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Hypoglycemia Paolo Aquino 29 January 2003 Overview of hypoglycemia What is it? Why do we care about it? What causes it? How do we diagnose it? What do we do about it? How do we prevent it? What is it? Strictly, hypoglycemia refers to a low level of serum glucose It occurs when a mismatch of endogenous glucose need with exogenous and endogenous glucose availability derails the metabolic engine of normal glucose homeostasis Often defined as a plasma glucose level < 2.5-2.8 mmol/L (< 45-50 mg/dL) Why do we care about it? Because hypoglycemia can kill Why do we care about it? Physiology – Glucose is an obligate metabolic fuel for the brain under physiologic conditions, while other organs can use other forms of fuel (i.e. fatty acids) – The brain can not synthesize its own glucose; it requires a continuous supply via arterial blood Why do we care about it? Physiology – As the plasma glucose concentration falls below the physiologic range, bloodto-brain glucose transport becomes insufficient for adequate brain energy metabolism and functioning Why do we care about it? Maintenance of glucose homeostasis – Narrow plasma glucose range is normally maintained despite fluctuations in food intake and activity levels – Maintenance through diet, glycogen breakdown (liver) and gluconeogenesis (liver and kidney) Glucose metabolism Glucose metabolism Glycogen stores can last 8-12 hours Precursors for gluconeogenesis coordinated amongst liver, muscle and adipose tissue – Muscle: lactate, pyruvate, amino acids – Adipose: glycerol, fatty acids Hormonal control Insulin- inhibits glycogenolysis and gluconeogenesisdecreased serum glucose Glucagon- promotes glycogenolysis and gluconeogenesis Epinephrine- limits utilization of glucose by insulin-sensistive tissues Growth hormone and cortisol have a role during prolonged hypoglycemia What causes it? Two major etiological classes – Increased insulin levels Over-medicating Insulinoma Sepsis – Underproduction of glucose Medications- alcohol, salicylates, b-blockers Adrenal insufficiency Liver disease Malnutrition, dehydration Hypoglycemia in diabetes Whipple’s Triad Symptoms of hypoglycemia Low plasma glucose levels Resolution of symptoms with administration of glucose Symptoms Adrenergic: diaphoresis, tachycardia, anxiety, hunger Neuroglycopenic: dizziness, confusion, slurred speech, seizure Diagnosis History – Drug use, infection, illness (hepatic, renal, cardiac), surgeries Laboratory tests- serum glucose, CBC, lytes, BUN/Cr, UA Other tests: ECG, CXR Diagnosis Differential – Neurologic: CVA/TIA, seizure disorder – Drug/alcohol intoxication – Psychosis, depression Treatment Glucose – Oral glucose – IV dextrose: 5-20% solutions, 50% ampules – IM glucagon Monitor glucose q 2-4 hours If adrenal insufficiency, administer 100 mg hydrocortisone & 1 mg glucagon If resistant hypoglycemia secondary to sulfonylureas, administer diazoxide 300 mg over 30 minutes IV q 4 hours PRN Prevention Treatment of underlying problem – Eliminate/reduce offending drug – Resection of insulinoma – Treat infection – Frequent feedings, avoidance of fasting