Hypoglycemia

Overview

• There is no universally accepted definition of hypoglycaemia (low blood glucose).
• Clinically significant hypoglycemia is confirmed by the presence of ‘Whipple triad’:
  1. the presence of symptoms consistent with hypoglycemia
  2. a low serum glucose level
  3. resolution of the symptoms and signs of hypoglycemia with the administration of glucose
• Clinical hypoglycaemia is defined as a blood glucose low enough to cause symptoms or signs (including brain impairment) or both. For most people this occurs at blood glucose levels less than  2.8- 3.3 mmol/L (50-60 mg/dL).
• Severe hypoglycaemia is defined as an event requiring the assistance of another person to actively administer carbohydrate, glucagon or provide other resuscitative measures.
• Relative hypoglycaemia occurs when a patient with diabetes reports hypoglycaemic symptoms, but the blood glucose remains above 3.8 mmol/L (70 mg/dL). This still requires treatment.
• Conversion of Blood Glucose: 1 mmol/L = 18 mg/dL, 1 mg/dL = 0.056 mmol/L

Causes

Known diabetics (most common)

• Hypoglycemic agents (suphonylureas, insulin)
• Decreased glucose delivery (missed meals or overnight fasting)
• Increased glucose utilisation (exercise)
• Reduced endogenous glucose production (alcohol ingestion)
• Increased insulin sensitivity (weight loss, increase in exercise)
• Reduced insulin clearance (renal failure)

No history of diabetes (rare) – mnemonic ‘EXPLAINS H)

• Exogenous drugs (e.g insulin, oral hypoglycemics, ethanol intoxication, quinine, chloroquine, beta-blocker overdose, valproate overdose, salicylate overdose, pentamidine)
• Pituitary insufficiency
• Post-prandial hypoglycemia (e.g. ’late dumping’ after gastric surgery)
• Liver disease (e.g hepatocellular cancer, hepatitis and rare genetic defects)
• Addison’s disease
• Islet cell tumours (e.g. insulinomas)
• Immune hypoglycemia (e.g. anti-insulin receptor antibodies in Hodgkin’s disease or anti-insulin antibodies that release insulin when insulin levels are relatively low)
• Infection (e.g. severe sepsis, malaria)
• Non-pancreatic neoplasms (e.g fibromas, sarcomas, mesotheliomas, and small cell carcinomas that produce IGF-2; extensive metastases that overwhelm the body’s ability to produce glucose)
• Nesidioblastosis or noninsulinoma pancreatogenous hypoglycemia (NIPH) syndrome (islet cell hyperplasia, which can be congenital or acquired, e.g. post-gastric surgery)
• Starvation and malnutrition
• Hypothyroidism (myxoedema coma)

Pseudohypoglycemia (delayed measurement of a sample in the presence of leukocytosis, thrombocytosis or erythrocytosis)

CCC Differential Diagnosis Series
NEURO	Anosmia, Ataxia, Blepharospasm, Bulbar and Pseudobulbar palsy, Central Pontine Myelinosis, Cerebellar Disease, Chorea, Cranial nerve lesions, Dementia, Dystonia, Exophthalmos, Eye trauma, Facial twitches, Fixed dilated pupil, Horner syndrome, Loss of vision, Meningism, Movement disorders, Optic disc abnormality, Parkinsonism, Peripheral neuropathy, Radiculopathy, Red eye, Retinal Haemorrhage, Seizures, Sudden severe headache, Tremor, Tunnel vision
RESP	Bronchial breath sounds, Bronchiectasis, High airway pressures, Massive haemoptysis, Sore throat, Tracheal displacement
CVS	Atrial Fibrillation, Bradycardia, Cardiac Failure, Chest Pain, Murmurs, Post-resuscitation syndrome, Pulseless Electrical Activity (PEA), Pulsus Paradoxus, Shock, Supraventricular tachycardia (SVT), Tachycardia, VT and VF, SVC Obstruction
GIT	Abdominal distension, Abdominal mass, Abdominal pain, Asterixis, Dysphagia, Hepatomegaly, Hepatosplenomegaly, Large bowel obstruction, Liver palpation abnormalities, Lower GI haemorrhage, Malabsorption, Medical causes of abdominal pain, Rectal mass, Small bowel obstruction, Upper GI Haemorrhage
GUT	Genital ulcers, Groin lump, Scrotal mass, Urine colour, Urine Odour, Urine transparency,
MSK	Arthritis, Shoulder pain, Wasting of the small muscles of the hand
DERM	Palmar erythema, Serious skin signs in sick patients, Thickened Tethered Skin, Leg ulcers, Skin Tumour, Acanthosis Nigricans
ENDO	Diabetes Insipidus, Diffuse Goitre, Gynaecomastia, Hirsutism, Hypoglycaemia, SIADH, Weight Loss
HAEM	Splenomegaly
PAEDS	Floppy infant
MISC	Anaphylaxis, Autoimmune associated diseases, Clubbing, Parotid Swelling, Splinter haemorrhages, Toxic agents and abnormal vitals, Toxicological causes of cardiac arrest
IMAGING	CHEST: Atelectasis, Hilar adenopathy, Hilar enlargement on CXR, Honeycomb lung, Increased interstitial markings, Mediastinal widening on mobile CXR, Pulmonary fibrosis, Pseudoinfiltrates on CXR, Pulmonary opacities on CXR, ABDO: Gas on abdominal X-ray, Kidney mass, BRAIN: Intracranial calcification, Intracranial structures with contrast, Ventriculomegaly, OTHER: Pseudofracture on X-Ray,
LABS	LOW: Anaemia, Hypocalcaemia, hypochloraemia, Hypomagnesaemia,  HIGH: Bilirubin and Jaundice, Hyperammonaemia, Hypercalcaemia, Hyperchloraemia, Hyperkalaemia, Hypermagnesaemia,  ACID BASE: Acid base disorders, Resp. acidosis, Resp. alkalosis, Creatinine, CRP, Dipstick Urinalysis, Laboratory Urinalysis, Liver function tests (LFTs), Pleural fluid analysis, Urea, Urea Creatinine Ratio, Uric acid, Urinalysis, Urine Electrolytes

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