Monday, May 5, 2008

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.

No comments: