Microalbuminuria, renal dysfunction and cardiovascular complication in essential hypertension.

OBJECTIVE: To evaluate the prevalence of microalbuminuria (albumin excretion rate, AER) in a wide hypertensive population, and to evaluate any relationship with cardiovascular damage and renal dysfunction. DESIGN: A transversal study. SUBJECTS AND METHODS: In 383 hospitalized Caucasian essential hypertensives (198 men, 185 women) of mean age 44 +/- 0.5 years and mean clinic blood pressure 170.3 +/- 0.95/ 103.4 +/- 0.47 mmHg, metabolic parameters, serum creatinine level (Cs), creatinine clearance rate (Ccs), 24 AER and plasma renin activity (PRA) were measured. Furthermore, each patient underwent 24 h ambulatory blood pressure monitoring (ABPM) and echocardiography to measure left ventricular mass, which was indexed both by body surface area to obtain left ventricular mass index (LVMI) and by height to obtain the left ventricular mass indexed for height (LVMH). By Doppler echocardiography, the diastolic compliance by early:late peak filling velocity ratio was analysed. The fundus oculi was also observed. Three subsets of hypertensives were obtained by dividing the 383 essential hypertensives on the basis of their AER: < or = 11 (group A), 11 < or = 20 (group B) and > 20 micrograms/min (group C). MAIN OUTCOME MEASURES: Microalbuminuria, creatinine clearance, PRA, ABPM, LVMI, LVMH, early:late peak filling velocity ratio, hypertensive retinopathy. RESULTS: Among the 383 essential hypertensives, AER was < 11 micrograms/min in 55% of the patients (group A), 18% had AER in the range 11-20 micrograms/min (group B) and 27% had AER > 20 micrograms/min (group C). In the entire essential hypertensive population the prevalence of left ventricular hypertrophy was 44.39% and hypertensive retinopathy was observed in 54.83%. Moreover, AER significantly correlated with clinic systolic blood pressure (SBP) and diastolic blood pressure (DBP), with 24 SBP and DBP and with 24 h daytime and night-time mean blood pressure (MBP). AER was correlated also with LVMH and creatinine clearance. The analysis of the three subsets revealed no differences in age, body mass index, serum creatinine level and PRA. Group C in comparison with group A showed higher values of clinic SBP, 24 h SBP, DBP and MBP, and of daytime and night-time MBP. Furthermore, in group C, LVMI and LVMH were significantly greater than in group A, with a prevalence of left ventricular hypertrophy of 55% in the former group. Group C showed a prevalence of hypertensive retinopathy of 69% whereas in group A the prevalence was 48%. In group C, AER was significantly correlated with serum creatinine level. CONCLUSIONS: The transversal phase of our research, performed in a homogeneous population of Caucasian essential hypertensives with no metabolic disturbances, confirms the relationship between blood pressure pattern and early glomerular changes in essential hypertensives without overt proteinuria. Furthermore, these results emphasize the role of microalbuminuria as a marker of early cardiac, renal and retinal structural and functional changes in essential hypertension. The longitudinal study, which is in progress, will confirm the prognostic value of microalbuminuria in essential hypertension.

Sympathetic overactivity and 24-hour blood pressure pattern in hypertensives with chronic renal failure.

In order to assess the activity of the sympathetic system and to evaluate the 24-h blood pressure pattern in hypertensives with chronic renal failure (CRF), 12 CRF patients and 16 essential hypertensives (EHs) were studied. In all subjects, plasma samples for catecholamines and renin activity were obtained both in the basal condition and after standing, and 24-h blood pressure monitoring (ABPM) was performed. The 24-h mean blood pressure results were quite similar between CRFs and EHs. In 50% of the CRFs, ABPM showed a nighttime decrease in diastolic BP (DBP) greater than 10%, while in the remaining 50% the ABPM indicated a nondipper blood pressure pattern. Of the 16 EHs, 4 had a nighttime decrease in DBP < 10%, that is, nondippers. The study of circulating catecholamines showed no significant differences in plasma epinephrine between CRFs and EHs, while plasma norepinephrine (NE) was significantly higher in hypertensives with CRF than in EHs, both at rest and after standing (p < 0.05 and 0.02, respectively). Among dipper hypertensives, subjects with CRF showed greater values of basal plasma NE than EHs (535 +/- 67 vs. 412 +/- 24.5 pg/mL, p < 0.05); the comparison between dipper and nondipper CRFs showed no differences in circulating NE levels (535 vs. 516 pg/mL). The present study shows that CRFs are characterized by higher values of plasma NE than EHs, and that there are no differences in sympathetic activity between dipper and nondipper hypertensives with CRF.

The renal functional reserve in recently diagnosed essential hypertension.

Recent studies have shown that both in hypertensives and in offspring of hypertensive parents there exists an altered renal functional reserve (RFR). The aim of this research was to study the RFR in newly diagnosed essential hypertensives, and to evaluate if any influences are played on RFR by circulating renin-angiotensin-aldosterone system, catecholamines, and plasma endothelin-1. In 16 essential hypertensives (EH) and in 10 healthy controls (C), on the 24-hour urine collection and on urine specimens taken after both an oral water load and an amino acids (AAs) infusion (4.16 ml/min for two hours), Ccr, microalbuminuria (AER) and its fractional clearance, and sodium excretion (Nau) were evaluated. Furthermore, both in basal condition and after the AAs load, blood samples were obtained to assay plasma renin activity (PRA) and aldosterone concentrations (PAC), circulating norepinephrine (NE) and endothelin-1 (ET-1). The C-group showed a mean increase in Ccr of 35%. No significant modifications in AER and in circulating hormones were observed. Among the 16 EH, thirteen subjects showed a significant increase in Ccr after the AAs load, with a mean increase of 32.5%. In the whole group of EH there were no significant differences in AER when comparing basal with after-load values, and Nau resulted significantly decreased after AAs infusion. The analysis of the hormonal pattern pointed out not significant changes in the behaviour of PRA, NE and ET-1, while a significant decrease in PAC was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

[Prevalence of microalbuminuria in recent-onset essential hypertension]. / Prevalenza della microalbuminuria nell'ipertensione essenziale di recente insorgenza.

To determine the prevalence of increased microalbuminuria (AER) in essential hypertension, we studied an omogeneous population comprehensive of 160 mild-moderate essential hypertensives (EH) and 30 normotensive controls. All subjects underwent measurement of AER and creatinine clearance (CCl) on the 24-hour urine collection, and of plasma renin activity (PRA). The 24-hour mean arterial pressure (24h-BP) was also obtained by non-invasive ambulatory BP monitoring. The EH were subdivided into subgroups on the basis of their AER values (less or over 11 micrograms/min). Among the 160 EH the prevalence of high AER levels was of 37.5% (n = 60), showing in this subgroup of EH a mean value of 29.5 +/- 4 micrograms/min. Moreover, in the whole population of 160 EH, AER was significantly correlated to 24h-diastolic BP (p < 0.05). The subgroup of 60 EH with AER > 11 micrograms/min showed also Ccl values higher than the other subgroup of EH (p < 0.02), while non significant differences between age, mean duration of EH, PRA, and 24h-BP, both systolic and diastolic, were observed. Our results lead to hypothesize that in essential hypertension there exists a subgroup of subjects characterized, in the early phase of disease, by high capillary glomerular pressure, GFR and microalbuminuria values.