Urinary phosphate-containing nanoparticle contributes to inflammation and kidney injury in a salt-sensitive hypertension rat model.

Although disturbed phosphate metabolism frequently accompanies chronic kidney disease (CKD), its causal role in CKD progression remains unclear. It is also not fully understood how excess salt induces organ damage. We here show that urinary phosphate-containing nanoparticles promote kidney injury in salt-sensitive hypertension. In Dahl salt-sensitive rats, salt loading resulted in a significant increase in urinary phosphate excretion without altering serum phosphate levels. An intestinal phosphate binder sucroferric oxyhydroxide attenuated renal inflammation and proteinuria in this model, along with the suppression of phosphaturia. Using cultured proximal tubule cells, we confirmed direct pathogenic roles of phosphate-containing nanoparticles in renal tubules. Finally, transcriptome analysis revealed a potential role of complement C1q in renal inflammation associated with altered phosphate metabolism. These data demonstrate that increased phosphate excretion promotes renal inflammation in salt-sensitive hypertension and suggest a role of disturbed phosphate metabolism in the pathophysiology of hypertensive kidney disease and high salt-induced kidney injury.

Mineralocorticoid Receptor Antagonists for Hypertension Management in Advanced Chronic Kidney Disease: BLOCK-CKD Trial.

Spironolactone, a steroidal mineralocorticoid receptor antagonist, is recommended as add-on therapy for treatment-resistant/uncontrolled hypertension. However, caution is advised in patients with advanced chronic kidney disease (CKD) due to an increased risk for hyperkalemia. KBP-5074 is a nonsteroidal mineralocorticoid receptor antagonist under investigation for the treatment of treatment-resistant and uncontrolled hypertension in patients with moderate-to-severe CKD. BLOCK-CKD is a phase 2, international, multicenter, randomized, double-blind, placebo-controlled, parallel-group study to evaluate the efficacy and safety of KBP-5074, on top of current therapy, in patients with stage 3B/4 CKD (estimated glomerular filtration rate ≥15 and ≤44 mL/[min·1.73 m2]) and resistant hypertension (trough cuff seated systolic blood pressure ≥140 mm Hg, despite treatment with maximally tolerated doses of 2 or more antihypertensive medicines with complementary mechanisms). Patients (n=240) will be randomized 1:1:1 to once-daily treatment with KBP-5074 0.25 mg, KBP-5074 0.5 mg, or placebo, stratified by estimated glomerular filtration rate (≥30 versus <30 mL/[min·1.73 m2]) and systolic blood pressure (≥160 versus <160 mm Hg). Approximately 30% of enrolled patients should have an estimated glomerular filtration rate of 15 to 29 mL/(min·1.73 m2). The primary efficacy analysis is the change in trough cuff seated systolic blood pressure from baseline to day 84 for the KBP-5074 doses compared with placebo. Changes in urinary albumin-creatinine ratio will be assessed along with changes in serum potassium/incidence of hyperkalemia and changes in estimated glomerular filtration rate and serum creatinine. BLOCK-CKD will determine whether the addition of KBP-5074 will effectively lower blood pressure without an increased risk of hyperkalemia in patients who are not candidates for steroidal mineralocorticoid receptor antagonists due to advanced CKD. Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT03574363.

Abnormal circadian rhythm of urinary sodium excretion correlates closely with hypertension and target organ damage in Chinese patients with CKD.

Whether the abnormal circadian rhythm of urinary sodium excretion is associated with hypertension in chronic kidney disease (CKD) is poorly understood. In this study, we assessed the relationship between the circadian rhythm of urinary sodium excretion and hypertension. Urinary samples were collected during both the day (07:00 to 22:00) and night (22:00 to 07:00) to estimate night/day urinary sodium excretion ratios. Blood pressure (BP) and clinical data were also measured. A total of 1,099 Chinese CKD patients were recruited, 308 patients were excluded, and 791 patients were final enrolled in this study. Among them, 291 patients were normotensive and 500 were hypertensive CKD patients. A 1:1 propensity score matching (PSM) analysis was performed with age and estimated glomerular filtration rate (eGFR) matched between 190 normotensive and hypertensive patients. In the full cohort and PSM cohort, multivariate regression analysis showed that the night/day urinary sodium excretion ratio was an independent risk factor for clinical hypertension, whereas 24 h urinary sodium excretion, diurnal and nocturnal urinary sodium excretion were not. When the night/day urinary sodium excretion ratios were further divided into tertiles (tertile 1 < 0.47, tertile 2, 0.47-0.84 and tertile 3 > 0.84), multivariate analysis showed that tertile 3 was independently associated with hypertension in the full and PSM cohorts. In addition, tertile 3 was also independently associated with eGFR ≤ 60 mL/min/1.73 m2 and left ventricular hypertrophy. These data suggested that an abnormal circadian rhythm of urinary sodium excretion was independently associated with hypertension and target-organ damage. Individualized salt intake and therapeutic strategies should be used to normalize the natriuretic dipping profile in CKD patients.

