Thursday, 14 October 2010

MRCP revision battle 29.1: Hypoglycaemia

After nearly a week away I'm back with a bumper set of battles, the first of which is hypoglycaemia, which has been a recurring theme in both my patients and myself this week!  Enjoy!

MRCP revision battle 29.1: Hypoglycaemia
MRCP revision battle 29.2: Thyroid eye disease
MRCP revision battle 29.3: Hyperlipidaemia
MRCP revision battle 29.4: Lipid-lowering treatment
MRCP revision battle 29.5: Restless legs syndrome
MRCP revision battle 29.6: Histocytosis X
MRCP revision battle 29.7: Bartter's Syndrome
MRCP revision battle 29.8: Gitelman Syndrome
MRCP revision battle 29.9: Liddle's Syndrome

MRCP revision battle 29.1: Hypoglycaemia

Hypoglycaemia is defined as plasma glucose <3mmol/l.

In general in diabetics autonomic symptoms of hypoglycaemia (sweating, anxiety, tremor, palpitations) occur below 3.5mmol and neurological symptoms (confusion, drowsiness, seizures, coma) occur below 2.5mmol.

If a diabetic has frequent hypos they may become 'insensitive' and no longer experience symptoms before becoming unresponsive.  Symptoms may be 'restored' by carefully avoiding hypos for 3 months.

Causes of hypoglycaemia are easy to remember as it "IS PLAIN" to see...
  • Insulin
  • Sulphonyureas/other drugs
  • Pituitary insufficiency
  • Liver failure
  • Addisons disease or alcohol
  • Insulinoma
  • Neoplasms eg retroperitoneal fibrosarcomas than secrete IGF

Take bloods for glucose, insulin, c-peptide and plasma ketones.
Normal/high insulin, no ketones: insulinoma, drugs
Insulin low, no ketones: non-pancreatic neoplasm
Insulin low, ketones high: alcohol, addissons, pituitary insufficiency.

Post-pradial hypoglycaemia can occur post-gastrectomy

Whipples Triad is a set of criteria which if fulfilled suggest a patient's symptoms are due to hypoglycaemia:
  • symptoms suggestive of hypoglycaemia
  • BM < or equal to 2.5
  • symptoms relieved by food.


I'm sure this is all old-hat to you all... get the pt to eat if they can, 1mg IM glucagon if they can't and no IV access (remember glucagon effects only last for 20 mins and may not work at all in alcoholics) and if IV is an option the 50mls of 50% glucose or the more modern 200mls of 10% (less abrasive to the veins)

Now for some TED time...