Gout is a common arthritis condition due to deposition of monosodium urate (MSU), and is closely related to hyperuricemia. Because of disorders of purine metabolism or impaired renal excretion, serum uric acid levels rise to be abnormally high, and finally there would be the deposition of uric acid and acute persistent inflammatory reactions in the joints.
The most common clinical manifestations of gout are acute burning sensation and swelling of the joints. In some cases, clinical manifestations such as joint damage and renal dysfunction are often present. Gout affects a significant portion of the population worldwide annually, and according to the estimates of World Health Organization, 3.9% of people worldwide are suffering from gout. The acute onset of arthritis, joint malformations, chronic joint injuries and the formation of renal calculus not only reduce the quality of life, but also lead to disability.
In TCM, gout pertains the category of Bi pattern. In general, the manifestations of Bi pattern are mainly characterized as pain, numbness and heaviness of muscles, tendons and joints or swelling of joints with hot sensation and limitation of movement.
According to TCM, the primary causes are the deficiency of healthy qi and the invasion of pathogenic factors like wind, cold, dampness or heat. It is recorded in Treatise on Blood Trouble that the transportation and transformation function of spleen is closely related to the disease mechanism of gout. The deficiency of spleen qi could cause obstruction in the digestion system and lead to the buildup of waste products like uric acid in the blood. In addition, the evidences from clinical trials suggested that the dampness accumulation and blood stasis in the meridian would result in the swelling and pain of joint and the buildup of uric acid in the blood.
Because of the individual difference of body constitution and different pathogenic factors, there are various types of Bi pattern. For example, people with yang-deficiency constitution are usually affected by the combined invasion of wind, cold and dampness, and therefore there would be a Bi pattern of cold-dampness type, while people with yang-predominance constitution or yin-deficiency and yang-hyperactivity constitution are usually affected by the combined invasion of wind, dampness and heat, and finally there would be Bi pattern of damp-heat type.
Among those factors, dampness and heat are the most common external causes of acute gout, while the deficiency of healthy qi and the invasion of dampness are the most common external causes for gout during remission.