Circulating miR-103a-3p contributes to angiotensin II-induced renal inflammation and fibrosis via a SNRK/NF-κB/p65 regulatory axis.

Although angiotensin II (AngII) is known to cause renal injury and fibrosis, the underlying mechanisms remain poorly characterized. Here we show that hypertensive nephropathy (HN) patients and AngII-infused mice exhibit elevated levels of circulating miR103a-3p. We observe a positive correlation between miR-103a-3p levels and AngII-induced renal dysfunction. miR-103a-3p suppresses expression of the sucrose non-fermentable-related serine/threonine-protein kinase SNRK in glomerular endothelial cells, and glomeruli of HN patients and AngII-infused mice show reduced endothelial expression of SNRK. We find that SNRK exerts anti-inflammatory effects by interacting with activated nuclear factor-κB (NF-κB)/p65. Overall, we demonstrate that AngII increases circulating miR-103a-3p levels, which reduces SNRK levels in glomerular endothelial cells, resulting in the over-activation of NF-κB/p65 and, consequently, renal inflammation and fibrosis. Together, our work identifies miR-103a-3p/SNRK/NF-κB/p65 as a regulatory axis of AngII-induced renal inflammation and fibrosis.

Urine Ammonium Predicts Clinical Outcomes in Hypertensive Kidney Disease.

Metabolic acidosis is associated with poor outcomes in CKD. Because impaired renal ammonium excretion is important in the pathogenesis of acidosis, urine ammonium excretion might be a better and perhaps earlier acid-base indicator of risk than serum bicarbonate, particularly in patients without acidosis. We evaluated the association between baseline ammonium excretion and clinical outcomes in African American Study of Kidney Disease and Hypertension participants (n=1044). Median daily ammonium excretion was 19.5 (95% confidence interval [95% CI], 6.5 to 43.2) mEq. In Cox regression models (adjusted for demographics, measured GFR, proteinuria, body mass index, net endogenous acid production, and serum potassium and bicarbonate), hazard ratios of the composite outcome of death or dialysis were 1.46 (95% CI, 1.13 to 1.87) in the low tertile and 1.14 (95% CI, 0.89 to 1.46) in the middle tertile of daily ammonium excretion compared with the high tertile. Among participants without acidosis at baseline, the adjusted hazard ratio for those with ammonium excretion <20 mEq/d was 1.36 (95% CI, 1.09 to 1.71) compared with those with ammonium excretion ≥20 mEq/d. Additionally, compared with participants in the high ammonium tertile, those in the low ammonium tertile had higher adjusted odds of incident acidosis at 1 year (adjusted odds ratio, 2.56; 95% CI, 1.04 to 6.27). In conclusion, low ammonium excretion is associated with death and renal failure in hypertensive kidney disease, even among those without acidosis. Low ammonium excretion could identify patients with CKD and normal bicarbonate levels who might benefit from alkali before acidosis develops.

Serum uric acid and the incidence of CKD and hypertension.

