Use of allopurinol in slowing the progression of renal disease through its ability to lower serum uric acid level

Study on hyperuricemia in HBV-associated glomerulonephritis

OBJECTIVES

To determine the prevalence and risk factors for hyperuricemia in hepatitis B virus-associated glomerulonephritis (HBV-GN).

METHODS

Univariate and multivariate logistic regression analysis was applied to decide the risk factors of hyperuricemia in HBV-GN, and clinical and pathologic data were compared between HBV-GN patients with hyperuricemia and those with normal serum uric acid.

RESULTS

Among our 227 HBV-GN cases, 31.3% of the patients had hyperuricemia at the time of renal biopsy. Univariate analysis showed that the level of serum creatinine and the severity of glomerular and tubular interstitial injury were significantly related to hyperuricemia. Multivariate logistic regression analysis identified the levels of serum creatinine and tubular interstitial injury as independent factors for hyperuricemia. The incidence of hypertension and lower estimated glomerular filtration rate was significantly higher in hyperuricemic patients with HBV-GN than in normouricemic patients. There were also fewer membranous nephropathy, more proliferative sclerosing glomerulonephritis, and more tubular interstitial injury in hyperuricemic patients with HBV-GN.

CONCLUSIONS

Our study results suggest that hyperuricemia is common in HBV-GN, which may facilitate the progression of HBV-GN and renal tubular interstitial injury as well as the development of hypertension.

Low protein diet inhibits uric acid synthesis and attenuates renal damage in streptozotocin-induced diabetic rats

AIM

Several studies indicated that hyperuricemia may link to the worsening of diabetic nephropathy (DN). Meanwhile, low protein diet (LPD) retards exacerbation of renal damage in chronic kidney disease. We then assessed whether LPD influences uric acid metabolism and benefits the progression of DN in streptozotocin- (STZ-) induced diabetic rats.

METHODS

STZ-induced and control rats were both fed with LPD (5%) and normal protein diet (18%), respectively, for 12 weeks. Vital signs, blood and urinary samples for UA metabolism were taken and analyzed every 3 weeks. Kidneys were removed at the end of the experiment.

RESULTS

Diabetic rats developed into constantly high levels of serum UA (SUA), creatinine (SCr) and 24 h amounts of urinary albumin excretion (UAE), creatinine (UCr), urea nitrogen (UUN), and uric acid (UUA). LPD significantly decreased SUA, UAE, and blood glucose, yet left SCr, UCr, and UUN unchanged. A stepwise regression showed that high UUA is an independent risk factor for DN. LPD remarkably ameliorated degrees of enlarged glomeruli, proliferated mesangial cells, and hyaline-degenerated tubular epithelial cells in diabetic rats. Expression of TNF-α in tubulointerstitium significantly decreased in LPD-fed diabetic rats.

CONCLUSION

LPD inhibits endogenous uric acid synthesis and might accordingly attenuate renal damage in STZ-induced diabetic rats.

Early progressive renal decline precedes the onset of microalbuminuria and its progression to macroalbuminuria

OBJECTIVE Progressive decrease in the glomerular filtration rate (GFR), or renal decline, in type 1 diabetes (T1D) is observed in patients with macroalbuminuria. However, it is unknown whether this decline begins during microalbuminuria (MA) or normoalbuminuria (NA). RESEARCH DESIGN AND METHODS The study group (second Joslin Kidney Study) comprises patients with T1D and NA (n = 286) or MA (n = 248) who were followed for 4-10 years (median 8 years). Serial measurements (median 6, range 3-16) of serum creatinine and cystatin C were used jointly to estimate GFR (eGFRcr-cys) and assess its trajectories during follow-up. RESULTS Renal decline (progressive eGFRcr-cys loss of at least 3.3% per year) occurred in 10% of the NA and 35% of the MA (P < 0.001). In both groups, the strongest determinants of renal decline were baseline serum concentrations of uric acid (P < 0.001) and tumor necrosis factor receptor 1 or 2 (TNFR-1 or -2, P < 0.001). Other significant risk factors included baseline HbA1c, age/diabetes duration, and systolic blood pressure. Relative impacts of these determinants were similar in NA and MA. Renal decline was not associated with sex or baseline serum concentration of TNF-α, IL-6, IL-8, IP-10, MCP-1, VCAM, ICAM, Fas, or FasL. CONCLUSIONS Renal decline in T1D begins during NA and it is determined by multiple factors, similar to MA. Thus, this early decline is the primary disease process leading to impaired renal function in T1D. Changes in albumin excretion rate, such as the onset of MA or its progression to macroalbuminuria, are either caused by or develop in parallel to the early renal decline.

Proteinuric renal disease in type 2 diabetes-is remission of proteinuria associated with improved mortality and morbidity?

AIMS

Patients with type 2 diabetes and macroalbuminuria are at high risk for end stage renal disease (ESRD), cardiovascular disease and death, but remission of proteinuria may improve prognosis. We examine the effectiveness of currently recommended treatments on inducing remission of proteinuria, and on morbidity and mortality.

METHODS

Observational study of 78 patients with type 2 diabetes (46 male) with mean age (SD) of 61.5 (11) years, with a urinary albumin/creatinine ratio (ACR)≥50 mg/mmol. All were treated with agents blocking the renin-angiotensin system. Follow-up was from recognition of ACR ≥ 50 mg/mmol until death or March 2011 (median 6 years). Remission of proteinuria was defined as ≥70 % reduction from peak ACR, sustained for ≥1 year.

RESULTS

Only 22 of 78 patients (28%) achieved remission of proteinuria. Thirty-six (46%) had at least one major event (death, dialysis or cardiovascular). Remission of proteinuria was associated with lower incidence of ESRD/death (9% vs 36%; p=0.02) but cardiovascular events were not reduced (32% vs 30%). A third of patients had no retinopathy when albuminuria was first recognised, suggesting that non-diabetic renal pathologies were prominent. There was a significant interaction between the severity of diabetic retinopathy and remission of proteinuria on the risk of ESRD/death (p=0.0003).

CONCLUSIONS

Remission of proteinuria was achieved in only a third of patients despite efforts to achieve blood pressure targets <130/80 mmHg. Failure to attain remission of proteinuria was associated with increased risk of ESRD or death, a risk compounded by the presence of severe diabetic retinopathy.

Hyperuricemia after exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans near a highly contaminated area

BACKGROUND

Hyperuricemia (too much uric acid in the blood) is the predisposing condition for gout and is associated with hypertriglyceridemia, diabetes mellitus, and coronary artery disease. Polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) cause renal toxicity and elevate uric acid. The aim of this analysis was to investigate and clarify the effect of moderate-to-high PCDD/F exposure on hyperuricemia risk.

