Overall health assessment: a renal perspective

Microalbuminuria in primary hypertension: a guide to optimal patient management?

Accurate assessment of the global risk profile is considered a prerequisite for the optimal management of hypertensive patients. In particular, the evaluation of subclinical organ damage, namely left ventricular hypertrophy, peripheral atherosclerosis and renal function, plays a key role in optimizing therapeutic targets and strategy in individual patients. Urine albumin excretion is a low-cost, easy-to-use test and a powerful predictor of cardiovascular diseases. The search for albuminuria has, therefore, become routine in the evaluation of hypertensive patients. Moreover, albuminuria has been shown to be associated with early signs of extra-renal organ damage such as left ventricular hypertrophy, and carotid atherosclerosis. Under effective antihypertensive treatment, changes in subclinical organ damage over time, especially regression of left ventricular hypertrophy, are paralleled by modification of risk status and may serve as intermediate endpoints for treatment. More recently, changes in albuminuria have also been proposed to reflect changes in the risk of cardiovascular events. If this is confirmed by large well-designed studies, microalbuminuria may not simply be regarded as a risk predictor but become itself an independent target for treatment.

Kidney and cardiovascular risk in primary hypertension

In patients with primary hypertension, therapeutic strategies should be based on global cardiovascular risk profile rather than on the severity of blood pressure alone. Accurate assessment of concomitant risk factors and especially of the presence and extent of subclinical organ damage is of paramount importance in defining individual risk. Given the high prevalence of hypertension in the population at large, however, extensive diagnostic evaluation is often impractical or unfeasible in clinical practice. Low cost, easy to use markers of risk are needed to improve the clinical management of patients with hypertension. Early renal abnormalities such as a slight reduction in glomerular filtration rate and/or the presence of microalbuminuria are well known and powerful predictors of cardio-renal morbidity and mortality and provide a useful, low cost tools to optimize cardiovascular risk assessment. A greater use of these tests should therefore be implemented in clinical practice in order to optimize the management of hypertensive patients.

Early renal abnormalities as an indicator of cardiovascular risk in type 2 diabetes

Accurate assessment of cardiovascular (CV) risk is a prerequisite for devising effective therapeutic strategies in patients with type 2 diabetes (T2DM) as it allows to refine prognosis and treatment targets as well as the cost-benefit ratio for specific pharmacological interventions. The presence of subclinical vascular organ damage plays a well known role in determining overall risk and a wider use of low cost, easy to perform diagnostic tools to stratify CV risk is very much needed. Besides their well known prognostic value for progression to end stage renal disease (ESRD), subclinical renal abnormalities such as microalbuminuria and/or a slight reduction in estimation of glomerular filtration rate (eGFR), have been shown to be powerful, independent predictors of CV diseases in patients with T2DM. Through the combined evaluation of these two biomarkers of chronic kidney disease (CKD), clinicians can usefully and reliably get a perspective on global and CV outcome of their diabetic patients.

Treatment Strategies to Prevent Renal Damage in Hypertensive Children

Hypertension secondary to chronic kidney disease prevails in earlier childhood and obesity-related primary hypertension in adolescence. Both are associated with a high risk of renal and cardiovascular morbidity. In children with chronic kidney disease, uncontrolled hypertension may accelerate progression to end-stage renal disease before adulthood is reached and increase a child’s risk of cardiac death a thousand-fold. Obesity-related hypertension is a slow and silent killer, and though early markers of renal damage are recognized during childhood, end-stage renal disease is a risk in later life. Renal damage will be a formidable multiplier of cardiovascular risk for adults in whom obesity and hypertension tracks from childhood. Management options to prevent renal damage will vary for these different target groups. This review provides a summary of the available renoprotective strategies in order to aid physicians involved in the care of this challenging group of children.

Antihypertensive treatment and renal protection: the role of drugs inhibiting the renin-angiotensin-aldosterone system

The prevalence of chronic kidney disease, currently estimated to vary between 8 and 12 % in the general population, is steadily rising due to aging and to the ongoing epidemic of hypertension and type 2 diabetes. Even in its early stages, chronic kidney disease entails a greater risk for cardiovascular mortality, and its prevention and treatment is rapidly becoming a key medical issue for many health care systems worldwide. Adequate blood pressure control and reduction of urine protein excretion, preferably obtained by the use of renin-angiotensin-aldosterone system inhibitors, have traditionally been considered the mainstay of therapeutic strategies in patients with renal disease. Given the pivotal role of renin-angiotensin-aldosterone system activity in the pathogenesis and progression of renal and cardiovascular damage, a more profound inhibition of the system, either by the use of multiple agents or by a single agent at high dosage has recently been advocated, especially in the presence of proteinuria. Recent trials, however have failed to confirm the usefulness of this therapeutic approach, at least in unselected patients. This article will critically review the current literature and will discuss the clinical implications of targeting the renin-angiotensin-aldosterone system in order to provide the greatest renal protection.

Sex differences in hypertension-related renal and cardiovascular diseases in Italy: the I-DEMAND study

AIM

The aim of this study is to evaluate the differences in the prevalence of chronic kidney disease (CKD) and of cardiovascular risk factors and diseases between men and women participating in the Italy Developing Education and awareness on MicroAlbuminuria in patients with hyperteNsive Disease (I-DEMAND) study.

