in the contralateral remnant kidney after unilateral nephrectomy without causing relevant restriction of kidney function or increasing the arterial pressure.

Glomerular filtration and volume regulation in gravid animal models

The gestational increase in glomerular filtration rate that occurs in the normal rat is exclusively the result of an increase in renal plasma flow and there is no sustained increase in glomerular capillary blood pressure during a normal pregnancy. The factor or factors that initiate the gestational renal vasodilatation (and plasma volume expansion) are maternal, not fetoplacental in origin. The precise nature of the initiating factors has not yet been defined, although it is unlikely that the gestational plasma volume expansion can be the sole cause of the increased glomerular filtration rate seen in pregnancy. A number of vasoactive hormones are activated in pregnancy but as yet no clear candidate has emerged as 'the renal vasodilator'. Preliminary evidence suggests that nitric oxide may play an important role in gestational vasodilatation. The normal kidney in pregnancy exhibits substantial renal reserve to amino acid infusion and unimpaired autoregulatory ability despite being already vasodilated by the gestational stimulus. There are marked and sometimes contradictory changes in the various volume sensing and control systems in pregnancy. In general, the sensors perceiving and controlling intravascular volume are reset during a normal pregnancy to enable to mother to accommodate the increased plasma volume without provoking a natriuretic response. Whether the expanded plasma volume of pregnancy is perceived as normal or underfilled is not clear at this time and may vary according to the volume regulatory system. Repetitive pregnancies do not have any cumulative, long-term deleterious effects on renal function, when the underlying function is normal, when it has been compromised by removal of renal mass or during chronic systemic hypertension in the spontaneously hypertensive rat. In the short term, pregnancy does not worsen kidney function when underlying glomerular damage is due to immune stimuli, ablation of renal mass or gentamicin, or in the spontaneously hypertensive rat. Therefore, the chronic renal vasodilatation of pregnancy does not appear to be a damaging entity, unlike other states of low preglomerular arteriolar resistance, studied in the male rat. When pregnancy is superimposed on Adriamycin nephrosis or chronic blockade of nitric oxide, hypertension occurs and renal function declines. In both situations endothelial damage/dysfunction occurs, as is also seen in pre-eclampsia. Further study of the effects of pregnancy in animal models of endothelial dysfunction will prove rewarding.

Unilateral nephrectomy and progression of renal failure

Extensive ablation of renal mass in experimental animals leads to progressive glomerulosclerosis and chronic renal failure (CRF). Clinical studies are far from answering the question whether patients with reduced renal mass are at risk of developing progressive CRF. The aim of our study was to examine the morphological and functional aspects of the remnant kidney in a group of patients who underwent unilateral nephrectomy for renal tuberculosis: 313 patients (161 M, 152 F) mean age 57.2 +/- 10.7, were examined after a period ranging from 13.56 to 591.2 months. All patients were on ad libitum diet. Hypertension was found in 34.19% of the patients; SBP was 155.29 +/- 19.9 mmHg and DBP was 92.74 +/- 13.07 mmHg. Estimation of renal size performed by ultrasound scanner gave the following results: length 116.78 +/- 8.99 mm; width 58.24 +/- 7.21 mm; thickness 17.88 +/- 1.96 mm. Kidney function assessed by serum creatinine levels showed a mean level of 1.28 +/- 0.53 mg%. Forty-two patients (13.41%) had serum levels > 1.5 mg% but 18 of them had nonconcomitant systemic or renal involvement. Microalbuminuria determined by RIA assay was found in 50.5% of the patients. In our group of patients renal functional impairment was low and hyperfiltration expressed as microalbuminuria does not appear to be a primary factor in the progression of renal failure.

Single kidney function: early and late changes in urate transport after nephrectomy

Renal urate transport was studied by means of pyrazinamide (PZA) and probenecid (PB): (a) before and at 2, 6, 24 weeks (24 patients), (b) 1 to 30 years after uninephrectomy in 27 and 12 patients with Ccr greater than 80 and 30 to 70 ml/min, respectively. Uninephrectomy was followed by important tubular urate transport modifications during at least two weeks, which lead to a marked uricosuria as indicated by significant increase in FEur (mean value +/- SD, 0.228 +/- 0.059 vs. 0.097 +/- 0.014 and 0.099 +/- 0.019 in normals and chronically diseased solitary kidneys). Reduced response to PZA and PB suggests a diminished reabsorptive capacity for urate mainly at the presecretory site which persisted after FENa normalization. Tubular compensations were presumably complete at six weeks, since pattern of urate transport returned to normal with an almost complete reabsorption of filtered urate load (99%) and a percentage of postsecretory reabsorption (80%) very close to those seen in normal subjects with a pair of kidneys. The adjustment in urate excretion in solitary kidneys was achieved by a significant increase of secreted urate as compared with 50% of pre-uninephrectomy values. Thus, increased urate secretion by the remaining intact organ is sufficient to maintain urate balance with a normal serum level.

