Evaluation of kidney function in renal transplant patients receiving long-term cyclosporine

Angiotensin-II receptor antagonist losartan reduces microalbuminuria in hypertensive renal transplant recipients

In recent years, it has been demonstrated that losartan lowers macroproteinuria in diabetic or non-diabetic renal transplant recipients (RTx) similar to angiotensin converting enzyme (ACE) inhibitors. Microalbuminuria (MAU) may reflect subclinical hyperfiltration damage of the glomerulus. It could be a marker of kidney dysfunction in renal transplantation. The aim of the study was to assess the efficacy of losartan in hypertensive RTx with MAU. This study was conducted in 17 (M/F: 4/13) stable RTx. No change was made in the medical treatment of the patients. All cases received 50 mg/day losartan therapy for 12 wk. Renal functions and MAU were determined 12 and 6 wk and just before the treatment as well as sixth and twelfth week of the treatment in all patients. Losartan satisfactorily lowered systemic blood pressure. A significant reduction in MAU was observed from 103 +/- 53 microg/min at the beginning to 59 +/- 25 microg/min in the sixth week and 47 +/- 24 microg/min in the twelfth week (p=0.0007 and 0.0005, respectively). From the sixth week of the treatment, the therapy significantly decreased hemoglobin, hematocrit and erythrocyte levels but did not change mean leukocyte and platelet counts, urea, creatinine levels and creatinine clearances. No serious side-effect was observed during the study. In conclusion, we found that losartan decreased MAU in hypertensive RTx. For that reason, it might be considered as the first choise antihypertensive agent for the renoprotection in selected patients.

Long-term improvement in renal function after cyclosporine reduction in renal transplant recipients with histologically proven chronic cyclosporine nephropathy

BACKGROUND

Chronic cyclosporine (CsA) nephropathy, which has been unequivocally documented in recipients of heart, heart-lung, liver, or bone marrow transplants, as well as in nontransplant situations, usually results in a progressive deterioration of renal function. In this study, we assessed the potential reversibility of chronic CsA nephropathy in renal transplant recipients.

PATIENTS AND METHODS

Twenty-three renal transplant patients with biopsy-proven CsA nephropathy associated with long-term CsA administration (27+/-4 months) were followed up for more than 2 years after CsA reduction (18/23 patients) or withdrawal (5/23 patients) and addition of azathioprine. Changes in effective renal plasma flow and glomerular filtration rate were assessed before and 2 years after CsA reduction, whereas serum creatinine, proteinuria, blood pressure, and CsA concentrations were monitored up to 5 years.

RESULTS

At 2-year follow-up, glomerular filtration rate increased from 40+/-3 to 47+/-4 (P<0.05) and effective renal plasma flow from 217+/-23 to 244+/-24 ml/min/1.73 m2 (NS). Mean arterial pressure significantly decreased from 98.7+/-2.9 to 93.1+/-2.7 mmHg (P<0.05). There was no significant change in renal vascular resistance, filtration fraction, or albumin excretion. A significant decrease in serum creatinine was also observed during the whole follow-up (73+/-6.5 months). CsA reduction was followed by only one episode of acute reversible rejection; chronic rejection developed in three patients 2 years or later after CsA reduction.

CONCLUSIONS

These data suggest that CsA nephropathy participates in graft dysfunction in a small group of renal transplant recipients. In addition, graft dysfunction may be reversible when CsA dosage is reduced early after diagnosis of chronic CsA nephropathy.

The true clinical significance of renography in nephro-urology

Isotopic renography is a non-invasive technique used routinely by the clinician to provide information about kidney structure and function. Whilst there is no doubt of its value in the accurate measurement of glomerular filtration rate and in the detection of parenchymal abnormalities, its role in the diagnosis of renovascular disease (especially in patients with renal insufficiency), the exclusion of obstruction and the evaluation of the patient with either acute renal failure or renal transplant dysfunction remains unproven. In part, this reflects a failure to standardise protocols and rigorously evaluate diagnostic techniques. Recent developments in ultrasound, computerised X-ray tomography and nuclear magnetic resonance now present the clinician with rival techniques and emphasise the need for the clinical development of isotopic renography.

