Gout (ancient Greek ποδάγρα, literally - a trap for the legs; from πούς, genus ποδός - leg and ἄγρα - fishing, hunting) is a chronic metabolic disease (metabolic disease in the body ), related to microcrystalline arthropathy. It is caused by a violation of protein (purine) metabolism and the accumulation of uric acid in the body. It is characterized by repeated attacks of acute gouty arthritis with crystal-induced synovitis, deposition of urates (uric acid salts) in tissues.
The prevalence of gout is 0.1%. Most often develops at the age of 40-50 years. Men get sick 20 times more often than women.
Causes of gout (etiology)
Depending on the cause of the disease, gout is divided into primary and secondary.
Primary gout - Most often caused by genetic defects:
- A hereditary decrease in the activity of enzymes involved in the metabolism of purines, which leads to increased synthesis of uric acid in the body. Their activity is controlled by the X chromosome, so their birth defect occurs only in males.
- Hereditary hypofunction of kidney enzyme systems that regulate the excretion of uric acid.
Secondary gout - the most common cause is kidney disease with renal failure, as well as blood diseases (polycythemia, leukemia), accompanied by cell breakdown and hyperuricemia.
The development of gout is also promoted by excess nutrition, monotonous meat food, consumption of alcoholic beverages (especially beer and dry wines), as well as a sedentary lifestyle.
Mechanism of gout development (pathogenesis)
The development of the disease is based on a violation of uric acid metabolism. There are 3 main factors:
- Hyperuricemia (increased levels of uric acid in the blood) - develops due to increased biosynthesis of uric acid and reduced excretion in the urine. The kidney is not able to remove all excess uric acid from the body.
- Deposition of urates (uric acid salts) in tissues - due to hyperuricemia and accumulation of urates in the body.
- Acute gouty inflammation – develops due to the deposition of urate microcrystals in the joint cavity, which activate the body’s immune system, and immune system enzymes begin to damage soft tissues. As a result, inflammation develops. Crystals are also deposited in the renal tubules, which leads to the development of gouty nephropathy.
Periods of development of gout
There are 3 periods:
- Premorbid – is asymptomatic, there is only hyperuricemia (increased uric acid in the blood). Asymptomatic hyperuricemia is observed in 8-14% of the adult population, it is not yet considered gout.
- Intermittent – there is an alternation of acute attacks of arthritis with asymptomatic intervals between attacks.
- Chronic gout - characterized by the appearance of tophi (gouty nodes), chronic gouty arthritis, as well as extra-articular manifestations (most often - kidney damage, in 50-75% of patients). Over time, patients develop chronic gouty polyarthritis with predominant damage to the joints of the lower extremities. 40% of patients develop kidney stones.
Diagnosis of gout and gouty arthritis:
Main complaints for gout:
In most cases, a typical (classic) acute attack is observed - severe pain often occurs suddenly in the middle of full health, often in the middle of the night. An attack can be triggered by fatty foods, alcohol, hypothermia, or injury.
In men, the first attack is characterized by monoarthritis and predominant damage to the joints of the foot. Most often, pain occurs in the metatarsophalangeal joint (big toe). The joint quickly swells, turns red and becomes bluish-purple, hot to the touch, body temperature can rise to 38-39℃, the function of the joint is impaired. Less typical is inflammation of the elbow and wrist joints. Very rarely the shoulder, sternoclavicular, and hip joints are affected.
In women, at the first attacks, oligo- or polyarthritis can often be observed, and the joints of the hand are often involved. Sometimes the ankle, knee, and wrist joints are affected.
The first attacks of gout usually last 3-10 days, then the pain disappears and function is completely restored. The next attack occurs after a certain time (sometimes after months, even years), but over time the light intervals become shorter.
Tofus (lat. tofus - porous stone, tuff) - gouty node - a specific sign of gout. Tophi are formed with high hyperuricemia and the duration of the disease is more than 5-6 years. These are yellowish nodules containing urates (uric acid salts), surrounded by fibrous tissue. They are most often localized on the ears, on the forehead, in the area of the cartilaginous septum of the nose, elbows, palmar surfaces of the forearms, fingers, the front surface of the thighs and legs, and on the feet. During attacks, the contents of tophi can liquefy and be released through fistulas (white, crumbly discharge). They rarely become infected (since urates have a bactericidal effect).
Laboratory tests for gout:
During an attack, ESR, sialic acids, fibrin, haptoglobin, seromucoid are increased in the blood, C-reactive protein appears, and neutrophilic leukocytosis with a shift to the left.
X-ray examination of joints with gout:
Changes are detected mainly in chronic gouty polyarthritis. Reliable signs appear no earlier than 5 years after the onset of the disease. Against the background of osteoporosis, signs of gouty arthritis are found (bone tophi - round “stamped” foci of clearing from several mm to 2-3 cm in diameter. Large nodes, increasing, destroy the cortical layer of the bone - a symptom of “bloating of the bone edge”).
Other instrumental studies for gout:
- Examination of synovial fluid - urate crystals are determined microscopically.
- Puncture biopsy of tophi - uric acid crystals are detected.
