Crystal Atrophy Flashcards
How are crystal deposition diseases characterised
Deposition of mineralised material with joints and peri-articular tissue
3 common crystal deposition diseases
- Gout (Monosodium urate)
- Pseudogout (Calcium pyrophosphate dihydrate)
- Calcific periarthritis/tendonitis (Basic calcium phosphate hydroxyl apatite)
How are purines metabolised
Purines => Hypoxanthine => Xanthine => Plasma urate => Urine uric acid => excretion
How do purines become hypoxanthine
HGPRT
2 basic reasons for hyperuricaemia
- Overproduction
- Under excretion
5 over production causes of hyperuricaemia
- Malignancy (lymphoproliferative, tumour lysis syndrome)
- Severe exfoliative psoriasis
- Drugs (ethanol, cytotoxic drugs)
- HGRPT deficiency
- Inborn errors of metabolism
5 under excretion causes of hyperuricaemia
- Renal impairment
- Hypertension
- Drugs (alcohol, low dose aspirin, diuretics, cyclosporin)
- Exercise, starvation, dehydration
- Lead poisoning
Describe Lesch Nyan Syndrome
- HGPRT deficiency
- X-linked recessive
- Intellectual disability
- Aggressive + impulsive behaviour
- Self mutilation
- Renal disease
- Gout
Is gout more prevalent in men or women
Men, by some margin (in UK)
Rx of an acute flare up of gout
- NSAIDs
- Colchicine
- Steroids (IA/IM/Oral)
When to treat hyperuricaemia
Only treat 1st attack if:
- Single attack of polyarticular gout
- Tophaceous gout
- Urate calculi
- Renal deficiency
- Treat if 2nd attack within 1 yr
- Prophylactically prior to certain malignancies
DO NOT TREAT ASYMPTOMATIC HYPERURICAEMIA
Rx to lower uric acid
- Xanthine oxidase inhibitor (Allopurinol, Febuxostat)
- Uricosuric agents (Sulphinpyrazone, Probenecid)
- Canakinumab (monoclonal antibody targeted at interleukin-1 beta)
3 rules of lowering uric acid levels
- Wait until the acute attack has settled before attempting to reduced the urate level
- Use prophylactic NSAIDs or low dose colchicine/steroids until urate level normal
- Adjust allopurinol dose according to renal function
Describe Pseudogout
- Elderly females (mainly)
- Erratic flares
- Idiopathic, familial, metabolic
Triggers of Pseudogout
- Trauma
- Intercurrent illness
Management of Pseudogout
-NSAIDs
-IA steroids
There are no prophylactic therapies
How are polymyalgia rheumatica, giant cell arteritis and High ESR + anaemia related
- 20% of patients with PMR have evidence of GCA
- 50% of patients with GCA may have PMR
PMR => GCA => HIGH ESR => PMR => GCA => HIGH ESR
Presentation of polymyalgia rheumatica
- SUDDEN onset of shoulder +/- pelvic girdle STIFFNESS
- Rare in <50 yr usually >70yr
- F:M = 2:1
- Anaemia
- ESR usually >45 often 100
- Malaise, weight loss, fever, depression
- Arthralgia/synovitis occasionally
How to diagnose polymyalgia rheumatica
- Compatible Hx (age >50)
- ESR > 50
- Dramatic steroid response
- No specific diagnostic test
DDx for polymyalgia rheumatica
- Underlying malignancy (multiple myeloma, lung cancer)
- Hypo/hyperthyroidism
- Bilateral shoulder capsulitis
- Fibromyalgia
- Myalgic onset inflammatory joint disease
Rx of polymyalgia rheumatica
- Prednisolone (15mg/day initially)
- 18-24 month course
- Bone prophylaxis