Divergent effects of calcium channel and angiotensin converting enzyme blockade on glomerulotubular function in cyclosporine-treated renal allograft recipients

The effects of amlodipine and perindopril on renal hemodynamics and tubular function in cyclosporine-treated hypertensive renal allograft recipients were evaluated in a randomized, double-blind crossover fashion. Ten patients were studied after a 2-week placebo run-in and, after 8 weeks of active treatment, allowing a 2-week placebo washout between treatments. At the end of each period, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured as 51Cr-EDTA and 123I-hippuran clearance, respectively, and tubular function evaluated by the lithium clearance technique was determined. Both drugs maintained GFR and ERPF and lowered mean arterial pressure (MAP, mm Hg) to a similar extent (time x treatment, P = 0.466): amlodipine from 126.9 +/- 2.5 to 115.9 +/- 2.2; perindopril from 126.9 +/- 2.5 to 117.9 +/- 3.9 (time effect of all treatments together, P = 0.003). Accordingly, renal vascular resistance (RVR, mm Hg/mL/min/1.73 m2) was equally reduced (time x treatment, P = 0.955): amlodipine from 0.36 +/- 0.03 to 0.30 +/- 0.02; perindopril from 0.36 +/- 0.03 to 0.32 +/- 0.01 (time effect all treatments together, P = 0.043). Sodium clearance and fractional excretion of sodium were not affected by either drug. Output of fluid from the proximal tubules measured as clearance of lithium (CLi, mL/min) and uric acid (CUr, mL/min) was higher after amlodipine than after perindopril (CLi 19.1 +/- 2.1 v 16.5 +/- 1.7, P =0.036 and CUr 7.0 +/- 0.6 v 5.9 +/- 0.4, P = 0.007). As a consequence, after amlodipine, distal absolute reabsorption of sodium was higher (DARNa 2.57 +/- 0.28 v 2.19 +/- 0.22 mEq/min, P = 0.027) and serum uric acid was lower (5.9 +/- 0.3 v 6.7 +/- 0.4 mg/dL, P = 0.001) in comparison with perindopril. In cyclosporine-treated renal allograft hypertensives, amlodipine and perindopril lower blood pressure equally and reduce RVR to the same extent. Overall sodium excretion is not affected by either agent. Urate clearance is higher and serum uric acid lower on amlodipine as compared with perindopril.

Pediatric renal transplantation

Renal transplantation in children is a most rewarding treatment that dramatically changes the overall health and lifestyle of children with ESRD. Complexities in different aspects of renal transplantation in children are obvious. Optimum technical conditions and drug therapy must be provided for the success of renal transplantation. Application of recent advances in immunology and long-term care to clinical transplantation continue to improve graft and patient survival rates. Optimization of growth and development also can be improved with the use of rhGH.

Comparison of perindopril and amlodipine in cyclosporine-treated renal allograft recipients

The objective of this study was to compare the antihypertensive efficacy and influence on renal function of perindopril and amlodipine in cyclosporine-treated renal allograft recipients with mild to moderate hypertension. We conducted a randomized, double-blind, double-dummy crossover trial in ambulatory patients. Four phases were conducted: 2 weeks on placebo, 8 weeks of maintenance (perindopril or amlodipine), and 2 weeks of washout between treatment periods. Ten hypertensive patients with stable renal allograft function transplanted more than 6 months previously and receiving cyclosporine as part of their immunosuppressive regimen were studied. The patients were allocated to perindopril (2 or 4 mg/d) and amlodipine (5 mg/d) in a random sequence. If office diastolic pressure was greater than or equal to 90 mm Hg after 4 weeks, the dosage was doubled and continued for another 4 weeks. The main outcome measures were office and 24-hour ambulatory blood pressure changes after 8 weeks of active treatment and treatment and time effect on glomerular filtration rate and effective renal plasma flow. Perindopril and amlodipine were equally effective in lowering office blood pressure and similarly efficacious for the 24-hour period of the day. Neither drug affected glomerular filtration rate or effective renal plasma flow. Both agents demonstrated equivalent capacity (time x treatment, P = .955) to reverse renal vascular resistance (amlodipine from 0.35 +/- 0.02 to 0.30 +/- 0.02 mm Hg/mL per minute per 1.73 m2; perindopril from 0.36 +/- 0.03 to 0.32 +/- 0.01) (time effect of all treatments together, P = .043).(ABSTRACT TRUNCATED AT 250 WORDS)