METHODS

In this cross-sectional study, we recruited 1531 healthy participants living near a deserted pentachlorophenol factory. We measured serum levels of 17 2,3,7,8-substituted PCDD/Fs, and then examined associations between the main predictor variable, serum TEQ(DF-2005) (total PCDD/Fs 2005 World Health Organization [WHO] toxic equivalency [TEQ]), and dependent variables such as uric acid, glomerular filtration rates, and hyperuricemia risk.

RESULTS

We observed a strong monotonic inverse relationship between serum TEQ(DF-2005) quartiles and the estimated glomerular filtration rate after adjusting for confounding factors (Men: β were 0, -4.7, -6.2, and -14.8; Women: β were 0, -6.7, -12.9, and -21.5). In addition, we observed a suggestive positive trend between serum TEQDF-2005 quartiles and uric acid only in men after adjusting for confounding factors (Men: β were 0, 0.40, 0.36, and 0.59; P for trend <0.05). Men with serum TEQ(DF-2005) higher than the reference group's (<7.4 pg WHO(2005)-TEQ(DF/g) lipid) had a higher hyperuricemia risk after adjusting for confounding factors (25th to <50th percentile, adjusted odds ratio [AOR] = 2.20 [95% confidence interval {CI} = 1.30-3.73]; 50th to <75th percentile, AOR = 1.86 [95% CI = 1.08-3.22]; ≥ 75th percentile, AOR = 3.00 [95% CI = 1.69-5.31]).

CONCLUSIONS

We conclude that serum TEQ(DF-2005) is an important determinant of serum uric acid levels and heightens the risk of hyperuricemia in general populations.

"Normoalbuminuric" diabetic nephropathy: tubular damage and NGAL

The aim of this study was to demonstrate that neutrophil gelatinase-associated lipocalin (NGAL) increased before the onset of microalbuminuria in patients with type 1 diabetes mellitus (T1DM), representing an important biochemical parameter with high sensitivity and specificity to make a precocious diagnosis of "normoalbuminuric" diabetic nephropathy (DN). Serum NGAL (sNGAL) and urinary NGAL (uNGAL) levels were evaluated in a cohort of fifty patients affected by T1DM. They had no signs of clinical nephropathy. Thirty-five healthy subjects (HS) were recruited. sNGAL levels were significantly higher compared with those measured in HS [193.7 (103.2-405.4) vs. 46.4 (39.8-56.2) ng/ml; p < 0.0001], as were uNGAL levels [25.5 (14.2-40.2) vs. 6.5 (2.9-8.5) ng/ml; p < 0.0001]. sNGAL was found to be directly correlated with glycated hemoglobin. uNGAL also positively correlated with albuminuria, whereas an inverse correlation was found with uric acid. After multivariate analysis, significance was maintained for the correlation between uNGAL and microalbuminuria. In ROC analysis, sNGAL showed a good diagnostic profile such as uNGAL. NGAL increases in patients with T1DM, even before diagnosis of microalbuminuria representing an early biomarker of "normoalbuminuric" DN with a good sensitivity and specificity. NGAL measurement could be useful for the evaluation of early renal involvement in the course of diabetes.

Sodium-glucose linked transporter-2 inhibitors: potential for renoprotection beyond blood glucose lowering?

The proximal tubule's sodium-glucose linked transporter-2 (SGLT2) accounts for the vast majority of glucose reabsorption by the kidney. Its selective inhibition, accordingly, leads to substantial glycosuria, lowering blood glucose, and facilitating weight loss in individuals with diabetes. During the past year, two SGLT2 inhibitors, canagliflozin and dapagliflozin, have been approved for the treatment of type 2 diabetes. Beyond their anti-hyperglycemic properties, however, this new class of drugs has several other attributes that provide a theoretical basis for kidney protection. Like agents that block the renin-angiotensin system, SGLT2 inhibitors also reduce single-nephron glomerular filtration rate (SNGFR) in the chronically diseased kidney, though by quite different mechanisms. Additional potentially beneficial effects of SGLT2 inhibition include modest reductions in blood pressure and plasma uric acid. Finally, cell culture studies indicate that glucose uptake from the tubular lumen, as well as from the basolateral compartment, can contribute to proximal tubular production of extracellular matrix proteins. Whether such attributes will translate into reducing the progression of chronic kidney disease will require the undertaking of long-term, dedicated studies.

Serum uric acid and chronic kidney disease: the role of hypertension

BACKGROUND

There are inconsistent findings on the role of hyperuricemia as an independent risk factor for chronic kidney disease (CKD). Hypertension has been implicated as a factor influencing the association between serum uric acid and CKD. In this population-based study we investigated the association between serum uric acid and decline in renal function and tested whether hypertension moderates this association.

METHODS

We included 2601 subjects aged 55 years and over from the Rotterdam Study. Serum uric acid and estimated glomerular filtration rate (eGFR) were assessed at baseline. After average 6.5 years of follow-up, second eGFR was assessed. CKD was defined as eGFR<60 ml/min/1.73 m(2). All associations were corrected for socio-demographic and cardiovascular factors.

RESULTS

Each unit (mg/dL) increase in serum uric acid was associated with 0.19 ml/min per 1.73 m(2) faster annual decline in eGFR. While the association between serum uric acid and incidence of CKD was not significant in our study population (Hazard Ratio: 1.12, 95% confidence interval [CI]: 0.98-1.28), incorporating our results in a meta-analysis with eleven published studies revealed a significant association (Relative Risk: 1.18, 95%CI: 1.15-1.22). In the stratified analyses, we observed that the associations of serum uric acid with eGFR decline and incident CKD were stronger in hypertensive subjects (P for interaction = 0.046 and 0.024, respectively).

CONCLUSIONS

Our findings suggest that hyperuricemia is independently associated with a decline in renal function. Stronger association in hypertensive individuals may indicate that hypertension mediates the association between serum uric acid and CKD.

Hyperuricemia is independently associated with endothelial dysfunction in postmenopausal women but not in premenopausal women

OBJECTIVES

The purpose of this study was to determine the relationships between uric acid, endothelial function and cardiovascular risk factors and to investigate whether menopausal status was associated with the relationship between uric acid and endothelial function in women.

DESIGN

Cross-sectional study.

SETTING

3 general hospitals in Japan.

PARTICIPANTS

749 Japanese women aged 30-74 years recruited from people who underwent health-screening examinations with agreement for measurement of vascular function.

