Uric Acid Crystals

Gout is caused by excess uric acid in the blood, a medical condition known as hyperuricemia. The accumulation of uric acid can lead to needle-like crystals precipitating in the joints resulting in a painful gout attack. But how exactly does the presence of uric acid crystals cause swelling and severe pain?

Uric Acid Production

First, uric acid is produced when the protein purine breaks down. Purine naturally occurs in the body from the death of our cells or introduced to the body from high uric acid foods. Uric acid is the final product of purine breakdown and in normal conditions they are removed by the kidneys. In the case of hyperuricemia, the body either makes too much uric acid or the kidneys cannot filter them efficiently. This leads to an excess of uric acid in the blood.

Uric Acid Deposition in the Joints

When a certain level of uric acid in the blood is reached (called the saturation point), the surplus uric acid forms crystals that are usually deposited in the joints. The saturation point varies from person to person. It can be affected by blood pH level, temperature or may be triggered by injury to joints, surgery, eating certain foods, binge drinking and eating, sometimes even for no apparent reason. This explains why there are lots of people with hyperuricemia without developing gout.

Immune System’s Response to Uric Acid Crystals

The deposited uric acid crystals are by themselves harmless. It is the body’s immune reaction to them that actually causes an acute gout attack. The body treats the uric acid crystals the same way it treats a bacterial or viral infection and sends white blood cells (leukocytes) to trap them. This results to the swelling and pain that is typical in acute gout. Once the crystals are engulfed and the immune reaction subsides, the swelling and pain are also removed.

When the white blood cells breakdown and uric acid crystals are released, this causes other white blood cells to ingest the debris and the freed uric acid crystals that again trigger swelling and pain. The same immune response also happens when uric acid lowering drugs are used to rapidly lower uric acid levels. The swelling and pain can be so severe making anti-inflammatory drugs a necessity in the treatment of gout.

Gout shows the clever way in which our immune system operates. It also shows that even a natural by-product of our body’s metabolic process such as uric acid can become a threat when present excessively.