Influence of converting enzyme inhibition on glomerular filtration rate and proteinuria

A pilot randomized controlled trial of renal protection with pioglitazone in diabetic nephropathy

BACKGROUND

Diabetic nephropathy progresses relentlessly to end-stage renal disease (ESRD). Animal experiments have found that peroxisome proliferator activated receptor-gamma (PPAR-gamma)-based therapy can have a glucose independent effect on renal protection. We hypothesized that PPAR-gamma-based antidiabetic therapy would result in greater reduction in proteinuria compared to sulfonylurea-based therapy.

METHODS

In 44 patients with overt diabetic nephropathy, an open-label, blinded end point trial was conducted in which subjects were randomized to either pioglitazone or glipizide to achieve similar glucose control. Proteinuria was assessed by two collections of 24-hour urine samples each month for 4 months.

RESULTS

The glipizide group had an adjusted mean increase in proteinuria of 6.1% (95% CI -11.7%, 23.8%), whereas the pioglitazone group had a reduction of 7.2% (95% CI -24.9%, 10.6%). The adjusted reduction with pioglitazone of 13.2% (95% CI -38.4%, 11.9%) was not statistically significant (P= 0.294). Baseline proteinuria, diastolic ambulatory blood pressure, and serum albumin concentration were independent predictors of reduction in proteinuria. The frequency and patterns of adverse events were similar in the two groups.

CONCLUSION

In patients with advanced diabetic nephropathy, we found no reduction in proteinuria over 4 months. These data are useful to design larger studies with longer duration of follow-up to demonstrate renal protection of PPAR-gamma agonists.

Pediatric IgA nephropathies: clinical aspects and therapeutic approaches

The pediatric IgA nephropathies are IgA nephrothapy (Berger's Disease) and Henoch-Schönlein purpura nephritis. Both conditions are reviewed in detail with respect to epidemiology, clinical features, outcome, prognostic markers, and therapeutic approaches. For both conditions variable disease severity and outcome along with the lack of conclusive evidence for efficacy of treatment based on randomized clinical trials makes it difficult to make strong recommendations regarding therapy.

A randomized controlled trial of mycophenolate mofetil in patients with IgA nephropathy [ISRCTN62574616]

BACKGROUND

IgAN is the most common type of glomerulonephritis in the world. Between 15 and 40 percent of adults and children diagnosed with IgAN eventually progress to ESRD. Despite the need for effective treatment strategies, very few RCTs for IgAN have been performed. The most effective therapies for IgAN appear to be corticosteroids, ACEi, and FOS that contain a high concentration of omega 3 fatty acids. While ACEi and FOS are generally well tolerated with minimal side effects, the use of high dose steroids over a long course of therapy is often associated with significant morbidity.

OBJECTIVE OF THE STUDY

The objective of the study is to test the hypothesis that treatment with the immunosuppressive agent, MMF, will lead to significant and sustained improvement in urinary protein excretion in patients with IgAN who have been pre-treated (and continue to be treated) with ACEi and FOS compared to a placebo control group of patients receiving comparable doses of ACEi and FOS without MMF.

DESIGN

After a three month treatment period with the ACEi, lisinopril and the FOS, Omacor, 100 (2 x 50) patients with IgAN and a urinary P/C ratio > or = 0.6 (males) and > or = 0.8 (females) and an estGFR > or = 40 ml/min/1.73 m2 will be randomized to treatment with either MMF or placebo for one year. All patients will be followed off study drug for a second year, but will continue treatment with lisinopril and Omacor for the two year duration of the study. The primary outcome measure of change in urine P/C ratio will be assessed at the end of years one and two.

Long-term antiproteinuric and renoprotective efficacy and safety of losartan in children with proteinuria

BACKGROUND

Angiotensin receptor antagonists are effective in reducing proteinuria by an action independent of blood pressure. As a consequence, such agents retard progressive renal dysfunction in adults with chronic proteinuria. Long-term efficacy and tolerability data in children are unavailable.

