Diurnal blood pressure variations in incipient and end stage diabetic renal disease

Diurnal blood pressure pattern may predict the increase of urinary albumin excretion in normotensive normoalbuminuric type 1 diabetes mellitus patients

To characterise the relationship between diurnal blood pressure and the subsequent increase of urinary albumin excretion (UAE) in normotensive normoalbuminuric type 1 diabetic patients, ambulatory blood pressure monitoring (ABPM) was performed in 53 patients, who were then followed for 5 years. Albumin excretion rate changed from 12.4 (8.9-17.2) to 29.3 (15.2-47.0) mg/day. Macroalbuminuria developed in 2 (3.8%), microalbuminuria in 22 (41.5%) patients, 29 (54.7%) remained normoalbuminuric. Night-time diastolic blood pressure was significantly higher (64.3+/-6.5 vs. 60.9+/-5.5 mmHg, P<0.05), diastolic diurnal index significantly lower (15.5+/-9.7 vs. 22.3+/-6.2%, P<0.01) in patients who later progressed to micro- or macroalbuminuria. Diastolic diurnal index (r=-0.40; P<0.01) and nocturnal diastolic pressure (r=0.35; P<0.01) were correlated to the change in albumin excretion. In a multivariate analysis model with the change of albumin excretion as dependent, and means and diurnal indices of systolic and diastolic blood pressure, baseline UAE, cholesterol, triglycerides, HbA1c and retinopathy as independent parameters (r=0.68; P=0.001), diurnal index for diastolic blood pressure (beta=-0.30; r=0.013), baseline HbA1c (beta=0.32; P=0.010) and retinopathy (beta=0.44; P=0.001) were significant independent correlates. We conclude that the relative increase of nocturnal blood pressure is associated with the subsequent increase of albuminuria, which in turn is predictive of overt diabetic nephropathy.

Ambulatory blood pressure monitoring in chronic renal disease: technical aspects and clinical relevance

PURPOSE OF REVIEW

To evaluate the current value of ambulatory blood pressure monitoring in patients with chronic renal disease and end-stage renal disease.

RECENT FINDINGS

Ambulatory blood pressure monitoring has become an important tool in hypertension research and clinical practice. Its use in essential hypertension shows a strong predictive ability in the assessment of cardiovascular outcomes. In chronic renal failure and end-stage renal disease, the role of ambulatory blood pressure monitoring is still being actively evaluated, and available evidence shows that it is better than office blood pressure in predicting left ventricular hypertrophy and progression of renal dysfunction in patients with chronic renal failure. In end-stage renal disease, preliminary data suggest better prediction of mortality in hemodialysis patients in comparison with clinic blood pressures. The most conspicuous problems with the literature on this subject are small sample sizes and the paucity of longitudinal observational studies and intervention trials.

SUMMARY

Preliminary data and extrapolations from essential hypertension have justified a growing excitement about the use of ambulatory blood pressure monitoring in renal disease. However, further research will have to address the limitations of the available literature before generalization of its use is implemented.

Nocturnal non-dipping: what does it augur?

The non-dipping pattern of blood pressure (defined as a nocturnal fall of less than 10%) occurs in about 25% of hypertensives, with increased prevalence in certain sub-groups such as diabetics, African-Americans, and patients with renal disease. It almost certainly has multiple causes, including factors such as the levels of activity and arousal during both the day and the night, the depth and quality of sleep, and the activity of the sympathetic nervous system, among others. In patients with uncomplicated hypertension, the reproducibility is relatively low. There is evidence suggesting that the non-dipping pattern may have an adverse prognosis: thus, it appears to predict the progression of renal disease, to be associated with increased target-organ damage (in some studies), and also to predict increased cardiovascular morbidity. Antihypertensive drug treatment can normalize the non-dipping pattern, but the therapeutic consequences of this are unknown.