Hypoglycaemia in the Non-Diabetic Patient Flashcards
What might hepatic glucose output be reduced by?
(General)
Inhibition of hepatic glycogenolysis and gluconeogenesis by insulin
Depletion of hepatic glycogen reserves by malnutrition, fasting, exercise or advanced liver disease
Impaired gluconeogenesis e.g. following alcohol ingestion
What can inhibition of hepatic glycogenolysis and gluconeogenesis by insulin be reversed by?
Injection of glucagon
Will injection of glucagon work in depletion of hepatic glycogen or impaired gluconeogenesis?
In this case insulin levels are already low.
Glucagon will be ineffective.
For example in malnutrition.
What type of symptoms are most common for hypoglycaemia?
Neurological
What are insulinomas?
Pancreatic islet tumours that secrete insulin.
Most of them are sporadic but some patients have multiple tumours arising from neural crest tissue due to multiple endocrine neoplasia.
Are insulomas benign or malignant?
95% are benign
Presenting features of insulinomas.
Recurrent hypoglycaemia often present for months or years before the diagnosis is made.
Diplopia
Sweating, palpitations, weakness
Confusion or abnormal behaviour
Loss of consciousness
Grand mal seizures
What are insulinomas commonly misdiagnosed as?
Psychiatric disorders such as:
Pseudodementia
Epilepsy
Cerebrovascular disease
What is the basis of clinical diagnosis of insulinomas?
Whipple’s triad
What is Whipple’s triad?
Symptoms are associated with fasting or exercise
Hypoglycaemia is confirmed during these episodes
Glucose relieves symptoms
What is a fourth criterion of insulinomas that may be useful?
Inappropriately high insulin levels during hypoglycaemia
How can a diagnosis of an insulinoma be confirmed?
Demonstration of hypoglycaemia in association with inappropriate and excessive insulin secretion.
What tests might be done to diagnose insulinoma?
Measurement of overnight fasting of 16h glucose and insulin levels. This is done on three occassions. It should show up as low glucose and high insulin.
If this is inconclusive a prolonged 72 hour supervised fast can be done.
Suppressive tests such as giving insulin IV and measure C-peptide can be done. Normally exogenous insulin suppresses C-peptide production, but this does not occur in insulinoma.
How can you tell if a patient has overdosed on insulin or whether it is an insulinoma in hypoglycaemia?
Measuring C-peptide or proinsulin.
In an insulinoma they will be high.
Management of insulinomas.
Surgical or medical.
