Document 23

Question 1

What is the most common inflammatory arthritis?

Answer 1

Gout

Gout is characterized by the deposition of monosodium urate crystals in joints.

Question 2

What is the prevalence of gout in Western developed countries?

Answer 2

3-6% in males and 1-2% in females.

Question 3

What factors increase the prevalence of gout?

Answer 3

• Age
• Serum urate levels
• Ethnicity (higher in certain groups like Maori, Pacific Islanders)

Question 4

What is the central risk factor for gout?

Answer 4

Hyperuricaemia.

Question 5

What is hyperuricaemia?

Answer 5

Serum urate concentrations above the solubility threshold for MSU under physiologic conditions: 0.405mmol/L.

Question 6

What percentage of patients with hyperuricaemia develop gout?

Answer 6

Less than 2/3.

Question 7

What are the common comorbidities associated with gout?

Answer 7

• Obesity
• Hypertension (HTN)
• Chronic Kidney Disease (CKD)
• Diabetes

Question 8

What metabolic process leads to the formation of urate?

Answer 8

Purine catabolism.

Question 9

What are the primary dietary sources of purines?

Answer 9

• Seafood (particularly shellfish)
• Red meat (particularly organ meat)

Question 10

What is the most common site for the first gout flare?

Answer 10

MTP 1 joint (podagra).

Question 11

What are the clinical features of a gout flare?

Answer 11

• Severe pain
• Exquisite tenderness
• Warmth
• Overlying skin changes

Question 12

What is a tophus?

Answer 12

An ordered structure of MSU crystals and the associated host tissue response.

Question 13

What is the primary mechanism causing inflammation in gout?

Answer 13

Precipitation of MSU crystals recognized by TLR 2 and 4 on chondrocytes and macrophages.

Question 14

What is the role of the NLRP3 inflammasome in gout?

Answer 14

Activation leads to cytokine production, including IL-1.

Question 15

What is the definitive diagnosis for gout?

Answer 15

Joint aspiration and analysis showing intracellular needle-shaped negatively birefringent crystals.

Question 16

What imaging technique can show gouty bone erosions?

Answer 16

Plain films.

Question 17

What is the first-line treatment for gout flares?

Answer 17

NSAIDs.

Question 18

What is the mechanism of action of allopurinol?

Answer 18

Inhibits xanthine oxidase, disrupting purine catabolism.

Question 19

What is the target serum urate level for gout patients?

Answer 19

<0.36mmol/L.

Question 20

What are uricosuric agents?

Answer 20

Medications that promote urinary excretion of uric acid.

Question 21

What is the association between calcium pyrophosphate deposition disease (CPDD) and age?

Answer 21

Rare under 55 years, prevalence increases with age.

Question 22

What condition is associated with hyperparathyroidism that may lead to CPDD?

Answer 22

Hypercalcemia.

Question 23

What is chondrocalcinosis?

Answer 23

Presence of calcium pyrophosphate crystals in articular cartilage.

Question 24

What is the role of ANKH in CPP crystal formation?

Answer 24

Transports inorganic pyrophosphate produced by chondrocytes.

Question 25

True or False: Hyperuricaemia is always symptomatic.

Answer 25

False.

Question 26

Fill in the blank: The majority of patients defined as having hyperuricaemia will not develop _______.

Answer 26

gout.

Question 27

What is the significance of the double contour sign in MSK ultrasound?

Answer 27

Indicates MSU crystal deposition.

Question 28

What are the classic symptoms of hypercalcaemia?

Answer 28

Stones, bones, groans, moans ## Footnote These symptoms represent common manifestations of hypercalcaemia, including kidney stones, bone pain, gastrointestinal issues, and psychological disturbances.

Question 29

What condition is associated with bone resorption leading to osteoporosis?

Answer 29

Hypercalcaemia ## Footnote Hypercalcaemia causes increased bone resorption, which can result in osteoporosis.

Question 30

What is haemochromatosis?

Answer 30

Iron overload ## Footnote Haemochromatosis is a condition characterized by excessive accumulation of iron in the body.

Question 31

What is hypophosphatasia?

Answer 31

A metabolic bone disorder ## Footnote Hypophosphatasia is characterized by inadequate mineralization of bones due to a deficiency of alkaline phosphatase.

Question 32

What is the aetiology of calcium pyrophosphate dihydrate (CPPD) deposition?

Answer 32

High levels of inorganic pyrophosphate ## Footnote CPPD crystals form in articular cartilage due to high levels of inorganic pyrophosphate produced by chondrocytes.

Question 33

What role does the transmembrane protein ANKH play?

Answer 33

Moves extracellular inorganic pyrophosphate ## Footnote ANKH is responsible for transporting inorganic pyrophosphate outside chondrocytes.

Question 34

What triggers inflammation in CPP crystal deposition?

Answer 34

Activation of NLRP3 inflammasome ## Footnote CPP crystals induce inflammation through the activation of the NLRP3 inflammasome.

Question 35

What enhances the nucleation of CPP crystals in cartilage?

Answer 35

* Increased calcium (hyperparathyroidism) * Increased iron (haemochromatosis) * Decreased magnesium ## Footnote Magnesium inhibits nucleation, hence its decreased levels promote crystal formation.

Question 36

What is the typical clinical presentation of acute CPP crystal arthritis?

Answer 36

Monoarthritis, commonly in the knee ## Footnote Acute CPP crystal arthritis typically presents as monoarthritis, with the knee being the most frequently affected joint.

Question 37

How long does acute inflammatory arthritis usually last?

Answer 37

1-3 weeks ## Footnote Acute inflammatory arthritis is generally self-limited and resolves within a few weeks.

Question 38

What can chronic CPP crystal inflammatory arthritis mimic?

Answer 38

* Seronegative RA * Polymyalgia rheumatica * OA with CPPD ## Footnote Chronic CPP crystal inflammatory arthritis can present similarly to these conditions, making diagnosis challenging.

Question 39

What is a common diagnostic finding in elderly patients with CPPD?

Answer 39

Radiographic chondrocalcinosis ## Footnote Chondrocalcinosis is often seen on radiographs and may be asymptomatic in older adults.

Question 40

What is the diagnostic approach for an acute flare of CPPD?

Answer 40

Synovial fluid aspirate ## Footnote Analysis of synovial fluid is crucial to diagnose CPPD during acute flares.

Question 41

What are the characteristics of CPDD crystals?

Answer 41

* Rhomboid or rod-shaped * Weak positive birefringence in 20% of cases ## Footnote CPDD crystals are identifiable under compensated polarized light microscopy but are generally more difficult to detect than MSU crystals.

Question 42

What imaging techniques can show crystal deposition?

Answer 42

* Plain films * MSK ultrasound * High-resolution ultrasound ## Footnote These imaging techniques can reveal crystal deposition in joints affected by CPPD.

Question 43

What is the significance of the double contour sign?

Answer 43

Indicates chondrocalcinosis on high-resolution ultrasound ## Footnote The double contour sign can help differentiate CPPD from gout.

Question 44

What blood tests are recommended for patients under 55 with CPPD?

Answer 44

* Serum calcium * Phosphate * ALP * PTH * Magnesium * Iron studies ## Footnote These tests help evaluate for underlying primary metabolic disorders.

Question 45

What medications are used to manage acute inflammatory arthritis in CPPD?

Answer 45

* NSAIDs * COX-2 inhibitors * Prednisolone * Intra-articular corticosteroids ## Footnote These treatments are similar to those used for gout management.

Question 46

What is a prophylactic treatment to reduce flares of CPPD?

Answer 46

Low-dose colchicine ## Footnote Colchicine is commonly prescribed at 500mcg daily or twice daily to prevent recurrence of flares.

Question 47

True or False: There are medications available to dissolve calcium-based crystals.

Answer 47

False ## Footnote No medications are currently available that can dissolve calcium-based crystals.