Management of Hypertension in Dialysis

Arterial hypertension is a highly frequent symptom in end-stage renal failure. This study was designed to evaluate the importance of total exchangeable sodium (NaE), plasma renin activity (PRA) and the adrenergic nervous system in the pathogenesis of high blood pressure. 86 patients were studied (26 with end-stage kidney disease and under conservative treatment and 60 on maintenance haemodialysis).

Under conservative treatment a simple linear regression analysis gave a correlation coefficient of 0.794 for NaE × log. PRA against mean arterial pressure (MAP). This data suggests that before the start of the haemodialytic treatment NaE and PRA are important determinants of hypertension.

In patients undergoing chronic heamodialysis the correlation between MAP and the product of NaE × log. PRA was lost. In hypertensive patients we have found indication of an increased adrenergic activity. In fact resting heart rate and two hours walking plasma catecholamines were significantly higher in hypertensive compared with normotensive patients on dialysis. A significant positive correlation was found between basal plasma noradrenaline levels and MAP in 34 patients treated with periodic haemodialysis when hypothyroid patients were excluded.

Arterial hypertension is a highly frequent symptom in end-stage renal failure and occurs in over 80% of all case histories (1, 2, 3, 4, 5).

This paper is a review of our experience concerned with the pathogenesis and management of hypertension in patients with chronic renal failure.

The ideal blood pressure target to prevent cardiovascular disease in type 2 diabetes: a neutral viewpoint

Type 2 diabetes mellitus (T2DM) and essential hypertension are often associated, and retrospective data analyses suggest an association between lower blood pressure (BP) values and lower cardiovascular (CV) risk in patients with T2DM. However, the most recent intervention trials fail to demonstrate a further CV risk reduction, for BP levels <130/80 mm Hg, when compared to levels <140/90 mm Hg. Moreover, a J-shaped, rather than a linear, relationship of BP reduction with incident CV events has been strongly suggested. We here debate the main available evidences for and against the concept of 'the lower the better', in the light of the main intervention trials and meta-analyses, with a particular emphasis on the targets to be pursued in elderly patients. Finally, the most recent guidelines of the scientific societies are critically discussed.

[Guidelines for management of hypertension: why doesn't evidence lead to unanimity?]

Guidelines are systematically developed statements to assist practitioner and patient decisions, and are being used to describe care based on scientific evidence. However, presence of multiple guidelines on the same subject does not help physicians make the best decision about healthcare. In this paper we examined the more recent guidelines (GL) for the management of arterial hypertension: World Health Organization-International Society of Hypertension (WHO-ISH) GL, European Society of Hypertension-European Society of Cardiology (ESH-ESC) GL, British Hypertension Society (BHS-IV) GL, and the report of Joint National Committee (JNC-7) from USA. Some differences emerged on the definition of hypertension, the blood pressure targets and the thresholds for treatment, the quantification of cardiovascular risk, the choice of initial drugs. These differences are likely to be based on divergent opinions about the relationship between hypertension and global cardiovascular risk (CVR). In the JNC-7 report, hypertension is thought to be the mainstay of CVR, hence BP treatment is to be started, taking into account the entity of blood pressure values and apart from other risk factors (with the exception of diabetes and renal insufficiency). The other GL, particularly BHS-IV GL, establish the thresholds for the start of treatment mainly taking into account the global CVR. Actually, BHS-IV GL do not recommend the start of pharmacological treatment in mild hypertension, provided that the global CVR was lower than 20% in ten years. Moreover, the difference in definition of hypertension, BP targets, choice of starting drug, is likely to spring from this different view on hypertensionglobal cardiovascular risk relationship.

[Refractory hypertention in a female patient with renal failure]

We report one sixty-seven years-old female who presented with hypertension refractory to antihypertensive drugs. She had an elevated BP for approximately 15 years. In the last 8-10 months her hypertension had become difficult to control. Her BP ranged between 180/100 mmHg and 220/1220 mmHg on atenolol 100 mg once daily, methyldopa 500 mg three times daily, furosemide 25 mg twice daily, doxazosine 4 mg twice daily. When she was referred to our unit serum creatinine was 2.3 mg/dL and she had a mild proteinuria (70 mg/dL) without microematuria. Ultrasonography showed a left kidney size in the low-normal range (LD 11 cm) and a small right kidney (LD 9 cm). Renal angiography showed a severe, ostial stenosis of the left renal artery and a total thrombosis of the right renal artery with a blood supply to the right kidney provided by collateral channels. An ACE-I was added to the therapy but a sharp increase in serum creatinina (up to 6.4 mg/dL) prompted us to withdraw the drug. She underwent a renal angioplasty on the left side and a Palmaz stent was placed. The control angiography showed a good anatomical result. Three months after the manoeuvre the patient was again referred to our unit with headache, nausea vomiting and hyper-tension refractory to amlodipine 10 mg/day, doxazosine 4 mg twice a a day, atenolol 50 mg/day, furosemide 50 mg/day. A doppler ultrasonography and a magnetic resonance angiogram showed no restenosis on the treated artery. An ACE-I was again administered and BP on this drug was 145/90 mmHg after one month and 130/85 after three months. Headache, nausea and vomiting disappeared. Serum creatinina kept unchanged (2.2 mg/dL). Comment. In this case the benefit of angioplasty on blood pressure control was indirect. Apparently the manoeuvre showed no effect on blood pressure, but the angioplasty allowed us to use of an ACE-Inhibitor, without any negative effect on renal function, and thus to adequately control blood pressure.

Posterior tibial nerve stimulation: is the once-a-week protocol the best option?

AIM

Aim of our study was to compare the results of posterior tibial nerve stimulation (PTNS) performed weekly with those of PTNS performed 3 times per week in patients with overactive bladder syndrome.

METHODS

Thirty-five patients (28 females, 7 males) with overactive bladder syndrome not responding to antimuscarinic therapy were enrolled in a prospective study. A total of 17 out of 35 patients were randomly assigned to group A and treated with a PTNS protocol based on weekly stimulation sessions; 18 out of 35 patients were randomly assigned to group B and treated with a PTNS protocol based on stimulation sessions performed 3 times per week. All subjects were evaluated by means of 24 h bladder diaries, quality of life questionnaires (I-QoL, SF36) and urodynamic evaluation before and after treatment. Patients were asked after each stimulation session to give their opinion on the efficacy of the treatment. We have considered ''success'' those patients who presented a reduction >50% of the micturition episodes/24 h (ME/24) or (if incontinent) of the incontinence episodes/24 h (IE/24). Results before and after treatments in both groups were collected and statistically compared.

RESULTS

As a whole, 11/17 patients (63%) in group A and 12/18 patients (67%) in group B were considered ''success''; 4/11 (36%) incontinent patients in group A and 5/11 (45%) incontinent patients in group B were completely cured after treatment. In both groups, patients reported subjective improvement after 6-8 stimulation sessions.

CONCLUSIONS

Our findings seem to show that the periodicity of stimulation does not effect the results of PTNS treatment. The advantage of more frequent stimulation sessions is to achieve earlier a clinical improvement.

[Hypertension, atherosclerosis and kidney]

Cardiovascular risk is dramatically increased in patients with end-stage renal disease (ESRD). However, even minor dys-functions such as microalbuminuria or a mild increase in serum creatinine (Cr) have a major impact on cardiovascular risk. Increased cardiovascular risk is present in multiple populations, including general populations, patients with moderate risk such as hypertensives, and high-risk patients including patients with heart failure and myocardial necrosis. There are many mechanisms underpinning the increased cardiovascular risk. Regarding atherosclerosis, the kidney can be victim or villain. On the one hand, both kidney disease per se and renal insufficiency can induce vascular damage, thereby increasing cardiovascular risk. Kidney disease without renal insufficiency can cause an increased prevalence in hypertension, dyslipidemia (nephrotic syndrome), sympathetic system hyperactivity, and in renin angiotensin system hyperactivity. A moderate-severe renal insufficiency can induce an increase in many vasculotoxic substances such as ADMA, lipoprotein(a), homocysteine, disturbances in calcium and phosphate metabolism, anemia and left ventricular hypertrophy. A more severe renal insufficiency can induce the ominous malnutrition-inflammation-atherosclerosis (MIA) syndrome. On the other hand, the kidney can be the victim of atherosclerosis. Ischemic nephropathy, caused by atherosclerotic renal artery disease and atheroembolism from abdominal aorta are two examples. Finally, it is important to consider that the kidney, being an organ with a wide vasculature, could be a sophisticated sensor of subclinical cardiovascular damage.

Role of 5-aminolevulinic acid in the diagnosis and treatment of superficial bladder cancer: improvement in diagnostic sensitivity

OBJECTIVES

To use 5-aminolevulinic acid (5-ALA) in diagnostic cystoscopy and during transurethral resection of the bladder (TURB) to treat transitional cell carcinoma. The efficacy of this new technique was compared with standard cystoscopy.

METHODS

The 5-ALA, instilled in the bladder 2 hours before cystoscopy, makes the pathologic tissue fluorescent when illuminated with blue light (375 to 400 nm). This allows a better recognition of the neoplastic forms for both diagnostic and therapeutic purposes during TURB. This method has been used since May 1997 on 49 patients in whom bladder tumor was diagnosed either immediately or during postchemotherapy follow-up.

RESULTS

One hundred seventy-nine biopsies were taken of fluorescent and nonfluorescent areas (3.5 per patient) to check the effectiveness of the new method compared with standard cystoscopy. A good correlation was found between 5-ALA cystoscopy and the histopathologic diagnosis, with a good sensitivity (87%). The 5-ALA cystoscopy allowed the diagnosis of a tumor in 24 patients with negative standard cystoscopic findings. Furthermore, 5-ALA cystoscopy detected 7 cases of carcinoma in situ. Neither local nor systemic (because of endovesical instillation) side effects were noted.

CONCLUSIONS

We believe that 5-ALA could be routinely used in the diagnosis of superficial bladder tumors, as it was shown to improve the diagnostic sensitivity for carcinoma in situ and to reduce the risk of recurrence related to missed cancerous lesions or incomplete TURB.

Percutaneous sclerotization of simple renal cysts with 95% ethanol followed by 24-48 h drainage with nephrostomy tube

AIM OF THE STUDY

We propose some technique devices for treating simple renal cysts with percutaneous puncture (PCN) to reduce recurrences.

MATERIALS AND METHODS

Between January 1995 and December 1998, a series of 42 patients, 13 females and 29 males, ranging in age between 49 and 73 were treated for symptomatic kidney cystic disease. The cysts varied between 7.4 and 13.6 cm in diameter and from 100 to 570 cm(3) in volume. This technique consists of echo-guided emptying of the cyst, and slowly inserting a quantity of pure 95% ethanol, equivalent to about 1/3 of the cyst volume, into the cavity. This acts as a sclerosant agent on the cyst walls. The protocol of this technique also includes positioning a curled drainage catheter, for 24-48 h, in suction, to ensure a correct collapse of the cyst walls and to avoid cyst recurrence.

RESULTS

Of the 42 patients treated, only 4 did not complete the protocol. In 3 cases, the patients were not able to stand the procedure because of intense pain during cyst filling with alcohol. The other patient had intracystic hemorrhage. The results were evaluated by ultrasonography at 7 days post-operatively and then at 1, 3, 6, 9 and 12 months later. There was a further follow-up lasting from 12 to 36 months. Of 38 patients treated, 29 (76%) did not have any recurrence. 8 patients (21%) developed a small liquid layer of 3-4 cm, which did not enlarge in subsequent check-ups. We observed a recurrence, which spontaneously reduced in volume, only in 1 patient.

CONCLUSIONS

This procedure was simple to apply in an out-patient setting and used low-cost materials which are easily obtained. Moreover, the results appear to confirm the validity of this technique.

The deletion polymorphism of the angiotensin-converting enzyme is associated with nephroangiosclerosis

The D allele of the angiotensin-converting enzyme (ACE) gene has been linked with diabetic nephropathy and IgA glomerulonephritis and with faster renal disease progression. The association of this allele with nephroangiosclerosis has been scarcely investigated. We have tested this association in 45 hypertensive patients (all whites) with well defined nephroangiosclerosis (diagnosis established on the basis of renal biopsy in all cases) and moderate to severe renal failure. As studies of genetic association of small size often produce conflicting results, besides a control group of 343 Italian patients with essential hypertension and normal renal function, we elected to use also a very large control group of race-matched subjects taken from a meta-analysis of 27,565 whites. The proportion of patients with the D allele (64%) was higher in patients with nephroangiosclerosis than that in Italian hypertensives (54%) and in whites (54%). DD and DI genotypes were more prevalent in patients than in control groups. The dominant model (DD and DI v II: nephroangiosclerosis v Italian controls: chi2 = 6.19, P = .012; nephroangiosclerosis v whites chi2 = 6.86, P = .009) fitted the data better than the codominant and the recessive model (P < or = .022). The D allele is associated with nephroangiosclerosis with a dominant effect in the sample of patients studied. Although intervention studies are needed to see whether these findings imply a causal association, our data suggest that this allele may at least act as disease marker in nephroangiosclerosis.

3 R study: renal outcome in renal ischemia: revascularisation or medical treatment

Ischemic nephropathy refers to the kidney damage following stenosis or an obstructive lesion in the main kidney arteries. This disorder has been overlooked in the past and a more rational and specific use of clinical criteria, and the development of not very invasive techniques with a good diagnostic accuracy such as spiral CT angiography, NMR angiography and echo-colour-Doppler have improved our ability to identify these patients. It is therefore likely that, in the next few years, we will find ourselves treating an increasing number of patients with renovascular ischemic disorders. Transluminal angioplasty and, more recently, the use of endovascular stents, have led to a marked improvement in the treatment of stenoses and, together with vascular surgery, allow to treat almost all patients with this disorder. There is, however, a lack of prospective and controlled studies, which demonstrate the long term benefit of revascularization treatment, as compared with optimum conservative treatment in reducing cardiovascular mortality, cardiovascular events and preserving renal function. The Ischemic Nephropathy Study Group of the Italian Society of Nephrology has organized a prospective, controlled study over a period of three years, aimed at comparing the effect of revascularization versus medical therapy in 300 patients with renal artery stenosis, ranging between 50 and 90 per cent, who will be randomly assigned to the two treatments. End point will be cardiovascular mortality and morbidity and need for renal replacement therapy.

Ischemic nephropathy

Ischemic nephropathy, involving stenotic lesions in the renal arteries, associated with renal insufficiency, is now recognized as a frequent disease. It may be responsible for a significant proportion of end stage renal disease, at least in the Caucasian population. Some non-invasive but reliable techniques such as echo-color-Doppler, gadolinium-enhanced magnetic resonance and spiral CT angiography are now available for diagnosis. Revascularization with either angioplasty, stent or surgery improves renal function in many patients. In the near future systemic and/or local medical therapy will provide better answers for renovascular disease.

Renovascular disease in diabetes mellitus: treatment by percutaneous transluminal renal angioplasty

BACKGROUND

Diabetes mellitus is an important cause of end-stage renal failure (ESRF). Although classic diabetic nephropathy accounts for the majority of patients reaching ESRF, renovascular disease, which is frequent in such patients, plays an increasingly important role. Percutaneous transluminal renal angioplasty (PTRA) has been proven to be an efficacious measure for renal revascularization.

