What are gouty tophi? What are their effects on the body? (Nodules formed by uric acid crystal deposition, which can lead to joint deformity and nerve compression.)

Gouty tophi can be understood as small "stones" formed from "waste products" that the body couldn't properly excrete.

This "waste" is uric acid. When uric acid concentration in the blood is too high for an extended period, it will find a place in the body to "crystallize" and turn into a solid. Just like water pipes freeze in winter, these urate crystals tend to accumulate in cooler areas, such as your finger joints, toe joints, elbows, and earlobes, forming hard lumps – these are gouty tophi.

Their impact on the body is significant:

Joint Damage, Leading to Deformity: This is the primary harm. These "small stones" are hard, and when they reside in the joints, it's like sand getting stuck in the gears of a machine. Every time you move, they slowly wear down your cartilage and bones. Over time (several years or even more than a decade), the joints will be "eroded," becoming swollen, stiff, and deformed, eventually leading to a loss of mobility, and your hands and feet might become grotesquely shaped.
Nerve Compression: If tophi happen to grow near nerves, such as in the wrists (carpal tunnel) or ankles, they can compress the nerves. This can lead to numbness, tingling, and even muscle weakness.
Skin Ulceration: Tophi will grow larger and larger, stretching the overlying skin thinner and thinner. To a certain extent, the skin may break open, and white, paste-like or chalky material will ooze out. These wounds are difficult to heal and are highly susceptible to infection.

In short, gouty tophi not only affect aesthetics but are also a "ticking time bomb" that continuously damages your joints and surrounding tissues, leading to a gradual loss of joint function and persistent pain and distress. Therefore, once you notice any signs of tophi formation, it is crucial to take it seriously and manage your uric acid levels effectively.