purine

Gout is a common type of inflammatory arthritis. It causes pain, swelling, and redness in one or more joints. It usually happens as a flare, which can last for a week or two and then gets better. The flares often begin in your big toe or a lower limb.

Gout happens when too much uric acid (urate) builds up in your body over a long time. Uric acid is a waste product your body makes when it breaks down purines. Purines are substances that are in your body's tissues and in many foods.

When your body breaks down old cells or digests foods that contain purine, most of the uric acid that's made dissolves in your blood. Your kidneys filter the uric acid out of your blood, and it leaves your body in your urine (pee).

However, sometimes your body can make too much uric acid or does not remove enough of it. Then the uric acid levels build up in your body, including in your blood. Having too much uric acid in the blood is called hyperuricemia. It does not cause health problems for everyone. But in some people, uric acid forms needle-like crystals. They can form in your joints, which causes gout. The crystals can also cause kidney stones.

Calcium pyrophosphate arthritis, sometimes called pseudogout, is a related disease. It causes similar symptoms and is sometimes confused with gout. But it is caused by a buildup of calcium phosphate, not uric acid.

Many people develop gout. You are more likely to get it if you:

• Are male.
• Are older; it usually develops in middle age.
• Have obesity.
• Have certain health conditions, such as:
  • Heart failure
  • High blood pressure
  • Metabolic syndrome
  • Chronic kidney disease
  • Conditions that cause your cells to break down more quickly, such as psoriasis or some cancers
  • Rare genetic conditions that lead to increased uric acid
• Have a family history of gout.
• Have an unhealthy diet and eat foods that are rich in purines, such as red meat, organ meats, certain seafoods.
• Drink alcohol.
• Eat and drink lots of foods and beverages that contain fructose (a type of sugar).
• Take certain medicines, such as diuretics (water pills), low-dose aspirin, and some medicines that weaken your immune system.
• Take high amounts of niacin (vitamin B-3).

Gout usually happens in only one joint at a time. It is often found in the big toe, but can also affect other joints, including your other toes, ankle, and knee.

Gout flares often start suddenly at night, and the symptoms in the affected joint often include:

• Intense pain, which may be bad enough to wake you up
• Swelling
• Redness
• Warmth

The flares typically get better within a week or two. In between flares, you usually don't have symptoms. Some people may have flares often, while others may not have another flare for years. But over time, if left untreated, your flares may happen more often and last longer.

And if gout is untreated over long periods of time, you can develop tophi. Tophi are hard, uric acid deposits under the skin. They start out as painless, but over time, they can become painful. They can also cause bone and soft tissue damage and misshapen joints.

To find out if you have gout, your health care provider:

• Will take your medical history, which includes asking about your symptoms.
• Will do a physical exam, including examining the affected joint(s).
• May order various tests, such as:
  • A test of a sample of fluid from one of your painful joints. The fluid is examined under a microscope and is checked for uric acid crystals.
  • A uric acid blood or urine test.
  • An ultrasound or special CT scan to look for uric acid crystal buildup in the affected joint and check for other conditions that may be causing the symptoms.

There are effective treatments for gout. Which treatment you get will depend on your symptoms and the cause of your gout. The goals of your treatment will be to:

• Reduce the pain from gout flares, by using medicines such as:
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen.
  • Acetaminophen and the anti-inflammatory drug colchicine.
  • Oral or injected corticosteroids.
• Prevent future flares, for example by:
  • Making lifestyle changes such as losing weight, limiting alcohol, and avoiding foods high in purines. If you are taking medicines that can cause high uric acid in the blood, your provider may suggest stopping or changing those medicines.
  • If needed, taking medicines to lower uric acid in the blood.
• Prevent tophi and kidney stones, for example with medicines that lower uric acid in the blood.

With early diagnosis, treatment, and lifestyle changes, gout is one of the most controllable forms of arthritis. Treatment and lifestyle changes may help people avoid gout flares, lessen their symptoms, and sometimes even become gout free.

NIH: National Institute of Arthritis and Musculoskeletal and Skin Diseases

Your immune system is a complex network of cells, tissues, and organs. Together they help the body fight infections and other diseases.

When germs such as bacteria or viruses invade your body, they attack and multiply. This is called an infection. The infection causes the disease that makes you sick. Your immune system protects you from the disease by fighting off the germs.

The immune system has many different parts, including:

• Your skin, which can help prevent germs from getting into the body
• Mucous membranes, which are the moist, inner linings of some organs and body cavities. They make mucus and other substances which can trap and fight germs.
• White blood cells, which fight germs
• Organs and tissues of the lymph system, such as the thymus, spleen, tonsils, lymph nodes, lymph vessels, and bone marrow. They produce, store, and carry white blood cells.

Your immune system defends your body against substances it sees as harmful or foreign. These substances are called antigens. They may be germs such as bacteria and viruses. They might be chemicals or toxins. They could also be cells that are damaged from things like cancer or sunburn.

When your immune system recognizes an antigen, it attacks it. This is called an immune response. Part of this response is to make antibodies. Antibodies are proteins that work to attack, weaken, and destroy antigens. Your body also makes other cells to fight the antigen.

Afterwards, your immune system remembers the antigen. If it sees the antigen again, it can recognize it. It will quickly send out the right antibodies, so in most cases, you don't get sick. This protection against a certain disease is called immunity.

There are three different types of immunity:

• Innate immunity is the protection that you are born with. It is your body's first line of defense. It includes barriers such as the skin and mucous membranes. They keep harmful substances from entering the body. It also includes some cells and chemicals which can attack foreign substances.
• Active immunity, also called adaptive immunity, develops when you are infected with or vaccinated against a foreign substance. Active immunity is usually long-lasting. For many diseases, it can last your entire life.
• Passive immunity happens when you receive antibodies to a disease instead of making them through your own immune system. For example, newborn babies have antibodies from their mothers. People can also get passive immunity through blood products that contain antibodies. This kind of immunity gives you protection right away. But it only lasts a few weeks or months.

Sometimes a person may have an immune response even though there is no real threat. This can lead to problems such as allergies, asthma, and autoimmune diseases. If you have an autoimmune disease, your immune system attacks healthy cells in your body by mistake.

Other immune system problems happen when your immune system does not work correctly. These problems include immunodeficiency diseases. If you have an immunodeficiency disease, you get sick more often. Your infections may last longer and can be more serious and harder to treat. They are often genetic disorders.

There are other diseases that can affect your immune system. For example, HIV is a virus that harms your immune system by destroying your white blood cells. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome). People with AIDS have badly damaged immune systems. They get an increasing number of severe illnesses.