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Sepsis Stress Response & Endocrine Changes: Cortisol, Insulin Resistance, and NTIS [ Medical Education ](https://mdster.com/blog?category=medical-education) Sepsis Stress Response & Endocrine Changes: Cortisol, Insulin Resistance, and NTIS ======================================================================================== A high-yield, anesthesia-focused way to think about hormones during fever, SIRS, and septic shock [ MDster Editorial Team ](https://mdster.com/about) · Feb 07, 2026 · 8 min read · 124 [ Reviewed by Dr. Ali Ragab, MBBCH, MSc, MCAI ](https://mdster.com/medical-reviewers/dr-ali-ragab) [Editorial Policy](https://mdster.com/editorial-policy) | [Corrections Policy](https://mdster.com/corrections) [ Sepsis ](https://mdster.com/blog?tag=sepsis) [ Critical Care Anesthesia ](https://mdster.com/blog?tag=critical-care-anesthesia) [ Endocrine Physiology ](https://mdster.com/blog?tag=endocrine-physiology) [ Board Review ](https://mdster.com/blog?tag=board-review) [ Perioperative Medicine ](https://mdster.com/blog?tag=perioperative-medicine) [ Anesthesiology ](https://mdster.com/blog?tag=anesthesiology) Share this article Share this post On this page 1. [ The mental model: three axes, one goal ](#the-mental-model-three-axes-one-goal) 2. [ Cortisol response: why pressors fail without it ](#cortisol-response-why-pressors-fail-without-it) 3. [ CIRCI: when “high cortisol” is still inadequate ](#circi-when-high-cortisol-is-still-inadequate) 4. [ What to do in septic shock (the “dose you should memorize”) ](#what-to-do-in-septic-shock-the-dose-you-should-memorize) 5. [ Insulin resistance in acute illness: stress hyperglycemia is a physiology problem, not a willpower problem ](#insulin-resistance-in-acute-illness-stress-hyperglycemia-is-a-physiology-problem-not-a-willpower-problem) 6. [ Targets: treat hyperglycemia, don’t worship euglycemia ](#targets-treat-hyperglycemia-dont-worship-euglycemia) 7. [ Thyroid changes (NTIS): low T3 is usually a marker, not a mandate ](#thyroid-changes-ntis-low-t3-is-usually-a-marker-not-a-mandate) 8. [ The board trap: “treat the number” ](#the-board-trap-treat-the-number) 9. [ Clinical correlations: how this changes what you do tomorrow ](#clinical-correlations-how-this-changes-what-you-do-tomorrow) 10. [ Key Takeaways ](#key-takeaways) 11. [ Conclusion ](#conclusion) 12. [ References ](#references-heading) On this page 1. [ The mental model: three axes, one goal ](#the-mental-model-three-axes-one-goal) 2. [ Cortisol response: why pressors fail without it ](#cortisol-response-why-pressors-fail-without-it) 3. [ CIRCI: when “high cortisol” is still inadequate ](#circi-when-high-cortisol-is-still-inadequate) 4. [ What to do in septic shock (the “dose you should memorize”) ](#what-to-do-in-septic-shock-the-dose-you-should-memorize) 5. [ Insulin resistance in acute illness: stress hyperglycemia is a physiology problem, not a willpower problem ](#insulin-resistance-in-acute-illness-stress-hyperglycemia-is-a-physiology-problem-not-a-willpower-problem) 6. [ Targets: treat hyperglycemia, don’t worship euglycemia ](#targets-treat-hyperglycemia-dont-worship-euglycemia) 7. [ Thyroid changes (NTIS): low T3 is usually a marker, not a mandate ](#thyroid-changes-ntis-low-t3-is-usually-a-marker-not-a-mandate) 8. [ The board trap: “treat the number” ](#the-board-trap-treat-the-number) 9. [ Clinical correlations: how this changes what you do tomorrow ](#clinical-correlations-how-this-changes-what-you-do-tomorrow) 10. [ Key Takeaways ](#key-takeaways) 11. [ Conclusion ](#conclusion) 12. [ References ](#references-heading) You induce a septic patient for an emergent laparotomy. The BP tanks despite norepi, the glucose is 280 mg/dL in a “non-diabetic,” and the intern proudly tells you the T3 is low so they “started levothyroxine.” That’s