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Endocrine — HPA, Thyroid, Glucose
TEXTPhysiology II · 10 min read
Stress steroid coverage, thyroid storm vs myxedema, DKA, pheochromocytoma. The intra-op crises that come from glands.
After this lesson you can
2 min read6 sections- Plan periop stress-dose steroids for adrenal-suppressed patients.
- Manage diabetes intraoperatively.
- Recognize thyroid storm and myxedema coma.
- Identify pheochromocytoma-specific concerns.
Stress steroid coverage
5 mg/day × ≥3 weeks (or equivalent).Dose by surgical magnitude: minor surgery — continue baseline only.
Moderate — hydrocortisone 50 mg IV at induction, repeat q8h × 24-48 hr.
Major — hydrocortisone 100 mg at induction, repeat q8h × 48-72 hr.
Recent evidence (RCTs) shows lower doses adequate; don't over-cover.
Stop coverage at planned home-dose continuation.
Thyroid storm
- tachycardia (often AF)
- hyperthermia
- agitation
- vomiting
- heart failure
- β-blocker (propranolol 1-2 mg IV titrated, or esmolol infusion)
- PTU
200-400 mgPO/NG (blocks new synthesis + T4→T3 conversion) - iodine 1 hr AFTER PTU (Wolff-Chaikoff)
- steroid (hydrocortisone 100 mg blocks T4→T3)
- active cooling
ICU admission.
Mortality 10-20% if untreated.
Myxedema coma
Hypothermia, bradycardia, hypotension, hyponatremia, hypoglycemia, altered mental status.
Levothyroxine 200-400 mcg IV loading + 50-100 mcg/day, hydrocortisone 100 mg (treat presumed adrenal insufficiency until ruled out), passive rewarming (active warming causes vasodilation + collapse), careful fluid + glucose.
Avoid sedatives.
Intra-op glucose
140-180 mg/dL in most surgical patients; ICU + cardiac surgery targets similar.Continue basal long-acting insulin pre-op (or 80% dose), hold short-acting unless eating.
Insulin pumps: continue at basal rate.
Check glucose at arrival, hourly intra-op.
Glucose-containing IVF avoided unless hypoglycemic.
Stress hyperglycemia common — treat with insulin infusion if persistently >180.
Hypoglycemia in unconscious patient is the bigger danger.
DKA management
1-2 L bolus then 250-500 mL/hr.Insulin infusion 0.1 U/kg/hr (no bolus).
Potassium replacement when K drops to 5.0 (insulin shifts K intracellularly; start replacement before hypokalemia develops).
Switch to D5/half-NS when glucose ~250 to allow ongoing insulin without hypoglycemia.
Bicarbonate only if pH <6.9.
Identify trigger (infection, missed insulin, MI).
Monitor ICU; cerebral edema risk in pediatric DKA.
Pheochromocytoma
Add β-blocker AFTER adequate α (unopposed α = hypertensive crisis).
Intra-op HTN spikes during tumor manipulation — phentolamine 1-5 mg, nitroprusside, magnesium 2 g, nicardipine/clevidipine.
Post-resection hypotension — norepinephrine + volume + vasopressin if catecholamine receptors are downregulated.
ICU postop.
Monitor glucose (rebound hypoglycemia common).
⚠ Common pitfalls
- Stress-dose steroids universal — current guidance is risk-stratified by daily dose + duration.
- Tight glucose control intraop — hypoglycemia harms more than mild hyperglycemia in short cases.
- Beta-blocker before alpha-blocker in pheo — unopposed alpha = hypertensive crisis.
- Missing thyroid storm — fever + tachycardia + altered mental status post-induction.
💎 Clinical pearls
- Stress-dose hydrocortisone: low risk = no extra; moderate = 50 mg + 25 mg q8h; high = 100 mg + 50 mg q8h.
- Pheo: alpha block (phenoxybenzamine) ×2 weeks → then beta (propranolol) if tachycardia.
- Thyroid storm: beta-block + thionamide + iodine + steroid + active cooling.
- Diabetic ketoacidosis: insulin + fluids + K replacement (anticipate K drop with insulin).
Recap
- Stress-dose hydrocortisone: low risk = no extra; moderate = 50 mg + 25 mg q8h; high = 100 mg + 50 mg q8h.
- Pheo: alpha block (phenoxybenzamine) ×2 weeks → then beta (propranolol) if tachycardia.
- Thyroid storm: beta-block + thionamide + iodine + steroid + active cooling.
- Diabetic ketoacidosis: insulin + fluids + K replacement (anticipate K drop with insulin).
Mark each section done to complete the module.