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Serum uric acid is associated with microvascular function in hypertensive individuals
T de A Coutinho1, S T Turner, I J Kullo
1Department of Internal Medicine, Mayo Clinic Foundation, Rochester, MN, USA.
Journal of Human Hypertension
|June 2, 2007
Summary
High serum uric acid (UA) levels in hypertensive adults are linked to increased resting forearm blood flow (FBF) and reduced reactive hyperaemia (RH), indicating microvascular dysfunction. These associations persist even after adjusting for various cardiovascular risk factors.
Area of Science:
- Cardiovascular Physiology
- Nephrology
- Vascular Biology
Background:
- Hypertension is a major risk factor for cardiovascular disease, often associated with endothelial dysfunction.
- Serum uric acid (UA) has emerged as a potential contributor to cardiovascular risk, but its specific role in vascular function in hypertensive individuals requires further elucidation.
- Microvascular and macrovascular functions are critical determinants of overall cardiovascular health.
Purpose of the Study:
- To investigate the association between serum uric acid levels and microvascular function (resting forearm blood flow [FBF] and reactive hyperaemia [RH]) and macrovascular function (flow-mediated dilation [FMD] of the brachial artery).
- To determine if these associations are independent of traditional cardiovascular risk factors in hypertensive adults.
Main Methods:
- Cross-sectional study involving 506 hypertensive adults (mean age 62 years, 59% women).
- Serum uric acid measured via colorimetric assay.
- Forearm blood flow (FBF), reactive hyperaemia (RH), and brachial artery flow-mediated dilation (FMD) assessed using high-resolution ultrasound.
- Multivariable regression analyses performed to adjust for numerous covariates including age, sex, blood pressure, lipids, diabetes, BMI, CRP, creatinine, alcohol, statin/diuretic use, and brachial artery diameter.
Main Results:
- Serum uric acid was significantly associated with higher resting FBF (P<0.0001) and lower RH (P=0.0001) in unadjusted analyses.
- After multivariable adjustment, higher UA levels remained independently associated with higher FBF (P=0.012) and lower RH (P=0.004).
- No significant association was found between serum UA and brachial artery FMD (P=0.43) in either unadjusted or adjusted models.
Conclusions:
- In hypertensive individuals, elevated serum uric acid levels are independently associated with impaired microvascular function, specifically higher resting forearm blood flow and reduced reactive hyperaemia.
- Serum uric acid does not appear to be associated with macrovascular endothelial function, as assessed by brachial artery flow-mediated dilation, in this population.
- These findings suggest a potential role for uric acid in modulating microvascular function within the hypertensive state.
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