BACKGROUND: Uric acid (UA) levels correlate positively with the prevalence of chronic kidney disease (CKD) and/or hypertension. We tested the hypothesis that UA may also have a link to a new incidence of CKD and hypertension. METHODS: Study design is a cohort study and the predictor is UA levels. Of the 15,470 screened cases, 8223 participants without CKD were eligible for the analysis of the incidence of CKD. Among these CKD candidates, 7569 participants were eligible for the analysis of the new development of hypertension. The observation period was 4 years. RESULTS: Relationship of UA with new cases of CKD. Higher UA levels had a closer association with the new development of CKD; 1.1 % (UA < 5 mg/dL), 1.5 % (5.0-5.9 mg/dL), 1.7 % (6.0-6.9 mg/dL), and 3.4 % (≧7 mg/dL), respectively (p < 0.001 by the Chi-square test). Cox proportional hazard analysis showed that the estimates of the CKD development were eGFR [Hazard Ratio (HR) 0.816, 95 % confidence intervals (CI) 0.791-0.840] and male gender (HR 0.562, 95 % CI 0.322-0.982). UA levels and new development of hypertension. Higher UA levels had a closer association with the new development of hypertension; 5.0 % (UA < 5 mg/dL), 8.9 % (5.0-5.9 mg/dL), 10.6 % (6.0-6.9 mg/dL), and 11.8 % (≧7 mg/dL), respectively (p < 0.001 by the Chi-square test). Cox proportional hazard analysis showed that the estimates of the hypertension development were BMI (HR 1.190, 95 % CI 1.155-1.226), age (HR 1.021, 95 % CI 1.010-1.032), HDL-cholesterol (HR 1.013, 95 % CI 1.007-1.019), male gender (HR 1.791, 95 % CI 1.338-2.395), UA level (HR 1.112, 95 % CI 1.024-1.207), and eGFR (HR 1008, 95 % CI 1.002-1.013). Furthermore, the logistic analysis showed that the odds ratio (OR) to estimate hypertension in the high UA group (UA ≧ 7 mg/dL; OR 1.33, 95 % CI 1.01-1.80) was greater than that in the low UA group (UA < 5 mg/dL). Kaplan-Meier analysis also confirmed the finding that the higher the UA levels the greater the hypertension development (p < 0.001 by the Log-rank test and Cox proportional hazard analysis). CONCLUSION: High UA levels are associated with the new development of hypertension, but not with the incidence of CKD.

Urinary angiotensin converting enzyme 2 increases in patients with type 2 diabetic mellitus.

BACKGROUND/AIMS: Angiotensin converting enzyme 2 (ACE2) is highly expressed in the kidney and recognized to be renoprotective by degrading Angiotensin II to Angiotensin (1-7) in diabetic nephropathy. However, little is known about the role of urinary ACE2 (UACE2) in diabetes. The present study was performed to evaluate UACE2 levels in type 2 diabetic patients with various degrees of albuminuria and its associations with metabolic parameters. The effect of RAS inhibitors on UACE2 excretion was also assessed. METHODS: A total of 132 type 2 diabetic patients with different degrees of albuminuria and 34 healthy volunteers were studied. UACE2 levels and activity were measured. RESULTS: Compared to healthy controls, UACE2 to creatinine (UACE2/Cr) levels were significantly increased in both albuminuric and non-albuminuric diabetic patients. UACE2/Cr levels were much higher in hypertensive diabetic patients compared with their normotensive counterparts and treatment with RAS inhibitors markedly attenuated the augmentation. Furthermore, UACE2/Cr was positively correlated with fasting blood glucose, hemoglobin A1C (HbA1C), triglyceride, and total cholesterol. In multiple regression analysis, UACE2/Cr was independently predicted by HbA1C and RAS inhibitors treatment. CONCLUSIONS: UACE2 increased in type 2 diabetic patients with various degrees of albuminuria and RAS inhibitors suppresses UACE2 excretion. UACE2 might potentially function as a marker for monitoring the metabolic status and therapeutic response of RAS inhibitors in diabetes.

[Nephrotic proteinuria in hypertensive nephrosclerosis: clinical and evolution characteristics]. / Proteinuria de tipo nefrótico en la nefroangioesclerosis hipertensiva: características clínicas y evolutivas.

