Gout, Pseudogout and Polymyalgia Rheumatica Flashcards
Monosodium urate is another term for which disease?
Gout
Calcium pyrophosphate dihydrate is another term for which disease?
Pseudogout
Where do we get urate from in the body?
2/3 of urate comes from the breakdown of purines:
- breakdown of DNA or RNA in our cells
- breakdown of purines from diet - high in meat and seafood
What does the body normally do with urate?
Excreted via the kidney or eliminated into the biliary tract and subsequently converted by colonic bacterial uricase to allantoin.
How does hyperuricaemia come about?
Either by the overproduction or under excretion of urate
Or lifestyle / RFs
What things cause an overproduction of urate in the body?
As purines in the body are produced via the breakdown of DNA/RNA, conditions with increased cell turnover means more purine breakdown such as:-
Malignancy
Severe exfoliative psoriasis
Drugs - ethanol, cytotoxic drugs
Inborn errors of metabolism
What things cause under excretion of urate in the body? (6)
Renal impairment Hypertension Hypothyroidism Drugs e.g. alcohol, low dose aspirin, diuretics, cyclosporin Exercise, starvation, dehydration Lead poisoning
What is Lesch Nyan Syndrome?
A rare condition where there is a deficiency in the HPRT enzyme. This enzyme is involved in the recycling of purine bases.
This causes an overproduction of uric acid - gout
What gender and age group is gout more commonly seen in?
Predominantly a disease of older men - men have higher urate levels than women and an increased prevalence of gout at all ages.
Ageing is an important risk factor in both men and women
Really uncommon in pre-menopausal women because oestrogen has a uricosuric effect (increase the excretion of uric acid in the urine). However, after menopause, urate levels rise and gout becomes increasingly prevalent
Risk factors for Gout (6)
Obesity
FH
Unhealthy diet + one rich in meat + seafood which are rich in purines
Alcohol excess - alcohol is a source of purines and also affects kidney function
Diuretic use - results in volume depletion which increases serum urate concentration
Dehydration – sporty or not taking in enough fluids - increases serum urate concentration
How does Gout typically present?
Gout episodes classically occur in the first MTP joint – usually last 5-7 days (self-limiting). Episodes tend to start at night and then you wake up in severe pain
It tends to present acutely in a single joint. The joint is usually red, hot, swollen and extremely painful
What is gouty tophi?
Subcutaneous deposits of uric acid (not in the joint) - these tend to affect small joints of the hand, ear and elbow
Gouty tophi most commonly affects DIPs
What would you likely see of a gout aspirate under a microscope?
Lots of needle-shaped crystals of gout
How is an acute flare of gout treated?
1st line = NSAIDs
2nd line = if they can’t tolerate NSAIDs then use Colchicine (side effects though)
3rd line = steroids (I/A, I/M, Oral)
When is long term prophylaxis treatment needed?
If the patient has a 2nd attack within 1 year.
What is the aim of prophylaxis treatment of gout?
To lower uric acid levels in the body
Which drugs can be used to lower uric acid?
1st line = Allopurinol
2nd line = Febuxostat - can be dangerous for those with CV risk
3rd line = uricosuric agents that enhance urinary ecretion of uric acid
4th line = canakinumab
When must you NOT start prophylactic treatment for gout?
You must not start prophylactic treatment during an acute attack because both Allopurinol and Febuxostat can trigger a flare of gout themselves.
Wait until the attack has settled!
If someone is already on allopurinol and they have an acute flare of gout then don’t stop the drug but instead adjust the dose
Which joint does pseudogout commonly affect?
The knee
How does pseudogout present?
Common in elderly females especially those who have suffered trauma (i.e a fall) or intercurrent illness (i.e UTI)
Erratic flares
What is the typical sign of pseudogout on an x-ray?
Chondrocalcinosis - calcium pyrophosphate crystals build up in the joints.
Management of pseudogout
NSAIDs
Intra-articular steroids
No prophylactic treatments available
What is polymyalgia rheumatica?
Inflammatory condition of the elderly.
Affects the muscles around the shoulders, neck and hips.
Which condition is polymyalgia rheumatica closely related to?
Giant cell arteritis
20% of patients with PMR may have evidence of GCA and this is a medical emergency
How does polymyalgia rheumatica present?
Classically SUDDEN onset of shoulder +/- pelvic girdle STIFFNESS
F>M
Rare in those under 50
A high ESR >45
Malaise ; Weight loss ; fever; depression
Arthralgia / synovitis occasionally
Diagnosis of polymyalgia rheumatica
No specific diagnostic tests can be done
Diagnosis is based on the history, age of patient, ESR and the patient’s response to steroids.
Treatment of polymyalgia rheumatica
Steroid - Prednisolone
+ Bone prophylaxis (to help keep bones strong whilst taking steroids)
What is the key difference between gout and pseudogout?
Gout is caused by uric acid crystals; pseudogout is caused by calcium pyrophosphate dehydrate crystals (CPPD)
