Thursday 28 October 2010

MRCP revision battle 36.1: Wilson's disease

Another set of battles written before commencing the joy of a 10 hour shift... and to think we all used to think revising for finals was hard!

MRCP revision battle 36.1: Wilson's disease
MRCP revision battle 36.2: Drugs causing impaired glucose tolerance
MRCP revision battle 36.3: Acromegaly
MRCP revision battle 36.4: Vitamin C
MRCP revision battle 36.5: Insulinoma
MRCP revision battle 36.6: Metabolic syndrome
MRCP revision battle 36.7: Phaeochromocytoma

MRCP revision battle 36.1: Wilson's disease

Wilson's disease is an autosomal recessive condition inherited on chromosome 13.
Approximately 1 in 400 people carry the gene, giving the disease an incidence of around 1 in 200 000

Wilson's disease is due to a mutation in the gene coding for a copper transporting ATPase, ATP7B.   This results in the failure of biliary copper excretion, causing raised urinary copper and raised tissue copper with accumulation of copper especially in the liver and basal ganglia.

Features include:
  • liver disease - hepatitis, cirrhosis
  • CNS  signs - tremor, ataxia, dementia, emotional lability
  • hypoparathyroidism
  • haemolysis
  • Kayser-Fleischer rings - copper deposits in descemet's membrane - pathognomonic
  • blue nails
  • hypermobile joints
  • arthritis

  • low serum caeruloplasmin
  • raised urinary copper

Treatment: penicillamine - remember this can cause low platelets and white cells so patients should be warned to report bruising/fever/sore throat to their doctor.

Note that the liver aspects of Wilson's tend to be reversible while the neuro problems have limited reversibility on treating.

Now on for a short battle about drugs causing impaired insulin tolerance...

MRCP revision battle 36.2: Drugs causing impaired glucose tolerance

Drugs associated with impaired glucose tolerance include:
  • thiazide diuretics
  • furosemide
  • steroids
  • tacrolimus
  • ciclosporin
  • IFN alpha
  • nicotinic acid

I'm afraid I can't think of any clever way to remember this list... if anyone can think of one please email me... marietreasure7 followed by at gmail .com.

Next up: acromegaly

MRCP revision battle 36.3: Acromegaly

Acromegaly is caused by excess growth hormone.  99% of cases are due to a pituitary tumour.  5% of cases are associated with MEN 1 (now might be a good time to re-revise battle 20.1 which covers MEN...)

For the purposes of revision I'll divide features into 'classical' and 'MRCP smaller print'

Classical features:
  • soft tissue growth
    • large tongue
    • large hands
    • big ears
    • coarsening facial features
    • widening of gaps between teeth
  • impaired glucose tolerance (40%)/diabetes (20%)
  • raised blood pressure
  • horse voice

MRCP features:
  • raised phosphate
  • raised triglycerides
  • pseudogout
  • colonic polyps
  • proximal muscle weakness
  • arthralgia

  • failure of GH to decrease (to a lab-specific level) after oral glucose tolerance test
    • false positives to this test may occur in puberty, pregnancy, DM, renal/liver impairment
  • serum IGF-1 is a screening test only

  • transphenoidal surgery (40-70% cure)
  • ocreotide = somatostatin analogue
  • bromocriptine (<20% effective)
  • pegvisomant = GH receptor antagonist, conclusive data on effectiveness still awaited

Now for a little vitamin C....

MRCP revision battle 36.4: Vitamin C

Vitamin C is an antioxidant.  It is found in many fruits, vegetables and in liver. 

A deficiency in vitamin C leads to scruvy:
  • gingivitis
  • loose teeth
  • malaise
  • poor wound healing
  • bleeding

Causes of deficiency include poor diet and pregnancy.

Now for another short battle, insulinoma...

MRCP revision battle 36.5: Insulinoma

Insulinoma is the commonest pancreatic endocrine tumour.

10% are malignant, 10% are multiple.
If multiple, 50% are associated with MEN-1.

Presentation tends to be with the symptoms of hypoglycaemia (revise battle 29.1 if you need to be reminded of these)

Diagnosis is by supervised prolonged fasting.

Treatment is surgical excision.

Onwards for a quick tour of metabolic syndrome...

MRCP revision battle 36.6: Metabolic syndrome

Metabolic syndrome (AKA syndrome X) is a combination of disorders that increase a patient's risk of cardiovascular disease/diabetes.

It is defined as:
  • central obesity (= waist >94cm in europeans) OR BMI >30 
  • PLUS 2 of the following 4:
    • triglycerides >1.7
    • low HDL
    • BP >130/85
    • fasting glucose >5.6 or type 2 DM

Metabolic syndrome is associated with:
  • raised uric acid levels
  • non-alcoholic fatty liver
  • PCOS

Now for the final battle of the day, phaeochromocytoma...

MRCP revision battle 36.7: Phaeochromocytoma

Phaeochromocytomas are rare, catecholamine (=adrenaline, noradrenaline, dopamine ) producing tumours.

Presentations are variable and can include:
  • headaches
  • visual disturbances
  • chest tightness
  • palpitations
  • hypertension (70% persistent, 30% episodic)
  • hypotension/postural hypotension is also possible
  • faints
  • abdominal pain

The triad of headache, sweating and palpitations is 90% predictive.

Lots of facts to remember about phaeochromocytomas follow the rule of 10%:
10% are familial (= MEN II, neurofibrosis, Von Hippel Lindau)
10% are bilateral, 10% are malignant and10% are extraadrenal

The commonest extraadrenal site is the organ of Zuckerkandl, which is adjacent to the bifurcation of the aorta.

Diagnosis is by VMA in urine and CT/MRI (show up bright white on T2 weighted MRI)

Treatment is surgery with pre-op alpha and beta blockade (alpha blocker of choice = phenoxybenzamine)

Recurrence is possible so these patients should be followed up lifelong.

Thats all for today, hopefully more tomorrow!