METHODS

Ninety-nine patients with diabetes mellitus and renal artery stenosis, corresponding to 16.6% of the entire population of diabetic patients, were treated by PTRA or with the Palmaz-Schatz stent in our clinic. Technical success was achieved by PTRA in 92/99 patients, in 10 patients a Palmaz-Schatz stent was implanted.

RESULTS

Hypertension was cured in eight and improved in 44 patients. In 47 patients, there was no impact on blood pressure. An improvement in renal function was evident 1 month after PTRA in 8/27 patients. A further improvement occurred in another four patients after 6 months. The re-stenosis rate was 22% after 5 years. Serious complications occurred in seven patients (one patient required surgery and two patients had regular dialysis treatment).

CONCLUSIONS

Renovascular disease is an important cause of ESRF in diabetic patients. PTRA is a valid tool to revascularize renal artery stenosis and improve blood pressure control and renal function both in diabetic and non-diabetic patients.

Ischemic nephropathy: diagnosis and treatment

Recent epidemiologic studies have shown that ischemic nephropathy secondary to stenosis or obstruction of the main renal arteries in the cause of renal insufficiency in a growing number of subjects. The clinicians dealing with renovascular disease need non-invasive diagnostic tools and effective therapeutic measures to successfully face the problem. Duplex ultrasound scanning is a non-invasive, non expensive diagnostic tool and when an experienced, dedicated technologist is available, it should be suggested as the first-step test. Magnetic resonance angiography and spiral CT angiography play an ancillary role in detecting patients with renovascular disease. Captopril-enhanced (CE) scintigraphy when positive indicates the activation of intrarenal renin-angiotensin system and may be useful in detecting patients with renal artery stenosis. Moreover, CE scintigraphy can play an important role in the choice between the revascularization and a wait-and-see approach. As a matter of fact, the presence of an activated intrarenal renin-angiotensin system furnishes theoretical as well practical reasons in favour of the revascularization. In the recent years percutaneous transluminal renal angioplasty has become the cornerstone of therapeutic strategy. The introduction of the metallic stent has dramatically improved its efficacy in ostial stenoses and has reduced the indication for surgical revascularization.

The kidney as a victim of essential hypertension

Over the past decade the prevalence of end stage renal disease has risen progressively in industrialized societies. According to the data of renal disease Registries hypertensive nephrosclerosis appears to be a very important cause of progressive renal disease. However epidemiological data on the risk of hypertensive patients to develop renal failure offer contrasting results. In observational longitudinal studies a higher rate of decline in renal function is generally found in hypertensive compared to normotensive subjects. On the other hand, the inability of antihypertensive therapy to influence kidney destiny emerges from the large majority of interventional studies on mild-moderate hypertension in caucasian patients. At variance, the role of hypertension as etiologic factor seems to be sufficiently clear in African Americ: hypertension is more common, more severe and less easily to handle in a black patients. It is probable that the diagnosis of hypertensive nephrosclerosis is a confounding label laidon a heterogeneous group of diseases comprising a true hypertensive nephropathy (typical of black patients) along with occlusive or atheroembolic diseases common in aged caucasian patients. Our future efforts will have to be directed towards better identifying and properly classifying the various subgroup in order to optimize the treatment and prevent renal failure.

Recent data on hypertension and progressive renal disease

Arterial hypertension may favour the progression of non-diabetic primary renal disease and participate in the appearance of atheromatous renovascular disease. In AIPRI trial (ACE-inhibition in the progression of renal insufficiency) the ACE-inhibitor benazepril was able to protect patients with mild-to-moderate renal disease against the progression of renal insufficiency. Some clinical observations suggest that in many aged patients with long-standing hypertension the appearance of renal failure may be related to atheromatous reno-vascular disease. This disease may be responsible for progressive renal failure through renal artery stenosis and/or cholesterol microembolization.

