Gout and pseudogout Flashcards
epidemiology, pathophysiology, presentation, investigation, management and prognosis
What is crystal arthropathy?
An inflammatory joint disorder resulting from deposition of crystals in the joint and surrounding soft tissues
What are the 2 types of crystal arthropathies?
Gout
Pseudogout/calcium pyrophosphate dihydrate (CPPD)
What is the difference between the crystals found in gout and pseudogout?
Gout is characterised by monosodium urate crystals
Pseudogout is characterised by calcium pyrophosphate crystals
What is the most common inflammatory arthritis in men over 40?
Gout
When in a women’s lifespan is gout most common?
Post-menopause
Why is gout most common in post-menopause stage then any other time in a woman’s life?
Oestrogen has an uricosuric effect (increases uric acid excretion)
Post-menopausal stage has decreased oestrogen levels, so excess uric acid isn’t excreted and builds up and crystallises
What is the prevalence of gout in individuals with comorbidities then prevalence of gout in individuals with no other conditions?
Gout is significantly more prevalent in individuals with comorbidities
Give 5 examples of common comorbidities of individuals with gout?
Hypertension, diabetes, CVD, Chronic Kidney Disease (CKD), obesity
Who amongst the ageing population is most likely to have severe gout attacks?
Individuals with medications to treat comorbidities
If an elderly individual takes diuretics to prevent heart failure, how can this increase the likelihood of gout attacks occuring?
Diuretics decrease uric acid excretion, so crystals can form
Is pseudogout more common in young or elderly populations?
Elderly populations, over 50 years old
What percentage of individuals aged 65-75 have pseudogout?
10-15%
What percentage of individuals aged over 85 have pseudogout?
30-60%
What condition does gout pathophysiology arise from, and define this condition?
Hyperuricaemia: abnormally high serum uric acid levels
What are the 2 types of uric acid production, and how can they cause hyperuicaemia?
Exogenous and endogenous uric acid overproduction can lead to build up of serum uric acid
What is exogenous uric acid production, and what type of purine precursor is used in the reaction?
Production of uric acid from exogenous purines, which are absorbed by body from consumed food
What is endogenous uric acid production, and what type of purine precursor is used in the reaction?
Production of uric acid from endogenous purines, which are made directly by body itself
How can high alcohol consumption/alcohol abuse cause hyperuricaemia?
Alcohol increases exogenous production of uric acid
What 2 groups of disorders increase endogenous production of uric acid, leading to hyperuricaemia?
Myeloproliferative
Lymphoproliferative
How can abnormal renal handling of urate result in hyperuricaemia?
Causes underexcretion of uric acid
What are 2 diseases that cause abnormal renal handling of urate?
Renal disease
Polycystic kidney disease
What percentage of individuals with hyperuricaemia/primary gout are underexcretors of uric acid?
90%
What are the 3 causes of hyperuricaemia that can result in gout?
Exogenous/endogenous overproduction of uric acid
Underexcretion of uric acid due to abnormal renal handling
Combination of overproduction and underexcretion of uric acid
Name 8 substances that cause hyperuricaemia (CANT LEAP)?
Cyclosporine
Alcohol
Nicotinic acid
Thiazides
Lasix (frusemide)
Ethambutol
Aspirin (low dose)
Pyrazinamide
How is monosodium urate formed from uric acid in gout?
Uric acid ions combine with sodium ions to from monosodium urate (a common salt)
How are calcium pyrophosphate crystals formed in pseudogout?
Excess pyrophosphate complexes combine with calcium
What is the pathophysiology of pseudogout?
Calcium pyrophosphate crystals form in joint cartilage, then are shed into synovial fluid in synovium/joint lining
In gout and pseudogout, what triggers inflammation of the joint/synovium?
Build up of crystals
What is the volume of synovial fluid in a normal knee joint compared to in a gouty/pseudogouty knee joint?
less than 3.5 ml in normal knee joint
More than 3.5 ml in gouty/pseudogouty knee joint
What is the viscosity of synovial fluid in a normal knee joint compared to in a gouty/pseudogouty knee joint?
