Gout Flashcards
What are the risk factors for gout?
Ratio of 5:1 of men to women Uric acid levels increase with age, obesity, western diet and metabolic syndrome Genetic predisposition Chemotherapy and radiotherapy Related to a purine rich diet
Describe the pathogenesis of gout?
Breakdown of purines results in uric acid formation
Uric acid is excreted in urine
Uric acid has limited solubility in body fluids
Hyperuricaemia - uric acid concentration exceeds that of it’s solubility (420micromole/L in men and 360 micromoles/L in women)
At a pH of 7.4 uric acid loses a proton to become a urate ion
Urate ions then combine with Na+ to form monosodium urate crystals
What factors determine serum uric acid concentrations?
Production, ingestion and breakdown of purines
What foods contain a lot of purines?
Shellfish, anchovies, red meat, organ meat
What can cause an increase in the production of purines?
Consumption of high fructose corn syrup beverages
Myelo- and lymphoproliferative disorders
What can cause a decreased clearance of uric acid?
Dehydration - low water, high alcohol intake
Drug therapy - aspirin, thiazide diuretics
CKD
Hypertension
Lead toxicity
Primary hyperparathyroidism
Hypothyroidism
What are the clinical features of acute gout?
Attack may be precipitated by excess food, alcohol, dehydration or diuretic therapy
Sudden onset of agonising pain, swelling, and redness of the first MTP joint
Wakes up feeling like their toe is on fire
The pain is most severe in the hours after the attack
Can last days to weeks
Other joints affected include: ankle, knee, wrist, elbow
What investigations are needed?
Clinical picture is often diagnostic along with rapid response to NSAIDs and colchicine
Joint fluid microscopy is most specific - technically hard to carry out
Serum uric acid - look for a level >600 micromoles/L (if not recheck after 2 weeks)
Serum urea
Serum creatinine
eGFR (these 3 monitored for renal impairment)
What are the components of treatment?
NSAIDs Corticosteroids Colchicine Lifestyle modification Xanthase oxidase inhibitors Uricosuric medications
How are NSAIDs used in gout?
Used in acute gout to reduce pain and swelling
Naproxen - 750mg first, then 250mg every 8 hours until the attack finishes
Diclofenac - 75-150mg daily in 2-3 divided doses
When is colchicine used in gout?
In acute gout and in short term prophylaxis
Why is colchicine used in gout?
It inhibits white blood cell migration
How is colchicine used in acute gout?
500mcg 2-4 times a day and a maximum of 6mg per course
Course cannot be completed within 3 days of completion
How is colchicine used in short term prophylaxis for gout?
Used in addition to allopurinol - 500mcg twice a day
How can lifestyle be modified to treat gout?
Stay well hydrated
Avoid precipitating foods
Stay fit
