crystal arthropathy

Question 1

what is the normal function of crystals within the body?

Answer 1

to strengthen the skeleton

to attract XS ions for removal from the body

Question 2

describe what a crystal is

Answer 2

a homogenous solid where the ions are bonded closely in an ordered, repeating, symmetric arrangement
stable
hard
high density

Question 3

what is a crystal arthropathy?

Answer 3

arthritis caused by crystal deposition in the lining of the joint

Question 4

Describe the crystals seen in gout

Answer 4

negatively birefringent

needles

Question 5

Describe the crystals seen in pseudogout

Answer 5

positively birefringent
rhomboids
more sparse distribution under the microscope

Question 6

What is the name given to the crystals in gout?

Answer 6

monosodium urate crystals

Question 7

what is the name given to the hard deposits formed in chronic gout?

Answer 7

tophaceous gout / tophi

Question 8

What should you be concerned about when you see gout in a young person?

Answer 8

inborn metabolic errors

Question 9

What is the most commonly affected joint in gout?

Answer 9

the first metatarsophalangeal joint (ie base of the big toe_

Question 10

Name some joints that gout can affect

Answer 10

big toe
ankle/foot
knee
finger
elbow
wrist

Question 11

what is the key enzyme in the uric acid formation pathway that can be targeted by treatment?

Answer 11

xanthine oxidase

Question 12

What is the serum level of uric acid that under which, there is negligible risk of gout?

Answer 12

0.3 mmol/L

Question 13

At what serum level of uric acid is there some risk of crystal deposition?

Answer 13

0.36 mmol/L

Question 14

at what level of uric acid is the serum supersaturated and urate crystal deposition likely?

Answer 14

0.42 mmol/L

Question 15

What is the primary method of excretion of uric acid?

Answer 15

renal

Question 16

What are the sources of purines in the body

Answer 16

diet
purine synthesis
tissue nucleic acids eg DNA and RNA

Question 17

What does xanthine oxidase do?

Answer 17

converts purines to uric acid

specifically converting purines to hypoxanthine and hypoxanthine to xanthine

Question 18

What type of cells are responsible for the inflammatory response seen in gout?

Answer 18

WBCs eg macrophages

Question 19

What is the main reason for hyperuricaemia?

Answer 19

underexcretion of uric acid

Question 20

What is the major risk factor for gout?

Answer 20

hyperuricaemia

Question 21

when would you not measure the level of uric acid in the blood?

Answer 21

during an acute attack as it can be paradoxically low

Question 22

List some causes of under excretion of uric acid

Answer 22

alcohol
renal impairment 
hypertension 
metabolic syndrome 
obesity 
diabetes 
drugs: low dose aspirin, diuretics esp thiazides, cyclosporin, tacrolimus, ethambutol and pyrazinamide

Question 23

What are the causes of overproduction of uric acid?

Answer 23

alcohol drinks
diet - XS meat, shellfish, offal, fructose sweetened
metabolic syndrome
myeloproliferative disease and cytotoxic drugs
psoraisis

Question 24

Name a differential diagnosis of gout and why it is a differential

Answer 24

joint sepsis - it is the only other condition where the skin is red and shiny

Question 25

What are the common precipitants of an attack?

Answer 25

``` aggressive treatment for hypouricaemia alcohol or shellfish binges sepsis acute MI dehydration ```

Question 26

What is the appearance of gout on XR?

Answer 26

punched out periarticular erosion joint space narrowing soft tissue calcification and crystal deposition

Question 27

What is the long term preventative treatment for gout?

Answer 27

allopurinol or febuxostat ie the xanthase oxidase inhibitors

Question 28

what must you do when you start sb on long term preventative treatment for gout?

Answer 28

Give them drugs for acute gout treatment initially as starting sb on preventative treatment can precipitate a gouty attack - so start on colchidine or NSAID

Question 29

what is the aim of preventative treatment?

Answer 29

To bring serum uric acid level to <300mmol/L

Question 30

What is the principle for allopurinol dosing?

Answer 30

start low, go slow - aka start with a low dose and titrate upwards according to the serum uric acid level

Question 31

What would you do if you were giving allopurinol to sb with renal failure and why?

Answer 31

reduce the dose - as allopurinol is excreted by the kidneys and if the kidneys can't excrete, then levels of the drug build up in the body

Question 32

What is the name given to the crystals deposited in pseudogout?

Answer 32

calcium pyrophosphate crystals

Question 33

What are the typical joints affected by pseudogout?

Answer 33

``` the MCPs in the hand wrists knees ankles most common in knee ```

Question 34

How does pseudogout present?

Answer 34

``` acute monoarthritis severe pain stiffness swelling redness ```

Question 35

How would you distingush OA from pseudogout?

Answer 35

pseudogout: joints that are involved inflammation - 4 pillars superimposition of acute attacks on chronic

Question 36

What are the triggers of an acute attack in pseudogout?

Answer 36

direct trauma to the joint surgery blood transfusion, IV fluid spontaneous - no obvious trigger

Question 37

What would an XR of the knee show in pseudogout?

Answer 37

chondrocalcinosis - deposition of calcium in the cartilage

Question 38

Name some metabolic disorders that may be associated with pseudogout esp. in a young person?

Answer 38

haemochromatosis hyperparathyroidism/hypoparathyroidism acromegaly hypomagnesaemia and hypophosphataemia

Question 39

How is pseudogout managed?

Answer 39

acute attacks - NSAIDs, analgaesia, aspirate the joint and give steroid injections long term - trial of methotrexate, hydrochloroquine, synovectomy or surgery

Question 40

What is the critical diagnostic test in gout/pseudogout?

Answer 40

joint aspiration!

Question 41

Give some points you would mention to a pt to educate them about prevention of gout

Answer 41

``` prevent dehydration lose weight reduce alcohol intake reduce red meat intake add more dairy products to the diet ```