Crystal arthropathies

Question 1

What is gout?

Answer 1

Deposition of urate crystals (negatively birefringent, needle shaped)
Acute inflammatory response with phagocytosis of crystals

Question 2

What is the cause of hyperuricaemia?

• increased urate production
• reduced urate excretion

Answer 2

INCREASED URATE PRODUCTION
Inherited enzyme defects
Myeloproliferative/Lymphoproliferative disorders
Psoriasis
Haemolytic disorders
Alcohol (beer, spirits)
High dietary purine intake (red meat, seafood, corn syrup

REDUCED URATE EXCRETION
	Chronic renal impairment
	Volume depletion eg heart failure
	Hypothyroidism
	Diuretics
	Cytotoxics eg cyclosporin

Question 3

Gout:

• what is seen in gout?
• how long does it take to settle with/without treatment?
• what is the nature of onset?

Answer 3

Usually monoarthropathy:- 1st MTP > ankle > knee
Settles in about 10 days without treatment
Settles in about 3 days with treatment
Abrupt onset, often overnight
May have normal uric acid during acute attack

Question 4

What is chronic tophaceous gout?

-what is this assoc. with?

Answer 4

A chronic form of gout. Nodular masses of uric acid crystals (tophi) are deposited in different soft tissue areas of the body.

Often diuretic associated
High serum uric acid
Tophi may ulcerate and extrude uric acid
May get acute attacks

Question 5

What investigations are done for gout?

Answer 5

Serum uric acid raised (may be normal during acute attack)
Raised inflammatory markers
Polarised microscopy of synovial fluid
Renal impairment (may be cause or effect
Xrays

Question 6

What is the acute treatment of gout?

Answer 6

NSAIDs
Colchicine
Steriods

Question 7

What is the treatment for gout prophylaxis?

Answer 7

Allopurinol – 1st line
	Febuxostat – 2nd line
	Start 2-4 weeks after acute attack
If start acutely ureate drops quickly and this can cause a flare up as a big change so wait until calmed down. Then you taper up until serum ureate becomes normal. 
	Require cover with NSAID etc

Question 8

Pseudogout:

-what is this?

Answer 8

All the ‘P’s
–pseudogout
-pyrophosphate (calcium pyrophosphate)
-positive alignment needles

Question 9

Pseudogout:

-how is this different from gout clinically??

Answer 9

Commoner in elderly
Chondrocalcinosis increases with age
Related to osteoarthritis
Affects fibrocartilage - knees, wrists, ankles

Question 10

What is the pathogenesis of pseudogout?

Answer 10

Acute attacks related to shedding of calcium pyrophosphate crystals (pseudogout)
Calcium pyrophosphate crystals-envelope shaped, mildly positively birefringent
Marked rise in inflammatory markers

Question 11

What is the treatment for pseudogout?

Answer 11

NSAIDS
Colchicine
Steroids
Rehydration

Question 12

What is hydroxyapatite?

-who does this affect?

Answer 12

What is it?
“Milwaukee shoulder”
Hydroxyapatite crystal deposition in or around the joint.
Release of collagenases, serine proteinases and IL-1
Acute and rapid deterioration.
Females, 50-60 years

Question 13

What is the treatment for hydroxyapatite?

Answer 13

NSAIDs
Intra-articular steroid injection
Physiotherapy
Partial or total arthroplasty