Source: Ernst ME, Clark
EC. Gout and Hyperuricemia. In: DiPiro JT, Talbert RL, Yee GC, Matzke
GR, Wells BG, Posey LM, eds. Pharmacotherapy:
A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=7997829.
Accessed May 27, 2012.
- Recurrent painful attacks of acute arthritis with hyperuricemia
and monosodium urate crystals in synovial fluid leukocytes.
- Excess accumulation of uric acid in gout from overproduction
or underexcretion of uric acid.
- Overproducers excrete >600 mg/day of uric acid after
purine-free diet for 3–5 days. Underexcretors are hyperuricemic
individuals who excrete <600 mg/day of uric acid.
- Agents that may decrease renal uric acid clearance:
- Thiazide and loop diuretics
- Nicotinic acid
- Salicylates (<2 g/day)
- Cytotoxic drugs
- Uric acid is waste product from purine degradation.
- Deposition of urate crystals in synovial fluid initiates inflammatory
process. Phagocytosis of urate crystals by leukocytes causes lysis
of cells and discharge of proteolytic enzymes, resulting in intense
joint pain, erythema, warmth, and swelling.
- Uric acid nephrolithiasis occurs in 10–25% of
patients with gout.
- Risk factors:
urinary excretion of uric acid
- Acidic urine
- Concentrated urine
- In uric acid nephropathy, acute renal failure occurs from
blockage of urine flow secondary to massive precipitation of uric
acid crystals in collecting ducts and ureters.
- Tophi may occur in longstanding hyperuricemia and may involve:
- Great toe
- Helix of ear
- Olecranon bursae
- Achilles tendon
- Affects men 7–9 times more often than women.
- Incidence increases with age, peaking at age 30–50
- Annual incidence ranges from 1 in 1000 for men ages 40–44
years and 1.8 in 1000 for those ages 55–64 years.
- Lowest rates in young women, approximately 0.8 cases per 10,000
- Rapid onset of excruciating localized joint pain, swelling,
erythema, and warmth.
- Attacks are typically monoarticular, most often first metatarsophalangeal
joint (podagra), but also insteps, ankles, heels, knees, wrists,
fingers, and elbows.
- Fever and leukocytosis common.
- Untreated attacks last from 3–14 days before spontaneous
Means of Confirmation
- Presumptive diagnosis based on presence of characteristic
signs and symptoms and the response to treatment.
- Elevated serum uric acid concentration, but acute gout
can occur with normal levels.
- X-rays may show asymmetric swelling within joint or subcortical
cysts without erosions.
- Definitive diagnosis requires aspiration of synovial fluid
from affected joint and identification of intracellular crystals
of monosodium urate monohydrate within leukocytes.
- Terminate acute attack.
- Prevent recurrent attacks.
- Prevent complications from chronic urate crystal deposition