MSK/Rheumatology Flashcards
(119 cards)
Define crystal arthropathies and name 2
Gout and Psuedogout
Describes acute intermittent episodes of joint inflammation caused by accumulation of urate crystals within synovial joints.
What type of crystals are found in gout and describe their structure and appearance (3)
Monosodium Urate Crystals
Needle-shaped
Negatively Bifringent under polarized light
What type of crystals are found in pseudogout and describe their structure and appearance (3)
Calcium pyrophosphate crystals
Small rhomboid brick shaped
Positively bifringent under polarized light.
Where does gout most commonly affect? (2)
1st metatarsophalangeal joint (big toe = podagra)
Osteoarthritic joints (ankle, foot, hand, wrist, elbow or knee)
What is the principle driver of gout?
Hyperuricaemia (high uric acid levels)
Describe the pathophysiology of gout (3)
Purines > Hypoxanthine > Xanthine > Uric acid
Uric acid precipitates, forming monosodium urate crystals.
Urate crystals trigger acute inflammatory response (recruitment of neutrophils) causing neutrophilic synovitis.
What enzyme catalyses the conversion of xanthine to uric acid?
Xanthine oxidase
What foods/drinks contain purines? (3)
Fizzy drinks
Alcohol
Red meats
Name 1 xanthine oxidase inhibitor
Allopurinol
Where is uric acid predominantly excreted from?
Kidneys
Give 5 risk factors for gout that result from reduced urate excretion
Elderly
Male
Impaired renal function
Post-menopausal women
Drugs (Aspirin, Indapamide, Tacrolimus, Pyrazinamide)
What drug is it important to stop in patients with hypertension presenting with gout? What should be given instead?
STOP Diuretics (indapamide)
Switch to ARB (losartan) as promotes uric acid excretion
Name 4 drugs associated with gout
Aspirin (high dose)
Indapamide (diuretic)
Tacrolimus (for severe eczema)
Pyrazinamide (TB)
Give 4 clinical features of gout
Acute monoarthritis (rapid onset - severe pain - big toe)
Urate deposits (tophi in pinna, tendons or extensor surfaces)
Joint stiffness, swelling, effusion
Renal disease (hyperuricaemia > CDK = radiolucent stones/interstitial nephritis)
Give 4 differentials for gout
Septic arthritis (consider in any monoarthropathy)
Pseudogout
Reactive arthritis
Haemarthrosis (bleeding into joints - haemophilia)
What investigation is used to definitively diagnose gout?
Joint aspiration (arthrocentesis) with synovial fluid analysis.
What additional investigations is it important to conduct when investigating ? gout(4)
Synovial Fluid Culture - To exclude septic arthritis
WBC - High neutrophils
Serum urate - Raised
X-ray (shows punched out erosions in juxta-articular bone and joint space narrowing)
What drugs can be used to manage acute gout? (4)
NSAIDs - Naproxen/Ibuprofen (contraindicated in CKD)
Corticosteroids - Prednisolone
Colchicine
IL-1 inhibitors - Anakinra or Canakinumab
What drugs are used to treat recurrent episodes of gout? (2-3 weeks post acute episode) (3)
Allopurinol (xanthine oxidase inhibitor)
Probenecid (inhibits uric acid reabsorption = increased uric acid excfretion in urine)
Rasburicase (recombinant urate oxidase)
Give 3 side effects of Colchicine
Diarrhoea
Nausea
Abdominal pain
What dietary change can help reduce the risk of developing gout in the future?
Switching to a high dairy diet
Define pseudogout
Crystal arthropathy characterised by the deposition of calcium pyrophosphate crystals within joints.
Can be acute or chronic
How may acute pseudogout present?(2)
Presents with acute monoarthropathy (usually of larger joints in the elderly).
Usually occurs spontaneously and can be provoked by illness, trauma or surgery.
How may chronic pseudogout present?
Presents as an inflammatory RA-like (symmetrical) polyarthritis and synovitis (>5 joints)