Long-term assessment of renal function following nephrectomy for stage I renal carcinoma

Environmental and stressful factors affecting the occurrence of kidney stones and the kidney colic

The first renal disease described from Hippocrates is nephrolithiasis with renal colic, which is the pain of stone passage and is also a common renal problem with easily recognizable characteristics. There has been much written about dietary factors, which have unequivocally been proved to play an important role in the formation of kidney stones. In this regard, it is of interest that the contribution of factors such as stressful events, life style, or occupation in the formation of kidney stones has not been well studied. This review examines the clinical evidence of the stressful events and other environmental factors affecting the occurrence of kidney stones.

Effects of aging on glomerular function and number in living kidney donors

To elucidate the pathophysiologic changes in the kidney due to aging, we used physiological, morphometric, and imaging techniques to quantify GFR and its determinants in a group of 24 older (≥ 55 years) compared to 33 younger (≤ 45 years) living donors. Mathematical modeling was used to estimate the glomerular filtration coefficients for the whole kidney (K(f)) and for single nephrons (SNK(f)), as well as the number of filtering glomeruli (N(FG)). Compared to younger donors, older donors had a modest (15%) but significant depression of pre-donation GFR. Mean whole-kidney K(f), renocortical volume, and derived N(FG) were also significantly decreased in older donors. In contrast, glomerular structure and SNK(f) were not different in older and younger donors. Derived N(FG) in the bottom quartile of older donors was less than 27% of median-derived N(FG) in the two kidneys of younger donors. Nevertheless, the remaining kidney of older donors exhibited adaptive hyperfiltration and renocortical hypertrophy post-donation, comparable to that of younger donors. Thus, our study found the decline of GFR in older donors is due to a reduction in K(f) attributable to glomerulopenia. We recommend careful monitoring for and control of post-donation comorbidities that could exacerbate glomerular loss.

The effect of nephroureterectomy on glomerular filtration rate

OBJECTIVE

To determine the effect of nephroureterectomy (NU) on the glomerular filtration rate (GFR), and to determine whether the estimated GFR after NU is influenced by age and other factors associated with renal impairment.

PATIENTS AND METHODS

We retrospectively identified 131 patients who had had a NU at either of two UK institutions. Their serum creatinine levels were recorded before and after NU, along with comorbidity data, and from this their GFR before and after NU was estimated using the Modification of Diet in Renal Disease Study Group equation.

RESULTS

At a median follow-up of 5 years there was an 18% deterioration in estimated GFR in the 131 patients. The percentage deterioration in estimated GFR was greater in those aged >or= 70 years than in those aged <70 years (20% vs 15% deterioration). Those with more risk factors for renal impairment had a greater percentage deterioration in estimated GFR than those with no such risk factors.

CONCLUSIONS

This study shows that NU has a profound effect on future estimated GFR, an effect that is further compounded in those with risk factors for renal impairment. This study therefore provides both the patient and the urologist with an idea of potential future renal function after NU and contributes greatly to preoperative counselling.