METHODS

Efficacy of losartan in reducing proteinuria and in preserving renal function was prospectively assessed in 52 consecutive children under 18 years of age with chronic proteinuric renal disorders, an initial creatinine clearance > or =25 mL/min/1.73 m(2), and a minimum of two or more follow-up visits. Thirty had proteinuria (P), and 22 had proteinuria combined with hypertension (P+H). Adverse effects were also evaluated.

RESULTS

Proteinuria had persisted or increased during a mean interval of 8.5 months before initiation of losartan at a mean dosage of 0.8 mg/kg/d. Mean protein excretion before starting losartan was 2453 mg/m(2)/d and fell by 34% at a mean follow-up time of six weeks (visit I, P<.05), and between 64% and 67% at mean follow-up periods of 0.38, 0.71, and 2.48 years corresponding to visits II, III, and IV (all P<.001 compared with baseline). The proportion of children with protein excretion exceeding 40 mg/m(2)/h (nephrotic range proteinuria) or nephrotic syndrome (>3500 mg/1.73 m(2)/d) fell from 42% and 40% at the start, to 24% and 8%, respectively, at visit IV (P<.01). Mean creatinine clearance as well as serum potassium and total CO(2) levels remained unchanged during the time of follow-up. Reduction in proteinuria in the P subgroup alone correlated with lowering in diastolic blood pressure at visit II and with both diastolic and systolic blood pressure at visits III and IV (all P<.05); it was largely independent of reduction in blood pressure in the P+H subgroup. The concomitant use of immunosuppressive agents in 28 of the 52 children had an influence on proteinuria only at baseline and at visit I (P<.05). There was no significant change in height or body mass index Z scores. Thirteen children had adverse effects potentially ascribed to losartan; most of these either improved or resolved with dosage adjustment or resulted in its discontinuation in 9 of the 52 children (17%).

CONCLUSION

Losartan therapy was associated with a marked and sustained reduction in proteinuria and in preservation of GFR in children with chronic proteinuric disorders. The association between proteinuria and systemic blood pressure reduction was complex: it was largely limited to the first year of losartan therapy and was more pronounced in the normotensive subgroup. Losartan was generally well tolerated.

The comprehensiveness care of sickle cell disease

Millions of people across the world have sickle cell disease (SCD). Although the true prevalence of SCD in Europe is not certain, London (UK) alone had an estimated 9000 people with the disorder in 1997. People affected by SCD are best managed by a multidisciplinary team of professionals who deliver comprehensive care: a model of healthcare based on interaction of medical and non-medical services with the affected persons. The components of comprehensive care include patient/parent information, genetic counselling, social services, prevention of infections, dietary advice and supplementation, psychotherapy, renal and other specialist medical care, maternal and child health, orthopaedic and general surgery, pain control, physiotherapy, dental and eye care, drug dependency services and specialist sickle cell nursing. The traditional role of haematologists remains to co-ordinate overall management and liase with other specialities as necessary. Co-operation from the affected persons is indispensable to the delivery of comprehensive care. Working in partnership with the hospital or community health service administration and voluntary agencies enhances the success of the multidisciplinary team. Holistic care improves the quality of life of people affected by SCD, and reduces the number as well as length of hospital admissions. Disease-related morbidity is reduced by early detection and treatment of chronic complications. Comprehensive care promotes awareness of SCD among affected persons who are encouraged to take greater control of their own lives, and achieves better patient management than the solo efforts of any single group of professionals. This cost-effective model of care is an option for taking haemoglobinopathy services forward in the new millennium.

Effect of pre-and postoperative plasmapheresis on posttransplant recurrence of focal segmental glomerulosclerosis in children

BACKGROUND

Posttransplant recurrence is frequent in patients who received renal transplantation for focal segmental glomerulosclerosis (FSGS). The recurrence has been ascribed to a circulating permeability factor or factors. We have used plasmapheresis (PP) to treat recurrent FSGS and also studied whether preoperative PP is effective in preventing recurrence of FSGS.

