High uric acid levels raise hypertension risk in African-American men.


Serum uric acid is strongly associated with hypertension in African Americans, suggesting that a simple blood test could predict risk, and that treatments to lower uric acid may be a novel way to reduce hypertension-related complications in this patient population, researchers say.

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The findings come from a study of 9,104 African-American and Caucasian participants in the Atherosclerosis Risk in Communities (ARIC) Study. All were free of hypertension at baseline and evaluated for development of hypertension at three-year intervals. At baseline, subjects had a mean age of 53.3 years (range 45-64 years), mean systolic and diastolic BP of 113.8 and 70.2 mm Hg, re-spectively, and mean serum uric acid level was 5.7 mg/dL.


After nine years, subjects in the highest quartile of serum uric-acid level had a 15% increased risk of hypertension compared with those in the lowest quartile, but the link between uric acid and hypertension was particularly strong among African-American men, according to a report in Hypertension (2006;48:1037-1042).


For African-American men in the highest quartile of uric-acid level, the researchers found a twofold higher risk of hypertension compared with African-American men in the lowest quartile, after adjusting for potential confounding variables such as age, baseline BP, BMI, renal function, diabetes, and smoking. In African-American women in the highest quartile, the risk was 30% higher than in women in the lowest quartile.


“The novel angle of our study is that the association between uric acid and hypertension is much stronger in blacks, a group that disproportionately suffers from kidney disease, stroke and other complications of hypertension,” said lead investigator Philip Mellen, MD, MS, assistant professor of internal medicine at Wake Forest University Baptist Medical Center in Winston-Salem, N.C.


High levels of uric acid cause gout, and recent animal and human studies have suggested that modest elevations of uric acid are also a cause of hypertension, he said. Studies are underway to evaluate whether lowering uric acid can prevent hypertension. “If these studies show that lowering uric acid is an effective treatment, our research suggests that it may be especially appropriate for blacks,” Dr. Mellen said.


The new findings are important, he said, because this is the first study to look at such a large number of African Americans and to track them for a long period (nine years).


“Our findings are consistent with earlier studies with smaller numbers of African Americans,” Dr. Mellen told Renal & Urology News.