Crystal Arthropathies

Question 1

In basic terms, what is a crystal arthropathy

Answer 1

When excess uric acid gets deposited in joints resulting in the syndrome of Gout

Question 2

Endogenous production of uric acid from the degradation of purine contributes to what amount of the urate pool

Answer 2

2/3rd

Question 3

What usually happens to uric acid in the body

Answer 3

The majority is excreted via the kidney and the remainder is eliminated into the biliary tract and subsequently converted by colonic bacterial uricase into allatoin.

Question 4

In the vast majority of patients with gout, what is the most common cause of hyperuricaemia

Answer 4

Reduced efficiency of renal urate clearance

Question 5

What results in the over production of uric acid

Answer 5

Malignancy, severe exfoliative psoriasis, ethanol and cytotoxic drugs, inborn errors of metabolism and HGPRT (Hypoxanthine-guanine phosphoribosyltransferase) deficiency

Question 6

What results in the under-excretion of uric acid

Answer 6

Renal impairment, hypertension, hypothyroidism, exercise, starvation, dehydration, lead poisoning

Question 7

Gout tends to effect what area of the population

Answer 7

Elderly males

Question 8

Why are males more prone to gout

Answer 8

They have higher urate levels

Question 9

Why is gout rare in younger women

Answer 9

Oestrogen has a uricosuric (increased excretion of uric acid in the urine) effect

Question 10

What are the factors that make increasing age a risk factor for gout

Answer 10

An increase in serum Uric Acid levels due to reduced renal function

Increased use of diuretic and other drugs that raise serum uric acid

Age related changes in connective tissues which may encourage crystal formation and an increase prevalence of osteoarthritis

Question 11

How is Gout diagnosed

Answer 11

Aspiration of the joint and checking for crystals - polarized light microscopy of synovial fluid will show negatively bi-refringent urate crystals

Serum urate is only useful in chronic settings

Question 12

State the management of acute gout

Answer 12

NSAID’s, colchicine if intolerant to NSAID’s, can give steroids if feel necessary

Question 13

Where does gout tend to occur

Answer 13

metatarsophalangeal joint of the big toe

Question 14

How can gout be prevented

Answer 14

Lose weight, avoid prolonged fasts, alcohol excess, purine-rich meats and low dose aspirin

Question 15

When should prophylactic treatment for gout be started

Answer 15

If there has been more than one attack in 12 months, tophi or renal stones

Question 16

State the aim of prophylaxis of gout

Answer 16

To reduce attacks and prevent damage caused by crystal deposition

Question 17

State the main mode of prophylactic treatment of gout

Answer 17

Allopurinol and titrate from 100mg24 increased every 4 weeks until plasma urate <0.3mmol/L

Question 18

State the different drugs used to lower uric acid

Answer 18

Allopurinol (Xanthine Oxidase Inhibitor), Febuxostat, Urisuric Agents (sulphinpyrazone, probenecid, benzbromarone), canakinumab

Question 19

What are the specific rules used when using medications to lower uric acid

Answer 19

Wait until the acute attack settles

Use prophylactic NSAIDS or lose dose colchicine/steroids until the urate level is normal

Adjust Allopurinol dose according to renal function

Question 20

Acute Calcium Pyrophosphate Deposition Disease (pseudogout)

Answer 20

Acute monoarthropathy usually of larger joints in the elderly

Question 21

Chronic CPPD (psuedogout)

Answer 21

Inflammatory rheumatoid arthritis like symmetrical polyarthritis with synovitis

Question 22

risk factors for psuedogout

Answer 22

Old age, hyperparathyroidism, haemochromatosis, hypophosphataemia

Question 23

Diagnosis of pseudogout

Answer 23

Polarized light microscopy of synovial fluid shows weakly positively birefringent crystals

Soft tissue calcium deposition on X-ray

Question 24

Management of acute attack of pseudogout

Answer 24

Cool packs, rest, aspiration, intra-articular steroids, NSAIDS and colchicine may prevent attacks

Question 25

Management of chronic psuedogout

Answer 25

Methotrexate and hydroxychloroquine

Question 26

What is polymyalgia rheumatica

Answer 26

Inflammatory condition of the elderly with close relationship to giant cell arteritis

Question 27

Presentation of polymyalgia rheumatica

Answer 27

Sudden onset of shoulder and or pelvic girdle stiffness, with high ESR, anaemia, malaise, weight loss, fever, depression, arthralgia and synovitis

Question 28

Diagnosis of polymyalgia rheumatica

Answer 28

Compatible history and dramatic steroid response

Question 29

Treatment of polymyalgia rheumatica

Answer 29

Prednisolone 15mg per day, 18-24 month course given after. Do bone prophylaxis.