6.6. Rheumatology - Crystal Arthropathies

Question 1

What characterises Crystal Arthropathies?

Answer 1

Deposition of Mineralised Material within the Joints and Peri-Articular Tissue

Question 2

What are common Crystal Arthropathies?

Answer 2

1. Gout
2. Pseudogout
3. Calcified Periarthritis / Tendonitis

Question 3

What crystal deposition is associated with Gout?

Answer 3

Monosodium Urate

Question 4

What crystal deposition is associated with Pseudigout?

Answer 4

Calcium Pyrophosphate Dihydrate

Question 5

What crystal deposition is associated with Calcified Periarthritis / Tendonitis?

Answer 5

Basic Calcium Phosphate Hydroxy-apatite (BCP)

Question 6

What is a Tophus?

Answer 6

A Massive accumulation of Uric Acid

Question 7

What contributes to the bodies Urate pool?

Answer 7

1. 2/3 - Endogenous production of Uric Acid from degradation or Purines
2. 1/3 - Dietary

Question 8

What happens to the Uric Acid (produced Daily)?

Answer 8

1. 70% - Excreted via the Kidney

2. 30% - Eliminated into the Biliary Tract, and converted into Allantoin (by Bacteria Uricase)

Question 9

What are the 2 methods by which Hyperuricaemia can occur?

Answer 9

1. Overproduction

2. Under-Secretion

Question 10

By what methods does Overproduction cause Hyperuricaemia?

Answer 10

1. Malignancy
2. Severe Exfoliative Psoriasis
3. Drugs
4. Inborn Errors of Metabolism
5. HGPRT Deficiency (Lesch-Nyan Syndrome)

Question 11

What types of Malignancy can cause Hyperuricaemia, via Overproduction?

Answer 11

1. Lymphoproliferative

2. Tumor Lysis Syndrome

Question 12

What types of Drugs can cause Hyperuricaemia, via Overproduction?

Answer 12

1. Ethanol

2. Cytotoxic Drugs

Question 13

By what methods does Under-Secretion cause Hyperuricaemia?

Answer 13

1. Renal Impairment
2. Hypertension
3. Hypothyroidism
4. Drugs
5. Exercise, Starvation, Dehydration
6. Lead Poisoning

Question 14

Why does Hyperuricaemia result in the vast majority of people with Gout?

Answer 14

Reduced Efficiency of Renal Urate Clearance

Question 15

What types of Drugs can cause Hyperuricaemia, via Under-Secretion?

Answer 15

1. Alcohol
2. Low-Dose Aspirin
3. Diuretics
4. Cyclosporin

Question 16

What deficiency is assoiciated with Lesch-Nyan Syndrome?

Answer 16

Deficiency of the enzyme Hypoxanthine-Guanine Phosphoribosyl Transferase (HGPRT)

Question 17

How is HGPRT Deficiency transferred in Lesch-Nyan Syndrome?

Answer 17

X-Linked Recessive

Question 18

What is the function of HGPRT?

Note - related to Lesch-Nyan Syndrome

Answer 18

This plays a key role in the recycling of the Purine Bases (Hypoxanthine and Guanine)

Question 19

What happens in the Absence of HGPRT?

Note - relates to Lesch-Nyan Syndrome

Answer 19

1. The Purine Bases cannot be salvaged, so are degraded / excreted as uric acid
2. Synthetic rate of Purines is accellerated - causing the overproduction of Uric Acid

Question 20

How does Lesch-Nyan Syndrome present?

Answer 20

1. Intellectual Disability
2. Aggressive and Impulsive Behaviour
3. Self-Mutilation
4. Gout
5. Renal Disease

Question 21

Who commonly gets Gout?

Answer 21

Elderly Males

Note - males have higher Urate Levels and increased prevalence at all ages

Question 22

How is Gout Diagnosed?

Answer 22

1. History
2. Examination
3. Appropriate Invetsigation

Question 23

How is an Acute Flare up of Gout managed?

Answer 23

1. NSAID’s
2. Cochicine
3. Steroids (I/A, I/M, Oral)

Question 24

When is the Hyperuricaemia of Gout managed?

Answer 24

1. Single attack of Polyarticular Gout
2. Tophaceous Gout
3. Urate Calculi
4. Renal Insufficiency
5. 2 x attacks in 1 year
6. Prophylactically prior to treating certain malignancies
   Note - this is not treated if asymptomatic

Question 25

What medications are used to treat the Hyperuricaemia associated with Gout?

Answer 25

1. Xanthine Oxidase Inhibitor (Allopurinol) 2. Febuxostat 3. Uricosuric Agents (Sulphinpyrazone) 4. Canakinumab

Question 26

What are the rules of Lowering Uric Acid Levels?

Answer 26

1. Wait until the acute attack has settles 2. Use Prophylactic NSAID's / Low dose Colchicine/Steroids until Urate Levels are normal 3. Adjust Allopurinol dose according to Renal Function

Question 27

What is the main treatment for Gout?

Answer 27

Adjusting Cardiovascular and Lifestyle Factors

Question 28

Who commonly presents with Pseudogout?

Answer 28

Elderly Females

Question 29

What is the Aetiology of Pseudogout?

Answer 29

1. Idiopathic 2. Familial 3. Metabolic

Question 30

How does Pseudogout present?

Answer 30

1. Erratic flares, triggered by: 1. a) Trauma 1. b) Intercurrent Illness 2. Chondrocalcinosis (on X-Ray) 3. Pyrophosphate Crystals (on Biopsy)

Question 31

What is the management of Pseudogout?

Answer 31

1. NSAID's 2. I/A Steroids Note - there are no prophylactic therapies

Question 32

What is Polymyalgia Rheumatica associated with?

Answer 32

Giant Cell Arteritis: 1. 20% of patients with PMR may have evidence of GCA 2. 50% of patients with GCA may have PMR

Question 33

Who is commonly affected by Polymyalgia Rheumatica?

Answer 33

1. Elderly (>50) | 2. Females (2:1)

Question 34

How does Polymyalgia Rheumatica present?

Answer 34

1. Sudden onset of Shoulder / Pelvic Girdle Stiffness 2. High ESR (>50) 3. Anaemia 4. Malaise / Weight Loss / Fever / Depression 5. Arthalgia / Synovitis (occasionaly)

Question 35

What is the Differential Diagnosis for Polymyalgia Rheumatica?

Answer 35

1. Myalgic Onset Inflammatory Joint Disease 2. Underlying Malignancy (Multiple Myeloma, Lung Cancer) 3. Inflammatory Muscle Disease 4. Hypo/Hyperthyroidism 5. Bilateral Shoulder Capsulitis 6. Fibromyalgia

Question 36

What is the treatment of Polymyalgia Rheumatica?

Answer 36

1. Steroid - Prednisolone | 2. Bone prophylaxis