MEASURES

We measured serum concentrations of uric acid and flow-mediated vasodilation (FMD). Percentage of FMD (peak diameter-baseline diameter/baseline diameter) was used for analysis. Endothelial dysfunction was defined as FMD ≤4.90%, division point for the lowest tertile and the middle tertile of FMD. Menopause women were defined as participants without menstruation for over 1 year or participants with a history of hysterectomy or bilateral oophorectomy.

RESULTS

Of the 749 participants, 368 (49.1%) were premenopausal women and 381 (50.9%) were postmenopausal women. Age, body mass index, systolic blood pressure, total cholesterol, triglycerides, glucose, estimated glomerular filtration rate and Framingham risk score were significantly correlated with serum uric acid level. FMD showed a gradual decrease in accordance with the serum uric acid level in the entire study population (<4 mg/dL, 6.85±3.65%; 4 to <5 mg/dL, 6.79±3.60%; 5 to <6 mg/dL, 6.24±3.58%; ≥6 mg/dL, 5.27±3.18%; p=0.01). Multivariate analysis revealed that uric acid was a significantly independent risk factor for endothelial dysfunction in postmenopausal women (OR 1.23, 95% CI 1.01 to 1.50), but not in premenopausal women.

CONCLUSIONS

These findings suggest that uric acid can be used as a risk marker of endothelial dysfunction in a female population, and particularly as an independent risk factor in postmenopausal women but not in premenopausal women.

REGISTRATION NUMBER OF THE STUDY

UMIN000003409.

Febuxostat (Feburic tablet) in the management of hyperuricemia in a general practice cohort of Japanese patients with a high prevalence of cardiovascular problems

Hyperuricemia is increasing in prevalence and this is paralleled by an increased incidence of acute gout. In addition, there is growing evidence of an association between high serum levels of uric acid (sUA) and cardiovascular disease (CVD). In this preliminary report, we present 12-16 week results from a multicenter, general practice study in which we evaluated the usefulness of febuxostat in a cohort of untreated patients with hyperuricemia with a high prevalence of CVD. Febuxostat titrated from 10 mg/day up to 40 mg/day resulted in statistically significant and clinically relevant reductions in sUA after 12-16 weeks. A "responder" level of 6.0 mg/dL or lower was achieved in 95 of 100 (95%) patients. Significant reductions in sUA were achieved regardless of the presence/absence of coexisting diseases (e.g. CVD, renal insufficiency, diabetes and obesity) or the class of antihypertensive agent being used by the patient. No serious adverse reactions were noted with febuxostat. Although allopurinol has been used generally for hyperuricemia/gout, it is excreted fully via the kidneys, restricting its use in patients with reduced renal function, and its three-times-daily administration leads to poor adherence. Based on the results of this study, febuxostat may provide an easier option than allopurinol for clinicians specializing in CVDs.

Serum Concentration of Uric Acid Associated With Prehypertension Among Chinese Population

We evaluated the association between serum uric acid (SUA) levels and prehypertension in a Chinese population. A cross-sectional study was performed during 2008 to 2010, and a total of 11199 participants without hypertension or other cardiovascular diseases (CADs), aged ≥35 years, were available for analysis. After adjusting for age, alcohol consumption, smoking status, body mass index, diabetes, total cholesterol, triglycerides, serum creatinine, the odds ratios (ORs) and 95% confidence intervals (CIs) of the prehypertension from the lowest (referent) to the highest levels of SUA were 1.00 (95% CI, 0.91-1.10), 1.12 (95% CI, 1.03-1.21), 1.17 (95% CI, 1.09-1.27), and 1.25 (95% CI, 1.13-1.39; linear trend P = .002). This association persisted in subgroup analysis by gender and was also consistent with separate analysis by classification of age, smoking status, alcohol usage, overweight, and diabetes mellitus. Independent of other cardiovascular risk factors, higher SUA levels are positively associated with prehypertension in a Chinese population without hypertension and CADs. Prospective trials should evaluate interventions that lower the SUA levels.

Acute effects of fructose consumption on uric acid and plasma lipids in patients with impaired renal function

OBJECTIVE

Metabolic disturbances are common in patients with renal function impairment and are related to high rates of cardiovascular incidents and mortality. Kidney transplantation leads to improved survival but may lead to additional metabolic alterations caused by immunosuppressive drugs and improved nutrition.

MATERIALS AND METHODS

The short-term effect of oral fructose load on serum uric acid (UA), plasma lipids, and blood pressure (BP) was studied in 85 patients with chronic kidney disease (CKD) and impairment of renal function (glomerular filtration rate 50-65 ml/min per 1.73 m(2)), comprising 55 renal transplant recipients (RTR) treated with standard triple immunosuppressive therapy including a calcineurin inhibitor (CNI) cyclosporine A (CsA) or tacrolimus (Tac) and 30 non-transplanted patients with CKD. Both non-transplanted CKD patients and RTR had stable renal function and a comparable degree of kidney dysfunction. All subjects received orally 70 g of fructose dissolved in 200 ml of water. Serum UA, lipids, and blood pressure were measured at baseline and 60, 120, 180, and 240 minutes after fructose administration.

RESULTS

There was a significant increase of serum UA concentration (p<0.001) in both CKD patients and RTR--CsA- or Tac-treated patients comparable in the latter. Total cholesterol (TC), LDL, and HDL cholesterol significantly decreased and serum triglycerides (TG) markedly increased in RTR, whereas in CKD patients all serum lipid fractions increased. Blood pressure was unaffected by fructose intake.

CONCLUSION

Both non-transplanted and transplanted patients with mild renal function impairment show similar acute purine metabolic disturbances following oral administration of fructose but in the latter dietary fructose may induce a smaller hyperlipidemic response.

Age, kidney function, and risk factors associate differently with cortical and medullary volumes of the kidney

The kidney atrophies in patients with advanced chronic kidney disease (CKD) but factors influencing kidney size in normal adults are less clear. To help define this we measured kidney volumes on contrast-enhanced CT images from 1344 potential kidney donors (ages 18 to 75 years). Cortical volume per body surface area progressively declined in both genders with increased age. Statistically, this was primarily dependent on the age-related decline in glomerular filtration rate (GFR). Independent predictors of increased cortical volume per body surface area were male gender, increased GFR, increased 24-hour urine albumin, current smoker, and decreased high-density lipid cholesterol. Medullary volume per body surface area increased with age in men while it increased with age in women until age 50 followed by a subsequent decline. Independent predictors of increased medullary volume per body surface area were older age, male gender, increased GFR, increased 24-hour urine albumin, increased serum glucose, and decreased serum uric acid. Thus, while cortical volume declines with age along the same biological pathway as the age-related decline in GFR and albuminuria some CKD risk factors are actually associated with increased cortical or medullary volume among relatively healthy adults. Underlying hypertrophy or atrophy of different nephron regions may explain these findings.

Uric acid level and erectile dysfunction in patients with coronary artery disease

INTRODUCTION

Erectile dysfunction (ED) is a frequent complaint of elderly subjects and is closely associated with endothelial dysfunction and cardiovascular disease (CVD). Uric acid is also associated with endothelial dysfunction, oxidative stress, and CVD, raising the hypothesis that an increased serum uric acid might predict ED in patients who are at risk for coronary artery disease (CAD).

AIM

This study aims to evaluate the association of serum uric acid levels with presence and severity of ED in patients presenting with chest pain of presumed cardiac origin.

METHODS

This is a cross-sectional study of 312 adult male patients with suspected CAD who underwent exercise stress test (EST) for workup of chest pain and completed a sexual health inventory for men survey form to determine the presence and severity of ED. Routine serum biochemistry (and uric acid levels) were measured. Logistic regression analysis was used to assess risk factors for ED.

MAIN OUTCOME MEASURES

The short version of the International Index of Erectile Function questionnaire diagnosed ED (cutoff score ≤ 21). Serum uric acid levels were determined. Patients with chest pain of suspected cardiac origin underwent an EST.

RESULTS

One hundred forty-nine of 312 (47.7%) male subjects had ED by survey criteria. Patients with ED were older and had more frequent CAD, hypertension, diabetes and impaired renal function, and also had significantly higher levels of uric acid, fibrinogen, glucose, C-reactive protein, triglycerides compared with patients without ED. Uric acid levels were associated with ED by univariate analysis (odds ratio = 1.36, P = 0.002); however, this association was not observed in multivariate analysis adjusted for estimated glomerular filtration rate.

CONCLUSION

Subjects presenting with chest pain of presumed cardiac origin are more likely to have ED if they have elevated uric acid levels.

Mendelian randomization analysis associates increased serum urate, due to genetic variation in uric acid transporters, with improved renal function

Increased serum urate predicts chronic kidney disease independent of other risk factors. The use of xanthine oxidase inhibitors coincides with improved renal function. Whether this is due to reduced serum urate or reduced production of oxidants by xanthine oxidase or another physiological mechanism remains unresolved. Here we applied Mendelian randomization, a statistical genetics approach allowing disentangling of cause and effect in the presence of potential confounding, to determine whether lowering of serum urate by genetic modulation of renal excretion benefits renal function using data from 7979 patients of the Atherosclerosis Risk in Communities and Framingham Heart studies. Mendelian randomization by the two-stage least squares method was done with serum urate as the exposure, a uric acid transporter genetic risk score as instrumental variable, and estimated glomerular filtration rate and serum creatinine as the outcomes. Increased genetic risk score was associated with significantly improved renal function in men but not in women. Analysis of individual genetic variants showed the effect size associated with serum urate did not correlate with that associated with renal function in the Mendelian randomization model. This is consistent with the possibility that the physiological action of these genetic variants in raising serum urate correlates directly with improved renal function. Further studies are required to understand the mechanism of the potential renal function protection mediated by xanthine oxidase inhibitors.

Effects of uric acid-lowering therapy on renal outcomes: a systematic review and meta-analysis

BACKGROUND

Non-randomized studies suggest an association between serum uric acid levels and progression of chronic kidney disease (CKD). The aim of this systematic review is to summarize evidence from randomized controlled trials (RCTs) concerning the benefits and risks of uric acid-lowering therapy on renal outcomes.

METHODS

Medline, Excerpta Medical Database and Cochrane Central Register of Controlled Trials were searched with English language restriction for RCTs comparing the effect of uric acid-lowering therapy with placebo/no treatment on renal outcomes. Treatment effects were summarized using random-effects meta-analysis.

RESULTS

Eight trials (476 participants) evaluating allopurinol treatment were eligible for inclusion. There was substantial heterogeneity in baseline kidney function, cause of CKD and duration of follow-up across these studies. In five trials, there was no significant difference in change in glomerular filtration rate from baseline between the allopurinol and control arms [mean difference (MD) 3.1 mL/min/1.73 m2, 95% confidence intervals (CI) -0.9, 7.1; heterogeneity χ2=1.9, I2=0%, P=0.75]. In three trials, allopurinol treatment abrogated increases in serum creatinine from baseline (MD -0.4 mg/dL, 95% CI -0.8, -0.0 mg/dL; heterogeneity χ2=3, I2=34%, P=0.22). Allopurinol had no effect on proteinuria and blood pressure. Data for effects of allopurinol therapy on progression to end-stage kidney disease and death were scant. Allopurinol had uncertain effects on the risks of adverse events.

CONCLUSIONS

Uric acid-lowering therapy with allopurinol may retard the progression of CKD. However, adequately powered randomized trials are required to evaluate the benefits and risks of uric acid-lowering therapy in CKD.

Allopurinol for prevention of progression of kidney disease with hyperuricemia

Hyperuricemia is associated with hypertension and progressive chronic renal disease. This is a retrospective cohort study in chronic kidney disease (CKD) patients with hyperuricemia from 1998 to 2008. Patients were divided into two groups: treatment group who received allopurinol in a dose of 100 mg/day and the other group remained untreated. Clinical, hematologic, biochemical parameters and outcome were measured at baseline and 6 months, 1 year, and 2 years of treatment. A total of 183 patients were enrolled. Mean age of the allopurinol group was 50.15 ± 14.42 years and control group was 53.23 ± 13.86 years. Male-female ratios were 2.57:1 and 2.21:1 for the treatment and control groups, respectively. Baseline characteristics and the laboratory parameters were similar in both groups. Patients who received allopurinol had lower blood pressure at 6 months, 1 year, and 2 years when compared to baseline. There was a significant decrease in the serum uric acid (UA) levels in the treatment group at the end of 6 months, 1 year, and 2 years with respect to base line. An inverse correlation as noted between serum UA levels and the estimated glomerular filtration rate at 6 months, 1 year, and 2 years. Allopurinol treatment decreases blood UA levels and is associated with better blood pressure control and decreased progression of renal disease in CKD patients with hyperuricemia.

