What is "tophus"

Tophus \To"phus\, n.; pl. Tophi. [NL.: cf. F. tophus a mineral concretion in the joint. See Toph.] [Written also tofus.]

1. (Med.) One of the mineral concretions about the joints, and in other situations, occurring chiefly in gouty persons. They consist usually of urate of sodium; when occurring in the internal organs they are also composed of phosphate of calcium.

2. (Min.) Calcareous tufa.

n. (context medicine English) A deposit of monosodium urate crystals in the body, caused by high levels of uric acid in the blood.

1. n. a deposit of urates around a joint or in the external ear; diagnostic of advanced or chronic gout [syn: chalkstone]

2. an incrustation that forms on the teeth and gums [syn: tartar, calculus]

3. [also: tophi (pl)]

A tophus (Latin: "stone", plural tophi) is a deposit of uric acid crystals, in the form of monosodium urate crystals, in people with longstanding hyperuricemia (high levels of uric acid in the blood). Tophi are pathognomonic for the disease gout. Most people with tophi have had previous attacks of acute arthritis, eventually leading to the formation of tophi. Chronic tophaceous gout is known as Harrison Syndrome.

Tophi form in the joints, cartilage, bones, and other places throughout the body. Sometimes, tophi break through the skin and appear as white or yellowish-white, chalky nodules. Without treatment, tophi may develop on average about ten years after the onset of gout, although their first appearance can range from three to forty-two years. The development of gouty tophi can also limit joint function and cause bone destruction, leading to noticeable disabilities, especially when gout cannot successfully be treated. When uric acid levels and gout symptoms cannot be controlled with standard gout medicines that decrease the production of uric acid (e.g., allopurinol, febuxostat) or increase uric acid elimination from the body through the kidneys (e.g., probenecid), this can be referred to as refractory chronic gout (RCG). They are more apt to appear early in the course of the disease in people who are older.

Although less common, tophi can also form in the kidneys and nasal cartilage.