the endocrine stress response in one messy snapshot—and it matters because your drugs only work as well as the patient’s physiology lets them. In fever, SIRS, and sepsis, endocrine changes aren’t trivia. They’re *how the body funds the fight*: maintain vascular tone, mobilize fuel, and throttle metabolism. Your job in anesthesia is to recognize when those adaptations are helping, when they’ve become harmful, and when “fixing the lab” is the wrong move. The mental model: three axes, one goal -------------------------------------- In acute illness the body pivots toward **(1) cortisol up**, **(2) insulin sensitivity down**, and **(3) thyroid signaling down (NTIS)**. Think of it as: *pressure, sugar, and speed*. - **Pressure:** cortisol makes catecholamines work and stabilizes endothelium. - **Sugar:** insulin resistance preserves glucose for immune cells and brain (at a cost). - **Speed:** NTIS lowers T3 signaling to reduce energy expenditure—often adaptive, sometimes a marker of severity. If you keep that frame, the ICU labs stop looking random and start looking predictable. Cortisol response: why pressors fail without it ----------------------------------------------- Sepsis activates the HPA axis through cytokines (notably IL-6), pain, hypoperfusion, and hypoglycemia risk. The result is usually **high total cortisol**, but the clinically relevant piece is **free cortisol**, which can rise even more because binding proteins fall in critical illness. Cortisol’s “board-relevant” effects are not subtle: - **Permissive vascular tone:** restores responsiveness to norepi/epi (upregulates adrenergic receptors, supports angiotensin effects). - **Barrier and anti-inflammatory effects:** reduces runaway nitric oxide/vasoplegia. - **Metabolic support:** gluconeogenesis, protein catabolism, lipolysis. ### CIRCI: when “high cortisol” is still inadequate **Critical illness–related corticosteroid insufficiency (CIRCI)** is the concept that cortisol activity is *insufficient for illness severity*—from impaired production, impaired signaling, or both. Practically, you’ll suspect it when shock is **vasopressor-dependent** despite reasonable resuscitation. Don’t get seduced by endocrine testing here. In critical illness, cortisol assays, binding changes, and timing make interpretation messy; importantly, contemporary sepsis guidance doesn’t require an ACTH stimulation test to decide on hydrocortisone. Common anesthesia-relevant risk factors and mimics: - **Chronic exogenous steroids** (suppressed axis): the classic periop trap. - **Etomidate exposure**: inhibits 11β-hydroxylase and can worsen adrenal steroidogenesis—still a favorite board question in septic shock intubations. - **Adrenal hemorrhage/infarct** (rare, but real in catastrophic sepsis/coagulopathy). ### What to do in septic shock (the “dose you should memorize”) For adults with **septic shock and ongoing vasopressor requirement**, Surviving Sepsis Campaign guidance supports **IV hydrocortisone 200 mg/day** (50 mg q6h or infusion), often considered when norepi/epi needs are substantial (e.g., around 0.25 mcg/kg/min after several hours). [\[1\]](#cite-1 "Reference [1]") Separate but aligned: SCCM’s updated corticosteroid guidance (2024) suggests corticosteroids in septic shock and recommends **against high-dose/short-duration regimens** (>400 mg/day hydrocortisone equivalent for <3 days). [\[2\]](#cite-2 "Reference [2]") > **Clinical Pearl:** In vasoplegic septic shock that’s chewing through pressors, don’t keep “re-inducing” the patient with fluid boluses. Add **hydrocortisone** early enough that catecholamines can start working again—and then reassess vasopressor dose honestly. Insulin resistance in acute illness: stress hyperglycemia is a physiology problem, not a willpower problem ---------------------------------------------------------------------------------------------------------- If cortisol is the “pressure hormone,” **insulin resistance** is the “fuel partitioning strategy.” Catecholamines, cortisol, glucagon, growth hormone, and inflammatory cytokines drive: - **Hepatic gluconeogenesis + glycogenolysis** (glucose production doesn’t shut off). - **Reduced peripheral glucose uptake** (muscle and fat become insulin resistant). - **Relative insulin deficiency** (beta-cell dysfunction can occur in severe illness). The bedside consequences you care about in anesthesia: - **Osmotic diuresis** and electrolyte shifts (K, Mg, Phos) worsen hemodynamics. - **Immune dysfunction and infection risk** rise with uncontrolled hyperglycemia. - **Tight control harms** when monitoring is imperfect (hypoglycemia under anesthesia is easy to miss and dangerous). ### Targets: treat hyperglycemia, don’t worship euglycemia Modern ICU practice has moved away from “80–110 or bust.” SCCM’s 2024 guideline emphasizes treating **persistent hyperglycemia ≥180 mg/dL** and suggests **avoiding lower (80–139) targets** in most critically ill adults because of hypoglycemia risk. [\[3\]](#cite-3 "Reference [3]") The ADA similarly recommends **140–180 mg/dL** for most critically ill patients once therapy is started. [\[4\]](#cite-4 "Reference [4]") Decision point (ICU adult)Practical thresholdWhy you care in the OR/ICUStart active insulin managementPersistent BG ≥ **180 mg/dL** [\[3\]](#cite-3 "Reference [3]")Stress hyperglycemia tracks severity; prolonged extremes add harmTypical treatment range once on insulinAbout **140–200 mg/dL** [\[3\]](#cite-3 "Reference [3]")Safer than tight control when monitoring/feeds/pressors change Anesthesia pitfall: if you run an insulin infusion intraop, **match measurement frequency to instability** (vasopressor changes, transfusion, stopping dextrose/TPN, renal failure). Many “mystery hypoglycemia” events are iatrogenic—insulin continues while glucose delivery stops. Thyroid changes (NTIS): low T3 is usually a marker, not a mandate ----------------------------------------------------------------- **Non-thyroidal illness syndrome (NTIS)**—aka euthyroid sick syndrome—is the predictable thyroid pattern in critical illness, major surgery, trauma, and sepsis. The usual early pattern is **low T3 with high reverse T3**, with **TSH often normal**; with prolonged/severe illness, **T4 and TSH can fall** and correlate with worse prognosis. [\[5\]](#cite-5 "Reference [5]") Mechanistically, this is a mix of: - **Deiodinase shift:** less T4→T3 activation (↓D1) and more inactivation to rT3 (↑D3). [\[5\]](#cite-5 "Reference [5]") - **Central downshift:** reduced TRH/TSH signaling in prolonged illness (can mimic central hypothyroidism biochemically). [\[5\]](#cite-5 "Reference [5]") ### The board trap: “treat the number” Multiple reviews and guideline-level discussions conclude that routine thyroid hormone therapy for NTIS has **not shown clear benefit**, and many sources explicitly note that **current guidelines do not recommend treatment** of NTIS itself. [\[6\]](#cite-6 "Reference [6]") So what *should* you do? PatternTypical labsWhat you do (high-yield)**NTIS (most ICU sepsis)**↓T3, ↑rT3, TSH ~normal; later ↓T4/TSH in severe illness [\[5\]](#cite-5 "Reference [5]")Don’t treat; repeat after recovery if needed; avoid reflex consults**Primary hypothyroidism****↑TSH**, ↓FT4Continue/replace LT4 (don’t miss myxedema coma)**Central hypothyroidism vs prolonged NTIS**Low/normal TSH with low FT4Look for pituitary story; **cover adrenal axis first** if giving thyroid hormone Anesthesia nuance: dopamine, glucocorticoids, and critical illness itself can suppress TSH—so a “normal TSH” doesn’t automatically reassure you if the clinical story screams endocrine catastrophe. But in *typical sepsis*, NTIS is the rule. Clinical correlations: how this changes what you do tomorrow ------------------------------------------------------------ In the OR and ICU, endocrine physiology shows up as **drug responsiveness** and **monitoring priorities**. - If shock is vasopressor-hungry, think “**is cortisol signaling missing?