This lesson will cover a condition known as gout as well as the physiological mechanism behind its formation. We’ll cover important clinical signs, diagnostics steps, and treatments utilized for this disease.
Garbage Accumulation in the Body
Garbage being strewn about the streets of a city can cause quite a stir. Besides the massive stink that it will cause, garbage accumulation can lead to the development of disease due to a wide variety of factors. The same principle occurs in your own body, where garbage accumulation can lead to a lot of diseases, one of which will be described in this lesson. However, the garbage in this malady isn’t the accumulation of banana peels people will slip on; it’s actually the formation of little crystals that will slice your joints apart.
What Is Gout?
However, these crystals, unlike many other minerals found in nature, are worthless. They’re truly garbage. They cause a condition called gout. This is a painful, inflammatory form of arthritis caused by urate crystal deposition in the joints.
You may have heard of gout and the many risk factors involved in its development. Risk factors include alcohol consumption, being overweight, kidney disease, being a man, and having a family history of this disease. Therefore, genetic defects may play a role in causing things to go haywire during the development of gout.
Why Does Gout Occur?
While many risk factors abound, the pathway of gout formation is as follows:In nature, there exist compounds called purines.
You’ve probably heard of two famous purines called adenine and guanine, the molecules that help to make up things like DNA and the energy currency of your body, called ATP. Naturally, humans break down purine through a series of steps. The second-to-last step involves something known as xanthine, a purine base.Xanthine oxidase is a type of enzyme that converts xanthine into uric acid, while uric acid is the end product of purine metabolism in humans.
Uric acid, the end product of this pathway, serves no use in the human body and is basically just garbage. Normally, your body makes sure uric acid is kept at a safe level by either excreting it in urine or by recycling purines using a salvage pathway to avoid forming uric acid in the first place. When a defect in this salvage pathway or in the excretion of uric acid occurs, uric acid crystals, also known as urate crystals, begin to form instead and deposit themselves in places like your joints.So you can liken what happens to real life. When garbage piles up in a city, the city garbage collection team picks it up and tosses it out into the local dump.
Or the garbage is sent to be salvaged and recycled for reuse. Your body does this as well. But if the recycling or garbage collection facilities shut down, then the garbage will accumulate in the city streets, predisposing people to disease.But it gets worse.
Since those uric acid crystals aren’t supposed to be in the joints, the body interprets them as a foreign invader and launches an inflammatory response to try and kill them. But they can’t be killed because they’re not alive to begin with!So, as white blood cells, called neutrophils, move in to eat the crystals in order to try and destroy them, the sharp crystals poke holes in the cell’s stomach-like structure, called a lysosome, killing the neutrophils and releasing the digestive enzymes of their stomachs into the surrounding area. Those digestive enzymes then begin to break down the joint as more inflammatory cells are recruited that also end up dying, causing a vicious cycle to continue.
Clinical Signs, Symptoms, and Diagnostics
This cycle of inflammation causes:
- Painful, swollen, and tender joints.
- Complications, such as kidney stones.
- Tophi, which are masses of uric acid crystal that form in the soft tissue of people with long-standing gout.
Tophi are a pathognomonic sign of gout, meaning they are a symptom or sign of a disease that is so distinct and unique in its nature it can be used on its own to diagnose a condition. Besides looking for tophi to diagnose gout, other things we can do include running blood tests to check for hyperuricemia, or abnormally high levels of uric acid in the blood that predispose to crystal formation. This is usually not diagnostic of gout, however, so a doctor may withdraw a sample of joint fluid, called synovial fluid, to look for uric acid crystals directly in the joint instead.
Treatment of Gout
Once diagnosed, doctors may prescribe anti-inflammatory medication to minimize the effects of the inflammatory process I described before.
Another thing that may be prescribed is allopurinol, a xanthine oxidase inhibitor. If you recall, xanthine oxidase is an enzyme that converts xanthine to uric acid. While there’s more to it than that, including increased use of the salvage pathway, for our purposes just know that if we inhibit this enzyme, less uric acid is made. That’s the bottom line. Xanthine levels then begin to rise as a result of allopurinol use, but because xanthine is more soluble than uric acid, it is more readily excreted out of the body via urine. This way, we avoid the trouble of uric acid formation.
Gout Fun Fact
As a final note, sit back and relax as I tell you about an interesting thing. Humans and some other animals would avoid all this trouble with gout had we not, somewhere along the evolutionary line, lost the ability to convert the insoluble and useless uric acid into a soluble compound known as allantoin via an enzyme called uricase. Like xanthine, allantoin is far more soluble than uric acid and is therefore easily excreted out of the body, thereby avoiding the problem of gout in animals who can utilize the enzyme uricase.These animals include species such as the dog. However, within each species of animal lie important physiological breed differences that are important to note for medical purposes. If you have a dog, but that dog is a Dalmatian, then your dog does not have the ability to use its uricase despite its presence and is actually predisposed to the formation of gout.
The spots may look cute, but gout is really painful for you and your Dalmatian. And yes, your Dalmatian may be treated with allopurinol as well.
So, with that little fun fact you’re now not only a human medical expert but a veterinary one as well! You should rightfully go brag to your friends. Regardless, human or otherwise, some species are predisposed to the formation of gout.
This is a painful, inflammatory form of arthritis caused by urate crystal deposition in the joints.Naturally, humans break down something known as purine through a series of steps. The second to last step involves something known as xanthine, a purine base. Xanthine oxidase is a type of enzyme that converts xanthine into uric acid, while uric acid is the end product of purine metabolism in humans.
The buildup of uric acid crystals in the body will result in inflammation, causing all sorts of signs, including tophi, which are masses of uric acid crystal that form in the soft tissue of people with long-standing gout. Tophi are pathognomonic for gout, meaning it is a symptom or sign of a disease that is so distinct and unique in its nature it alone can be used to diagnose a condition.Well, besides looking for tophi to diagnose gout, we can also run blood tests to check for hyperuricemia, or abnormally high levels of uric acid in the blood that predispose to crystal formation.
Once diagnosed, doctors may prescribe anti-inflammatory medication to minimize the effects of the inflammatory processes I described in this lesson. Another thing that may be prescribed is allopurinol, a xanthine oxidase inhibitor, in order to prevent the buildup of uric acid.
When this lesson is complete, you should be able to:
- Define what gout is
- Identify what causes gout in the joints
- Recognize the symptoms and main treatment