Adaptive hyperfiltration in the aging kidney after contralateral nephrectomy

We examined the magnitude of adaptive hyperfiltration in the remaining kidney of 16 aging (>57 yr) and 16 youthful (<55 yr) individuals who had undergone a contralateral nephrectomy. Healthy volunteers who were youthful ( n = 143) or aging ( n = 37) provided control values for the binephric condition. One-kidney glomerular filtration rate (GFR; +42%), renal plasma flow (+38%), plasma oncotic pressure (+2.8 mmHg), and mean arterial pressure (+7.0 mmHg) were all higher in youthful uninephric vs. binephric subjects. Corresponding excesses in aging uninephric vs. binephric subjects were by 38 and 36% and 1.4 and 14.0 mmHg, respectively. Modeling of these data revealed that an isolated increase in either the glomerular ultrafiltration coefficient ( Kf) by 110% or in the transcapillary hydraulic pressure gradient (ΔP) by 7 mmHg, could account for the observed level of hyperfiltration in youthful uninephric subjects. Corresponding increases for aging uninephric subjects were 61% for Kf and 5 mmHg for ΔP. We conclude that the magnitude of adaptive hyperfiltration is similar in aging to that in youthful uninephric subjects, albeit at a lower absolute GFR level. Isolated increases in either Kf or ΔP or a combination of smaller increases in both can account for the hyperfiltration. Greater adaptive arterial hypertension in aging than youthful uninephric subjects raises the possibility of a disproportionate role for glomerular hypertension and ΔP elevation in aging compared with youthful uninephric subjects. Glomerular hypertension could exacerbate the sclerosing glomerulopathy of senescence and lead to renal insufficiency. We recommend that living donors of a kidney transplantation in or beyond the seventh decade be used with caution.

CHARACTERIZATION OF CATIONIC AMINO ACID TRANSPORT SYSTEMS IN RAT ERYTHROCYTES: LACK OF EFFECT OF URAEMIA ON l-ARGININE INFLUX

1. Chronic renal failure (CRF) is associated with the abnormal regulation of nitric oxide (NO) synthesis at the systemic level. The transport of L-arginine, upregulated in blood cells from uraemic patients, modulates NO synthesis in this pathological condition. The model of partial nephrectomy in rats is widely accepted as a valid model of uraemia. Because there are no reports of L-arginine transport in blood cells from uraemic rats, the aim of the present study was to investigate L-arginine transport in red blood cells (RBCs) from these rats. 2. The kinetics of L-arginine transport in RBC and plasma and the amino acid profiles of RBC were investigated in control, sham-operated and subtotally nephrectomized rats. 3. L-Arginine transport was mediated via the cationic amino acid transport system y+ and a transport system with kinetics resembling the human system y+L. In control RBC, the apparent Ki for L-leucine inhibition of L-arginine transport via system y+L was 0.16 +/- 0.02 and 4.8 +/- 2 mmol/L in the presence of Li+ and Na+, respectively. 4. The Vmax values for L-arginine transport via system y+L and system y+ were similar in RBC from control sham-operated and uraemic rats. Moreover, L-arginine concentrations in plasma and RBC were not affected by uraemia. 5. The findings of the present study provide the first evidence that L-arginine transport in rat erythrocytes is mediated by two distinct cationic transport systems with characteristics of systems y+ and y+L, which accept neutral amino acids only in the presence of Li+. In contrast with previous studies in uraemic patients, plasma levels and maximal transport rates of L-arginine were not altered in this rat model of CRF.

Long-term consequence of renal function following nephrectomy for renal cell cancer

AIM

A retrospective analysis was performed involving patients who had undergone radical nephrectomy for renal cell cancer to determine the long-term outcome of this surgery on renal status.

MATERIALS AND METHODS

Between 1977 and 2001, 172 patients having undergone radical nephrectomy for renal cell cancer were followed for a period of more than one year at the Department of Urology Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan. The preoperative and postoperative serum creatinine values of these individuals were reviewed. Long-term effects of radical nephrectomy on renal function and factors influencing postoperative renal dysfunction were analyzed.

RESULTS

Six (3.5%) of the 172 individuals progressed to hemodialysis. Eleven (6.4%) patients displayed serum creatinine values of > or =1.6 mg/dL. The remaining 155 patients (90.1%) demonstrated postoperative serum creatinine values of <1.6 mg/dL. The present study suggests that aging, a high degree of proteinuria, hypertension and diabetes mellitus were the predominant risk factors for renal deterioration following nephrectomy.

CONCLUSIONS

We have primarily selected radical nephrectomy for cases exhibiting smaller renal tumors with a normal contralateral kidney. We encourage nephron-sparing surgery where possible in patients displaying risk factors, including a high degree of proteinuria, hypertension, or diabetes mellitus.