A cohort of 227 untreated essential hypertensive patients from north-western Italy was studied in order to evaluate the prevalence of micro- and macroalbuminuria and their relationship with other ...cardiovascular risk factors. Albuminuria was evaluated as the albumin to creatinine ratio (Alb/Cr) in three non-consecutive first morning samples. The prevalence of microalbuminuria and macroalbuminuria was 10% and 2.2%, respectively. Albuminuric patients showed higher blood pressure, serum creatinine, triglycerides and uric acid as well as a greater prevalence of retinopathy. Stepwise multiple regression analysis demonstrated that only a small part of variations in albuminuria was explained by changes in blood pressure. Duration of disease did not seem to influence microalbuminuria. The presence of hypertensive retinopathy was associated with greater albuminuria, longer duration of hypertension, and higher prevalence of major ECG changes, but not with higher blood pressure levels. Microalbuminuria, rather than a consequence of elevated blood pressure levels, seems to be a marker of a syndrome featuring, among other characteristics, essential hypertension. Furthermore, microalbuminuria must be considered as an independent cardiovascular risk factor.
Urinary albumin excretion and left ventricular mass are related to each other and to the risk of cardiovascular events in patients with primary hypertension. We aimed to identify a lower threshold ...for albuminuria that might improve detection of patients with left ventricular hypertrophy (LVH) and cost-effectiveness in cardiovascular risk assessment.
Albuminuria and left ventricular mass index were assessed in 448 untreated, nondiabetic patients with primary hypertension. The impact that lower albuminuria cut-off levels might have on detecting LVH was evaluated with regard to test cost and sensitivity. This was done by a diagnostic algorithm consisting of albuminuria evaluation followed by echocardiography in the presence of normoalbuminuria.
The area under the ROC curve of albuminuria in predicting LVH was 0.73. Using a lower albumin to creatinine ratio threshold than what is recommended by the guidelines (ie, 11.5 mg/g), the sensitivity and specificity of albuminuria in identifying patients with LVH was 39% and 92%, respectively, which translated to positive and negative predictive values of 76% and 69%, respectively. When considering only patients without electrocardiographically detected LVH, routine screening for albuminuria, followed by echocardiography in the presence of albuminuria ≤11.5 mg/g, allowed us to decrease the number of echocardiograms by 23%.
Adopting a lower threshold to define microalbuminuria could prove to be cost-effective for assessing cardiovascular risk in hypertensive patients.
Microalbuminuria has recently emerged as a strong, independent predictor of cardiovascular mortality in patients with essential hypertension, yet the pathophysiological mechanisms underlying this ...association remain to be elucidated.
To study the relationship between microalbuminuria and left ventricular geometry and function and extra-cardiac vascular changes in a group of 211 untreated hypertensive patients.
Albuminuria was evaluated as albumin-to-creatinine ratio in three non-consecutive first morning urine samples. Left ventricular mass index and function were assessed by M-B mode echocardiography and carotid wall thickness by high-resolution ultrasound scan.
The prevalences of microalbuminuria and left ventricular hypertrophy were 14 and 47% respectively. Patients in the top quartile of albuminuria showed a higher left ventricular mass index (57 +/- 1.8, 55 +/- 2, 47 +/- 1.4 and 48 +/- 1.6 g/m2.7, respectively; P< 0.0001) as well as a higher prevalence of left ventricular hypertrophy (72, 65, 26 and 25%, respectively; P< 0.001) and especially concentric hypertrophy (56, 47, 17 and 21%, respectively; P< 0.0001) in the four quartiles of albuminuria. Microalbuminuric patients showed depressed left ventricular performance as indicated by a reduced midwall fractional shortening (15.7 +/- 0.3, 15.9 +/- 0.3, 16.7 +/- 0.4 and 16.8 +/- 0.3%, respectively; P< 0.02). Furthermore patients in the top quartile of albuminuria showed increased carotid wall thickness as compared to normoalbuminuric patients (0.78 +/- 0.03, 0.7 +/- 0.04, 0.65 +/- 0.03 and 0.6 +/- 0.03 mm, respectively; P < 0.001).
Hypertensive patients with microalbuminuria show a higher prevalence of unfavourable left ventricular geometric patterns, depressed left ventricular function and early signs of extra-cardiac vascular damage. These findings strengthen the role of microalbuminuria as an indicator of subclinical cardiovascular disease and may account for the worse outcome that is usually associated with increased urinary albumin excretion in essential hypertension.
Renal ammonia metabolism in humans with chronic potassium depletion. Renal ammonia production and distribution and ammonia precursor utilization were evaluated in eight patients with chronic ...potassium depletion (CPD) and aldosterone-producing adenoma and in 20 controls. In CPD, urinary ammonia excretion and ammonia added to renal venous blood were about twofold higher than in controls; thus, total ammonia production was significantly augmented (88.0 ± 10.3 µm/min·1.73 m2 vs. 45.0 ± 2.6 in controls). Total ammonia production was inversely correlated with serum potassium and directly correlated with urine flow. Stepwise multiple regression analysis snowed that both factors, mainly serum potassium, significantly influence ammonia production and account for 61.4% of variations in ammonia production. Renal extraction of glutamine was significantly increased (56.6 ± 5.9 µmol · 1.73 m2 vs. 34.6 ± 3.1 in controls), and this could account for ammonia production. The ratio of urinary ammonia excretion to total ammonia production, an index of the intrarenal ammonia distribution, was similar in patients and controls, and was significantly correlated with urine pH and true renal blood flow (RBF). Stepwise multiple regression analysis showed that RBF, urine pH and urine flow also significantly affected ammonia distribution. However, these factors accounted for only 41.7% of variations in intrarenal ammonia partition, urine pH having a minor role. We conclude that in patients with CPD other factors besides urine pH, urine flow and RBF intervene in the ammonia partition between urine and blood.
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