Factors associated with glomerular hyperfiltration in the early stage of hypertension.
BACKGROUND
Glomerular hyperfiltration predicts development of nephropathy in hypertension but the factors responsible for increased glomerular filtration rate (GFR) are not well known. Aim of this study was to examine which clinical variables influence GFR in the early stage of hypertension.


METHODS
Participants were 1,106 young-to-middle-age hypertensive adults with creatinine clearance >60 ml/min/1.73 m(2). Clinic and ambulatory blood pressures (BPs) were measured and the difference between clinic and 24-h systolic BP was defined as the white-coat effect (WCE). In 606 participants, 24-h urinary epinephrine and norepinephrine were also measured. Glomerular hyperfiltration, defined as a GFR ≥150 ml/min/1.73 m(2), was present in 201 subjects.


RESULTS
Patients' mean age was 33.1 ± 8.5 years and office BP was 146 ± 10.5/94 ± 5.0 mm Hg. In multivariable linear regression, significant predictors of GFR were younger age (P < 0.0001), male gender (P < 0.0001), 24-h systolic BP (P = 0.0001), body mass (P < 0.0001), WCE (P = 0.02), log-epinephrine (P = 0.01), and coffee use (P < 0.01). In a logistic model, independent predictors of glomerular hyperfiltration were obesity (odds ratio, 95% confidence interval = 6.1, 3.8-9.8), male gender (2.9, 1.8-4.9), age <33 years (2.1, 1.5-3.1), ambulatory hypertension (2.0, 1.4-3.0), WCE >15 mm Hg (1.6, 1.1-2.3), heavy coffee use (2.0, 1.1-3.8), and epinephrine >25 mcg/24 h (1.9, 1.2-3.1).


CONCLUSIONS
The novel finding of this study is that hyper-reactivity to stress, as determined by urinary epinephrine level and WCE, and coffee use contribute to determining glomerular hyperfiltration in the early stage of hypertension. Our data may help to identify a subset of patients with glomerular hyperfiltration, who may be at increased risk of chronic kidney disease and may benefit from antihypertensive treatment.
Clinica Medica 4, University of Padova, Padova, Italy. palatini@unipd.it
Paolo
P
Palatini
Francesca
F
Dorigatti
Francesca
F
Saladini
Elisabetta
E
Benetti
Lucio
L
Mos
Adriano
A
Mazzer
Giuseppe
G
Zanata
Guido
G
Garavelli
Edoardo
E
Casiglia
D000328:Adult; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D003069:Coffee / Q000009:adverse effects; D004837:Epinephrine / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000503:physiopathology*; D007678:Kidney Glomerulus / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000652:urine; D059466:White Coat Hypertension / Q000503:physiopathology
D003069:Coffee; D009638:Norepinephrine; D004837:Epinephrine