My Clinical Notes

• Defined as being a plasma glucose concentration of less than 2.5mmol/L
• Requires that specimen is collected in a container that contains inhibits of glycolyis
• Systems of hypoglycaemia are more likely to occur if there has been a rapid fall
• Symptoms are likely to be less obvious with a slow drop or if the individuals autonomic nervous system has been made unresponsive due to beta-blockers or the patient has severe peripheral neuropathy (diabetics)

Clinical features

• Acute
• Due to neuroglycopenia;
  • Tiredness
  • Confusion
  • Lasck of concentration
  • Ataxia
  • Dizziness
  • Convulsions
  • Coma
• Due to sympathetic stimulation;
  • Palpitation and tachycardia
  • Sweating
  • Facial flushing
  • Tremor
  • Anxiety
• Non-specific
  • Hunger
  • Weakness
  • Blurred vision
• Chronic neuroglycopenia
  • Personality change
  • Memory loss
  • Psychosis
  • Dementia

Causes

• Reactive hypoglycaemia
• Post-prandial;
  • Gastric surgery
  • Essential (idiopathic)
• Drug induced;
  • Insulin
  • Sulphonylureas
  • Alcohol
• Inherited metabolic disorders;
  • Galactosaemia
  • Hereditary fructose intolerance

• Fasting hypoglycaemia
• Hepatic and renal disease (rare)
• Endocrine disease;
  • Adrenal failure
  • Pituitary failure
  • Isolated ACTH and GH deficiency
• Inherited metabolic disorders;
  • Glycogen storage disease type I
• Hyperinsulinism
  • Insulinoma
  • Nesidioblastosis
• Non-pancreatic neoplasms
• Alcohol induced fasting hypoglycaemia
• Neonatal hypoglycaemia septicaemia

• In fasting hypoglycaemia the symptoms occur at night or early in the morning, they are precipitated by prolonged fasting or exercise. This suggests an excessive utilisation of glucose of an abnormality of glucose sparing or glucose forming mechanisms
• In nonfasting hypoglycaemia symptoms occur around 5 hours after a meal and may be related to ingestion of a particular food type
• Reative and drug induced hypoglycaemia are the most common in adults

Insulin- or drug induced hypoglycaemia

• Perhaps caused by and insulin overdose, changing insulin requirements or a change in diet
• Sulphonylureas may cause hypoglycaemia particularly in the elderly
• Hypoglycaemia due to exogenous insulin results in inhibition of endogenous insulin production and c-peptide secretion. C-peptide measurement may help to distinguish between exogenous insulin induced hypoglycaemia or endogenous insulin due to an insulinoma or following pancreatic stimulation with sulphonylureas

Insulinoma

• Usually a small, benign primary tumour of the islet cells of the pancreas
• May present at any age
• Multiple tumours may occur and it may be part of the syndrome of multiple endocrine neoplasia
• Hormone secretion is excessive and inappropriate

Alcohol induced hypoglycaemia

• May develop between 2 and 10 hours after ingestion of large amounts of alcohol
• Probably caused by suppression of gluconeogenesis during the metabolism of alcohol
• Non-pancreatic tumours
• Hypoglycaemia most commonly caused by retroperitoneal tumours of mesenchymal origin
• Mechanism of hypoglycaemia not always clear but may be due to the secretion of an insulin-like growth factor
• Can also be associated with carcinomas (especially of the liver) and sarcomas

Reactive (functional) hypoglycaemia

• Hypoglycaemia between 2 and 4 hours after a glucose load
• LOC is rare
• Can occur with gastrectomy when rapid passage of glucose into the intestine and rapid absorption may stimulate excessive insulin secretion ‘late dumping syndrome’

Impaired liver function

• The reserve of the liver is so great that despite its central role in maintaining glucose concentration hypoglycaemia is rare in liver disease
• It may complicate severe hepatitis, hypoxic liver associated with cardiac failure or liver necrosis

Hypoglycaemia is infants and children

• Not uncommon, may cause brain damage
• Causes of hypoglycaemia in childhood;
• Hyperisulinaemia
  • Islet cell hyperplasia
  • Nesidioblastosis (islet cell hyperplasia)
  • Insulinoma
• Inherited metabolic disorders;
  • Glycogen storage diseases
  • Galactosaemia
  • Herieditary fructose intolerance
  • Fatty acid beta-oxidation defects
  • Ketotic hypoglycaemia
• Other causes;
  • Prematurity
  • Small-for-dates
  • Endocrine disorders
  • Starvation
  • Drugs

• Clinical signs include;
  • Convulsions
  • Tremors
  • Apnoea with cyanosis

• Neonatal hypoglycaemia is particularly common in;
  • Infants born to diabetic mothers. During pregnancy fetal islet cell hyperplasia develops resulting in hyperisulinaemia
  • Premature babies – lack store of glycogen

• Hypoglycaemia in early infancy can be due to;
  • A deficiency in enzymes involved in glucogenesis or glycogenolysis
  • Hereditary fructose intolerance due to a deficiency in fructose-1-phosphate aldolase

• Hypoglycaemia in later infancy can be caused by;
  • Idiopathic hypoglycaemia of infancy
    • Diagnosis of exclusion
    • Symptoms usually develop after a fasting or febrile illness
    • High incidence of brain damage
    • In come cases there is high insulin secretion making it difficult to distinguish for nesidioblastosis
  • Leucine sensitivity
    • Family incidence
    • During the first 6 months of life, casein present in milk causes severe hypoglycaemia due to high leucine content
    • Probably due to stimulation of insulin secretion by the amino acid
    • Condition is self-limiting and doesn’t persist beyond the age of 6

This entry was posted on Sunday, October 14th, 2007 at 1:00 pm and is filed under Diabetes. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.