METHODS

We retrospectively analyzed 21 allografts of 20 patients with nephrotic syndrome and biopsyproven FSGS. They were divided into two groups depending on whether they had prophylactic PP; a prophylactic (n=15) and a nonprophylactic group (n=6). PP was performed two to three times prophylactically and therapeutically until proteinuria was markedly reduced. In each session, 50-75 ml/kg of the patient's plasma was exchanged with 5-8% albumin.

RESULTS

FSGS recurred in 9 of 21 allografts, 4 of 6 in the nonprophylactic group, and 5 of 15 in the prophylactic group. Therapeutic PP was performed in seven of nine recurrent patients without definite adverse effect, with satisfactory results except in one patient. Children lost proteinuria after 6 to > 100 sessions of PP and the number correlated with the pretreatment level of proteinuria. The mean follow-up periods were 62.7 and 41.6 months for the prophylactic and nonprophylactic groups, respectively. At the last follow-up, 66.7% of relapsing and 81.8% of nonrelapsing patients had a functioning graft.

CONCLUSION

PP appears to be effective for the prevention and treatment of posttransplant recurrence of FSGS, although further consideration of cost/benefit and risks is required before a conclusive judgement can be made.

A subdepressor low dose of ramipril lowers urinary protein excretion without increasing plasma potassium

Angiotensin-converting enzyme (ACE) inhibitors are increasingly administered to patients with chronic renal disease. One issue of concern with the use of ACE inhibitors in patients with impaired renal function is the possible development of hyperkalemia. We reasoned that the impact of ACE inhibitors on plasma potassium could be minimized by administering these agents at very low doses. To examine this issue, we investigated the effect of a low dose of ramipril (1.25 mg orally once daily) and an eight-fold higher dose (10 mg orally once daily) on plasma potassium in 13 patients with proteinuria and mild chronic renal insufficiency. The study was divided into four phases: placebo (4 weeks), low-dose ramipril (8 weeks), high-dose ramipril (8 weeks), and washout phase (4 weeks). With the low dose of ramipril, urinary protein excretion decreased significantly as early as after 1 week of administration (from 4.4 +/- 0.5 to 3.7 +/- 0.4 g/24 h; P < 0.025) and did not decrease any further thereafter even when the dose was increased eight-fold. Mean arterial blood pressure and plasma potassium did not change significantly with the low dose of ramipril, whereas with the higher dose, mean arterial blood pressure decreased significantly (from 107 +/- 2.0 to 100 +/- 2.0 mm Hg, P < 0.005), and plasma potassium increased significantly (from 4.53 to 4.78 mEq/L, P < 0.05). We conclude that a low dose of ramipril can reduce proteinuria to the same extent as an eight-fold higher dose without significantly lowering blood pressure or increasing plasma potassium. This latter feature may be advantageous for the treatment of patients at risk for hyperkalemia who require ACE inhibitors.

Nephroprotective effect of antihypertensive drugs in essential hypertension

BACKGROUND

Effective antihypertensive treatment has prevented target-organ involvement in hypertension, markedly reducing morbidity and mortality from strokes, coronary heart disease, cardiac failure, and hypertensive emergencies. However, the incidence of hypertension-related end-stage renal disease continues to increase, suggesting that therapeutic reduction in arterial pressure by itself is not sufficient to prevent the development of hypertensive renal failure.

OBJECTIVE

To examine experimental and clinical data concerning the protective effect of reduction of arterial pressure on the progression of hypertension-related renal disease, and the evidence indicating that some antihypertensive agents may afford more nephroprotection, over and above that attributable to reduction of arterial pressure.

