HYPOGLYCEMIA

A critically low blood glucose concentration is an emergency because severe and prolonged hypoglycemia can potentially cause permanent neurologic deficits. Most cases of hypoglycemia in the ICU represent isolated or short-term events. Common causes in this setting are excessive insulin administration, sepsis, hepatic or renal dysfunction, adrenal insufficiency, and abrupt cessation of parenteral nutrition formulas. A number of drugs may cause hypoglycemia, including ethanol, sulfonylurea agents, and β-adrenergic blockers. Pancreatic islet cell tumors and other unusual causes may require diagnostic evaluation of insulin levels, C-peptide levels, or insulin antibodies; however, these etiologies are comparatively rare and do not need to be pursued unless the hypoglycemia recurs over a more prolonged period.

Whipple's triad encompasses the classic diagnostic criteria for hypoglycemia:

1. ▪ Hypoglycemia, i.e., blood glucose concentration <50 mg/dL

2. ▪ Clinical signs and symptoms ascribable to hypo-glycemia

3. ▪ Abatement of symptoms following dextrose administration

Clinical manifestations are due either to the resulting hyperadrenergic reaction or to neuroglycopenia. The former can result in tremulousness, diaphoresis, anxiety, tachycardia, palpitations, nausea, and vomiting; whereas the latter can cause headache, confusion, behavioral changes, stupor, coma, and seizures.