METHODS

This is an observational, cross-sectional, multicenter study aimed at assessing prevalence and correlates of CKD among Italian hypertensive patients attending out-patient referral clinics. CKD was defined as glomerular filtration rate (GFR) less than 60 ml/min per 1.73 m(2) [Modification of Diet in Renal Disease (MDRD) study equation and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation] and/or urine albumin-to-creatinine ratio of at least 2.5 mg/mmol in men and of at least 3.5 mg/mmol in women or both. Left-ventricular hypertrophy (LVH) was diagnosed by either ECG or echocardiography.

RESULTS

A total of 3558 study patients with renal data available were considered for this analysis: mean age was 61 ± 4 years and 37% had diabetes mellitus. Female patients (n = 1636, 46%) were older, with a greater prevalence of obesity and lower prevalence of smoking. The prevalence of concomitant coronary artery and peripheral artery diseases, but not of hypertension, diabetes mellitus, or heart failure, was lower in women than in men. The overall prevalence of albuminuria (21 vs. 32%; P = 0.001) and of microalbuminuria (16 vs. 23%; P = 0.001) was lower in women than in men. In women the prevalence of a reduced GFR estimated by both MDRD (33 vs. 21%; P = 0.001) and CKD-EPI equations (32 vs. 23%; P = 0.001) was higher than in men. CKD prevalence was similar in women and men (44 vs. 41%; P = 0.095 and 43 vs. 43%; P = 0.475, respectively, when MDRD and CKD-EPI eGFR estimations were used). The prevalence of LVH (diagnosed by either ECG or echocardiography) was similar in men and women (18 vs. 20%; P = 0.12).The main independent determinants of CKD were age, glycemia, uricemia, pulse pressure, hypertension duration, and previous cardiovascular diseases in men, and increasing age, glycemia, uricemia, pulse pressure, and a lower BMI in women.

CONCLUSION

Renal abnormalities are present in a significant number of female hypertensive patients attending hypertension clinics. Prevalence of reduced eGFR and of microalbuminuria, associated risk factors, and clinical conditions are different between men and women, suggesting the need to develop specific therapeutic strategies to prevent renal dysfunction and reduce associated morbidity and mortality.

Within-person variability in kidney measures

BACKGROUND

Our objective was to quantify short-term total within-person variability in standard and nontraditional kidney measures using national data.

STUDY DESIGN

Repeated examination study of serum and urine kidney measures.

SETTING & PARTICIPANTS

Participants 18 years or older in the Third National Health and Nutrition Examination Survey (NHANES III) who had repeated blood and urine samples collected during visits occurring approximately 18 days apart.

MEASUREMENTS

Standardized serum creatinine, standardized cystatin C, β-trace protein (BTP), β(2)-microglobulin (B2M), and urine albumin and creatinine. We calculated the within-person coefficient of variation (CV(w)), which includes both biological and analytical variability. We also evaluated the impact of variability on estimates of the prevalence of reduced estimated glomerular filtration rate and albuminuria.

RESULTS

Serum cystatin C level demonstrated the lowest short-term within-person variability (CV(w) = 6.8%). Serum creatinine and B2M levels (CV(w) = 7.6% and 8.4%, respectively) also had low variability. BTP level had the most variability of the serum markers (CV(w) = 11.6%). As expected, urine albumin and urine creatinine measurements showed high variability (CV(w) >30% for both); however, albumin-creatinine ratio performed much better than either measure alone, with CV(w) of 11.3%. The effect of short-term variability on the prevalence of reduced estimated glomerular filtration rate was moderate, with an ~20% lower prevalence when defined based on single measurements compared to repeated application of the same test approximately 18 days apart. Repeated testing for albuminuria had a larger effect, showing a 33% lower prevalence of albuminuria when repeated testing was applied.

LIMITATIONS

Only 2 measurements available. General population with low prevalence of kidney disease.

CONCLUSIONS

Our results suggest that creatinine, cystatin C, and B2M levels have similarly low short-term variability. BTP level was more variable compared with the other serum filtration markers. Urine albumin and creatinine levels were highly variable and may benefit from repeated assessments to reduce the misclassification of albuminuria.

Differences in estimation of creatinine generation between renal function estimating equations in an Indian population: cross-sectional data from the Hyderabad arm of the Indian migration study

Background

Creatinine based formulae for estimating renal function developed in white populations may be less valid in other ethnic groups. We assessed the performance of various estimating formulae in an Indian population.

Methods

917 subjects were recruited from the Hyderabad arm of the Indian Migration Study. Data were collected on comorbidity, serum creatinine and body composition from DXA scans. Renal function was compared using the modified Cockcroft-Gault, MDRD and CKD-EPI formulae. 24-hour creatinine production was derived from each estimate and the agreement with measured muscle mass examined. 24-hour creatinine production estimates were compared to that derived from a formula by Rule incorporating DXA measured muscle mass. Potential systematic biases were examined by age and eGFR. We assessed the association of renal function by each formula with hypertension and self-reported measures of vascular disease.

Results

Mean modified Cockcroft-Gault eCCl was 98.8 ml/min/1.73 m², MDRD eGFR 91.2 ml/min/1.73 m² and CKD-EPI eGFR 96.3 ml/min/1.73 m². MDRD derived 24-hour creatinine production showed the least age-related underestimation compared to the Rule formula. CKD-EPI showed a marked bias at higher eGFRs. All formulae showed similar strength associations with vascular disease and hypertension.

Conclusions

Our analyses support the use of MDRD for estimating renal function in Indian populations. Further work is required to assess the predictive value of formulae for incident disease and complications of CKD.