RESULTS

Results of numerous studies clearly indicate that adequate control of arterial pressure, irrespective of the antihypertensive agent used, slowed the progression of renal disease. Results of some studies suggest that lowering arterial pressure below the level that is usually considered adequate has an additional beneficial effect by slowing the progression of renal injury.

CONCLUSION

Results of a number of studies evaluating nephroprotective effects of various drugs and regimens have indicated that certain agents, most notably angiotensin converting enzyme inhibitors and their combination with calcium antagonists, afford more protection than do others at similar levels of reduction of arterial pressure. Results of still other studies suggest that certain agents that exert greater nephroprotection are more efficient at controlling arterial pressure. Therefore, further data are needed before any final conclusion can be drawn. However, it is clear that, in order to establish nephroprotection in patients with essential hypertension, the problem should not be further complicated by additional comorbid diseases such as diabetes mellitus.

Effects of captopril on morphologic changes in kidney of spontaneously hypertensive rats with adriamycin nephropathy

Antihypertensive therapy has been shown to slow down the progression of chronic renal failure. Angiotensin converting enzyme inhibitors and calcium antagonists have been emphasized as the agents with the most protective effect. Our previous study showed that captopril slowed down renal function deterioration in the early course of adriamycin (ADR) nephropathy in spontaneously hypertensive rats (SHR). The present study was undertaken with the aim to examine morphologic changes associated with that slower renal function deterioration. Adult (24 weeks) female SHR were randomly divided into the following groups: the control group (n = 12) was given tap water to drink; the adriamycin (ADR) group (n = 25) was treated with ADR; the ADR-captopril (ADR-C) group (n = 27) was treated with ADR and thereafter with captopril (60 mg/kg/day). Rats were sacrificed at weeks 6, 12 and 18 and histologic analysis was semiquantitatively performed. In the control group the glomeruli exhibited only minor changes at the end of the study. In the ADR group slight glomerular mesangial hypercellularity appeared in the sixth week and progressed in focal and segmental sclerosis. Some glomeruli showed segmental proliferation and increased fibrular matrix of a tuft adherent to a fibrocellular crescents. In the ADR-C group, glomeruli with a slight increase of mesangial matrix were seen at the end of the sixth week, mesangial hypercellularity developed until the end of the sixth week, mesangial hypercellularity developed until the end of the 12th week and segmental glomerulosclerosis until the end of the study. Semiquantitative analysis revealed that the mean semiquantitative scores for mesangial expansion and glomerular sclerosis were significantly lower in ADR-C group than in ADR group throughout the study. We concluded that captopril slowed down mesangial expansion and reduced the development of glomerular sclerosis.

A comparison of the effect of ramipril, felodipine and placebo on glomerular filtration rate, albuminuria, blood pressure and vasoactive hormones in chronic glomerulonephritis. A randomized, prospective, double-blind, placebo-controlled study over two years

The effects of an ACE-inhibitor (ramipril), a calcium antagonist (felodipine) and placebo on glomerular filtration rate (GFR), urinary albumin/creatinine ratio, blood pressure (BP) and vasoactive hormones were investigated in a randomized, prospective, double-blind, placebo-controlled study of patients with chronic glomerulonephritis and hypertension, with measurements at entrance and after 12 and 24 months. In total, 33 patients were included: 21 completed the study with 7 patients in each group. GFR was measured as 51Cr-EDTA clearance and the vasoactive hormones with radioimmunoassays. The reduction in GFR was significantly more pronounced in the felodipine group (-7 ml/min) than in the ramipril group (0 ml/min) but the same as in the placebo group (-6 ml/min). The urinary albumin/creatinine ratio was significantly more reduced in the ramipril group (-74 mg/mmol) than in the placebo group (-11 mg/mmol), which did not deviate from the felodipine group (-10 mg/mmol). BP was significantly reduced by ramipril and felodipine, but not by placebo. Angiotensin II and aldosterone in plasma increased or tended to increase in the felodipine and placebo groups, but were unchanged in the ramipril group. Endothelin increased only in the placebo group, and vasopressin, atrial natriuretic peptide, and brain natriuretic peptide were not significantly changed in any of the groups. It is concluded that ramipril seems to be superior to felodipine in chronic glomerulonephritis owing to better preservation of GFR.