Late withdrawal of cyclosporine in stable renal transplant recipients

The use of cyclosporine (CsA) in renal transplantation has been associated with an improvement in 1-year graft survival, but has not changed the rate of late graft loss. We sought to determine whether the intent to withdraw CsA late after renal transplantation affects renal transplant survival and whether there is a racial difference in the effect of CsA withdrawal. This retrospective study included 384 consecutive patients receiving a renal transplant during the 1984 to 1991 period who were treated with CsA/azathioprine/prednisone and who had a functioning allograft 6 months following transplantation. Of these, 97 were electively withdrawn from CsA at a median of 22 months following transplantation. Factors significantly associated with the decision to withdraw CsA included white race, older age, and lower serum creatinine. Acute rejection within 6 months of stopping CsA occurred in 12 patients (12.4%), including nine of 78 (11.5%) white patients and three of 19 (15.8%) black patients. For the group of 287 patients who were not withdrawn from CsA, the 6-year graft survival rate was 59% (95% confidence interval, 52%, 66%). For the group of patients taken off of CsA, the 6-year graft survival rate was 84% (95% confidence interval, 76%, 92%). Cox proportional hazard survival analysis indicated that the intent to discontinue CsA was associated with better graft survival, with a hazard ratio of 0.37 (95% confidence interval, 0.20, 0.70), independent of other variables that may affect graft survival. A separate analysis controlling for waiting time bias also favored the CsA withdrawal group. There was no detectable racial difference in the effect of CsA withdrawal on graft survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal functional reserve in cyclosporin-treated recipients of kidney transplant

The aims of this study were to determine whether renal functional reserve (RFR) is still present in cyclosporin-treated renal transplant recipients, and to examine the relationship between RFR and proximal reabsorption. A serial study was carried out in 12 renal allograft recipients (R) with good renal graft function at 20 +/- 2.5 days (S1) and at 7.6 +/- 0.4 months (S2) post-transplantation, and the results were compared to those in eight subjects who had undergone unine-phrectomy (one-kidney controls: UNx.C) and in 12 healthy volunteers (two-kidney controls: 2K.C). R and C were in similar sodium and protein balance and with similar plasma renin and aldosterone levels. R had normal serum creatinine level on moderate doses of cyclosporin (whole blood cyclosporin concentration: 212 +/- 20 and 125 +/- 20 ng/ml at S1 and S2, respectively). Eight one-hour clearance periods were performed prior to, during and following a three-hour i.v. infusion of a mixture of 20 l-amino acids (Azonutril 25, 4.5 mg amino acids/kg/min). Baseline glomerular filtration rate (GFR) was lower in recipients at S1 and S2 (55 +/- 5 and 54 +/- 4 ml/min/1.73 m2, respectively) than in UNx.C and 2K.C (72 +/- 4 and 113 +/- 4 ml/min/1.73 m2, respectively, P < 0.05 and 0.001). Amino acid infusion elicited significant GFR increases in controls as well as in recipients in spite of higher renal vascular resistances (RVR). The greater measured increase in GFR, which represented RFR, was 18 +/- 3 and 28 +/- 2 ml/min/1.73 m2 in UNx.C and 2K.C, respectively (P < 0.001), and 17 +/- 3 ml/min/1.73 m2 in R at both S1 and S2 (P < 0.001). Contrary to both UNx and 2K controls, the acute hyperfiltration in R at S1 and S2 occurred with a significant increase in effective renal plasma flow, no alteration in filtration fraction and a large decrease (approximately 20 and 17%) in RVR while no correlation could be detected between the RFR and baseline GFR. Baseline lithium clearance, used as a marker of overall proximal fluid delivery (CLi), was significantly lower, whereas baseline fractional excretion of lithium (FELi) was significantly higher in R at S1 and S2 and in UNx.C (41 +/- 4, 40 +/- 3 and 38 +/- 3%, respectively) than in 2K.C (31 +/- 2%, P < 0.05). Consistent and significant increase in CLi, FELi and absolute proximal reabsorption occurred both in R at S1 and S2 and in UNx and 2K controls during elicitation of RFR.(ABSTRACT TRUNCATED AT 400 WORDS)