BACKGROUND AND OBJECTIVE: Nephrotic range proteinuria can occur in patients with biopsy proven hypertensive nephrosclerosis (HN). We analysed the differential clinical and evolution characteristics of these patients compared with other glomerular diseases. MATERIAL AND METHOD: This is a case-control descriptive analysis obtained from the renal pathology registry of our hospital. Clinical features, treatment and evolution of these patients (cases) were compared with nephrotic patients with other glomerular diseases (controls). RESULTS: Five point one percent of biopsies with HN diagnosis. Case/control characteristics were: proteinuria 4.7 [3-11.4] versus 5.5 [3-28.1] g/24h/1.73m(2) (P=NS). Normal albumin compared with controls (39.5 [6.4] versus 29.4 [10] g/dL; P=.001), significant oedemas only in 10 versus 63% of controls. HN were older (58.8 [12.6] versus 45.5 [19.6] years), had longer hypertension duration before renal biopsy and more previous cardiovascular events (39 versus 16%). Mean blood pressure was higher (166/90 versus 133/75mmHg; P=.01) and had worse renal outcome. CONCLUSIONS: HN must be included in the differential diagnosis of nephrotic range proteinuria in hypertensive patients. The absence of oedema and normal serum albumin are distinctive clinical characteristics that can help in decision-making before performing a renal biopsy.

Redox proteomics in study of kidney-associated hypertension: new insights to old diseases.

SIGNIFICANCE: The kidney helps to maintain low blood pressure in the human body, and impaired kidney function is a common attribute of aging that is often associated with high blood pressure (hypertension). Kidney-related pathologies are important contributors (either directly or indirectly) to overall human mortality. In comparison with other organs, kidney has an unusually wide range of oxidative status, ranging from the well-perfused cortex to near-anoxic medulla. RECENT ADVANCES: Oxidative stress has been implicated in many kidney pathologies, especially chronic kidney disease, and there is considerable research interest in oxidative stress biomarkers for earlier prediction of disease onset. Proteomics approaches have been taken to study of human kidney tissue, serum/plasma, urine, and animal models of hypertension. CRITICAL ISSUES: Redox proteomics, in which oxidative post-translational modifications can be identified in protein targets of oxidative or nitrosative stress, has not been very extensively pursued in this set of pathologies. FUTURE DIRECTIONS: Proteomics studies of kidney and related tissues have relevance to chronic kidney disease, and redox proteomics, in particular, represents an under-exploited toolkit for identification of novel biomarkers in this commonly occurring pathology.

Effect of exercise on albuminuria in people with diabetes.

AIM: Spot urine measurement of albumin is now the most commonly accepted approach to screening for proteinuria. Exertion prior to the collection may potentially influence the result of spot urine albumin estimation. We aim to evaluate the effect of exercise on albuminuria in subjects at various stages of diabetic nephropathy in comparison with healthy control volunteers. METHODS: Thirty-five people with diabetes (19 with normoalbuminuria (NA), nine with microalbuminuria (MA) and seven with overt proteinuria (OP)) and nine control subjects were assessed. A 1 km treadmill walk was performed. Four spot urine specimens were collected: first morning void, immediately prior to exercise, and 1 h and 2 h after exercise. A random effects linear regression mixed model was used to assess the effect of exercise on albumin/creatinine ratio (uACR). Results are presented separately for male and female subjects with diabetes due to a significant exercise/gender interaction (P < 0.05). RESULTS: No significant effect of exercise on uACR was seen in control subjects. In NA males with diabetes no effect of exercise was seen, while in females uACR 1 h after exercise was significantly higher than the early morning sample (3.55 mg/mmol (96% confidence interval 0.27-6.83). Both female and male diabetes subjects with MA have increase in uACR 1 h after exercise (87.8, -24.3-199.4 and 6.7, 2.1-11.3). For both males and females with OP, uACR was significantly increased 1 h post exercise (67.5, 22-113 and 21.6, 8.4-34.8, respectively). In all groups uACR at 2 h after exercise was not significantly different to the early morning sample. CONCLUSIONS: Exercise increased uACR estimation in normoalbuminuric subjects with diabetes with a larger effect in females. Whether exercise unmasks early diabetic nephropathy in NA subjects requires further study.

Altered urinary excretion of aquaporin 2 in IgA nephropathy.