Renal failure in sickle cell anemia

ESRD is a major complication in young adults with sickle cell anemia. As more patients with sickle cell anemia reach the third and fourth decades of life, the incidence of clinically apparent renal insufficiency will increase. As we understand the pathophysiology of renal damage and the effects of various therapies on the sickle renal vasculature, we can tailor specific management without further compromising already impaired renal function. Diagnostic clues must be recognized prior to the onset of irreversible damage, with appropriate intervention initiated at each age group. Bone marrow transplantation (BMT) is the only available cure for SCA at the present time. The demonstration that several distinct haplotypes of the beta s gene cluster on chromosome 11 influence the clinical expression of sickle cell anemia may be useful in delineating children who are at high risk for severe disease, and hence candidates for such hazardous therapeutic interventions as BMT prior to onset of clinically discernable disease. Current BMT preparative regimens can produce renal cortical and pulmonary toxicity, posing a patient selection problem in those cases in which the vasculopathy of the major organs is at an early stage and might be potentially repairable. Gene therapy without toxic preparative regimens is the ultimate answer. The challenge for the near future is the development of effective early therapeutic intervention during childhood and young adulthood.

Effect of ramipril on blood pressure and protein excretion rate in normotensive nondiabetic patients with proteinuria

Angiotensin-converting enzyme inhibitors reduce proteinuria in both normotensive and hypertensive patients with proteinuric renal disease. However, the mechanism of the antiproteinuric effect has not been clarified. We performed a prospective, double-blind, placebo-controlled, randomized crossover trial to test the hypothesis that the antiproteinuric effect of ramipril was due to an improvement in glomerular permselectivity independent of blood pressure and glomerular filtration rate. The effect of low-dose (1.25 mg/d) and high-dose (5 mg/d) ramipril was assessed in 15 normotensive nondiabetic patients with proteinuria (> 150 mg/d). The study was divided into four 12-week periods: placebo, high- or low-dose ramipril, crossover to low- or high-dose ramipril, and placebo. Blood pressure, glomerular filtration rate, renal plasma flow rate, urinary protein excretion rate, and plasma angiotensin II levels were measured at the end of each period. Mean arterial pressure, urine protein to creatinine ratio, and albumin excretion rate decreased significantly during low- and high-dose ramipril. Glomerular filtration rate and renal plasma flow rate were not changed significantly. Plasma angiotensin II levels decreased with both low- and high-dose ramipril. There were no episodes of hypotension and only one subject developed cough during ramipril that did not require discontinuation of the study drug. In conclusion, administration of ramipril in both low and high doses lowered blood pressure and reduced proteinuria in this cohort of normotensive patients with a variety of proteinuric renal diseases. The antiproteinuric effect of ramipril is probably mediated by a reduction in glomerular capillary pressure.

Effect of plasma protein adsorption on protein excretion in kidney-transplant recipients with recurrent nephrotic syndrome

BACKGROUND

Among patients with the idiopathic nephrotic syndrome who have focal and segmental glomerulosclerosis and undergo renal transplantation, 15 to 55 percent have recurrent nephrotic syndrome. The recurrence may be caused by a plasma factor or factors that increase glomerular permeability, because plasma exchange transiently decreases or abolishes proteinuria in some patients. We studied the effect on proteinuria of the removal of protein (mostly immunoglobulins) by adsorption onto protein A from the plasma of patients with recurrent nephrotic syndrome.

METHODS

Eight patients were treated with one to three cycles of two to seven 1-day sessions of protein adsorption, and the patients' urinary protein excretion was measured repeatedly. Their immunosuppressive regimens were not changed during the treatment. The adsorbed proteins were eluted from the protein A and injected into rats, and the urinary albumin excretion of the rats was measured.

