Uric Acid & Hypertension

Keeping with our theme of uric acid from yesterday: Do elevated uric acid levels play a causative role in essential hypertension?

I just finished attending the Renal Grand Rounds at Beth Israel-Deaconess Hospital featuring Dr. Rick Johnson, a physician-scientist who makes a very compelling argument in favor of an etiologic role for uric acid in primary HTN.

As I see it, the strongest evidence supporting such a link includes:

1. In most large, epidemiologic studies, uric acid is a clear risk factor for developing hypertension; furthermore indigenous cultures with low uric acid levels (probably due to a non-Western diet) have low incidences of high blood pressure.

2. In some small observational studies involving pediatric patients with essential hypertension and uric acid levels > 6, treatment with allopurinol clearly decreased high blood pressure.

3. Making rats hyperuricemic induces hypertension due to a mechanism involving a direct endothelial toxic effect of uric acid.

There are certainly caveats to this hypothesis--for instance, rats aren't humans, epidemiologic evidence does not imply causation, and a large randomized controlled trial is really necessary before we should be using allopurinol as a blood pressure lowering agent. But it's an interesting story thus far and if it's true, it could really impact one of the most important public health problems which exists.