Very high viscosity in normal knee joint
Very low viscosity in gouty/pseudogouty knee joint
What is the colour of synovial fluid in a normal knee joint compared to in a gouty/pseudogouty knee joint?
Clear synovial fluid in normal knee joint
Opaque, straw-coloured synovial fluid in gouty/pseudogouty knee joint
What is the WBC/mm3 of synovial fluid in a normal knee joint compared to in a gouty/pseudogouty knee joint?
200 mm3 in normal knee joint
Over 100,000mm3 in gouty/pseudogouty knee joint
What is the percentage of neutrophils composing synovial fluid in a normal knee joint compared to in a gouty/pseudogouty knee joint?
Less than 25% in normal knee joint
Over 50% in gouty/pseudogouty knee joint
What procedure is used to obtain a synovial fluid sample from a joint, and what are the steps?
Joint aspiration
Insert needle into joint and remove synovial fluid, send culture to lab
Give 3 factors that can be tested from a synovial fluid sample obtained from joint aspiration of an individual with gout/pseudogout?
Infection, this is necessary to rule out as it can permanently destroy joint
Inflammatory markers
Crystals so that condition can be distinguished between pseudogout and gout
Give 6 examples of predisposing factors of gout?
Immediate postoperative period
Alcohol abuse
Local infection
Stroke
Large food intake high in purine
Fasting
What are the 4 clinical phases of gout?
Asymptomatic hyperuricaemia
Acute gout attack
Intercritical gout
Chronic tophaceous gout
What occurs in the asymptomatic hyperuricaemia phase of gout?
Serum uric acid level is elevated but there are no symptoms/signs of gout eg. no inflammation
How can acute gout attacks be described in terms of when they occur in the day, onset and how they affect the joint?
Often occur in early morning or night with rapid onset and makes joints red, hot, swollen, tender
Give 6 examples of joint commonly affected by acute gout attacks?
Ankle
Wrist
Hand
Knee
Big toe
Other toes
Are acute gout attacks normally monoarticular or polyarticular?
Monoarticular
What percentage of acute gout attacks are polyarticular?
10-15%
In 50% of acute gout attack cases, what joint is initially affected?
1st metatarsophalangeal (MTP) joint (big toe)
What is podagra?
Acute gout attack of 1st metatarsophalangeal joint (big toe)
What is the intercritical gout phase?
Time between gout attacks where individual has no symptoms but monosodium urate crystals are still accumulating
What occurs in the chronic tophaceous gout phase?
Large, white, solid bumps of monosodium urate crystals form under skin and over joints, cartilage, bones
What is the difference in intercritical gout phases in acute gout and chronic gout?
In chronic gout, the intercritical gout phases are shorter (less time between attacks)
What are the 4 ways in which pseudogout can present?
Asymptomatic chondrocalcinosis
Acute pseudogout
Pseudo-OA/CPPD with OA
Chronic pseudogout
How does asymptomatic chondrocalcinosis occur?
Accumulation of calcium crystals in joint cartilage
How is asymptomatic chondrocalcinosis diagnosed, and what joint does it normally affect?
Diagnosed as a radiographical imaging finding in asymptomatic pseudogout patients
Mostly affects knee joint
How does pseudo-OA occur?
Pseudogout causes accelerated OA in joints not commonly affected by OA, such as MCP and elbow joints
Is pseudo-OA more common in men or women?
Women
What is the most common form of pseudogout when it presents as inflammatory?
Acute pseudogout
What is acute pseudogout?
Sudden, self-limiting monoarthritis (1 large joint) or olgioarthritis (2-4 large joints), that is the most common form of inflammatory pseudogout
How can you tell that there is joint inflammation in acute pseudogout?
Cardinal signs of inflammation
Do acute pseudogout attacks affect men or women more?
Men
What 7 joints are commonly affected by acute pseudogout?
Knee, wrist, shoulder, hip, ankle, elbow, toe
What 3 factors can trigger acute pseudogout attacks?
Trauma
Surgery
Severe medical illness
What is the difference between acute and chronic pseudogout, in terms of how many large joints are affected?