RESULTS

The protein-adsorption treatment consistently decreased urinary protein excretion by an average of 82 percent at the end of a cycle (P < 0.001). In one patient proteinuria disappeared, and in another urinary protein excretion remained below 2.5 g per day with repeated cycles of protein adsorption. In all but one patient the effect of adsorption was limited in time, with a return to the preadsorption level of protein excretion within a maximum of two months. The administration to rats of material eluted from the protein A increased urinary albumin excretion 2.9- to 4.6-fold (P < 0.001 and P = 0.005, respectively). Although protein A primarily binds immunoglobulins, the active fraction of the eluted proteins had a molecular weight below 100,000, indicating that immunoglobulin was not directly involved.

CONCLUSIONS

Adsorption of plasma protein decreases urinary protein excretion in patients with recurrence of the nephrotic syndrome after renal transplantation. Studies of the adsorbed proteins should provide information about the mechanism of this disease.

Captopril inhibits the 72 kDa and 92 kDa matrix metalloproteinases

Gelatinases are metalloproteinases in the kidney which can cleave type IV collagen as well as gelatin. We partially purified the 72 kDa and 92 kDa gelatinases. The gelatinolytic activity was measured by zymography and a quantitative biotin-avidin assay. By zymography, captopril in concentrations of 20 mM and 40 mM added to the incubation buffer reduced the gelatinolytic activity in a dose-dependent manner. The addition of zinc in a concentration of 50 to 100 microM reversed most of the inhibitory effect of captopril. By the biotin-avidin assay, captopril in a concentration of 30 to 50 nM reduced half of either the 72 kDa or 92 kDa gelatinolytic activity. Zinc in a concentration of 50 microM completely reversed the inhibitory effect of 1 microM captopril on both gelatinases. Lisinopril, a non-sulfhydryl ACE inhibitor, similarly inhibited the gelatinases, but a 100-fold higher concentration of the drug was needed. These findings suggest that captopril reversibly inhibits the 72 kDa and 92 kDa metalloproteinases by interacting with the zinc ion at their active sites. This inhibitory effect is observed with captopril levels comparable to the concentrations needed to inhibit the angiotensin converting enzyme in vivo and may at least partially explain some of the renoprotective effects seen with this drug.

Angiotensin-converting enzyme inhibitors in the treatment of mild arterial hypertension

Angiotensin-converting enzyme inhibitors are nowadays widely employed for the treatment of arterial hypertension. They exhibit comparable levels of efficacy and better tolerability when compared with the other antihypertensive agents. In mild arterial hypertension they have been shown to be more efficacious than nonpharmacological therapy that is recommended as the first-step therapeutic approach for most cases of this type of hypertension. Potential advantages for the control of associated metabolic risk factors and specific renal and cardiac effects make these drugs suitable for the first step pharmacological therapy on mild hypertension.

Long-term benefits of the antiproteinuric effect of angiotensin-converting enzyme inhibition in nondiabetic renal disease

The long-term (1.5 years) effects of angiotensin-converting enzyme inhibition were evaluated in 22 mostly normotensive patients with nondiabetic renal disease and moderate to severe proteinuria. The nephrotic-range proteinuria of 7.5 g/24 hr fell to 2.9 g/24 hr (-62%) after 2 months' treatment with an angiotensin-converting enzyme inhibitor and remained relatively stable at this level during continued treatment. The antiproteinuric response varied between study days and between individuals. Of note was the fact that the best antiproteinuric response was observed on those study days when no more than the instituted daily sodium intake (50 to 100 mEq/24 hr) was excreted. The sustained reduction in urinary protein excretion was accompanied by an increase in serum albumin and a slight but significant decrease in serum cholesterol. Those patients with the most pronounced initial antiproteinuric response showed less deterioration of renal function, estimated from the slope of the inverse serum creatinine value in time. These data suggest that long-term angiotensin-converting enzyme inhibitor treatment may be beneficial in normotensive patients with nephrotic-range proteinuria, not only to reduce the symptoms of a nephrotic syndrome, but also to prevent further renal damage.

Renal hemodynamics and reduction of proteinuria by a vasodilating beta blocker versus an ACE inhibitor

The effects of a nonselective beta-adrenergic blocking drug with beta-2 agonist activity (dilevalol 200 mg) on proteinuria and renal hemodynamics were evaluated in a double-blind crossover study versus an ACE inhibitor (enalapril 5 mg) in eight patients with glomerulonephritis, moderate renal function impairment and proteinuria greater than 1 g/24 hr. Patients were studied after a one week placebo phase while off all other medications, except steroids in a few cases, and after three weeks of treatment. A 10-day placebo washout perod was included between the various drug treatments. During each period renal hemodynamics were measured by clearance techniques, and urinary protein excretion as well as fractional clearance of albumin and IgG were determined. Both drugs reduced mean arterial pressure and proteinuria to a similar extent [mean arterial pressure: placebo 108 +/- 13 mm Hg; dilevalol 103 +/- 11 mm Hg (P less than 0.05); enalapril 103 +/- 12 mm Hg (P less than 0.05); protein excretion: placebo 5.1 +/- 4.2 g/day; dilevalol 3.3 +/- 3.0 g/day (P less than 0.05); enalapril 2.8 +/- 2.8 g/day (P less than 0.05)]. The antiproteinuric effect was greater with enalapril than dilevalol. Dilevalol reduced GFR [baseline inulin clearance: 73.3 +/- 38 ml/min/1.73 m2; after dilevalol: 63.3 +/- 28 ml/min/1.73 m2 (P less than 0.05)] and the decrease of proteinuria correlated positively with the reduction of GFR. Enalapril did not significantly lower the GFR (inulin clearance during enalapril 66.8 +/- 23 ml/min/1.73 m2) and the reduction of proteinuria did not correlate with the lowering of the GFR.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence and pathologic features of sickle cell nephropathy and response to inhibition of angiotensin-converting enzyme

BACKGROUND

Nephropathy may develop in patients with sickle cell disease. We determined the prevalence of proteinuria and renal insufficiency in a group of patients with sickle cell disease and investigated the renal pathologic changes and the effects of an angiotensin-converting-enzyme inhibitor (enalapril) on protein excretion in patients found to have nephropathy.

METHODS

We prospectively screened 381 patients with sickle cell disease for the presence of proteinuria and renal insufficiency. Renal biopsy and measurements of glomerular filtration rate, effective renal plasma flow, and urinary protein excretion were performed in 10 patients with mild nephropathy before and after the administration of enalapril, and again two to three weeks after its discontinuation.

RESULTS

Of the 381 patients with sickle cell disease, 26 (7 percent) had serum creatinine concentrations above the normal range and 101 (26 percent) had proteinuria of at least 1+. The renal lesions in the 10 patients who had biopsies consisted of glomerular enlargement and perihilar focal segmental glomerulosclerosis. The mean (+/- SD) glomerular area in these patients was 28.7 +/- 4.1 x 10(3) micron 2, as compared with 15.8 +/- 4.3 x 10(3) micron 2 in 10 control patients without renal disease who had died of trauma (P less than 0.0001). During the administration of enalapril, the mean 24-hour urinary protein excretion decreased 57 percent (range, 23 to 79 percent) below the base-line value (P less than 0.001), and it increased to 25 percent below the base-line value after enalapril was discontinued. The glomerular filtration rate and effective renal plasma flow did not change significantly.

CONCLUSIONS

Approximately 25 percent of patients with sickle cell disease have proteinuria. Treatment with enalapril reduces the degree of proteinuria in these patients, suggesting that glomerular capillary hypertension may be a pathogenic factor in sickle cell nephropathy.