Serum uric acid levels and long-term outcomes in chronic kidney disease

Hyperuricemia is common in chronic kidney disease (CKD), but data regarding the relationship between serum uric acid levels and the long-term outcomes of CKD patients have been limited. The present study evaluated the associations between baseline serum uric acid levels with mortality and end-stage renal disease (ESRD). The subjects of this study were 551 stage 2-4 CKD patients. Cox proportional hazards models were used to evaluate the relationship between serum uric acid tertiles and all-cause mortality, cardiovascular disease (CVD) mortality, 50 % reduction in estimated glomerular filtration rate (eGFR), and development of ESRD, initially without adjustment, and then after adjusting for several groups of covariates. The mean age of the study subjects was 58.5 years, 59.3 % were men, and 10.0 % had diabetes. The mean eGFR was 42.02 ± 18.52 ml/min/1.73 m(2). In all subjects, the mean serum uric acid level was 6.57 ± 1.35 mg/dl, and 52.2 % of study subjects were on hypouricemic therapy (allopurinol; 48.3 %) at baseline. Thirty-one patients (6.1 %) died during a follow-up period of approximately 6 years. There was no significant association between serum uric acid level and all-cause mortality, CVD mortality, development of ESRD and 50 % reduction in eGFR in the unadjusted Cox models. In the adjusted models, hyperuricemia was found to be associated with all-cause mortality and CVD mortality after adjustment with CVD risk factors, kidney disease factors, and allopurinol, but not associated with development of ESRD and 50 % reduction in eGFR. The results of this study showed that hyperuricemia but not serum uric acid levels were associated with all-cause mortality, CVD mortality after adjustments with CVD risk factors, kidney disease factors, and allopurinol in stage 2-4 CKD patients.

Uric acid lowering to prevent kidney function loss in diabetes: the preventing early renal function loss (PERL) allopurinol study

Diabetic kidney disease causes significant morbidity and mortality among people with type 1 diabetes (T1D). Intensive glucose and blood pressure control have thus far failed to adequately curb this problem and therefore a major need for novel treatment approaches exists. Multiple observations link serum uric acid levels to kidney disease development and progression in diabetes and strongly argue that uric acid lowering should be tested as one such novel intervention. A pilot of such a trial, using allopurinol, is currently being conducted by the Preventing Early Renal Function Loss (PERL) Consortium. Although the PERL trial targets T1D individuals at highest risk of kidney function decline, the use of allopurinol as a renoprotective agent may also be relevant to a larger segment of the population with diabetes. As allopurinol is inexpensive and safe, it could be cost-effective even for relatively low-risk patients, pending the completion of appropriate trials at earlier stages.

The pathophysiology of hyperuricaemia and its possible relationship to cardiovascular disease, morbidity and mortality

Uric acid is the end product of purine metabolism in humans. High levels are causative in gout and urolithiasis. Hyperuricaemia has also been implicated in the pathophysiology of hypertension, chronic kidney disease (CKD), congestive heart failure (CHF), the metabolic syndrome, type 2 diabetes mellitus (T2DM), and atherosclerosis, with or without cardiovascular events. This article briefly reviews uric acid metabolism and summarizes the current literature on hyperuricaemia in cardiovascular disease and related co-morbidities, and emerging treatment options.

Urinary metabonomic study of the surface layer of Poria cocos as an effective treatment for chronic renal injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Poria cocos Wolf (Polyporaceae) is a well-known medicinal fungus. The epidermis of the sclerotia ("Fu-Ling-Pi" in Chinese) is used as a diuretic and traditionally used for promoting urination and reduce edema.

AIM OF THE STUDY

Traditional Chinese medicines (TCM) treat many diseases through multi-components, multi-ways and multi-targets. However, the molecular mechanisms of TCM are not yet well understood. In the present work, ultra performance liquid chromatography-based metabonomics analysis was applied to investigate the urinary metabolite profiling of the renoprotective effect of FLP on adenine-induced chronic kidney disease (CKD) rat model and involved possible mechanism.

MATERIAL AND METHODS

A metabonomic approach based on ultra performance liquid chromatography coupled with quadrupole time-of-flight high-sensitivity mass spectrometry and a novel mass spectrometry(Elevated Energy) data collection technique was developed. The resulting dataset was analyzed by principal component analysis and partial least squares discriminant analysis. The identification of all potential biomarkers was performed using reference standard by comparing their mass spectra, MS(E) fragments information, isotopic pattern and MassLynx i-FIT algorithm.

RESULTS

By partial least squares-discriminate analysis, 15 biomarkers in rat urine were identified and 11 of them were related to the pathway of adenine metabolism and amino acid metabolism. Among these biomarkers, eight biomarkers like adenine, L-acetylcarnitine, 8-hydroxyadenine, hypoxanthine, creatine, methionine, phytosphingosine and phenylalanine were reversed to the control level in FLP-treated group and six biomarkers like 2,8-dihydroxyadenine, indole-3-carboxylic acid, 3-methyldioxyindole, ethyl-N2-acetyl-L-argininate, 3-O-methyldopa and xanthurenic acid were reversed to high control group by FLP, which indicates that the urinary metabolic pattern significantly changed after FLP treatment.

CONCLUSIONS

Our study indicates that FLP treatment can ameliorate CKD by intervening in some dominating metabolic pathways, such as adenine metabolism and amino acid metabolism. The metabonomic results not only supplied a systematic view of the development and progression of CKD and mechanism studies of FLP but also provided the theoretical basis for the prevention or treatment of CKD.

Association of kidney disease with prevalent gout in the United States in 1988-1994 and 2007-2010

OBJECTIVE

To determine the prevalence of gout associated with progressive degrees of kidney disease in the US population.

METHODS

We performed a cross-sectional analysis among non-institutionalized adults (age 20 and older) of the National Health and Nutrition Examination Surveys in 1988-1994 and 2007-2010. Gout status was ascertained by self-report of physician-diagnosed gout. Chronic kidney disease (CKD) was defined in stages based on estimated glomerular filtration rate (GFR) and single albuminuria measurements (albumin-to-creatinine ratio). Prevalence ratios comparing successive categories of GFR, albuminuria, and CKD as well as temporal trends over a 22-year interval were determined via Poisson regression.

RESULTS

In the US, the crude prevalence of gout was 2-3% among participants without CKD, 4% among participants with CKD stage 1, 6-10% for stage 2, 11-13% for stage 3, and over 30% for stage 4. The adjusted prevalence ratio comparing the CKD stage 4 stratum to participants without CKD was 3.20 (95% CI: 1.96, 5.24) in 2007-2010 and remained significant even after adjustment for serum uric acid. Notably, there was a statistically significant, progressively greater adjusted prevalence ratio of gout associated with successively lower categories of GFR and higher categories of albuminuria.