**” before escalating to exotic vasopressors. Hydrocortisone is a rational, guideline-supported adjunct in vasopressor-dependent septic shock. [\[1\]](#cite-1 "Reference [1]") - If glucose is high, treat it—**but don’t tighten the noose**. Aim for safer ranges and avoid hypoglycemia, especially when NPO status, feeds, and vasopressors change quickly. [\[3\]](#cite-3 "Reference [3]") - If thyroid labs are abnormal, ask: “**Is this NTIS?**” In most septic patients, it is. Avoid starting levothyroxine because of a low T3 alone; you’ll be treating a marker of illness severity, not a thyroid disease. [\[5\]](#cite-5 "Reference [5]") Key Takeaways ------------- - In sepsis/SIRS, endocrine changes follow a pattern: **cortisol up**, **insulin resistance up**, **T3 signaling down (NTIS)**. - Cortisol is **pressor-permissive**; suspect functional insufficiency (CIRCI) in **vasopressor-dependent septic shock**. - For septic shock with ongoing vasopressor needs, **hydrocortisone 200 mg/day** is the dose to know. [\[1\]](#cite-1 "Reference [1]") - Stress hyperglycemia is driven by hormones + cytokines; treat persistent **≥180 mg/dL**, usually targeting about **140–200 mg/dL** to reduce hypoglycemia risk. [\[3\]](#cite-3 "Reference [3]") - NTIS is common: **low T3/high rT3**, often normal TSH early; routine thyroid hormone therapy for NTIS is **not recommended**. Conclusion ---------- If you want a simple sepsis endocrine checklist in your head, keep it this tight: **cortisol supports tone, insulin resistance reallocates fuel, and NTIS slows the metabolic thermostat**. Your job isn’t to normalize every lab—it’s to recognize when these “adaptive” shifts have tipped into hemodynamic instability, iatrogenic hypoglycemia, or diagnostic misfires that derail care. References (6) ------------------ 1. 1. [ sccm.org/survivingsepsiscampaign/guidelines-and-resources/surviving-sepsis-campaign-adult-guidelines ](https://sccm.org/survivingsepsiscampaign/guidelines-and-resources/surviving-sepsis-campaign-adult-guidelines) [↩](#cite-ref-1-1 "Back to text") 2. 2. [ www.guidelinecentral.com/insights/july-2025-sccm-corticosteroidssepsis-guideline-timeline ](https://www.guidelinecentral.com/insights/july-2025-sccm-corticosteroidssepsis-guideline-timeline) [↩](#cite-ref-2-1 "Back to text") 3. 3. [ journals.lww.com/ccmjournal/fulltext/2024/04000/society\_of\_critical\_care\_medicine\_guidelines\_on.22.aspx ](https://journals.lww.com/ccmjournal/fulltext/2024/04000/society_of_critical_care_medicine_guidelines_on.22.aspx) [↩](#cite-ref-3-1 "Back to text") 4. 4. [ www.ncbi.nlm.nih.gov/books/NBK279093 ](https://www.ncbi.nlm.nih.gov/books/NBK279093/) [↩](#cite-ref-4-1 "Back to text") 5. 5. [ academic.oup.com/jes/article/3/12/2313/5587649 ](https://academic.oup.com/jes/article/3/12/2313/5587649) [↩](#cite-ref-5-1 "Back to text") 6. 6. [ pubmed.ncbi.nlm.nih.gov/35620389 ](https://pubmed.ncbi.nlm.nih.gov/35620389/) [↩](#cite-ref-6-1 "Back to text") Keep going Build momentum in Anesthesiology with focused, exam‑style practice -------------------------------------------------------------------- - Airway, ventilation, and crisis drills - High‑yield anesthesia pharmacology made practical - Track weak topics and improve faster [ Start practicing ](https://mdster.com/user/dashboard) [ Explore Anesthesiology ](https://mdster.com/speciality/anesthesiology) [ View pricing ](https://mdster.com/pricing) [ Explore features ](https://mdster.com/features) No credit card required. Full access to all features. No commitment. Cancel anytime. 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