Developments and dilemmas in renal transplantation

The number of patients waiting for a kidney transplant is about three times greater than the number of transplants performed each year. This article highlights current immunosuppression protocols and the newer immunosuppressive drugs under investigation in a number of multicenter trials. These hold out the promise of reducing the frequency of acute rejection and of prolonging graft survival. They are divided into three groups. The first, like cyclosporine, interferes with the action of interleukin 2. The second, like azathioprine, are antimetabolites; and the third, new monoclonal antibodies. The use of antibody-induction therapy is compared with standard regimens. There are risks related to prednisone withdrawal protocols and inadequate cyclosporine dosing that may lead to accelerated graft loss. Cardiovascular disease is a significant problem in older diabetic patients for whom coronary angiography is recommended. A defined set of risk factors is outlined that predicts which younger diabetic patients should have a cardiovascular evaluation. Chronic liver disease is a growing problem and rational strategies are emerging from studies of patients with biopsy-proven active hepatitis. The presence of hepatic inflammation is associated with progressive liver disease and patients must be made aware of this risk when seeking transplantation. A large number of studies of various prophylactic regimens are starting to provide data on the cost-effective reduction of cytomegalovirus disease in transplant recipients. It is recommended that patients receiving antibody therapy also receive preemptive gangciclovir. The issue of chronic allograft rejection is discussed briefly. The most important predictors of chronic allograft rejection are the frequency of acute rejection, inadequate immunosuppression, and infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Converting-enzyme inhibitor versus calcium antagonist in cyclosporine-treated renal transplants

The influence of antihypertensive treatment on the long-term evolution of arterial pressure and renal function was studied in a prospective controlled trial conducted in renal transplant recipients treated by cyclosporine. Within six months after transplantation, patients were randomly allocated to treatment by the angiotensin-converting enzyme inhibitor, lisinopril (ACEI, alone or associated with frusemide; N = 14), or the calcium antagonist, nifedipine (CA, alone or associated with atenolol; N = 11). Glomerular filtration rate (TcDTPA clearance) and effective renal plasma flow (hippuran clearance) as well as 24-hour urinary excretion of electrolytes and albumin were estimated at about 1 and 2.5 years of follow-up. Before initiation of antihypertensive therapy, the two groups were similar with regards to mean arterial pressure (119 +/- 2 vs. 120 +/- 4 mm Hg), effective renal plasma flow (285 +/- 26 vs. 248 +/- 33 ml/min/1.73 m2) and glomerular filtration rate (59 +/- 4 vs. 61 +/- 8 ml/min/1.73 m2 in the ACEI and CA groups, respectively). Both ACEI and CA treatments were associated with no change in renal function, a similar change in mean arterial pressure (ACEI -18 +/- 3; CA -13 +/- 5 mm Hg) and identical trough blood levels of cyclosporine. Urinary albumin excretion did not change significantly in any groups. Of interest, only in the ACEI group did filtration fraction significantly decrease (from 0.22 +/- 0.01% to 0.19 +/- 0.01% at final studies). These results indicate that in cyclosporine-treated transplant recipients, a satisfactory control of hypertension is obtained by chronic ACEI, which is as effective on arterial pressure as a combination of CA and atenolol.(ABSTRACT TRUNCATED AT 250 WORDS)