Hypertension and renal dysfunction

The various end-stage renal disease registries have documented a progressive and substantial increase of hypertension as a cause of renal failure. However, the relationship between essential hypertension and progressive renal disease is unclear. Black hypertensive patients, who are more prone to renal failure during their middle age, have a peculiar hypertensive nephropathy possibly requiring an aggressive antihypertensive therapy. Hypertension-associated progressive renal disease in the Caucasian population usually appears in the elderly and may be related to atheromatous renovascular disease. Only a few hypertensive patients have a true progressive hypertensive nephrosclerosis.

Renal artery angioplasty for renovascular hypertension and preservation of renal function: long-term angiographic and clinical follow-up

OBJECTIVE

Percutaneous transluminal angioplasty of stenoses of the renal artery can be used to treat hypertension and renal insufficiency. Although many studies have been published on the short-term results of this procedure, few long-term studies are available.

SUBJECTS AND METHODS

One hundred ninety-five patients (123 men and 72 women 19-79 years old; mean age, 56 years) with stenosis of the renal artery and hypertension underwent renal percutaneous transluminal angioplasty at our institution. The stenosis was unilateral in 66% of patients, bilateral in 26%, and in a solitary functioning kidney in 8%. Renal insufficiency was present in 31% of patients. After renal percutaneous transluminal angioplasty, long-term clinical and angiographic follow-up was evaluated by life-table analysis.

RESULTS

In patients with fibromuscular disease, blood pressure returned to normal in 57%, improved in 21%, and was unchanged in 21%. In patients with atherosclerotic stenosis, blood pressure returned to normal in 12%, improved in 51%, and was unchanged in 37%. After percutaneous transluminal angioplasty, renal function improved in 48% of patients with renal insufficiency due to bilateral stenosis or stenosis in the single functioning kidney, whereas none of the patients with unilateral stenosis of renal artery and renal insufficiency had any notable improvement. Long-term follow-up showed a high rate (82%) of patency of revascularized arteries and a low rate (21%) of hypertension recurrence at 5 years.

CONCLUSION

Renal percutaneous transluminal angioplasty is useful for treating hypertension and for reestablishing renal function. Its effects on blood pressure and renal function are long-lasting in the large majority of patients.

The diagnostic dilemma of hypertensive nephrosclerosis: the nephrologist's view

The appearance of progressive renal disease in elderly patients with essential hypertension, sometimes irrespective of blood pressure control, is frequently related to the association of hypertension and atheromatous renal disease. This disease may lead to renal failure through a renal artery stenosis and/or chronic microembolization into the kidney. Nonsevere uncomplicated essential hypertension is constantly associated with renal vascular changes that are qualitatively indistinguishable from those related to aging. Notwithstanding the fairly constant presence of so-called benign hypertensive nephrosclerosis in patients with established hypertension, only a subset of these patients show progressive renal damage. Three mechanisms of progression may be at play: (1) a combination of ischemic and hypertensive glomerular mechanisms in some susceptible humans; (2) nonhemodynamic factors such as local immune mechanisms; or (3) the involvement of metabolic abnormalities which favor glomerulosclerosis.

Fibromuscular dysplasia of the renal arteries associated with antiphospholipid autoantibodies: two case reports

A relationship appears to exist between antiphospholipid autoantibodies (APLA) and vascular occlusion, although the exact mechanism is still a matter of debate. We present and comment on two cases of renal artery occlusion in patients with concomitant presence of arterial fibromuscular dysplasia and high APLA titers.