OBJECTIVE: The intrarenal renin-angiotensin system (RAS) activation plays a pivotal role in immunoglobulin A nephropathy (IgAN) pathogenesis, which is still largely undefined. Recently, vasopressin (AVP) has been advocated to contribute to the genesis and progression of chronic kidney diseases (CKD) directly, and indirectly, via RAS activation. Our aim is to explore the intrarenal activity of AVP, its relationship with RAS activity, as well as its modulation by therapies in IgAN. DESIGN: In this observational study, we measured plasma copeptin, a surrogate marker of AVP, the urine excretion of aquaporin 2 (AQP2), a protein reflecting renal AVP action, and angiotensinogen (AGT), a parameter of renal RAS activation, and their relationship with renal function in 44 IgAN patients at the time of renal biopsy, without any drug therapy, and after 6-month treatment with ACEi or steroid+ACEi. Twenty-one patients with other CKD and 40 healthy subjects were recruited as controls. METHODS: ELISAs were used to measure all variables of interest. RESULTS: At baseline, IgAN patients showed higher urinary levels of AQP2, compared with controls and patients with other CKD. Urinary AQP2 and AGT levels strongly correlated with the presence of arterial hypertension. Steroids+ACEi caused the decrease of all the variables examined. The fall of urinary AQP2 and AGT following drug treatments was associated with the decrease of daily proteinuria. CONCLUSION: Our findings would support the involvement of AVP-AQP2 axis, interacting with the RAS, in the progression of IgAN and candidate AQP2 as a possible novel marker of the disease.

Relationship between body mass index and proteinuria in hypertensive nephrosclerosis: results from the African American Study of Kidney Disease and Hypertension (AASK) cohort.

BACKGROUND: Few studies have examined the association between obesity and markers of kidney injury in a chronic kidney disease population. We hypothesized that obesity is independently associated with proteinuria, a marker of chronic kidney disease progression. STUDY DESIGN: Observational cross-sectional analysis. SETTING & PARTICIPANTS: Post hoc analysis of baseline data for 652 participants in the African American Study of Kidney Disease (AASK). PREDICTORS: Obesity, determined using body mass index (BMI). MEASUREMENTS & OUTCOMES: Urine total protein-creatinine ratio and albumin-creatinine ratio measured in 24-hour urine collections. RESULTS: AASK participants had a mean age of 60.2 ± 10.2 years and serum creatinine level of 2.3 ± 1.5 mg/dL; 61.3% were men. Mean BMI was 31.4 ± 7.0 kg/m(2). Approximately 70% of participants had a daily urine total protein excretion rate <300 mg/d. In linear regression analyses adjusted for sex, each 2-kg/m(2) increase in BMI was associated with a 6.7% (95% CI, 3.2-10.4) and 9.4% (95% CI, 4.9-14.1) increase in urine total protein-creatinine and urine albumin-creatinine ratios, respectively. In multivariable models adjusting for age, sex, systolic blood pressure, serum glucose level, uric acid level, and creatinine level, each 2-kg/m(2) increase in BMI was associated with a 3.5% (95% CI, 0.4-6.7) and 5.6% (95% CI, 1.5-9.9) increase in proteinuria and albuminuria, respectively. The interaction between older age and BMI was statistically significant, indicating that this relationship was driven by younger AASK participants. LIMITATIONS: May not generalize to other populations; cross-sectional analysis precludes statements regarding causality. CONCLUSIONS: BMI is associated independently with urine total protein and albumin excretion in African Americans with hypertensive nephrosclerosis, particularly in younger patients.

Urinary sodium and potassium excretion and risk of hypertension in Chinese: report from a community-based cohort study in Taiwan.

BACKGROUND: Dietary sodium intake is associated with blood pressure and hypertension risk. However, most of the studies have been conducted in whites and it is not clear whether the effects exist in Asian populations. OBJECTIVE: The purpose of the present study was to investigate the role of 24-h urinary sodium excretion and hypertension risk among ethnic Chinese. DESIGN: A prospective cohort design on community. SETTING AND PARTICIPANTS: One thousand five hundred and twenty middle-aged and elderly participants who were free from hypertension at baseline and had available urine electrolyte data. MAIN OUTCOME MEASURES: Hypertension incidence. RESULTS: During a median 7.93 years of follow-up (interquartile range = 4.07-9.04 years), we documented 669 cases of incident hypertension. The multivariate risk was 1.26 (95% confidence interval = 1.01-1.57; P = 0.043) for individuals in the highest quartile of urinary sodium excretion as compared with those in the second quartile. A significant J-shape relationship between urinary sodium excretion and the risk of hypertension was observed, with the test for linear relation being rejected (P = 0.046). Participants who were in the highest quartile of urinary sodium excretion and higher baseline blood pressure had a 2.43-fold increased risk of hypertension (95% confidence interval = 1.72-3.22) compared with those in the lowest quartiles of urinary sodium and lower blood pressure. CONCLUSION: Urinary sodium excretion was associated with the risk of hypertension among ethnic Chinese. Urinary sodium excretion, as a marker of dietary sodium intake, can be useful for a comprehensive evaluation of hypertension risk in Asian populations.