Acute is mono/oligoarthritic (1 or 2-4 large joints)
Chronic is polyarthritic (5 or more large joints)
What 2 lab findings are used to diagnose gout?
Serum Uric acid is a negative acute phase reactant so has decreased level in gout attack, level should be re-checked 1-2 weeks after attack has settled and must be 360 micromol/L or more in remission period
polarised light microscopy of synovial fluid shows negatively birefringent, needle-shaped crystals
How can urinalysis with a urine dipstick suggest gout?
hematuria
What lab finding is used to diagnose pseudogout?
Polarised light microscopy of aspirated synovial fluid shows positively birefringent rhomboid-shaped crystals
What are the 3 examples of lifestyle advice to give patients to manage gout?
Educating the patient to eat low-purine diet, less alcohol, lose weight to avoid obesity
Give 5 examples of high-purine food?
Shellfish eg. scallops, mussels
alcohol
red meat
animal organs
fish
Give 5 examples of medium-purine food?
Vegetables
legumes
lobster
crab
oyster
Give the main 2 ways of managing an acute gout attack?
Joint rest and ice
Take a first-line drug
What are the 3 first-line drugs of acute gout attacks, and when is each drug used?
NSAIDs or COX II inhibitors are used first
Oral colchicine used if NSAIDs or COX II inhibitors are contraindicated
Local corticosteroid injection used if oral colchicine is contraindicated
What are the first and second line drug classes to manage intercritical gout?
First-line is xanthine oxidase inhibitors
Second-line is uricosuric agents
What is the first-line drug used for intercritical gout, and what is its alternative drug?
Allopurinol, but febuxostat is an alternative drug is allopurinol isn’t well-tolerated
Give 3 examples of uricosuric agents that are second-line drugs for intercritical gout?
probenecid, sulfinpyrazone, benzbromarone
Why is colchicine prophylaxis used with allopurinol to treat intercritical gout, and how long is it used for with allopurinol?
Colchicine prophylaxis used for first 3-6 months of allopurinol, as allopurinol increases chances of gout flare up in first few months of use
Give 3 side effects of allopurinol when used to treat intercritical gout?
Rashes, hepatotoxicity, hypersensitivity
What is a side effect of uricosuric agents when they are used to treat intercritical gout?
Increased risk of uric acid stone formation
Which 2 uricosuric agents are ineffective in treating intercritical gout when the individual has CKD?
Sulfinpyrazone and probenecid
What 3 antihypertensive drugs decrease chance of gout flares?
losartan, fenofibrate, atorvastatin
How is asymptomatic chondrocalcinosis treated?
It isn’t treated as it usually settles itself
What are the 2 steps of managing acute pseudogout?
Joint aspiration
Local corticosteroid injection
What 2 drugs can be used to manage chronic pseudogout?
NSAIDs, corticosteroids
To manage chronic pseudogout, what needs to be treated other than the pseudogout itself?
Associated diseases
Give examples of predisposing factors to pseudogout?
Aging
Hyperparathyroidism
Hemochromatosis
Hypomagnesemia
Hypophosphatasia
May follow parathyroidectomy
Acromegaly
Hypothyroidism
Trauma
Infection
Osteoarthritis
What stage of gout is associated with bone erosion?
Chronic tophaceous gout
Give 4 characteristic features of the bone erosion caused by chronic tophaceous gout?
Well defined erosion
Sclerotic borders
Overhanging edges
No osteoporotic bone
What are 4 radiological findings that are associated with CPPD?
Triangular fibrocartilage calcification (calcification of stabilising joint at wrist)
Subchondral sclerosis: hardening of bone below cartilage, common in load-bearing joints, common in OA
Joint space narrowing
Subchondral cyst formations
What are 6 differential diagnoses of gout?
RA
OA
PsA
ReA
Septic arthritis
Pseudogout
What are the 6 differential diagnoses of pseudogout?
RA
OA
PsA
ReA
Septic arthritis
Gout
How can pseudogout and gout be differentiated from RA?
RA has different degree of inflammation
How can pseudogout and gout be differentiated from septic arthritis?
Synovial fluid culture is tested for infectious agents that cause septic arthritis