Long-term comparison between captopril and nifedipine in the progression of renal insufficiency

To verify the hypothesis that angiotensin-converting enzyme (ACE) inhibitors possess a unique renoprotective effect in progressive chronic renal disease, we decided to compare the effects of an ACE inhibitor and a calcium antagonist on both hypertension and the progression of non-diabetic renal insufficiency in a long-term study. A four-year, multicenter, prospective, randomized trial was conducted on 142 hypertensive patients (pts) with established chronic renal failure from six Italian nephrology departments. They were on standard antihypertensive therapy with a low-protein diet and underwent twice-monthly surveillance for a one year pre-randomization period. After that year, 121 pts were randomly allocated to captopril or slow-release nifedipine therapies for a three-year study period. The progression of renal insufficiency was monitored every two months. Blood pressure control was significantly better after randomization than during the year of standard antihypertensive therapy. The progression rate before randomization (BR) was definitely higher before than after randomization (AR): Creatinine clearance (CCr) change BR = -0.46 +/- 0.45 ml/min/month, creatinine clearance change AR = -0.23 +/- 0.43 ml/min/month (P less than 0.01). After randomization, the mean blood pressure values were virtually the same throughout the three year period of the study in the two groups treated by captopril (group I), or nifedipine (group II).(ABSTRACT TRUNCATED AT 250 WORDS)

[Duplex and Doppler color echocardiography for the study of renovascular hypertension. Comparison with arteriography]

Doppler US was employed to examine 46 patients with suspected renovascular hypertension (RVI) to detect stenosis/occlusion of the renal artery. In 25 cases duplex-Doppler technique was used, in 19 color-Doppler US, and 2 patients were examined with both methods. Doppler US was always performed before angiography which was considered as the reference gold standard. Using duplex-Doppler US, the diagnosis of renal artery stenosis was based on qualitative (spectral analysis of the waveform and absence of flow signal in cases of renal artery occlusion), and semiquantitative parameters (resistive index). Diagnostic accuracy of duplex US--which was compared with that of angiography--was 83%, its sensitivity was 91.6%, and specificity was 85%. With color-Doppler, two additional quantitative parameters were used (peak systolic frequency shift at the stenosis and stenosis index). In this group of patients sensitivity was 70%, specificity was 100%, and accuracy 85%. The good diagnostic yield of the method is counter-balanced by some limitations--e.g., operator dependence and long examination time (30-40 minutes, especially with duplex US). In the authors' opinion, Doppler technique can be used in the diagnosis of RVI, even though further study is necessary to exactly define diagnostic parameters, and to verify reproducibility and both inter- and intra-observer repeatibility. Technological progress may in the future reduce both difficulty and time of the examination.

Renal functional reserve in patients with a reduced number of functioning glomeruli

Renal functional reserve (RFR) has been reported to be either reduced or absent in patients with renal insufficiency. Our study consisted in measuring RFR by acute protein load (PL) in 3 groups of patients: the first one was composed of 20 patients (pts) with biopsy-proven glomerular disease (GN) and a varying percentage of sclerotic glomeruli (15-70%); the second one consisted of 10 patients with acquired single kidney (SK) and the third group contained 5 patients with surgical ablation of more than 50% renal tissue (LRRM). Twenty-four healthy volunteers were studied as control subjects. The GFR percentage increase (delta GFR%) after PL in CS did not differ from that of the three groups of patients, despite a significant difference in resting GFR (CS = 113 +/- 11 ml/min/1.73 m2: GN 72 +/- 28 ml/min/1.7, p less than 0.01 vs CS; SK 81 +/- 20 ml/min/1.73 m2, p less than 0.01 vs CS; LRRM 45 +/- 10 ml/min/1.7, p less than 0.01 vs CS; Moreover, an inverse correlation was not found either between GFR and the percentage of sclerotic glomeruli in GN (r = 0.01, p = NS) or between GFR and the extent of excised renal tissue in the other two groups (r = 0.38, p = NS). In conclusion, our data do not confirm that RFR is necessarily reduced or absent in patients with a reduced number of functioning glomeruli, nor do they uphold the hypothesis of constant hyperfiltration in the remaining glomeruli.