The inflammatory arthritic condition of gout.

Gout, the inflammatory arthritic condition triggered by crystallization of uric acid within the joints, has risen in the United States. A research studied by Dr. Choi (Hyon K. Choi, MD, DrPH) and his colleagues shown that 74% of US gout patients also have hypertension. Dr. Choi’s group also has shown that hypertension is an important independent risk factor for gout. In patients with hypertension, the incidence of gout has been calculated as 3 times higher than in normotensive patients.

Simplistic speaking, much of this added risk is attributed to the use of diuretics, which are associated with increased serum uric acid levels. But hypertension itself is associated with increased risk of gout. Not only diuretics, but also other nondiuretic classes of antihypertensive drugs have been shown to affect serum uric acid levels.

Generally, with the use of diuretics, beta-blockers, ACEI, and non-losartan angiotensin II receptor blockers (ARBs), the risk of gout incresed.

However as antihypertensive drugs, calcium channel blockers (CCBs) and losartan (a kind of ARBs), are associated with reduced risk of gout.

In an editorial published alongside the study report, Luis M. Ruilope, MD, (Hospital 12 de Octubre and University Autonoma, Madrid, Spain) noted that a reduction in serum uric acid “as well as reducing incident gout, could also improve the cardiovascular and renal prognosis of patients with hypertension.” Thus, to control the serum uric level is important for hypertensive patients.

A number of variables affect serum uric acid levels and the risk of gout, including many life style factors such as adiposity, represented by BMI; dietary factors, particularly alcohol consumption, fructose-rich beverages such as sugary sodas, and a purine-rich diet, particularly animal sources of purine such as red meat or seafood. And in right here, finally, drugs can cause increased risk of gout.

The mechanism of increased risk of gout with hypertension is that as blood pressure elevates, serum uric acid concentration increases, which appears to be a dose-response relationship. Also urate excretion is lower in hypertensive patients than in normotensive individuals. Reduced renal blood flow with increased renal and systemic vascular resistance may also contribute to elevated serum uric acid levels. eventually leading to an increased risk of gout.

The mechanism of increased risk of gout with antihypertensive drugs are variable. Diuretics, the loop and thiazide-type diuretics, can increase serum uric acid levels and the risk of gout. The mechanism of the nondiuretic antihypertensive drugs include ACE inhibitors, non-losartan ARBs are unknown. But clinical trials has shown beta-blockers can increase serum uric acid levels slightly. the mechanism of beta-blockers is unknown neither.

Here I find some data. With beta-blockers, the risk of gout was 48% higher in people with hypertension. ACEIs also have the identical effect. But there is an exception – the diuretics.

Fortunately, specific antihypertensive drugs contribute to the reduce risk for gout. The unique ARB, losartan, lowered uric acid levels in one clinical trial. Bench studies have shown that losartan causes increased uric acid secretion (uricosuria) by inhibiting urate/anion transport in brush-border cells of the renal proximal tubules through inhibition of urate transporter 1 (URAT 1). That is losartan inhibits uric acid reabsorption, causing uricosuria, eventually driving down blood uric acid levels and the reduced risk of gout.

Also CCBs including dihydropyridines and nondihydropyridines have the ability to decrease the risk of gout. The mechanism is unkown. For people with hypertension, taking CCBs lowered their risk of gout by 13% compared with people with hypertension who were not taking a CCB.

To rudece the risk of gout in hypertensive patients, we couldn’t avoid these antihypertensive drugs such as ACEIs, ARBs, or diuretics. Because these patients benefits from these drugs. Thus when the antihypertensive regimen contains drugs increasing risk of gout, we may add another antihypertensive drug that decreases the risk of gout. With the use of the protective drugs, like CCB or losartan, the risk should become even lower.