Crystal Disease Flashcards
What is gout and what crystal type is involved?
Gout is an inflammatory arthritis associated with hyperuricaemia and intra-articular monosodium urate crystals
What is normal purine metabolism?
- Half of uric acid pool derived from endogenously synthesized purine nucleotides; rest from ingested dietary purines.
- 60% of pool is replenished daily by catabolism of purine nucleotides and bases.
- Uric acid is the end product of purine metabolism
- Two-thirds of uric acid formed each day is excreted by the kidney and one-third is eliminated via the gastrointestinal tract
What are the features of gout?
- Acute monarthropathy - sudden onset, severe pain - especially on movement
- Tophi (in very high urate levels)- Urate deposits over extensor surface, especially elbows, knees and achilles tendon
What are the risk factors associated with gout?
- Male
- Menopause
- Increased age
- Heredity
- Alcohol Excess
- Diuretics
- Increased dietary purines
- Leukaemia
- Renal disease
What would be the differential diagnosis for someone presenting with features of gout?
- Septic arthritis
- Haemarthritis
- CPPD
- Palindromic RA
What investigations would you do for suspected gout?
Clinical Diagnosis
Bloods
- Serum Urate - usually raised, can be normal
Imaging
- X-Ray - soft tissue swelling, punched out lesions
Other
- Polarised microscopy of aspirate - Negatively bifringent urate crystals
How would you treat someone with gout?
Acute Gout
- NSAIDs
- Colchicine
- Steroids
Chronic Gout
- Treat hyperuricaemia if symptomatic
- Prevention measures
What prophylaxic medications would you use for someone with gout?
Medications - >1 attack in 12 months
- Allopurinol
- Febuxostat
- Uricosuric drugs - increase excretion
What is pseudogout?
- Acute monoarthropathy of larger joints in elderly patients
- Spontaneous and self limiting
- Crystal involved is calcium pyrophosphate dihydrate (CPPD) - shed from cartilage into articular space, which leads to an inflammatory response
What are the risk factors for pseudogout?
- Old age
- Hyperparathyroidism
- Haemochromatosis
- Hypophosphataemia
What can trigger pseudogout?
- Trauma
- Intercurrent illness
What are the clinical features of pseudogout?
- Inflammatory arthritis - knee pain classical presentation
- Risk Factors - metabolic conditions, surgery, kidney stones, DM, liver disease
How would you investigate suspected pseudogout?
Clinical Diagnosis
Imaging
- X-ray - Soft tissue calcium deposition
Other
- Polarised light microscopy - Weakly positive birefringent crystals
What is the treatment for pseudogout?
- NSAIDs
- I/A Steroids
- No prophylactic therapies
What are the causes of Hyperuricaemia?
- Overproduction - Malignancy, Drugs, HGPRT deficiency, severe psoriasis
- Under excretion - Renal impairment, HTN, hypothyroid, drugs, alcohol, lead posoning, exercise, starvation
How would you manage someone with Hyperuricaemia?
1st Attack
- No treatment, unless - single attack polyarticular gout, tophaceous gout, urate calculi, renal insufficiency
2nd Attack - within a year
- Treat
Prophylaxis
- Prior to treating malignancies
Do not treat asymptomatic hyperuricaemia
What medications could you use in to treat hyperuricaemia?
Wait for attack to subside before treating - use NSAIDs and low dose colchicine until urate levels are normal
- Allopurinol - xanthine oxidase inhibitors
- Febuxostat
- Uricosuric drugs
- Canakinumab
Adjust dose according to renal function
Why does the menopause increase a womens risk of developing gout?
Oestrogen has uricosuric effect → Urate levels rise after menopause
What lifestyle factors need to be addressed in someone with gout?
- Weight loss
- Avoid prololnged fasts
- Avoid alcohol excess
- Avoid purine rich meals
Which joints are most commonly affected in gout?
- MTPJ - most common
- Small joints of the hand
- Wrist
- Elbow
- Knee
Which joint does pseudogout classically affect?
The knee
What is podagra?
Gout of the foot, especially the big toe.
What is the average time span of an acute episode of gout?
3-7 days
What type of crystals are implicated in gout?
Monosodium urate crystals
What type of crystals are implicated in pseudogout?
Calcium pyrophosphate dihydrate
Are pseudogout crystals positively or negatively bifringent?
Positively bifringent
Psuedogout is Positive
Are gout crystals positively of negatively bifringent crystals?
Negative
