Pentoxifylline is as effective as captopril in the reduction of microalbuminuria in non-hypertensive type 2 diabetic patients--a randomized, equivalent trial

AIMS: To compare the efficacy of pentoxifylline and captopril on urinary albumin excretion (UAE) rate in non-hypertensive diabetic patients with microalbuminuria. METHODS: 450 subjects were screened; of these 130 eligible, non-hypertensive, type 2 diabetic subjects were enrolled and randomly allocated to receive either pentoxifylline 400 mg t.i.d. (n = 65) or captopril 25 mg t.i.d. (n = 65) for six months in a randomized equivalent trial design study. Patients were eligible to participate if they had microalbuminuria, defined by UAE rate of 20-200 microg/min, and systolic/diastolic blood pressure lower than 140/85 mmHg. Diagnosis of high blood pressure and renal failure were exclusion criteria. In addition, subjects receiving ACE inhibitors or pentoxifylline were not included. RESULTS: Both treatments were well tolerated, without serious adverse events; nonetheless, one subject (1.6%) in the group with pentoxifylline had severe headache, and three (4.7%) subjects in the group with captopril had intense dry cough and nasal congestion that required stopping pentoxifylline and captopril. In addition, slight headache and mild dry cough that did not require specific treatment or interruption of medication were present in two (3.2%) and five (7.8%) subjects treated with pentoxifylline and captopril. Four subjects dropped-out (one in the pentoxifylline group and three in the captopril group). Blood pressure and fasting glucose levels were similar between the two groups throughout the study. The UAE rate decreased from the first month of treatment in the subjects of both groups, a reduction that was sustained in the following months. At the end of the study, the average UAE rate in the subjects of both groups was lower than 25 microg/min. CONCLUSIONS: Pentoxifylline showed to be an effective alternative to ACE inhibitors in reducing UAE in non-hypertensive diabetic patients with microalbuminuria.     

Renal protection in diabetes: is it affected by glucose control or inhibition of the renin-angiotensin pathway?

BACKGROUND: Recent reports indicate increased risk of renal failure with long-term use of angiotensin-converting enzyme inhibitors (ACEI) in diabetes. End-stage renal disease (ESRD) in diabetes has increased despite ACEI and angiotensin receptor blocker (ARB) use. This study questions renal protection by ACEI or ARB. Our hypothesis is that uncontrolled hyperglycemia is central to diabetic ESRD while tight glucose control is renoprotective. Cultured endothelial cells show morphological damage that increases with duration of exposure to high glucose and is prevented by insulin and more so by a combination of insulin and heparin. METHODS: Findings from individual patients are compared to clinical trial results wherein ACEI or ARB was emphasized as the prime therapy to prevent progression of diabetic nephropathy to ESRD. Serum creatinine (Scr) changes were the main indicator of renoprotective effects in clinical trials. Creatinine clearance (Ccl), an important marker of glomerular filtration rate, was seldom reported. RESULTS: Our observations show that ACEI-treated patients develop progressive renal failure, whereas renal function remains stable with optimum glucose control. Clinical trials showed that reduction of proteinuria, with ACEI, reduces the risk of ESRD. Our studies show that reduction of proteinuria with use of ACEI or ARB parallels a reduction in Ccl, suggesting that a change in proteinuria is related to Ccl changes. Scr changes are small, giving a deceptive view of renal protection. CONCLUSIONS: Our observations find no evidence of renal protection with ACEI or ARB use in diabetes. Laboratory studies and clinical observations suggest that adequate glucose control is the key to renal protection in diabetes.     

舒洛地特对糖尿病肾病患者尿蛋白的影响

目的：观察舒洛地特对已应用ACEI/ARB类药物的2型糖尿病肾病患者尿蛋白的影响。方法：据尿白蛋白排泄率将92例2型糖尿病肾病患者分为微量白蛋白尿组和大量白蛋白尿组,患者在入组前至少服用一种ACEI或ARB类降压药6个月,入组后先接受10d舒洛地特注射剂60mg/d静脉滴注,再接受110d舒洛地特软胶囊100mg/d口服。用药前、用药4周、8周、12周及120d分别检测患者血压、空腹血糖、肝肾功能、凝血功能、24h尿蛋白定量等指标。结果：两组患者治疗12周后均出现尿蛋白显著降低（P0.05）。结论：对已应用ACEI/ARB的伴有微量白蛋白尿或大量白蛋白尿的2型DN患者,舒洛地特能有效降低其尿蛋白。     

