| Backgroud: Hypertension has become a serious disease which threaten human's survival and health. Hypertension onset and evolve slowly, the final cause of death usually are congestive heart failure,renal failure and cerebrovascular accident et al, which is the most popular disease in cardiovascular diseases. It is estimated that there are one billion people with hypertension in the world. WHO published the adult prevalence of hypertension as high as 15%, in our country the disease prevalence is about 7-10%. In recent years, with changes of people's living patterns and living environment and the world's population ageing process, hypertension morbidity and mortality rate are increasing day by day. With the in-depth development of hypertensive research and recognition, the diagnosis and treatment of hypertension has made a considerable progress, but it's still not possible to solve the problem fundamentally, people think highly of the method and approach of how to predict and control the occurrence of hypertension. Traditionally, the cause of hypertension are multiple factors that can be divided into two aspects—genetic factor and environmental factor. Hypertension is the result of interaction of genetic predisposition and environmental factor. Genetic factor mainly refers to familial inheritance, environmental factor concludes diets(intake more sodium,protein,saturated fatty acid which exceed the normal deal),spirit stress et al. Recently, new methods of predicting and evaluating hypertension occur continuously, as Body Mass Index (BMI),Insulin Resistance (IR),Impaired Glucose Tolerance (IGT), organismic marker and structural/functional marker et al. Among them, the relationship of uric acid and hypertension has been paid highly attention constantly. Many epidemiology and clinical study consequences have confirmed it, since Frederick Akbar Mohamed first posed that uric acid has correlation with the increasing of blood pressure in 1897. The pathogenic mechanism is concluded approximately as follow: 1. Mild hyperuricemia can induce inflammatory reaction of kidney, to urge activation of renin-angiotensin system and down regulation of nitrogen monoxidum(NO). 2. Uric acid induces proliferation of vascular smooth muscle cell(VSMC). 3. Uric acid mediates the expression of C-reactive protein (CRP) in vascular endothelial cell and smooth muscle cell. 4. Soluble uric acid has the action of proinflammatory. 5. Uric acid can induce injury of function of blood vessel endothelium. 6. Uric acid has a lower solubility in blood. In hyperuricemia uric acid forms crystal which separates from blood and deposits on vessel wall of arteriole and damage endarterium directly. 7. Uric acid is a antioxidant, meanwhile a oxidizing agent. It can act through oxidative stress,increasing of ox radical, to promote oxidation of low density lipoprotein(LDL) and over oxidation of lipid to injury vascular endothelial cell(VEC).Objective: Through the detection of serum uric acid (SUA) and flow-mediated endothelium-dependent vasodilatation (FMD) for Hypertensive patients, we want to study the correlation between them and significance.Methods: Select 48 hypertensive patients that contained outpatients and in hospital in Cardiovascular department of CJUH of Jilin University as hypertension group, 39 people that took health examination as the control group from September 2007 to September 2008 as study object. FMD is used as the detecting index of endothelial function. We used color Doppler ultrasonic machine to measure the diastasis internal diameter(D0),diastasis internal diameter after compression(D1) and internal diameter after buccaling Nitroglycerin(D2) of brachial artery. Calculating brachial artery diameter change in the percentage of S1 = (D1-D0) / D0×100%, put it as the estimated indicators of FMD. Using S2= (D2-D0)/D0×100% as the indicator to evaluate the nitroglycerin-induced endothelium-independent vasodilation (NMD). Meanwhile we collecting age,gender,smoking,family history, and the biochemical consequence of uric acid,blood fat. We divided hypertension group into high blood pressure level 1,2,3 according the WHO/ISH(1999). In addition, we divided hypertension group into normal UA group (90-420μmol/L) and hyperuricemia group(UA>420μmol/L). The focal point is studying the correlation between SUA and FMD in hypertensive patients.Result: SUA of hypertension group and the control group is respectively (363.69±90.27)μmol/L and (303.32±99.27)μmol/L,between the two groups with significant difference, p=0.004. Brachial artery diameter change percent of normal SUA group and hyperuricemia group is respectively (10.27±4.79)﹪and (6.17±2.37)﹪, between the two groups with significant difference, p<0.05. NMD of the two group is respectively (14.19±6.45)﹪and (10.75±3.52)﹪, there's no significant difference between them, p>0.05. In patients who is high blood pressure level 1,2,3, the mean of FMD of normal uric acid group respectively is 12.84﹪,10.89﹪and 6.29﹪; the mean of FMD of hyperuricemia group respectively is 7.04﹪,6.39﹪and 5.41﹪.FMD descending with the increasing of the ranking of the high blood pressure;FMD of the same ranking blood pressure descending with the increasing of SUA. SUA is negative correlation with FMD(r= -0.325), p<0.05.SUA has a noticeable correlation with LDL.Conclusion: Level of SUA of hypertension group is higher than the control group. SUA correlates with injury of FMD. FMD descending with the increasing of SUA; SUA has a noticeable correlation with LDL. Serum uric acid is a convenient,accurate,shortcut,well reduplicate clinical method, it has an important value to judge injury of blood vessel endothelium. It applies to primary hospital and large scale health examination, can be include to routine examine item. It's convenient to early discovery of hypertension, thus control pathogenetic condition of hypertension as early as possible and prevent development of complication. It will contribute to take effective measure for sub-clinical patients and to choose more reasonable valid drugs, thus controlling morbidity and mortality of hypertension comprehensively. Simple traditional risk factor mode is relatively limited, we could increase accuracy of the prediction of hypertension and injury of blood vessel endothelium if we add the examination of UA which can provide valid evidence to prevention and treatment in clinic.
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