Crystal Arthopathy

Question 1

What are crystal arthopathy diseases characterised by?

Answer 1

Characterised by deposition of mineralised material within joints and peri-articular tissue

Question 2

What are some common crystal arthopathy diseases?

Answer 2

• Monosodium urate (gout)
• Calcium pyrophosphate dehydrate (CPPD, also called pseudogout)
• Basic calcium phosphate hydro-apatit (BCP, also called calcific periarthritis/tendonitis)

Question 3

What crystals cause gout?

Answer 3

Monosodium urate

Question 4

What crystals cause pseudogout?

Answer 4

Calcium pyrophosphate dehydrate

Question 5

What crystals cause calcific periarthritis/tendonitis?

Answer 5

Basic calcium phosphate hydro-apatit

Question 6

Where does most of the urate in the body come from?

Answer 6

2/3 of urate in body comes from breakdown of purines produced within body (breakdown of DNA and RNA), remainder comes from breakdown of purines in food and drinks

Question 7

Where is most uric acid excreted?

Answer 7

70% of uric acid is excreted in kidney, and 30% in biliary tract

Question 8

What can hyperuricaemia occur due to?

Answer 8

Hyperuricaemia can occur due to overproduction or under excretion:

• Overproduction
  
  • Malignancy such as lymphoproliferative
• Severe exfoliative psoriasis
• Drugs
  
  • Such as ethanol, cytotoxic drugs
• Inborn errors of metabolism
• HGPRT deficiency
  
  • Known as Lesch Nyan syndrome
  • X-linked recessive
  • Intellectual disability, aggressive and impulsive behaviour, gout, renal disease
• Under excretion (commonest cause)
  
  • Renal impairment
  • Hypertension
  • Hypothyroidism
  • Drugs
    
    • Such as alcohol, low dose aspirin, diuretics, cyclosporine
  • Exercise, starvation, dehydration
  • Lead poisoning

Question 9

Is overproduction or underexcretion the more common cause of hyperuricaemia?

Answer 9

Under excretion

Question 10

What are some causes of overproduction of uric acid?

Answer 10

• Malignancy such as lymphoproliferative
• Severe exfoliative psoriasis
• Drugs
  
  • Such as ethanol, cytotoxic drugs
• Inborn errors of metabolism
• HGPRT deficiency
  
  • Known as Lesch Nyan syndrome
  • X-linked recessive
  • Intellectual disability, aggressive and impulsive behaviour, gout, renal disease

Question 11

What are some causes of underexcretion of uric acid?

Answer 11

• Renal impairment
• Hypertension
• Hypothyroidism
• Drugs
  
  • Such as alcohol, low dose aspirin, diuretics, cyclosporine
• Exercise, starvation, dehydration
• Lead poisoning

Question 12

Are more woman or men affected by gout?

Answer 12

M>F (as oestrogen helps excretion of uric acid in kidney)

Question 13

What are some lifestyle risk factors for gout?

Answer 13

• Diet high in meat/fish
• Alcohol drinking
• Lots of sports
• Dehydration

Question 14

What is the clinical presentation of gout?

Answer 14

• Red
• Hot
• Erythema
• Pain
• Often the foot

Question 15

What is the mangement of gout?

Answer 15

• Acute flair
  
  • NSAIDs
  • Colchicine
  • Steroids
• Long term
  
  • Think does it need to be treated?
  • 1^st attack not treated unless
    
    • Single attack of polyarticular gout
    • Tophaceous gout
    • Urate calculi
    • Renal insufficiency
  • Treat if 2^nd attack within 1 year
  • Prophylactically prior to treating certain malignancies
  • Do not treat asymptomatic hyperuricaemia
• Address cardiovascular and lifestyle risk factors

Question 16

How can you prophylactically lower uric acid?

Answer 16

• Xanthine oxidase inhibitor (first line)
  
  • Such as allopurinol
• Or febuxostat
  
  • For those unable to tolerate allopurinol
  • Avoid in patients with cardiac history
• Uricosuric agents
  
  • Such as sulphinpyrazone
• Canakinumab

Question 17

What are the rules for lowering uric acid levels?

Answer 17

• Wait for acute attack to settle before lowering urate levels
• Use prophylactic NSAIDs or low dose colchicine/steroids until urate level normal as the above treatments could trigger flair
• Then adjust allopurinol dose according to renal function, starting low and working up

Question 18

Where does gout most commonly affect?

Answer 18

Feet

Question 19

Where does pseudogout most commonly affect?

Answer 19

Knee

Question 20

Does pseudogout affect more males or females?

Answer 20

Usually affects older females, with erratic flares of joint swelling

Question 21

What is the aetiology of pseudogout?

Answer 21

• Idiopathic
• Familial
• Metabolic

Question 22

What are some triggers of pseudogout?

Answer 22

• Trauma
• Intercurrent illness

Question 23

What are some clinical features of pseudogout?

Answer 23

• Chondrocalcinosis (depositions of CPPD crystals into fibrous or hyaline cartilage) on x-ray
• Can see pyrophosphate crystals on aspiration

Question 24

What is chondrocalcinosis?

Answer 24

(depositions of CPPD crystals into fibrous or hyaline cartilage)

Question 25

What is the mangement of pseudogout?

Answer 25

* NSAIDs * I/A steroids * There are no prophylactic therapies

Question 26

What is polymyalgia rheumatica?

Answer 26

Inflammatory condition in elderly with close relation to giant cell arthritis

Question 27

Does polymyalgia rheumatica affect more males or females, and what age group?

Answer 27

* F \> M * Rare \<50 years, usually \>70 years

Question 28

What are clinical features of polymyalgia rheumatica?

Answer 28

* Sudden onset of shoulder with or without pelvic girdle stiffness * Anaemia * Arthralgia * Systemic features * Malaise * Weight loss * Fever * Depression

Question 29

What is the differential diagnosis for polymyalgia rheumatica?

Answer 29

* Myalgic onset inflammatory joint disease * Underlying malignancy * Inflammatory muscle disease * Hypo/hyperthyroidism * Bilateral shoulder capsulitis * Fibromyalgia

Question 30

What is the treatment for polymyalgia rheumatica?

Answer 30

* Prednisolone 15mg per day initialy * 18-24 month course * Bone prophylaxis