Crystal arthopathy Flashcards
How are crystal arthropathies characterised?
Characterised by deposition of mineralised material within joints and peri-articular tissue
What are the three common crystal arthropathies?
- GOUT: Monosodium urate
- PSEUDOGOUT: Calcium pyrophosphate dihydrate (CPPD)
- Calcific periarthritis/tendonitis: Basic calcium phosphate hydroxy-apatite (BCP)
Please briefly explain purine metabolism and how this contributes to gout:
- Endogenous production of uric acid from degradation of purines usually contributes about two-thirds of the body urate pool, the remainder being dietary in origin.
- Of the uric acid produced daily, the majority (∼ 70%) is excreted via the kidney and the remainder is eliminated into the biliary tract and subsequently converted by colonic bacterial uricase to allantoin.
- In the vast majority of people with gout, hyperuricaemia results from reduced efficiency of renal urate clearance
Gout is caused by hyperuricaemia - what are reasons for overproduction of urate?
- Malignancy e.g lymphoproliferative, tumour lysis syndrome
- Severe exfoliative psoriasis
- Drugs e.g. ethanol, cytotoxic drugs
- Inborn errors of metabolism
- HGPRT deficiency
Gout is caused by hyperuricaemia - what are reasons for underexcretion of urate?
- Renal impairment
- Hypertension
- Hypothyroidism
- Drugs e.g. alcohol, low dose aspirin, diuretics, cyclosporin
- Exercise, starvation, dehydration
- Lead poisoning
Who is most likely to be effected by gout?
- It is predominantly a disease of older men.
- Men have higher urate levels than women and an increased prevalence of gout at all ages
What is the management of an acute flare of Gout?
- NSAIDs
- Colchicine
- Steroids: I/A, I/M, oral
What is the management of hyperuricaemia causing chronic gout?
- Does it need to be treated ?
- 1st attack not treated unless;
- Single attack of polyarticular gout
- Tophaceous gout
- Urate calculi
- Renal insufficiency
- Treat if 2nd attack within 1 yr
- Prophylactically prior to treating certain malignancies
- DO NOT treat asymptomatic hyperuricaemia
Pharmacological treatment of hyperuricaemia?
- Xanthine oxidase inhibitor e.g. Allopurinol
- Febuxostat
- Uricosuric agents e.g. sulphinpyrazone, probenecid, benzbromarone
- Canakinumab
Rules for lowering uric acid levels?
- Wait until the acute attack has settled before attempting to reduce the urate level
- Use prophylactic NSAIDs or low dose colchicine/steroids until urate level normal
- Adjust allopurinol dose according to renal function
What are lifestyle factors that contribute to gout?
- Seafood consumption
- Meat consumption
- Alcohol consumption
What is pseudogout?
- Calcium pyrophosphate arthritis is caused by deposition of calcium pyrophosphate (CPP) crystals.
- It can be difficult to diagnose as CPP crystals in synovial fluids can be small, sparse, and difficult to find.
Who is more likely to get pseudogout?
- Elderly females
- Erratic flares
- Aetiology
- Idiopathic, familial, metabolic
What are triggers of pseudogout?
- Trauma, Intercurrent illness
What is the management of pseudogout?
- NSAIDs
- I/A steroids
- There are no prophylactic therapies
Please note the relationship between GCA and polymyalgia rheumatica:
