Gout Flashcards
(29 cards)
Gout is an excessive amounts of
uric acid (end product of purine metabolism)
What are the signs of Gout Arthritis?
Recurrent episodes of acute arthritis, large crystalline aggregates called tophi, and chronic joint deformity
Gout has precipitation of
Precipitation of monosodium urate crystals
Factors that contribute to Gout
Age of the individual and duration of the hyperuricemia: usually after 20to 30 years of hyperuricemia
Genetic predisposition: X-linked abnormalities of HGPRT, primary gout multifactorial inheritance
Heavy alcohol consumption
Obesity
Certain drugs (e.g., thiazides) reduce excretion of urate and predispose to the development of gout
Lead toxicity
Primary gout is
Overproduction of uric acid Normal excretion (majority) Increased excretion (minority)
Secondary Gout
Increased nucleic acid turnover ( leukemias )
Renal causes (Reduced excretion of uric acid with normal production (80 to 90% cases)
Inborn errors of metabolism (Lesch-Nyhan syndrome: (Overproduction of uric acid, increased urinary excretion - complete HGPRT deficiency
What is the morphology of Gout arthritis
Neutrophil infiltrate in synovium/synovial fluid
Needle-shaped monosodium urate crystals in cytoplasm of neutrophils and in synovium
Synovium is edematous and congested
Synovium: forms pannus
Location: articular cartilage of joints and peri-articular ligaments, tendons, soft tissue of ear lobes, nasal cartilages, skin of fingertips
What is Tophi?
pathognomonic, urate crystals surrounded by lymphocytes, macrophages, and foreign-body giant cells, attempting to engulf the masses of crystals
In Gouty Arthritis, how does the synovial fluid look with special polarization?
Negative birefringence (yellow)
Pathogenesis of Gout arthritis
- Hyperuricemia
- precipitation of rate crystals in joints
- activate complement pathway
- Neutrophil chemotaxis
- Phagocytosis of crystals by neutrophils
- lysis of neutrophils and release of lysosomal enzymes
Also
- phagocytosis of monocytes
- release iL-1, TNF, IL-6
- release proteases
Clinical features of Gout arthritis
95% cases in men > 30 years of age
Acute gouty arthritis
Mostly first attack is mono-articular; 50% in 1st metatarsophalangeal joint (great toe)
Four stages of gout
(1) asymptomatic hyperuricemia
(2) acute gouty arthritis
(3) “intercritical” gout
(4) chronic tophaceous gout
Asymptomatic hyperuricemia
around puberty in males and after menopause in women
Intercritical period:
Untreated acute arthritis may last for hours to weeks, but it gradually resolves and patient becomes asymptomatic
Chronic tophaceous gout:
After a decade of recurrent attacks, radiographs show characteristic juxta-articular bone erosion caused by the crystal deposits and loss of the joint space leading to severe crippling disease
Treatment of Gouty arthritis
Non-pharmacologic - modify diet to eliminate diets high in purine, moderation in alcohol intake
Pharmacologic Rx
Acute gout: NSAIDs or colchicine (if intolerant then corticosteroids)
Chronic treatment to normalize serum uric acid:
Uricosuric agents for underexcretors (e.g., probenecid)
Allopurinol (xanthine oxidase inhibitor) for overproducers
Pseudogout is caused by
Calcium pyrophosphate crystal deposition disease
Most common joint involved in Pseudogout is
the knee
Pseudogout happens in which population?
elderly population ( 50% of patients who are 85 years old )
What is the pathogenesis of Pseudogout?
CPPD disease: ↑ with
Hemochromatosis, hemosiderosis – Iron is presumed to inhibit pyrophosphatase accounting for decreased degradation of pyrophosphate
(2) Primary hyperparathyroidism (HPTH) - Increase in calcium
Chondrocalcinosis: linear deposits of calcium pyrophosphate in articular cartilage
Pseudogout is what type of birefringence?
Calcium pyrophosphate: positive birefringence
blue
Suppurative Arthritis is caused by?
Haemophilus influenzae in children <2 years
S. aureus in older children and adults
Gonococcus in late adolescence/young adulthood (more in women)
Individuals with sickle cell disease – Salmonella
Septic arthritis/tendinitis due to cat/dog bite - Pasteurella multocida
Suppurative Arthritis is characterized by?
Sudden onset of pain, redness, and swelling of the joint with restricted range of motion
Fever, leukocytosis, and elevated ESR (but in gonococcal infections – subacute)
In 90% of nongonococcal suppurative arthritis, single joint - usually the knee, followed by hip, shoulder, elbow, wrist, and sternoclavicular joints
Joint aspiration is typically purulent,allows identification of the causal agent
Deficiency of C6-9 predisposes to disseminated gonococcal infections (septic arthritis involving knee, tenosynovitis and dermatitis of the wrists & ankles)
Staphylococcus aureus - most common non-gonococcal cause, Treatment: Nafcillin + cephalosporin (third generation)