Nighttime blood pressure and nocturnal dipping are associated with daytime urinary sodium excretion in African subjects.

Blood pressure (BP) follows a circadian rhythm, with 10% to 15% lower values during nighttime than during daytime. The absence of a nocturnal BP decrease (dipping) is associated with target organ damage, but the determinants of dipping are poorly understood. We assessed whether the nighttime BP and the dipping are associated with the circadian pattern of sodium excretion. Ambulatory BP and daytime and nighttime urinary electrolyte excretion were measured simultaneously in 325 individuals of African descent from 73 families. When divided into sex-specific tertiles of day:night ratios of urinary sodium excretion rate, subjects in tertile 1 (with the lowest ratio) were 6.5 years older and had a 9.8-mm Hg higher nighttime systolic BP (SBP) and a 23% lower SBP dipping (expressed in percentage of day value) compared with subjects in tertile 3 (P for trend <0.01). After adjustment for age, the SBP difference across tertiles decreased to 5.4 mm Hg (P=0.002), and the SBP dipping difference decreased to 17% (P=0.05). A similar trend across tertiles was found with diastolic BP. In multivariate analyses, daytime urinary sodium and potassium concentrations were independently associated with nighttime SBP and SBP dipping (P<0.05 for each). These data, based on a large number of subjects, suggest that the capacity to excrete sodium during daytime is a significant determinant of nocturnal BP and dipping. This observation may help us to understand the pathophysiology and clinical consequences of nighttime BP and to develop therapeutic strategies to normalize the dipping profile in hypertensive patients.

Predicting proteinuria in hypertensive pregnancies with urinary protein-creatinine or calcium-creatinine ratio.

OBJECTIVE: Evaluate the value of random urinary protein-creatinine (PrCr) and calcium-creatinine (CaCr) ratios to predict 24-h proteinuria in hypertensive pregnancies. STUDY DESIGN: Spot urine samples were collected before routine 24-h urine collections from consecutive pregnant women with hypertension (n=83). Reliability of spot urinary PrCr and CaCr to detect significant proteinuria (>or=300 mg/day) using 24-h urine protein as 'gold-standard' was assessed by receiver-operating characteristic (ROC) curve. RESULTS: Fifty-one patients (61.4%) had significant proteinuria (45 pre-eclampsia, 5 superimposed pre-eclampsia, 1 renal hypertension). Area under ROC curve to predict proteinuria was 0.82 (95% confidence interval (CI) 0.73 to 0.92, P<0.001) for PrCr and 0.55 (95% CI 0.43 to 0.68, P=0.2) for CaCr. A cutoff value of >0.19 for PrCr best predicted significant proteinuria with sensitivity, specificity, positive and negative predictive values and likelihood ratios (positive and negative), respectively, of 80.4, 68.8, 80.4, 68.8%, 2.57 and 3.51. CONCLUSION: Spot urinary PrCr predicts total urinary protein excretion in hypertensive pregnancies.

Measurement of aldosterone in feline, canine and human urine.

