Chapter 19: Endocrine Alterations

The stress response to critical illness triggers significant endocrine changes, notably the development of stress-induced hyperglycemia driven by counterregulatory hormones that increase hepatic glucose production. Patients frequently experience adrenal insufficiency in its various forms and thyroid hormone dysregulation, particularly decreased triiodothyronine levels. Glycemic control represents a central management priority, with evidence-based guidelines recommending initial glucose targets not exceeding 180 milligrams per deciliter, transitioning to 140 to 180 milligrams per deciliter once insulin therapy begins. Intravenous short-acting insulin administered through nurse-managed protocols with frequent monitoring remains the preferred glycemic control method, with eventual transition to basal-bolus subcutaneous regimens. The chapter addresses two critical pancreatic emergencies: diabetic ketoacidosis, characterized by absolute insulin deficiency, metabolic acidosis, and ketone production, and hyperosmolar hyperglycemic state, distinguished by severe hyperglycemia exceeding 1000 milligrams per deciliter with profound dehydration but minimal ketosis. Management of both conditions involves fluid resuscitation with normal saline, intravenous insulin administration, and electrolyte replacement, particularly potassium monitoring. Adrenal crisis represents a life-threatening cortisol and aldosterone deficit typically resulting from abrupt corticosteroid withdrawal, requiring immediate volume repletion and hormone replacement with dexamethasone followed by hydrocortisone. Thyroid emergencies encompass thyroid storm, a hypermetabolic state managed with beta blockers and thioamides, and myxedema coma, an extreme hypothyroid condition requiring intravenous thyroid hormone replacement. Antidiuretic hormone disorders include diabetes insipidus with its polyuria and hypernatremia treated with desmopressin, syndrome of inappropriate antidiuretic hormone characterized by water retention and dilutional hyponatremia managed through fluid restriction and careful hypertonic saline administration, and cerebral salt wasting involving hypovolemia requiring simultaneous sodium and fluid restoration. The chapter incorporates lifespan considerations, recognizing that pregnant patients face gestational diabetes risks with specific glucose targets, while elderly patients present with atypical symptoms and experience age-related pancreatic decline, reduced cortisol clearance, and increased susceptibility to antidiuretic hormone disorders.