Is it time to change the definition of normal urinary albumin excretion? ACTA ACUST UNITED AC. 2008;4:650-651. [PMID: 18852732 DOI: 10.1038/ncpneph0971]

Serum Uric Acid and Coronary Arterial Disease in Predialysis Chronic Kidney Disease Patients

Background–Aim:

Uric acid is considered a marker of high cardiovascular risk. We investigated the association between serum uric acid and coronary arterial disease (CAD) in pre-dialysis chronic kidney disease (CKD) patients.

Methods:

We enrolled 110 subjects on mean age 69.02 ± 14.3 years old. The participants were categorized for both estimated glomerular filtration rate (eGFR) and albuminuria according to criteria 2012 of the Kidney Disease Improving Global Outcomes. Estimated pulse wave velocity (ePWV) was calculated using an equation including the age and mean blood pressure. The CAD prevalence rate was recorded.

Results:

The patients were divided in two groups according to uric acid cutoff point value related to high ePWV. The patients with higher uric acid were older and they had significantly higher systolic blood pressure, pulse pressure, and parathyroid hormone, but significantly lower eGFR and 1,25(OH)2 Vit D3 levels. The association between high uric acid and both high ePWV and CAD occurrence was found to be significant ( x2 = 6.7, P = .008 and x2 = 4.1, P = .03, respectively), although the relationship with albuminuria was found to be nonsignificant. In a built multifactorial model, the low serum uric acid rather than the high was found to be an independent predictor for CAD demonstration entering traditional and specific confounders.

Conclusion:

The low serum uric acid levels were proved to be a significant predictor for CAD accounting potential covariates, even though the high uric acid per se was found to be connected with cardiovascular disease characteristics including arterial stiffness in predialysis CKD patients.

Albuminuria as a marker of arterial stiffness in chronic kidney disease patients

AIM: To access the association between albuminuria levels and arterial stiffness in non-diabetic patients with hypertension and chronic kidney disease (CKD) stages 1-2, treated with renin angiotensin blockade agents plus other hypertensive drugs when needed.

METHODS: One hundred fifteen patients [median age 52 years (68% males)] were consequently enrolled in the study. For each patient, we recorded gender, age, body mass index (BMI), peripheral systolic blood pressure (pSBP), peripheral diastolic blood pressure, peripheral pulse pressure, central systolic blood pressure (cSBP), central diastolic blood pressure (cDBP), central pulse pressure (cPP), hematocrit, hemoglobin, hsCRP, total cholesterol triglycerides, high-density lipoprotein-C, low-density lipoprotein-C, calcium, phosphorus, parathormone, and albumin, as well as 24 h urine albumin excretion. According to 24-h urine albumin collection, patients were then classified as those with moderately increased albuminuria (formerly called macroalbuminuria) (≤ 300 mg/d) and those with severely increased albuminuria (formerly called macroaluminuria (> 300 mg/d). We considered aortic stiffness (AS) indices [carotid femoral pulse wave velocity (PWVc-f) and augmentation index (AIx)] as primary outcomes of the study. We explored potential correlations between severely increased albuminuria and AS indices using a multiple linear regression model.

RESULTS: Fifty-eight patients were included in the moderately increased albuminuria group and 57 in the severely increased albuminuria. Blood pressure measurements of the study population were 138 ± 14/82 ± 1.3 mmHg (systolic/diastolic). There were no significant differences in age, sex, and BP measurements between the two groups. Patients with severely increased albuminuria had higher PWV and AIx than patients with moderately increased albuminuria (P < 0.02, P < 0.004, respectively). In addition these patients exhibited higher BMI (P < 0.03), hsCRP (P < 0.001), and fibrinogen levels (P < 0.02) compared to patients with moderately increased albuminuria. In multivariate linear regression analysis, severely increased albuminuria (β = 1.038, P < 0.010) pSBP (β = 0.028, P < 0.034) and Ht (β = 0.171, P = 0.001) remained independent determinants of the increased PWVc-f. Similarly, severely increased albuminuria (β = 4.385, P < 0.012), cSBP (β = 0.242, P < 0.001), cPP (β = 0.147, P < 0.01) and Ht levels (β = 0.591, P < 0.013) remained independent determinants of increased AIx.

