Uric Acid is a Byproduct of Normal Body Functions
Uric acid occurs naturally in the human body as a result of the metabolism of purine. Purine is a muscle protein that enters the body either through dietary intake (about 30 percent) or from the breakdown of the body's own cells during cell turnover (about 70 percent). Normal blood serum uric acid levels are 2.4 to 6.0 mg/dl for woman and 3.4 to 7.0 mg/dl for men.
Humans Cannot Metabolize Uric Acid, So It Is Excreted
Humans lack the enzyme (uricase) that breaks down uric acid. So uric acid is excreted by the kidneys and the intestines. Under normal circumstances about 70 percent of uric acid is excreted in the urine, with the intestines passing the remaining 30 percent. However, when renal function is insufficient, a greater percentage is excreted via the intestines. Uric acid is relatively insoluble. So, when concentrations exceed normal levels, it may crystallize in the joints, the urinary tract or under the skin.
High Uric Acid Is Associated With Kidney Problems
Renal failure is associated with high uric acid levels, and uric acid crystals may accumulate in the kidneys, as kidney stones, or in the bladder. But kidney problems can not be assumed to be caused by high uric acid. Rather, high uric acid levels may be the result of renal insufficiency.
High Uric Acid is Associated With Gout
In gout, uric acid crystals deposit on cartilage, tendons and tissues surrounding the joints. Symptoms include rapid onset of severe, burning pain; swelling, redness, warmth and extreme skin tenderness. The big toe is the most common location for gouty flair ups, but ankle, wrist, knee and elbow involvement are also reported, though less commonly. Men tend to have higher uric acid levels than women. So, it's not surprising that men get gout more often than women. However, gout can occur without high uric acid levels, and high uric acid does not always cause gout. So, other causes for gout cannot be rule out. For instance, heredity is thought to be a predisposing factor for gout.
Diet, Health and Heredity Affect Uric Acid Levels and Gout
A diet high in fat and muscle protein such as red meat, poultry, fish and other seafood, is associated with high uric acid levels and also with gout. Though causation is not firmly established, alcohol consumption, consumption of high fructose corn syrup, obesity, starvation, excessive exercise and sleep apnea are also correlated with gout. The common metabolic phenomenon among these is that they all, in one way or another, cause the body to metabolize it's own tissues, thus releasing purine into the blood stream. Gout seems to occur more often within certain racial groups, Pacific islanders and African Americans, for instance. Age and sex also seem to make a difference, with gout afflicting men age 50 to 60 most often.
Continuing Research Helps Us Understand the Effects Uric Acid
Researchers have found statistical links between high uric acid levels and high blood pressure, diabetes and senile dementia. This does not necessarily mean that high uric acid causes these problems, just that a some physical factors may be common to all of them. With this knowledge uric acid levels becomes an increasingly important marker for other medical conditions.