Glomerular hyperfiltration is associated with blood pressure abnormalities in normotensive normoalbuminuric IDDM patients

Abstract

OBJECTIVE: To analyze the blood pressure patterns in normoalbuminuric IDDM patients with glomerular hyperfiltration. PATIENTS AND METHODS: A controlled cross-sectional study of 38 normotensive normoalbuminuric (urinary albumin excretion rate 134 ml × min-1× 1.73m-2] and 20 normofiltering) and 20 normal individuals matched for age, sex, and body mass index was performed. The 24-h ambulatory blood pressure was monitored using an auscultatory technique; the glomerular filtration rate was measured by 51Cr-labeled EDTA method; extracellular volume by the distribution volume of 51Cr-labeled EDTA; and 24-h urinary albumin excretion rate by radioimmunoassay. RESULTS: Mean nocturnal diastolic blood pressure was higher in hyperfiltering IDDM patients (70.4 ± 7.8 mmHg), when compared with the control group (65.1 ± 5.3 mmHg, P = 0.04). Diastolic blood pressure night:day ratio was higher in hyperfiltering IDDM patients (92.0 ± 8.6%), when compared with normofiltering IDDM patients (85.9 ± 4.8%) and control subjects (87.0 ± 6.8%, P = 0.02). In IDDM patients, the glomerular filtration rate significantly correlated with the diastolic blood pressure night:day ratio (r = 0.5, P = 0.002), extracellular volume (r = 0.4, P = 0.002), and HbA1 (r = 0.3, P = 0.03). In stepwise multiple regression analysis, factors associated with glomerular filtration rate were diastolic blood pressure night:day ratio, extracellular volume, and HbA1 (adjusted r 2 = 0.27, P = 0.003). CONCLUSIONS: Glomerular hyperfiltration is associated with higher nocturnal diastolic blood pressure and with a blunted nocturnal decrease in diastolic blood pressure levels in normotensive and normoalbuminuric IDDM patients