BACKGROUND: Systemic hypertension is an important problem in older cats associated with kidney disease and hypokalaemia, suggesting that excessive activity of the renin-angiotensin-aldosterone system might contribute to the hypertensive state. Fluctuations in plasma renin activity and plasma aldosterone concentrations complicate the interpretation of these assays. OBJECTIVES: The aim of this study was to determine whether measurement of urinary aldosterone excretion in cats aided the investigation of hypertension. METHODS: Urine concentrations of free (ethyl acetate extract) and 18-glucuronidated aldosterone (acid hydrolysis before extraction) were measured by radioimmunoassay in normal, normotensive and hypertensive azotaemic cats (n=11 per group). Urine samples from 11 healthy human volunteers and eight normal dogs were also analysed for comparison. Urinary aldosterone concentration was corrected for the urinary creatinine concentration. RESULTS: Cats excreted 7.3 times less free aldosterone than human beings, and no free aldosterone was detected in dog urine. Acid hydrolysis led to large increases in aldosterone recovery from both human beings and dog but not feline urine. No significant effect of hypertension or azotaemia on feline urinary aldosterone concentration was found. CLINICAL SIGNIFICANCE: Measurement of aldosterone in feline urine using the available methodology has limited or no utility in investigating feline hypertension.

A comparative study of three kidney biomarker tests in autosomal-dominant polycystic kidney disease.

BACKGROUND: The relationship between the progress of tubular damage and renal insufficiency in autosomal-dominant polycystic kidney disease (ADPKD) is a subject of doubtless interest, and is the object of this present work. METHODS: A total of 92 adult ADPKD patients of both genders were studied, none of which presented end-stage renal disease (ESRD), and classified according to an ultrasound score based on kidney size and number of cysts. Urinary albumin and beta-N-acetylhexosaminidase (Hex) and its isoenzymes were determined, together with serum glutathione peroxidase, cystatin C, creatinine, and urea. RESULTS: A frequent elevation of the urinary Hex was found and an alteration of its isoenzymatic profile, with 31% of the normotensive patients with normoalbuminuria already presenting an increased proportion of Hex B isoenzyme. Keeping age constant, a partial significant correlation was found between the ultrasound score and the proportion of Hex B (r = 0.352, P < 0.05), but not with albuminuria or cystatin C. In 42 patients the different biochemical variables were again determined after 1 year, finding that in the 13 normotensive patients with normoalbuminuria there had been a significant decrease in the concentration of cystatin C (P < 0.05), and a significant increase in the urinary excretion of albumin and Hex B isoenzyme (P < 0.05). By the other hand, in the other 29 patients with micro- or macroalbuminuria and hypertension, no significant differences were found. CONCLUSION: The results point toward an important participation of tubular damage in the pathogenesis of this disease. It may also be suggested that in normotensive and normoalbuminuric ADPKD patients, a gradual increase of glomerular filtration would be produced. After the start of hypertension and microalbuminuria, the glomerular filtration rate (GFR) would decrease progressively, although more slowly.

Correlation between left ventricular mass and urinary sodium excretion in specific genotypes of CYP11B2.

BACKGROUND: Aldosterone has essential roles in regulating intravascular volume and blood pressure, and is suggested to influence cardiac structure. However, the association of polymorphisms in the aldosterone synthase gene (CYP11B2) with hypertension or cardiac hypertrophy remains controversial. OBJECTIVE: To evaluate the distribution of polymorphisms in the CYP11B2 gene and the possible associations between genotypes and blood pressure, urinary excretion of aldosterone or electrolytes and echocardiographic measurements, in a Japanese population. METHODS AND RESULTS: We examined the association of two common diallelic polymorphisms within CYP11B2, one in the promoter -344T/C and the other an intron 2 gene conversion, with blood pressure, 24-h urinary excretion of aldosterone and electrolytes, and echocardiographic measurements, in a Japanese population. We confirmed significant linkage disequilibrium between these polymorphic loci and ethnic differences in frequency of the alleles. The -344C and -344T haplotypes apparently diverged before the intron conversion polymorphism was generated on the latter haplotype. Allele frequencies did not differ between 535 normotensive and 360 hypertensive individuals or between hypertensive individuals with higher and lower concentrations of renin. The only significant correlation was a positive correlation of left ventricular mass with 24-h urinary excretion of sodium, which occurred only in individuals with the -344CC genotype or the intron 2 conversion (-/-) genotype. CONCLUSIONS: The -344CC or intron 2 conversion (-/-) genotype in CYP11B2 may be a risk factor for developing sodium-sensitive cardiac hypertrophy. Ethnic differences in the distribution of CYP11B2 genotypes combined with differences in salt intake might account for inconsistencies between previous reports.