CONCLUSIONS

Among US adults, there exists a strong dose-response association between impaired renal function and prevalent gout. Health providers should be aware of the elevated burden of gout among patients with CKD especially when evaluating new onset joint pain and swelling.

Uric acid and chronic kidney disease: A time to act?

A role for uric acid in the pathogenesis and progression of renal disease had been proposed almost a century ago, but, too hastily dismissed in the early eighties. A body of evidence, mostly accumulated during the last decade, has led to a reappraisal of the influence of uric acid on hypertension, cardiovascular, and renal disease. The focus of this review will be solely on the relationship between serum uric acid and renal function and disease. We will review experimental evidence derived from animal and human studies, evidence gathered from a number of epidemiological studies, and from the few (up to now) studies of uric-acid-lowering therapy. Some space will be also devoted to the effects of uric acid in special populations, such as diabetics and recipients of kidney allografts. Finally we will briefly discuss the challenges of a trial of uric-acid-lowering treatment, and the recent suggestions on how to conduct such a trial.

Hyperuricemia is an independent risk factor for new onset micro-albuminuria in a middle-aged and elderly population: a prospective cohort study in taiwan

Background

Hyperuricemia is now regarded as a risk factor for cardiovascular disease. Micro-albuminuria is associated with increased risk for cardiovascular disease and chronic kidney disease. We hypothesized that elevated serum uric acid (UA) is associated with development of micro-albuminuria in the general population.

Methodology/Principal Findings

We conducted a community-based prospective cohort study. A total of 1862 subjects from southern Taiwan, all older than 40 years, were screened and 993 of these participants without micro-albuminuria were followed for 4 years. Urinary albumin-to-creatinine ratio was measured two times per year. A multiple linear regression model indicated that serum UA was independently associated with ln(ACR) after adjustment for 8 factors (age, sex, and 6 metabolic metrics) (β = 0.194, p<0.01). Logistic regression analysis indicated that each 1 mg/dL increase of UA was associated with a 1.42-fold increased risk of micro-albuminuria after adjustment for the same 8 factors (OR = 1.42, 95% CI: 1.27–1.59, p<0.01). A Cox regression model using subjects with serum UA less than 5 mg/dL as reference group indicated higher hazard ratios (HRs) only found in subjects with serum UA more than 7 mg/dL (HR = 3.54, 95% CI: 2.11–5.93, p<0.01) and not in subjects with serum UA of 5 to 7 mg/dL (HR = 1.30, 95% CI: 0.82–2.07, p = 0.15).

Conclusion

Hyperuricemia is significantly associated with micro-albuminuria in middle-aged and elderly males and females from a general population in Taiwan. Elevated serum UA is an independent predictor for development of micro-albuminuria in this population.

Serum uric acid and cardio-renal diseases

OBJECTIVES

In this article, the results of clinical and experimental studies that examine the association of hyperuricemia and gout with hypertension and kidney disease are presented and discussed.

METHODS

Key papers for inclusion were identified by a PubMed search, and articles were selected according to their relevance for the topic, according to the authors' judgment.

RESULTS AND CONCLUSIONS

Increasing evidence supports a causal role for Uric acid (UA) in hypertension. Further larger studies are needed to confirm the possible beneficial role of UA lowering drugs and/or xantine-oxidase (XO) inhibitors. Overall, clinical evidence suggests a relationship of UA level with incident chronic kidney disease (CKD). In addition, the results of clinical trials using urate lowering therapy provide some promising evidence that lowering UA levels may retard the progression of CKD. Reviewed data indicate the need for large, well designed studies in these patients to evaluate XO inhibitors or uricosuric drugs in cardio-renal diseases and further elucidate the role of UA in the development and progression of CKD.

Uric acid and chronic kidney disease: which is chasing which?

Serum uric acid is commonly elevated in subjects with chronic kidney disease (CKD), but was historically viewed as an issue of limited interest. Recently, uric acid has been resurrected as a potential contributory risk factor in the development and progression of CKD. Most studies documented that an elevated serum uric acid level independently predicts the development of CKD. Raising the uric acid level in rats can induce glomerular hypertension and renal disease as noted by the development of arteriolosclerosis, glomerular injury and tubulointerstitial fibrosis. Pilot studies suggest that lowering plasma uric acid concentrations may slow the progression of renal disease in subjects with CKD. While further clinical trials are necessary, uric acid is emerging as a potentially modifiable risk factor for CKD. Gout was considered a cause of CKD in the mid-nineteenth century, and, prior to the availability of therapies to lower the uric acid level, the development of end-stage renal disease was common in gouty patients. In their large series of gouty subjects Talbott and Terplan found that nearly 100% had variable degrees of CKD at autopsy (arteriolosclerosis, glomerulosclerosis and interstitial fibrosis). Additional studies showed that during life impaired renal function occurred in half of these subjects. As many of these subjects had urate crystals in their tubules and interstitium, especially in the outer renal medulla, the disease became known as gouty nephropathy. The identity of this condition fell in question as the presence of these crystals may occur in subjects without renal disease; furthermore, the focal location of the crystals could not explain the diffuse renal scarring present. In addition, many subjects with gout also had coexistent conditions such as hypertension and vascular disease, leading some experts to suggest that the renal injury in gout was secondary to these latter conditions rather than to uric acid per se. Indeed, gout was removed from the textbooks as a cause of CKD, and the common association of hyperuricemia with CKD was solely attributed to the retention of serum uric acid that is known to occur as the glomerular filtration rate falls. Renewed interest in uric acid as a cause of CKD occurred when it was realized that invalid assumptions had been made in the arguments to dismiss uric acid as a risk factor for CKD. The greatest assumption was that the mechanism by which uric acid would cause kidney disease would be via the precipitation as crystals in the kidney, similar to the way it causes gout. However, when laboratory animals with CKD were made hyperuricemic, the renal disease progressed rapidly despite an absence of crystals in the kidney. Since this seminal study, there has been a renewed interest in the potential role uric acid may have in both acute and CKD. We briefly review some of the major advances that have occurred in this field in the last 15 years.

Comparison of effects of cilnidipine and azelnidipine on blood pressure, heart rate and albuminuria in type 2 diabetics with hypertension: A pilot study

Previous studies reported that both cilnidipine and azelnidipine have a renoprotective effect compared with amlodipine. The aim of this study was to compare the effects of cilnidipine and azelnidipine on blood pressure, heart rate and albuminuria. An open-label prospective crossover trial was carried out. We recruited 19 type 2 diabetics treated with amlodipine (5 mg/day) at least for 12 weeks. At study entry, amlodipine was changed to cilnidipine (10 mg/day) or azelnidipine (16 mg/day) and each administered for 16 weeks. Then, the drugs were switched and the treatment was continued for another 16 weeks. Despite no differences in 24-h blood pressure and heart rate between cilnidipine and azelnidipine, treatment with cilnidipine resulted in a greater reduction in urinary albumin:creatinine ratio than azelnidipine. Our results suggested that cilnidipine is more efficient in reducing albuminuria than azelnidipine independent of its blood pressure lowering effect in type 2 diabetic patients with hypertension. This trial was registered with UMIN (no. 000007201).

