Causes and Countermeasures for Hypouricemia.
What is Uric Acid?
If you drink alcohol, you might have heard of “uric acid”. Even if you have heard of “uric acid”, you might think, “What is uric acid? Does it have something to do with urine?” This website describes how uric acid is generated and its effect on the human body.
Uric Acid is a Metabolite Generated Through Degradation of Purines in the Human Body
In order to sustain our lives, our body manages not only the muscles of our limbs, but the whole body including our heart, kidneys, and brain. Purines are used as a source of energy, and the final metabolite after the consumption of that source of energy is uric acid.
In addition, purines are also a component of DNA in cells. In our body, cells are constantly regenerated and old cells are steadily broken down. Purines are also broken down and uric acid is generated as a waste product. The human body is considered to be comprised of 37 trillion cells, and each cell contains DNA. Therefore, a certain amount of uric acid is generated every day in a healthy human body.
Purines are generated in the body or consumed via food intake. Approximately 20% of purines are consumed via food and 80% are generated in our body.
Three Mechanisms to Generate Uric Acid from Purines
Purines in the human body or those consumed through food are degraded into uric acid using several mechanisms.
1. Uric Acid Generated from Metabolism
All organisms including humans, other animals, insects, and plants are comprised of cells. Each cell contains nucleic acids (DNA) which contain genetic information, and these nucleic acids are comprised of purines. While one lives, metabolism is occurring with generation of new cells and death of old cells. Once the old cells die after serving their roles, nucleic acids are degenerated into purines. Purines are further degenerated through several processes and become uric acid.
2. Uric Acid Generated from Exercise
When we move our body, adenosine triphosphate (ATP) is consumed as a source of energy. In many cases, ATP is degenerated to be used as a source of energy for body movement and then it is regenerated back into ATP. However, when a large amount of ATP is rapidly consumed, purines are generated instead, and they are further degenerated into uric acid. A large quantity of ATP is consumed in intense exercise, temporarily increasing the uric acid levels.
Excessive drinking and eating also require a large amount of energy, and they tend to increase uric acid levels. Especially the degradation of alcohol generates a large amount of uric acid and causes a decline of excretion of uric acid from the kidneys. Beer is well known to increase uric acid levels since beer not only has the effect of alcohol but is also high in purines.
3. Uric Acid Generated from Purines Contained in Food
When food containing a lot of purines are consumed, purines consumed via food are changed into uric acid. The amount of purines is proportional to the number of cells, and a larger amount of purines is contained in food consisting of a larger number of cells. Food containing larger amounts of purines include fish eggs, liver, some seafoods (e.g. shrimp and bonito), dried fish and dried shiitake mushrooms.
Uric Acid is in Equilibrium in the Body
Purines generated in the body is degenerated in the liver into uric acid and then excreted with urine or feces to the outside of the body. In the body of a healthy person, uric acid levels in the body are maintained within a normal range based on the mechanisms of the kidneys and small intestine to equilibrate the volume of the excreted uric acid.
While it depends on each institution, the results of medical examination reports describe the standard value of serum uric acid levels as 3.7 – 7.8 mg/dL for males and 2.6 – 5.5 mg/dL for females*1.
Is Uric Acid Necessary for Human Body?
While uric acid is dissolved in the blood or body fluid, it can crystalize as it cannot dissolve if it exists in an excessive amount. If uric acid is crystalized and is accumulated in the joints, causing inflammation, it is called gout. According to a common preconception of a direct connection between uric acid and gout, uric acid tends to be thought of as an unnecessary substance. However, uric acid has a function to protect our body. Uric acid has antioxidative effects*2 to eliminate an excess of active oxygen in the body. Even if uric acid levels are too low, this alone does not cause any disease nor subjective symptoms. However, there are some complications that can occur due to low levels of uric acid.
*1 Common reference interval of Japanese Society of Laboratory Medicine, Japan Society of Clinical Chemistry, Japanese Association of Medical Technologists and Japanese Society for Laboratory Hematology.
*2 Effects which protect the body from oxidation by suppressing active oxygen which cause deterioration of human body via oxidization.