Angiotensin-converting enzyme inhibitors versus AT1 receptor antagonist in cardiovascular and renal protection: the case for AT1 receptor antagonist

The development of pharmacologic agents that directly inhibit the angiotensin II receptor (angiotensin receptor blocker [ARB]) has provided clinicians with an alternative to the previously available angiotensin-converting enzyme inhibitors (ACEI) to downregulate the renin-angiotensin system. This review focuses on the available data that can guide the clinician to the use of these two classes of agents vis à vis their ability to provide cardiovascular (CV) and renal protection. Although the CV protective effect of ACEI in high-risk populations is widely appreciated, whether such an effect is entirely BP independent can be questioned. Most head-to-head comparisons between ACEI and ARB have yielded comparable CV protective effects, with ARB being associated with fewer adverse effects. Likewise, several-but not all-studies have demonstrated a CV protective effect of ACEI when compared with other active agents in patients with type 2 diabetes. One study demonstrated a similar protection with ARB when compared with a beta blocker. In terms of renal protection, there are ample data to support a role for both ACEI and ARB to prevent the progression from microalbuminuria to overt albuminuria in both type 1 and type 2 diabetes. However, when progression of renal disease is used as an end point, protection has been demonstrated with ACEI only for type 1 but not type 2 diabetes. In this latter group, only ARB have been shown to slow progression to ESRD.     

Vasopressin increases urinary albumin excretion in rats and humans: involvement of V2 receptors and the renin-angiotensin system.

BACKGROUND: An increase in urinary albumin excretion (UAE) represents an early predictor of glomerular damage in diabetes mellitus (DM) and a risk factor for cardiovascular complications in hypertension. Vasopressin is elevated in DM and in some forms of hypertension. Previous studies in rats suggested that this hormone could play a role in the albuminuria observed in chronic renal failure or diabetic nephropathy, but no information is available concerning the mechanism of these effects and the possible influence of vasopressin on UAE in the healthy kidney. The present study was thus designed to evaluate whether vasopressin influences UAE in normal rats and humans, whether this effect is V(2)-receptor-dependent, and whether it is mediated by the renin-angiotensin system. METHODS: UAE was measured in normal Wistar rats and healthy humans, or in subjects with various forms of diabetes insipidus (DI), before and after acute or chronic infusion of the vasopressin V(2) receptor agonist dDAVP. Chronic dDAVP administration was also performed in normal Wistar rats previously submitted to either chronic angiotensin-converting enzyme inhibition (ACEI) or chronic blockade of AT1 receptors (ARB). RESULTS: In rats, acute or chronic dDAVP infusion increased UAE significantly and reversibly (4-fold and 6-fold, respectively). In healthy subjects, acute infusion of dDAVP tripled UAE (P<0.01) but did not change creatinine and beta(2)-microglobulin excretion, thus suggesting that the rise in UAE was due to an increased glomerular leakage of albumin. dDAVP also increased UAE in patients with central DI and in patients with hereditary nephrogenic DI bearing AQP2 mutations. However, UAE was not increased in patients with hereditary nephrogenic DI bearing mutations of the V(2) receptor. In rats, ACEI and ARB blunted the dDAVP-induced rise in UAE by 70% (P<0.05) and 50% (NS), respectively. CONCLUSIONS: The present studies reveal for the first time that vasopressin induces a marked increase in UAE in healthy rats and humans. This albuminuric effect seems to result from increased glomerular leakage, requires functional vasopressin V(2) receptors, and is, at least in part, mediated by the renin-angiotensin system. These results bring additional support for an involvement of vasopressin in the albuminuria observed in pathological states such as diabetes mellitus or hypertension.     

Asymmetric Dimethylarginine (ADMA) and Progression of Nephropathy in Patients with Type 2 Diabetes

Diabetic nephropathy is the leading cause of kidney failure all over the world. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide (NO) synthase. ADMA is in part eliminated via urinary excretion. It is found to be elevated in end stage renal disease. Identification of the plasma concentrations of ADMA in patients with different stages of diabetic nephropathy compared with healthy age-matched control subjects for estimation of the role of ADMA as a marker of progression of kidney disease in diabetic patients. Seventy-five diabetic patients were divided into five groups: Group I: patients with normoalbuminuria (urinary albumin excretion UAE < 30 mg/d), Group II: patients with microalbuminuria (UAE: 30–300 mg/d), Group III: patients with macroalbuminuria (UAE > 300 mg/d), Group IV: patients one month after renal transplantation and Group V: patients on haemodialysis. Patients were compared to 15 healthy control subjects matched for age and sex. All subjects subjected to thorough clinical examination and laboratory investigations including: serum albumin, urea, creatinine, fasting and postprandial blood glucose, UAE, urinary albumin/creatinine ratio and serum ADMA level. All patients groups had significantly higher levels of ADMA when compared to control group P < 0.01. The levels of ADMA were positively correlated with disease progression and degree of proteinuria. ADMA can be used as a marker of progression of kidney disease among diabetic patients.     

When to initiate ACEI/ARB therapy in patients with type 1 and 2 diabetes

Angiotensin converting enzyme inhibitors (ACEI) and angiotensin 2 receptor blockers (ARB) have become a mainstay of adjunctive therapy for the prevention and amelioration of diabetic nephropathy. Although ACEI were shown over 20 years ago to slow the rate of loss of renal function in diabetic subjects with decreased renal function, the question of how early in the course of diabetes to introduce them remains unresolved. Recent studies suggest that very early initiation of ACEI/ARB therapy may not have demonstrable beneficial effects even over a period of years.     

Effects of sulodexide in patients with type 2 diabetes and persistent albuminuria.

BACKGROUND: Urinary albumin excretion frequently persists in diabetic patients who are treated with angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB). Sulodexide, a glycosaminoglycan mixture of 80% heparan sulfate and 20% dermatan sulfate, has been hypothesized to reduce persistent albuminuria. We have conducted a multi-center randomized double-blind pilot study in order to determine the effect of 6 months' therapy with sulodexide on urinary albumin excretion and to address logistical issues for a full-scale trial. METHODS: A total of 149 patients with type 2 diabetes and an albumin:creatinine ratio (ACR) between 20 and 300 mg/g were randomized with equal allocation to either placebo, 200 mg of sulodexide or 400 mg of sulodexide. The primary endpoint was the achievement, at 6 months, of either 3(1) return to normoalbuminuria (ACR < 20 mg/g with a decrease of at least 25%) or (2) a decrease in ACR of at least 50% from the baseline value. All patients used a maximum tolerated recommended FDA approved dose of an ACEI or ARB for at least 60 days and had stable blood pressure prior to randomization. RESULTS: The primary efficacy endpoint was achieved in 25.3% of the patients in the two sulodexide groups combined versus 15.4% of the placebo-treated patients (P = 0.26). The primary endpoint was achieved in 33.3% (P = 0.075 for the comparison to placebo) in the sulodexide 200 mg group and 18.4% (P = 0.781) in the sulodexide 400 mg group. (No consistent patterns of side effects were observed. CONCLUSION: Based on the experience gained in this pilot study, one full-scale trial is currently being conducted to evaluate the effects of sulodexide on change in ACR in patients with persistent microalbuminuria, and a longer-term trial is underway to evaluate the effects of sulodexide on long-term renal disease progression in patients with overt proteinuria.     

ACE-inhibitor or AT2-antagonist therapy of renal transplant recipients is associated with an increase in serum potassium concentrations.

BACKGROUND: Angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II type 1 receptor blockers (ARB) are frequently prescribed to renal transplant recipients with a reduced glomerular filtration rate (GFR). The aim of this study was to investigate the association of ACEI/ARB use and serum potassium levels in renal graft recipients. METHODS: We conducted an open cohort study of 2041 first renal allograft recipients, transplanted at the Medical University of Vienna between 1990 and 2003. Serum potassium levels were compared over an up to 10 years of observation period between subjects with versus without ACEI/ARB therapy using a mixed effects general linear model. The analysis was adjusted for several covariables known to influence serum potassium such as the use of diuretics, beta blockers, calcineurin inhibitor (CNI) based immunosuppression, estimated GFR, time since renal transplantation, diabetes, years on dialysis and recipient age. RESULTS: The overall adjusted estimated serum potassium difference between recipients with versus without ACEI/ARB therapy was 0.08 mmol/l (P < 0.001). The use of diuretics was associated with a 0.11 mmol/l (P < 0.001) lower potassium concentration whereas each GFR decrease by 10 ml/min led to an increase of 0.04 mmol/l (P < 0.001). CNI intake increased serum potassium by 0.06 mmol/l (P = 0.002). Furthermore, serum potassium increased by 0.17 mmol/l within the first decade after transplantation (P < 0.001) while holding the other covariables constant. No effect modification between ACEI/ARB and time since transplantation was observed. Nineteen subjects (2.4%) discontinued the ACEI/ARB therapy due to hyperkalaemia. CONCLUSIONS: In summary, relevant hyperkalaemia associated with ACEI/ARB therapy is negligible in renal transplant recipients during long-term follow-up. The hyperkalaemic effect of ACEI/ARB is balanced by the use of diuretics.     

Observations of glomerular epithelial cell structure in patients with type I diabetes mellitus

Overt proteinuria is a hallmark of diabetic nephropathy while microalbuminuria is thought to be a predictor of later onset of diabetic nephropathy. Yet the mechanisms for abnormal urinary protein leak in diabetes have not been defined. We studied 28 patients with type I diabetes for 7 to 33 years. Creatinine clearance, urinary albumin excretion rate (UAE), and multiple blood pressures were obtained in each patient. A renal biopsy was performed in each patient and in 28 normal subjects. Quantitative stereology was used to determine foot process (FP) width, filtration slit length density (FSLV) and filtration slit length/glomerulus (FSLG). FP width was slightly wider than normal in diabetic patients with UAE less than 250 mg/24 hr while FP was significantly wider than both of these groups in diabetics with UAE greater than 250 mg/24 hr. FSLV and FSLG were similar in normals and diabetics with UAE less than 250 mg/24 hr but both were reduced in diabetics with UAE greater than 250 mg/24 hr. UAE correlated with FP width (P less than 0.05), FSLG (P less than 0.01) and most precisely and FSLV (P less than 0.001). Diabetics with microalbuminuria had values for all the structural parameters measured here not different from diabetics with UAE in the normal range. Perturbations of epithelial cell structure are present in diabetes mellitus especially in patients with nephropathy. The exact relationships between albuminuria and epithelial cell structure remains to be elucidated.     

Clinical correlates with microalbuminuria in non-insulin dependent diabetes: Preliminary results of the appropriate blood pressure control in diabetes trial

Summary: Clinical correlates associated with urinary albumin excretion (UAE) in non-insulin dependent diabetes (NIDDM) are less well known than in insulin dependent diabetes (IDDM). We therefore performed a cross sectional study examining the relationships of clinical risk factors and diabetic complications with UAE in 950 NIDDM patients. the UAE status was classified into the following categories: (i) no albuminuria (<20 μmg/min), (ii) microalbuminuria (20–200 μg/min); and (iii) overt albuminuria (>200 μg/min). Univariate and miltivariate analyses were initially performed evaluating the associations between clinical risk factors and UAE. Univariate and multivariate analyses were then performed examining the relationships between UAE and the diabetic complications (retinopathy, neuropathy and cardiovascular disease). Using multivariate logistic regression analyses controlling for diabetes duration, glycosylated haemoglobin, gender and race, the most significant predictors of microalbuminuria and overt albuminuria were systolic hypertension, increased body mass index (BMI), decreased high-density lipoprotein (HDL) cholesterol, insulin use and smoking pack years. Univariate and multivariate analyses evaluating the associations between UAE and diabetic complications revealed that UAE was a strong predictor of retinopathy (odds ratio [OR]=1.31:95% confidence interval [CI]=1.05,1.66), neuropathy (OR=1.47; CI=1.19,19.83), and cardiovascular diseases (OR=1.28; CI=1.05,1.52). Thus, in the present study increases in UAE were associated with retinopathy, neuropathy and cardiovascular disease. Urinary albumin excretion may therefore be a marker of diffuse vascular disease in NIDDM. Aggressive treatment of smoking, cholesterol and hypertension may not only diminish UAE but may also play a significant role in decreasing the other NIDDM vascular complications.     

Treatment strategies in patients with chronic renal disease: ACE inhibitors,angiotensin receptor antagonists,or both?

We discuss the evidence supporting the use of angiotensin-converting enzyme inhibitors (ACEI), angiotensin II type 1 receptor blockers (ARB), or the combination of both in children with chronic renal disease. Several large-scale, prospective, randomized studies with clinical end points have been performed in adult patients, but studies in children are relatively scarce. In adult patients with chronic renal diseases, ACEI clearly delay the progression of chronic non-diabetic renal diseases, and nephropathy in patients with type 1 diabetes. The benefits of ACEI are most apparent in glomerular diseases with marked proteinuria but extend also to kidney diseases with lower proteinuria. This notion is also supported by several smaller or retrospective trials in children. Therefore, ACEI should be given to children with chronic renal diseases, particularly if high blood pressure and/or proteinuria are present. In adults, large-scale trials have documented that ARB exert similar effects as ACEI but tend to exert fewer undesired side effects. Data on ARB in children with chronic renal disease are still very scarce, but these substances offer an alternative for patients who cannot tolerate ACEI due to unwarranted side effects. Combination therapy with ARB plus ACEI may be more effective than either drug class alone. However, we will need the results of further long-term prospective clinical studies, as well as a better understanding of the role of the AT₂ receptor, before combination therapy can be widely recommended. A trial of ARB plus ACEI is justified in selected patients if blood pressure and/or proteinuria cannot adequately be lowered by ACEI or ARB alone.     

Polymorphic genes for kinin receptors,nephropathy and blood pressure in type 2 diabetic patients

BACKGROUND/AIMS: There is evidence that hereditary predisposition contributes to the development of diabetic nephropathy and hypertension. Polymorphisms in the genes for bradykinin receptors (B(1)R and B(2)R) were found to be associated with decreased risk of the development of end-stage renal disease. This study examines whether B(1)R G(-699)C and B(2)R C(181)T polymorphisms are associated with microalbuminuria or overt nephropathy, or blood pressure variation in type 2 diabetic subjects. METHODS: B(1)R and B(2)R polymorphisms were determined in 153 type 2 diabetic patients with microalbuminuria, 132 with overt nephropathy (macroalbuminuria or chronic renal failure), and 161 patients with normoalbuminuria despite diabetes duration longer than 10 years. RESULTS: Distributions of the examined polymorphisms did not differ between patients with microalbuminuria or overt nephropathy, compared to normoalbuminuric control subjects. Patients carrying the B(2)R T allele had lower DBP, compared with non-carriers: 83.6 +/- 12.0 vs. 87.4 +/- 12.1 mm Hg, p < 0.05. Among patients not receiving ACEI, both SBP and DBP was significantly lower in B(2)R T allele carriers, compared to non-carriers (137.2 +/- 20.3 vs. 146.5 +/- 21.7 mm Hg, and 80.3 +/- 11.9 vs. 85.8 +/- 11.6 mm Hg, p < 0.05). CONCLUSIONS: Examined polymorphisms are not associated with the increased risk of incipient or overt nephropathy in type 2 diabetic patients. B(2)R C(181)T polymorphism may contribute to blood pressure variation in these subjects.     

Oxidative stress and nitric oxide synthase in rat diabetic nephropathy: effects of ACEI and ARB.

BACKGROUND: Angiotensin II (Ang II) can up-regulate nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase, whose product superoxide anion (O2-) can interact with nitric oxide (NO) to form peroxynitrite (ONOO-). We tested the hypothesis that Ang II subtype 1 (AT1) receptor activation enhances oxidative stress and nitrotyrosine deposition in the kidneys of rats with diabetes mellitus (DM). METHODS: After two weeks of streptozotocin-induced DM, rats received either no treatment, an angiotensin-converting enzyme inhibitor (ACEI) or an angiotensin receptor blocker (ARB) for two weeks. At four weeks, renal expression of the p47phox component of NAD(P)H oxidase, endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), and nitrotyrosine were evaluated by Western blot and immunohistochemistry and related to plasma lipid peroxidation products (LPO), hydrogen peroxide production in the kidney and 24-hour protein excretion. RESULTS: Immunoreactive expression of p47phox and eNOS were increased in DM with an increase in plasma LPO, renal hydrogen peroxide production and nitrotyrosine deposition. Expression of nNOS was unaltered. Treatment with either ACEI or ARB prevented all these findings and also prevented significant microalbuminuria. The treatments did not affect the elevated blood sugar, nor did DM or its treatment affect the blood pressure or the creatinine clearance. CONCLUSION: Early proteinuric diabetic nephropathy increases renal expression of the p47phox component of NAD(P)H oxidase and eNOS with increased indices of systemic and renal oxidative/nitrosative stress. An ACEI or an ARB prevents these changes and prevents the development of proteinuria, independent of blood pressure or blood sugar. This finding indicates a pathogenic role for AT1 receptors in the development of oxidative damage in the kidneys during early DM.     

The Effects of Spironolactone on Nephron Function in Patients with Diabetic Nephropathy

Increasing evidence suggests that circulating aldosterone per se contributes directly to renal and cardiovascular diseases. We sought to evaluate the effects of a three-month treatment with 25 mg spironolactone, an aldosterone receptor antagonist, on nephron function in 20 type II diabetic patients with persistent microalbuminuria, despite at least six months' use of an ACEi or ARB (combination group), and in eleven type II diabetic patients with persistent microalbuminuria who have never used an ACEi or an ARB (spironolactone group). In the combination group, urinary protein excretion (UPE, p = 0.015), urinary albumin excretion (UAE, p = 0.010), and the urinary albumin to creatinine ratio (ACR, p = 0.007) decreased, and serum potassium (sK⁺, p = 0.004) was significantly elevated. ACR (p = 0.016) decreased significantly in the spironolactone group. In 31 patients given spironolactone (all patients group), UPE (p = 0.019), UAE (p = 0.002), and ACR (p = 0.011) decreased, and serum creatinine (sCr, p = 0.025) and sK⁺ (p = 0.002) were significantly elevated. Changes in albuminuria showed a positive correlation with changes in GFR (p = 0.002) and a negative correlation with changes in sCr (p = 0.007), and changes in ACR showed a negative correlation with changes in sCr (p = 0.004) in all patient groups. In our study, we observed that spironolactone, both alone and in combination with ACEi/ARB treatment, was well tolerated, and that it slowed down the progression of diabetic nephropathy with a marked antialbuminuric effect. Our results showed that the antialbuminuric effect developed by the decrease of intraglomerular pressure, particularly in patients with persistent microalbuminuria despite long-term ACEi/ARB treatment; adding aldosterone blockers to treatment was beneficial.     

The association between angiotensin converting enzyme inhibitor or angiotensin receptor blocker use during postischemic acute transplant failure and renal allograft survival

BACKGROUND: Postischemic acute renal transplant failure occurs in approximately one fourth of all dead donor transplantations. Uncertainty exists regarding the putative association between the use of angiotensin converting enzyme inhibitors (ACEIs) or angiotensin II AT1 receptor blockers (ARBs) and kidney transplant graft survival in patients with delayed allograft function. METHODS: We conducted an open cohort study of all 436 patients who experienced an acute renal transplant failure out of all 2,031 subjects who received their first kidney transplant at the Medical University of Vienna between 1990 and 2003. Actual and functional graft survival was compared between users and nonusers of ACEI/ARB using exposure propensity score models and time-dependent Cox regression models. RESULTS: Ten-year actual graft survival averaged 44% in the ACEI/ARB group, but only 32% in patients without ACEI/ARB (P=0.002). The hazard ratio of actual graft failure was 0.58 (95% confidence interval: 0.35-0.80, P=0.002) for ACEI/ARB users compared with nonconsumers. Seventy-one percent of subjects with ACEI/ARB had a functional graft at 10 years versus 64% of ACEI/ARB nonusers (P=0.027). The hazard ratio of functional graft loss was 0.48 (95% confidence interval: 0.24-0.91, P=0.025). CONCLUSIONS: Use of ACEI/ARB in patients experiencing delayed allograft function was associated with longer actual and functional transplant survival.     

Time to abandon microalbuminuria?

The term microalbuminuria--a urinary albumin excretion (UAE) between 20 and 200 microg/min--has been introduced to identify subjects at increased risk of renal and cardiovascular disease. However, the relationship between albuminuria and risk is not restricted to the microalbuminuric range and extends to as low as 2-5 microg/min. On the contrary, the increase of UAE above 200 microg/min (macroalbuminuria) heralds the onset of proteinuria (urinary protein excretion above 0.5 g/24 h) and progressive renal and cardiovascular disease. Albuminuria is a component of the metabolic syndrome and may represent a marker of the increased risk of renal and cardiovascular disease associated with insulin resistance and endothelial dysfunction. Proteinuria is a sign of established kidney damage and plays a direct pathogenic role in the progression of renal and cardiovascular disease. Albuminuria reflects functional and potentially reversible abnormalities initiated by glomerular hyperfiltration, proteinuria, a size-selective dysfunction of the glomerular barrier normally associated with glomerular filtration rate (GFR) decline that may result in end-stage renal disease. Thus, the limit of 200 microg/min segregates patients with albuminuria or proteinuria who are at quite different risk. Among subjects with albuminuria, however, there is a continuous relationship between albumin excretion and risk and no lower bound between normal albuminuria and microalbuminuria can be identified that segregates subjects at different risk. Thus, the terms microalbuminuria and macroalbuminuria could be replaced by the concepts of albuminuria- and proteinuria-associated diseases. Future studies are needed to identify levels of albuminuria below which therapy is no longer beneficial.     

