7: Crystal Arthropathies and Polymyalgia Rheumatica (PMR)

Question 1

crystal deposition diseases are characterised by

Answer 1

deposition of mineralised material within joints and peri-articular tissue

Question 2

which crystals are commonly seen in crystal deposition diseases?

name the diseases associated with each crystal type

Answer 2

• monosodium urate > gout
• calcium pyrophosphate dihydrate (CPPD) > pseudogout
• basic calcium phosphate hydroxy-apatite (BCP) > calcific periarthritis/tendonitis

Question 3

list some causes of hyperuricaemia caused by overproduction

Answer 3

overproduction:
- malignancy
- severe exfoliative psoriasis
- drugs e.g. ethanol, cytotoxic drugs
- inborn errors of metabolism
- HGPRT deficiency

Question 4

list some causes of hyperuricaemia caused by underexcretion

Answer 4

underexcretion:
- renal impairment
- hypertension
- hypothyroidism
- drugs e.g. alcohol, low dose aspirin, diuretics, cyclosporin
- exercise, starvation, dehydration
- lead poisoning

Question 5

describe Lesch Nyan syndrome

Answer 5

• congenital disease caused by HGPRT deficiency which causes overproduction of uric acid.
• X-linked recessive

Question 6

clinical features of Lesch Nyan Syndrome

Answer 6

• intellectual disability
• aggressive and impulsive behaviour
• self mutilation
• gout
• renal disease

Question 7

the 1st attack of gout is not treated unless

Answer 7

• single attack of polyarticular gout
• tophaceous gout
• urate calculi
• renal insufficiency

Question 8

what treatment can be used to manage gout?

Answer 8

• NSAIDS
• colchicine
• steroids: I/A, I/M, oral

Question 9

which drugs can be used to lower uric acid levels?

Answer 9

• xanthine oxidase inhibitor e.g. allopurinol
• febuxostat
• uricosuric agents e.g. probenecid, benzbromarone
• canakinumab

Question 10

what are the rules for lowering uric acid levels?

Answer 10

1. wait until the acute attack has settled before attempting to reduce the urate level
2. use prophylactic NSAIDs or low dose colchicine/steroids until urate level normal
3. adjust allopurinol dose according to renal function

Question 11

most common area for pseudogout to occur?

Answer 11

knee

Question 12

who is typically affected by pseudogout?

Answer 12

elderly females
erratic flares

Question 13

what is the aetiology of pseudogout?

Answer 13

idiopathic
familial
metabolic

Question 14

what are two triggers for pseudogout?

Answer 14

trauma
intercurrent illness

Question 15

what is the mangement for pseudogout?

Answer 15

NSAIDs
intra-articular steroids
no prophylactic therapies

Question 16

which conditions are associated with polymyalgia rheumatica?

Answer 16

giant cell arteritis
high ESR anaemia

Question 17

clinical presentation of polymyalgia rhheumatica

Answer 17

• SUDDEN onset of shoulder +/- pelvic girdle STIFFNESS
• usually > 70y
• F:M 2:1
• ESR > 45 often 100
• anaemia
• malaise; weight loss; fever; depression
• arthralgia/synovitis occasionally

Question 18

what factors are used to help diagnose polymyalgia rheumatica?

Answer 18

• compatible history
• age > 50
• ESR > 50
• dramatic steroid response
• no specific diagnostic test

Question 19

what is the treatment for polymyalgia rheumatica?

Answer 19

• prednisolone 15mg per day initially
• 18-24 mth course
• bone prophylaxis