Crystal Arthropathies

Question 1

Crystal Arthropathies

Name 2 characteristics common in crystal deposition diseases

Answer 1

Crystal deposition diseases are characterised by:

1. Desposition of mineralised material
2. In joints and peri-articular tissue

Question 2

Excretion of uric acid allantoin - physiology (3)

Answer 2

70% by kidney

Rest by biliary tract > GI bacterial uricase

Question 3

Crystal Arthropathies

What are the chemical compounds that are pathogenic in these cases?

Gout = ?

Pseudogout = ?

Answer 3

Gout = monosodium urate

Pseudogout = calcium pyrophosphate dihydrate (CPPD)

Question 4

3 categories: causes of hyperuricemia

Answer 4

1. Overproduction of uric acid
2. Underexcretion of uric acid
3. Excess intake of uric acid - alcohol

Question 5

4 causes of overproduction induced hyperuricemia

Answer 5

1. Congenital - inborn errors of metabolism, HGPRT def
2. Severe exfoliative psoriasis
3. Malignancy - lymphoproliferative, tumor lysis syndrome
4. Drugs - cytotoxic drugs

Question 6

Explain how alcohol causes hyperuricemia (5)

Answer 6

Excess intake of uric acid
Alcohol - rich in purines e.g. beer
Metabolism of ethanol > acetyl CoA leads to adenine nucleotide degradation
Results in increased formation of adenosine monophosphate (uric acid precursor)
Raised serum lactic acid level - inhibition of uric acid excretion

Question 7

6 causes of under excretion induced hyperuricemia

Answer 7

Renal impairment, dehydration
HTN
Hypothyroidism
Drugs - low dose aspirin, diuretics, cyclosporin
Lead poisoning

Question 8

What is Lesch Nyan syndrome/HGPRT deficiency
Hereditary pattern
Cognitive manifestations (3)
Physiologic manifestations (2)

Answer 8

Hereditary pattern: x-linked recessive
Cognitive manifestations
- intellectual disability
- aggressive, impulsive behaviour
- self-mutilation
Physiologic manifestations
- gout
-renal disease

Question 9

Prevalence of gout - gender distribution

Answer 9

Men have increased prevalence of gout across all ages, less in older age

Question 10

Why is gout very rare in young women

Why is gout more prevalent after menopause

Answer 10

estrogen has uricosuric effect

urate levels rise after menopause so gout becomes more prevalent

Question 11

Gout Clinical Dx (3)

Answer 11

History - dehydration
Examination - typically first MTP
Joint aspiration

Question 12

Management gout (3)

Answer 12

Acute flare 3 drugs
Therapies to lower uric acid
Address risk factors

Question 13

What are the 3 drugs used in acute flares of gout

Answer 13

Colchicine 500mg BD (SE diarrhea)
NSAIDs - high dose
Steroids

Question 14

When would you use oral steroids in an acute flare of gout?

Answer 14

if the gout is polyarticular ie more serious

Question 15

Indications where the first attack is treated (4)

Answer 15

Single attack of polyarticular gout
Tophaceous
Renal insufficiency
Urate calculi - in kidneys

Question 16

When would you treat gout prophylactically [4]

What to use in prophylactic treatment of gout? SE [3]?

Answer 16

If >1 attack in 1y
Tophi
Renal calculi
Certain malignancies - tumor lysis syndrome

Allopurinol
SE: rash, fever, decreased WCC

Question 17

What are the therapies to lower uric acid? [3]

Answer 17

Xanthine oxidase inhibitor - allopurinol, febuxostat
Uricosuric agents
Canakinumab - IL-1 antagonist

Question 18

What are 3 uricosuric agents

Answer 18

Sulphinpyrazone
Probenecid
Benzbromarone

Question 19

What are 4 metabolic syndromes and one social factor that is associated with gout

Answer 19

1. Obesity
2. DM
3. Hypercholesterolemia
4. HTN
5. Social factor - smoking

Question 20

Why wait 3 weeks until the acute attack has settled before attempting to reduce urate level? What to give patient in the meantime?

Answer 20

Starting drugs to reduce urate level can trigger an acute attack of gout.
Give NSAIDs to cover or colchicine in the meantime.

Question 21

Pseudogout epidemiology

Answer 21

Elderly, females

Question 22

Pseudogout - characteristics (4)

Answer 22

Erratic flares
Acute onset of
red hot swollen joint
deposition of CPPD crystal

Question 23

Pseudogout -risk factors [3]

Answer 23

Hyperparathyroidism
Haemochromatosis
Hypophosphatemia

Question 24

Triggers of pseudo gout (2)

Answer 24

Trauma and intercurrent illness

Question 25

2 features of CPPD crystals on polarized light microscopy

X-ray appearance

Answer 25

Rhomboid shaped
Positive birefringence
X-ray: associated with soft tissue calcium deposition (chondrocalcinosis) in the knee this can be seen as linear calcifications of the meniscus and articular cartilage

Question 26

Management of pseudogout (2)

Answer 26

NSAIDS

IA steroids

Question 27

PMR

3 symptoms

Answer 27

Sudden onset shoulder and/or pelvic girdle stiffness
High ESR and anemia
Arthralgia/synovitis occasionally

Question 28

PMR epidemiology - gender distribution, age

Answer 28

F:M 2:1

>70 yo

Question 29

Diagnosis of PMR

Answer 29

History compatible
Age > 50
ESR > 50
Dramatic steroid response

Question 30

DDX of PMR (6)

Answer 30

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

Question 31

Treatment of PMR (1)

Answer 31

Prednisolone 15mg initially for 18-24 month course

Question 32

What prophylactic measure should be taken in conjunction with PMR treatment?

Answer 32

DEXA bone scanning during course of treatment with steroids

Question 33

Investigations gout [3] and what result would they show if dx was gout

Answer 33

Polarised light microscopy of synovial fluid showing negatively birefringent urate crystals
Serum urate - usually raised but may be normal
Radiographs - soft tissue swelling early stages, punched out erosions (non-sclerotic changes) late stages

Question 34

Prevention Gout

Lifestyle modification [4]

Answer 34

Lose weight
Avoid prolonged fasts
Avoid alcohol excess
Avoid purine rich meats