Combination therapy of trandolapril and candesartan cilexetil reduces microalbuminuria and urinary endothelin-1 excretion in patients with type 2 diabetes

Background. Angiotensin (AT)-converting enzyme inhibitors (ACEIs) and AT1-receptor blockers (ARBs) are widely used to reduce urinary albumin excretion (UAE) and slow the progression of diabetic nephropathy. The aim of the present study was to determine whether treatment with trandolapril (an ACEI) and candesartan cilexetil (an ARB) in combination has more effect on UAE and urinary endothelin (ET)-1 excretion than treatment with trandolapril or candesartan cilexetil alone in patients with type 2 diabetes. Methods. Sixty normotensive type 2 diabetes patients with microalbuminuria were randomly assigned to four treatment groups: (A) treatreatment with trandolapril at 2 mg/day (n = 15), (B) treatment with candesartan cilexetil at 8 mg/day (n = 15), (C) treatment with trandolapril at 2 mg/day and candesartan cilexetil at 8 mg/day (n = 15), and (D) treatment with placebo (n = 15). The study period was 18 months. UAE, urinary ET-1, and plasma ET-1 levels were measured in the patients before treatment and after 12 and 18 months of treatment. Results. Before treatment, UAE, urinary ET-1, and plasma ET-1 levels differed little between the four groups. Trandolapril and candesartan cilexetil administered alone reduced UAE and urinary ET-1 excretion to a similar extent (12 months; P < 0.05 and 18 months; P < 0.01). When trandolapril and candesartan cilexetil were coadministered, UAE and urinary ET-1 excretion decreased to a significantly greater extent at 12 and 18 months (P < 0.05) than with trandolapril or candesartan cilexetil alone. However, plasma ET-1 and systemic blood pressure levels were not affected. Conclusions. The data suggest that combination therapy with trandolapril and candesartan cilexetil has an additive effect on the reduction of microalbuminuria in microalbuminuric normotensive type 2 diabetes patients. Received: December 19, 2001 / Accepted: June 12, 2002     

Albuminuria as a predictor of cardiovascular and renal outcomes in people with known atherosclerotic cardiovascular disease

BACKGROUND: Microalbuminuria predicts elevated cardiovascular risk in those with and without diabetes. In diabetes, microalbuminuria also heralds overt diabetic nephropathy. The predictive value of albuminuria below the microalbuminuria cutoff, and the development of overt nephropathy in nondiabetics with microalbuminuria, have not been well studied. We review findings of the HOPE Study. METHODS: The HOPE Study database includes data on first morning urine albumin/creatinine ratio (ACR) in 9043 participants at baseline, and in 7674 participants at baseline and at last follow-up. Inclusion criteria were known vascular disease or diabetes, plus one other cardiovascular risk factor; exclusion criteria included heart failure or known impaired left ventricular function, dipstick-positive proteinuria (> 1+), and serum-creatinine > 2.3 mg/dL (200 micromol/L). Microalbuminuria was defined as an ACR > or = 2 mg/mmol. RESULTS: Microalbuminuria at baseline approximately doubled the relative risk (RR) of the primary outcome (myocardial infarction, stroke, or CV death). For every 1 mg/mmol rise of ACR, even below the level of microalbuminuria, the adjusted hazard of the primary outcome increased by about 15%. Baseline microalbuminuria predicted subsequent clinical proteinuria, RR 17.5, similarly in participants without and with diabetes. New microalbuminuria developed in 1542 participants, and clinical proteinuria in 317. CONCLUSION: Albuminuria is a continuous risk factor for CV events even below the level of microalbuminuria. Microalbuminuria predicts clinical proteinuria in nondiabetics.