Changes in serum uric acid have a reciprocal effect on eGFR change: a 10-year follow-up study of community-based screening in Okinawa, Japan

Hyperuricemia is common among patients with hypertension and metabolic syndrome and therefore may be a cause of or result from these comorbid conditions. Few studies, however, have examined the relationship between the presence-absence of hyperuricemia and changes in the estimated glomerular filtration rate (eGFR) using the large cohort of the general population. We examined subjects who participated in two screenings, in 1993 and 2003, in Okinawa, Japan, yielding data on serum creatinine and uric acid levels (N=16,630). eGFR (ml min(-1) per 1.73 m(2)) was calculated using the formula used by the Japanese Society of Nephrology. In both sexes, a uric acid (UA) level >7.0 mg dl(-1) was defined as hyperuricemia (H), and a UA level below that threshold was classified as normouricemia (N). Based on the absence or presence of hyperuricemia in both the 1993 screening and the 2003 screening, we categorized patients into four groups: group 1, N/N; group 2, H/N; group 3, N/H; and group 4, H/H. Multiple regression analysis was performed to estimate the independent effects of several variables on the decline in eGFR. In all groups, an increase in UA from 1993 to 2003 (ΔUA) was a strong independent risk factor for a decline in eGFR than that of the baseline levels of UA, the presence of hypertension, or diabetes. The estimated decline in eGFR per 1 mg dl(-1) increase in UA was 4.19, 1.91, 2.36 and 2.01 ml min(-1) per 1.73 m(2) in groups 1, 2, 3 and 4, respectively. The results suggest that UA has a role in chronic kidney disease (CKD) progression. We have no information on medications used, such as xanthine oxidase, uricosuric drugs and hypotensives; therefore, the impact of hyperuricemia might be underestimated in our analysis. The results suggest that maintaining a normal range of UA is important to maintain eGFR decline in a normal range.

Pharmacotherapy for hyperuricemia in hypertensive patients

BACKGROUND

High blood pressure represents a major public health problem. Worldwide, approximately one fourth of the adult population has hypertension. Epidemiological and experimental studies suggest a linkage between hyperuricemia and hypertension. Hyperuricemia affects 25-40 % of patients with untreated hypertension. A much lower prevalence has been reported in normotensives or in the general population. However, whether lowering serum uric acid (SUA) might lower blood pressure (BP) is an unanswered question.

OBJECTIVES

To determine whether uric acid lowering agents reduce BP in patients with primary hypertension.

SEARCH METHODS

Electronic searches of the following sources were performed without language restriction: Cochrane Hypertension Group Specialised Register (1946 to May 2012), Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2012 Issue 4), MEDLINE (1946 to May 2012), EMBASE (1974 to May 2012), LILACS (1982 to July 2012), Scirus and ClinicalTrials.gov. Authors of relevant papers were also contacted regarding further published and unpublished work.

SELECTION CRITERIA

To be included in this review, the studies had to meet the following criteria: 1) Randomised or quasi-randomised with a group assigned to receive a uric acid lowering agent and another group assigned to receive placebo; 2) Double-blind, single-blind or open label; 3) Parallel or crossover trial; 4) For crossover trial, a washout period of at least two weeks; 5) Minimum treatment duration of four weeks; 6) Participants with diagnosis of essential hypertension and hyperuricemia, serum uric acid greater than 6 in women, 7 in men and 5.5 in children/adolescents; 7) Outcome measures includes change in casual or ambulatory, systolic or diastolic blood pressure.

DATA COLLECTION AND ANALYSIS

Two independent reviewers collected the data using a data extraction form. Disagreements were resolved by discussion. Risk of bias was accessed by the Cochrane Collaboration Risk of Bias Tool.

MAIN RESULTS

Three hundred and thirty-six abstracts were examined. One study (enrolling hypertensive and hyperuricemic patients) met the inclusion criteria for the review and was independently rated by both authors. No other studies were identified by the supplementary searches. The study identified as eligible for this review was a randomised controlled trial conducted in the USA (FEIG 2008 ) . This well designed double-blind, placebo-controlled, crossover trial randomised 30 adolescents (11-17 years), newly diagnosed stage 1 primary hypertension and with SUA ≥ 6mg/dl, to receive allopurinol 200 mg twice daily for 4 weeks, and placebo for 4 weeks, with a 2 week washout period between treatments. Casual BP during the allopurinol phase decreased - 6.9 mmHg (95 % CI, - 4.5 to - 9.3), systolic, and - 5.1 mmHg (95 % CI, - 2.5 to - 7.8), diastolic, versus during the placebo phase, - 2.0 mmHg (95 % CI, 0.3 to - 4.3) systolic and - 2.4 mmHg (95 % CI, 0.2 to - 4.1) diastolic. For the secondary outcome (change in 24 ambulatory BP), change in systolic BP with allopurinol was - 6.3 mmHg (95 % CI, - 3.8 to - 8.9), systolic, and - 4.6 mmHg (95% CI, - 2.4 to - 6.8), diastolic, and with placebo, 0.8 mmHg (95 % CI, 3.4 to - 2.9) systolic and - 0.3 mmHg (95 % CI, 2.3 to - 2.1) diastolic. P-value results ranged from 0.004 to 0.05. No participant dropout occurred and no adverse effects were seen in patients treated with allopurinol.

AUTHORS' CONCLUSIONS

Meta-analysis was not possible in this systematic review. In the one study that matched the inclusion criteria allopurinol decreased "in office" and ambulatory systolic and diastolic BP. Because there was only one included RCT, the number of patients providing data on pharmacotherapy for hyperuricemia in hypertension is small and restricted to adolescents with recently diagnosed mild essential hypertension. Hence, there is insufficient evidence to recommend the use of allopurinol or other hypouricemic drugs as an initial or adjuvant treatment of hypertension and more RCTs are needed.