Renal function after tumor enucleation in a solitary kidney

Whether extensive ablation of renal mass in humans leads to progressive glomerulosclerosis, proteinuria, and hypertension, as it does in animal models, is a matter of controversy. We have studied kidney function in six patients who underwent enucleation of a renal cell carcinoma in a solitary kidney. Four patients had previously had a nephrectomy. The two others each had one atrophic, nonfunctioning kidney. Serum creatinine levels before surgery were within the normal range (mean, 99.9 mumol/L [1.13 mg/dL]). Two weeks after tumor enucleation, creatinine levels were significantly higher than the preoperative values (mean, 124.6 mumol/L [1.41 mg/dL]). The follow-up period varied from 10 to 23 months. In all patients, kidney function improved during the following months. Serum creatinine levels nearly reached preoperative values in all patients (mean, 105.2 mumol/L [1.19 mg/dL]). None of the patients showed a progressive deterioration in renal function or proteinuria. We found a modest increase in blood pressure in two patients who had been normotensive before surgery. In conclusion, tumor enucleation in a solitary kidney did not cause significant renal injury to the remnant kidneys in our patients, at least in the short term.

Transplants from living donors in the United Kingdom and Ireland: a centre survey

A survey was carried out to determine for the first time the extent of transplantation from living donors in the United Kingdom and Republic of Ireland and the views of transplant surgeons regarding future developments. Questionnaires were sent to 32 transplant centres representing 18 health regions and covered their extent of experience of transplantation, sources of donors, ages of donors and recipients, outcome of transplantation, and views on expansion of living donor transplantation services. Replies received from 27 transplant centres representing 17 health regions gave data on more than 1200 transplants from living donors. Transplants from living donors accounted for 0-25% of the total experience of health regions. Two centres had abandoned living donor transplantation. Sixty per cent of transplant surgeons favoured expansion of the living donor programme to meet a shortage of kidneys from cadavers, and the remainder thought that existing programmes were optimal. Living donor transplantation promises to be an important factor in the future planning of health care resources.

The solitary kidney: a model of chronic hyperfiltration in humans

Reduction of renal mass (11/12) in rats leads to progressive azotemia, proteinuria, and hypertension. Less extensive renal ablation resulting from uninephrectomy also accelerates the progression of focal glomerulosclerosis (FGS) induced by experimental diabetes, renal irradiation, aminonucleoside nephrosis, or aging. The consequence of the absence of one kidney in man are examined in three different clinical situations. Unilateral renal agenesis seems to predispose to the development of FGS, but most reports include isolated cases and the true incidence of FGS is not known. The solitary kidney following uninephrectomy for acquired unilateral disease undergoes a compensatory rise in glomerular filtration rate (GFR) that remains stable for several decades. Finally, kidney donors followed for over 2 decades show unimpaired GFR, elevated at 70% to 80% of the normal (two-kidney) GFR. Some donors develop mild, nonprogressive proteinuria. Their incidence of hypertension matches that in the control population. Thus, hyperfiltration secondary to 50% reduction of renal mass in humans does not lead to loss of function of the remaining parenchyma.

