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Crystal Arthropathy- Gout and Tophaceous gout (What is a crystal ? (Two…
Crystal Arthropathy- Gout and Tophaceous gout
What is a crystal ?
Homogenous solid. Specific hard, stable, high density crystal .
They help to strengthen the end and eco skeleton. Help to remove excess ions
Abnormal when they form in the wrong joints
They lead to inflammatory response
Crystals in the kidney --> nephrolithiasis (stones)
Crystals in the gall bladder nephrolithiasisis (stones)
Two types of crystals
Monosodium urate crystals (needle-shaped and bifringent under polarised light)
Calcium Pyrophosphate crystals are rhomboid brick shaped and are positive bifringent under polarised light
Diagnosis
Blood teststs
Aspiration
History
Look at the earls to see if there is any deposition of material
Look at renal function tests and constantly check the GFR
Pathophysiology
Purines: there are many high purine foods we ingest
These substances are then broken down in the body to make hypoxanthine.
Hypoxanthine --> Xanthine
Xanthine --> Uric acid. By the enzyme Xanthine oxidase
Most uric acid is secreted in the kidney (why we get kidney stones) and in the intestine (why we get gallstones)
If the uric acid is not excreted then there is hyperuricaemia and this can be converted to monosodium urate crystals
Monosodium urate crystals tend to form in the joints that have had previous trauma of are at a lower temperature
It's an amplification reaction. In which more crystal deposition causes an increased chain of reactions
Epidemiology
Uncommon men <30 years
Rise in post menopausal women (can be triggered by diuretics)
Commonest arthritis in men >40 yrs old
More men affected
Worldwide. It is increased in Chinese Polynesian and Filipino countries
Signs: Acute Gout monosodium urate crystals form
. It presents as sudden onset of agonizing pain, swelling and redness of the first MTP joint (Big Toe). Normally only affects one joint. Precipitated by dehydration food or excessive alcohol
Risk Factors/ Causes
Ischaemic causes
Likely to happen in people who have just had Heart Attacks
Renal causes
Defective gene
High insulin levels lower the uric acid excretion
Diuretics impair uric acid excretion
Reduced excretion
Renal impairement
Inherited
Alcohol
Metabolic- hypothyroidism
Obesity
Diabetes
Diuretics
Low dose aspirin
Cyclosporin ,Ethambutol and Pyrazinamide
Increased production of uric acid
Lymphoproliferative disease such as leukaemia
Cell death in surgery
Myeloproliferative e.g. polycythaemia vera
Cell death in chemotherapy. Increased amount of purines in the blood stream
Hyperlipidaemia
High alcohol intake (in beers then spirtis and wine)
Purine rich foods (i.e. red meat, liver and seafood)
High fructose intake (sugary drinks, cakes, sweets and fruit sugars). Increased production of uric acid
SO what is hyperuricaemia. this is a uric acid level of greater than 0.42mmol/l or 0.36 in females. You need to have a raised uric acid to get gout. But not all hyperuricaemia causes gout
Treatment
Colchicine or NSAID
These inhibit the phagocytes so mean that there isn't an inflammatory reaction
Chronic gout- you want a xanthine inhibitor such as allopurinol and also you want to use NSAIDs and Colchicine
Colchine is very toxic in an overdose and SE include diarrhea and abdomen pain
Xanthine oxidase inhibitors- Allopurinol
Headache
Myalgia
SE: rash
Constantly check the blood serum urate levels and adjust the amount needed accordingly
Use in chronic presentation. USE FEBUXOSTAT if allopurinol is contraindicated
Tophaceous gout - THI S IS DIFFERENT TO ACUTE GOUT
Tophi are onion like aggregates of monosodium irate crystals with inflammatory cells
There is the release of proteolytic enzymes causing the punched out holes in bone
Happens in people that have permanently high levels of uric acid. The monosodium rate orbs in the skin, joints , ear, fingers and the Achilles tendon
Acute: use Colchicine and NSAIDs . You can also advice reduction of RF and drinking of milk . Use of IM oral or intra articular corticosteroid e.g. prednisone