Pseudogout Flashcards
Differentiate between gout and pseudogout
Pseudogout is due to CPPD crystals whereas gout is due to monosodium urate crystals
What does CPPD stand for?
Calcium pyrophosphate dihydrate deposition
Define
CPPD associated with acute and chronic arthritis
Which joints are affected?
Primarily knees and wrists
shoulders
Elbows
Also:
Hands
Ankles
Epidemiology
No sex predilection
Aetiology
Chondrocalcinosis (calcification of cartilage) is the hallmark but no causative factors have been found
Risk factors
Older age FH Previous injury/surgery to joins Haemochromatosis Hyperparathyroidism Hypomagnesemia Hypophosphatasia Acromegaly Hypothyroidism Other metabolic disorders
Symptoms
Red and swollen joints
Joint effusion and fluctuance
Fever and malaise (inflammation)
acute inflammatory episodes superimposed on daily non-inflammatory-type pain.
Why is hypomagnesemia associated with CPPD?
Magnesium is thought to be an important cofactor for enzymes that normally break down pyrophosphate
What can cause hypomagnesemia?
Rennal disorders such as Gitelman variant of Bartter’s syndrome
Why does hypophoshatasia cause CPPD?
This rare metabolic disorder is caused by deficiency of the alkaline phosphatase enzyme. It is hypothesised that reductions in alkaline phosphatase activity result in less pyrophosphate degradation and foster excess pyrophosphate accumulation and CPP crystal formation.
Investigations
Arthrocentesis Xray Serum calcium Serum PTH Iron studies Serum magnesium Serum alkaline phosphatase
What would arthrocentesis show? Compare this to gout
Positively birefringent rhomboid-shaped crystals under polarised light confirms CPPD
(gout shows negatively birefringent needle shaped crystals)
Treatment for oligoarticular disease is dependent on?
Accessibility to the joint
If it’s one joint and you can access it, what is the treatment?
Intraarticular corticosteroid injection
PLUS paracetamol