Glomerular filtration and volume regulation in gravid animal models

The gestational increase in glomerular filtration rate (GFR) that occurs in the normal rat is the result exclusively of an increase in plasma flow rate, and there is no sustained increase in glomerular capillary blood pressure during a normal pregnancy. The factor or factors that initiate the gestational renal vasodilatation (and plasma volume expansion) are maternal, not fetoplacental in origin. Apart from ruling out prostaglandins as an initiating agent, animal studies have not yet defined the precise nature of the initiating factors; it is unlikely that the gestational plasma volume expansion can be the sole cause of the increased GFR seen in pregnancy. The normal kidney in pregnancy exhibits substantial renal reserve to amino acid infusion, despite being already vasodilated by the gestational stimulus. The renal volume-sensing and control system of tubuloglomerular feedback is fully operative in pregnancy, and appears to be 'reset' to perceive the expanded plasma volume of pregnancy as normal. This observation agrees with many other indications that the sensors perceiving and controlling intravascular volume are reset during a normal pregnancy to enable the mother to accommodate the increased plasma volume without provoking a natriuretic response. Multiple pregnancies do not have any cumulative, long-term deleterious effects on renal function, either when the underlying function is normal or when it has been compromised by removal of renal mass plus high-protein feeding. In the short-term, pregnancy does not worsen kidney function when underlying glomerulonephritis is present. Therefore, the hyperfiltration of pregnancy does not appear to be a damaging entity, unlike other hyperfiltration states studied in the male rat. Still unknown is the mechanism by which pregnancy does worsen underlying glomerular disease in some women. The preliminary data in the rat, presented above, suggest that the exacerbating influence may be something other than the glomerular haemodynamic changes of pregnancy.

Compensatory renal hypertrophy after donor nephrectomy

Renal length was measured radiographically in 65 living kidney donors, aged 27-69 years, who had undergone unilateral nephrectomy during the past 20 years. In 34 of these subjects, pre- and post-operative kidney length, glomerular filtration rate (GFR) and blood pressure were available for analysis. Male donors developed greater compensatory hypertrophy than female donors. The extent of renal enlargement correlated negatively with the age of the subject at the time of nephrectomy and with the current mean arterial blood pressure. However, no correlation was found between the percentage change in renal length and either GFR or time since nephrectomy.

The effect of pregnancy on kidney function in renal allograft recipients

In women with renal transplants glomerular filtration rate (GFR) increases during pregnancy but how soon the increment occurs, its relation to pre-pregnancy GFR, and the overall pattern of change are unknown. Twenty-four hour creatinine clearance (24-hr CCr) were measured prospectively in ten pregnancies in eight allograft recipients before conception, throughout pregnancy, 8 to 12 weeks postpartum, and 4 to 6 monthly thereafter. Inulin (CIn) in creatinine (CCr) clearances during infusion were also determined and protein excretion was evaluated. The results were compared to those in similar studies in ten healthy women. By the tenth gestational week 24-hr CCr was 124 +/- (SD) 15.9 ml/min in healthy women (an increase of 38%; range, 18 to 69%) and in transplant patients was 105 +/- 28.1 ml/min (an increase of 34%: range, 10 to 60%), with the greatest increments in those whose allografts functioned best before conception, regardless of donor source and sex or the transplant-pregnancy interval. In late pregnancy mean 24-hr CCr decreased by 19% (range, 6 to 28%) in healthy women and by 34% (range, 12 to 57%) in the transplant patients, but in most this did not represent graft deterioration nor lead to permanent impairment. At all time points CIn values were 5 to 10% greater than those for 24-hr CCr but slightly less than infusion CCr values. Protein excretion increased throughout pregnancy and by the third trimester in healthy women averaged 200 mg in 24 hr and regularly exceeded 500 mg in 24 hr in transplant patients, which was three times non-pregnant levels and probably not clinically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Experience with live donor nephrectomy

We studied 100 patients undergoing nephrectomy for living related renal transplantation. after completion of tissue typing preoperative studies included urinalysis and culture, creatinine clearance determination, excretory urography and renal arteriography. Patient characteristics, preoperative test, surgical approach, complications, long-term followup and cost factors were reviewed. There was no mortality and morbidity was minimal except for wound complications. Renal function generally remained normal. Donor nephrectomy is a worthwhile and safe procedure with an acceptably low incidence of postoperative complications.

Living related renal transplantation: experience in 22 cases

Twenty-two living related renal transplant operations have been performed at Prince Henry's Hospital over the last seven years. Donors have been accepted for nephrectomy only after exhaustive examination of their health and serach for renal disease. The one and three year graft survival rates have been 85% and 64% respectively. Only two recipients have died, and recipient morbidity has been low. Donors have not suffered any serious complication from nephrectomy. It is concluded that living related renal transplantation has many advantages over cadaveric renal transplantation and is a relatively safe procedure for the donor, provided that rigid criteria are used in donor selection.