CONCLUSION: These findings demonstrate an independent association between AS indices and severely increased albuminuria in non-diabetic, hypertensive patients with CKD stages 1-2 treated with renin angiotensin aldosterone system blockers.

Should proteinuria reduction be the criterion for antihypertensive drug selection for patients with kidney disease?

PURPOSE OF REVIEW

Proteinuria, that is, more than 200 mg/day of urinary albumin, is associated with the presence of kidney disease. Its increase over time is strongly correlated with progression of nephropathy. Retrospective analyses of nephropathy outcome trials show that proteinuria reduction of 30% or more after initiation of blood pressure (BP)-lowering therapy is associated with slower nephropathy progression than lowering BP without its reduction.

RECENT FINDINGS

Retrospective analyses of five large nephropathy outcome trials demonstrate that nephropathy progression slowed by an additional 28-39% over the control or placebo group when proteinuria was reduced in concert with BP. Two separate trials demonstrate that nephropathy progression was slowed to a lesser degree when BP was reduced to a similar degree, but proteinuria reduced less than 30%. These associations do not hold for those with microalbuminuria, in which BP reduction is the key element to slowing nephropathy progression. Recent cardiovascular outcome trials fail to show a relationship between reductions in proteinuria and nephropathy outcomes. This large cardiovascular endpoint trial, however, was not only powered for nephropathy outcomes but also failed to show a benefit between proteinuria reduction and cardiovascular events, a previously established observation.

SUMMARY

All patients with a history of hypertension and either kidney disease or diabetes should have an annual check for albuminuria. If albumin is present in amounts of more than 200 mg/day, strategies for BP-lowering therapy should also focus on a reduction of more than 30% of urinary protein.

Management of hypertension in patients with diabetes: the place of angiotensin-II receptor blockers

Hypertension is an important cardiovascular (CV) risk factor in patients with diabetes mellitus. In this setting, tight control of blood pressure (BP) significantly reduces CV morbidity and mortality. In the UK Prospective Diabetes Study, a 10 mmHg reduction in systolic blood pressure (SBP) was superior to a 0.7% decrease in glycosylated haemoglobin A1c (HbA1c) as far as reducing morbidity and mortality was concerned. In the Hypertension Optimal Treatment study, the risk of CV events decreased by 51% among patients with type 2 diabetes randomized to the lower BP level. Based on these findings, contemporary treatment guidelines recommend a target SBP/diastolic blood pressure of <130/80 mmHg for patients with diabetes.

Higher levels of urinary albumin excretion within the normal range predict faster decline in glomerular filtration rate in diabetic patients

OBJECTIVE To assess the relationship between albuminuria, including elevation within the normal range, and decline in glomerular filtration rate (GFR) in diabetic patients. RESEARCH DESIGN AND METHODS A total of 5,449 Japanese diabetic patients were categorized according to sex and urinary albumin-to-creatinine ratio (ACR; <5, 5-9, 10-29, 30-99, 100-299, 300-999, 1,000-2,999, and > or =3,000 mg/g) and followed for at least 5 years. The rate of change in estimated GFR (eGFR) adjusted for age and baseline eGFR was compared among ACR categories. RESULTS A higher baseline ACR predicted a faster decline in eGFR for both sexes. Even within the normal range (<30 mg/g), ACR > or =10 mg/g in women and > or =5 mg/g in men was associated with a significantly greater rate of decline in eGFR relative to subjects with ACR <5 mg/g. CONCLUSIONS Elevated ACR, even within the normal range, is associated with a faster decline in eGFR in diabetic patients.