The effects of a long-term physical activity intervention on serum uric acid in older adults at risk for physical disability

Observational studies show a relationship between elevated serum uric acid (UA) and better physical performance and muscle function. The purpose of this paper was to determine whether regular participation in an exercise intervention, known to improve physical functioning, would result in increased serum UA. For this study, 424 older adults at risk for physical disability were randomized to participate in either a 12-mo moderate-intensity physical activity (PA) or a successful aging (SA) health education intervention. UA was measured at baseline, 6, and 12 mo (n = 368, 341, and 332, respectively). Baseline UA levels were 6.03 ± 1.52 mg/dl and 5.94 ± 1.55 mg/dl in the PA and SA groups, respectively. The adjusted mean UA at month 12 was 4.8% (0.24 mg/dl) higher in the PA compared with the SA group (p = .028). Compared with a health education intervention, a 1-yr PA intervention results in a modest increase in systemic concentration of UA in older adults at risk for mobility disability.

Uric acid-induced phenotypic transition of renal tubular cells as a novel mechanism of chronic kidney disease

Recent experimental and clinical studies suggest a causal role of uric acid in the development of chronic kidney disease. Most studies have focused on uric acid-induced endothelial dysfunction, oxidative stress, and inflammation in the kidney. The direct effects of uric acid on tubular cells have not been studied in detail, and whether uric acid can mediate phenotypic transition of renal tubular cells such as epithelial-to-mesenchymal transition (EMT) is not known. We therefore investigated whether uric acid could alter E-cadherin expression and EMT in the kidney of hyperuricemic rats and in cultured renal tubular cells (NRK cells). Experimental hyperuricemia was associated with evidence of EMT before the development of significant tubulointerstitial fibrosis at 4 wk, as shown by decreased E-cadherin expression and an increased α-smooth muscle actin (α-SMA). Allopurinol significantly inhibited uric acid-induced changes in E-cadherin and α-SMA with an amelioration of renal fibrosis at 6 wk. In cultured NRK cells, uric acid induced EMT, which was blocked by the organic anion transport inhibitor probenecid. Uric acid increased expression of transcriptional factors associated with decreased synthesis of E-cadherin (Snail and Slug). Uric acid also increased the degradation of E-cadherin via ubiquitination, which is of importance since downregulation of E-cadherin is considered to be a triggering mechanism for EMT. In conclusion, uric acid induces EMT of renal tubular cells decreasing E-cadherin synthesis via an activation of Snail and Slug as well as increasing the degradation of E-cadherin.

Urine NGAL and KIM-1 in children and adolescents with hyperuricemia

BACKGROUND

The aim of this study was to test the hypothesis that urine levels of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) are enhanced in pediatric patients with hyperuricemia.

METHODS

The study included 88 children and adolescents (60 males, 28 females) with a median age of 16 (range 11-18.5) years who had been referred to our department to rule out or confirm hypertension. The subjects were divided into two groups: the hyperuricemic (HU) group comprising 59 subjects with hyperuricemia (defined as serum uric acid >4.8 and >5.5 mg/dl in girls and boys, respectively) and the reference group comprising 29 patients with normouricemia. Urine NGAL and KIM-1 levels were evaluated using a commercially available kit.

RESULTS

Concentrations of the examined biomarkers [urine NGAL, NGAL/creatinine (cr.) ratio, urine KIM-1, KIM-1/cr. ratio] were increased in the HU group compared with the reference group (p < 0.01). There were positive correlations between the serum uric acid and urine NGAL/cr. ratio (R = 0.67, p < 0.001) and the urine KIM-1/cr. ratio (R = 0.36, p < 0.001). In the multiple regression models, serum uric acid, systolic blood pressure and cholesterol accounted for more than 49 % of the variation in the NGAL/cr. ratio (R = 0.702, p < 0.001). In the second model, serum uric acid, gender, age and systolic blood pressure accounted for more than 36 % of the variation in the KIM-1/cr. ratio (R = 0.604, p < 0.001).

CONCLUSION

We demonstrated that male, obese, hypertensive adolescents with hyperuricemia have higher urine NGAL and KIM-1 levels relative to a reference group with normouricemia.

Hypertension and the development of new onset chronic kidney disease over a 10 year period: a retrospective cohort study in a primary care setting in Malaysia

BACKGROUND

Little is known about the rate of progression to chronic kidney disease (CKD) among hypertensive patients, particularly at the primary care level. This study aims to examine risk factors associated with new onset CKD among hypertensive patients attending a primary care clinic.

METHODS

This is a 10-year retrospective cohort study of 460 patients with hypertension who were on treatment. Patient information was collected from patient records. CKD was defined as a glomerular filtration rate <60 ml/min per 1.73 m2 (Cockcroft-Gault equation). Multiple logistic regression statistics was used to test the association in newly diagnosed CKD.

RESULTS

The incidence of new CKD was 30.9% (n = 142) with an annual rate of 3%. In multivariate logistic regression analysis, factors associated with development of new onset of CKD among hypertensive patients were older age (odds ratio [OR] 1.123, 95% confidence interval [CI] 1.078-1.169), presence of diabetes (OR 2.621, 95% CI 1.490-4.608), lower baseline eGFR (OR 1.041, 95% CI 0.943-0.979) and baseline hyperuricaemia (OR 1.004, 95% CI 1.001-1.007).

CONCLUSIONS

The progression to new onset CKD is high among urban multiethnic hypertensive patients in a primary care population. Hence every effort is needed to detect the presence of new onset CKD earlier. Hypertensive patients who are older, with underlying diabetes, hyperuricaemia and lower baseline eGFR are associated with the development of CKD in this population.

Endothelin-A receptor antagonism modifies cardiovascular risk factors in CKD

Arterial stiffness and impaired nitric oxide (NO) bioavailability contribute to the high risk for cardiovascular disease in CKD. Both asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO production, and endothelin-1 (ET-1) oppose the actions of NO, suggesting that ET-1 receptor antagonists may have a role in cardiovascular protection in CKD. We conducted a randomized, double-blind, three-way crossover study in 27 patients with proteinuric CKD to compare the effects of the ET(A) receptor antagonist sitaxentan, nifedipine, and placebo on proteinuria, BP, arterial stiffness, and various cardiovascular biomarkers. After 6 weeks of treatment, placebo and nifedipine did not affect plasma urate, ADMA, or urine ET-1/creatinine, which reflects renal ET-1 production; in contrast, sitaxentan led to statistically significant reductions in all three of these biomarkers. No treatment affected plasma ET-1. Reductions in proteinuria and BP after sitaxentan treatment was associated with increases in urine ET-1/creatinine, whereas reduction in pulse-wave velocity, a measure of arterial stiffness, was associated with a decrease in ADMA. Taken together, these data suggest that ET(A) receptor antagonism may modify risk factors for cardiovascular disease in CKD.