Anaes · Applied cardiovascular & respiratory physiology
Endocrine physiology: glucose, thyroid & adrenal
Also known as Glucose homeostasis · Insulin glucagon · Thyroid hormones · Cortisol · Stress response · Adrenal medulla
The endocrine system controls glucose, metabolic rate and the stress response, and its disorders are among the most common comorbidities the anaesthetist manages. The framework rests on five exam-critical ideas: blood glucose is held within a narrow range by insulin (beta-cell, anabolic, lowers glucose by driving it into cells and promoting glycogen and fat synthesis) and glucagon (alpha-cell, catabolic, raises glucose by glycogenolysis and gluconeogenesis); the thyroid axis (TRH then TSH then T4 and T3) sets the basal metabolic rate, heart rate and thermogenesis, and hyperthyroidism raises and hypothyroidism lowers them; the adrenal cortex makes cortisol (the stress hormone, driving gluconeogenesis and suppressing inflammation) and aldosterone (sodium and water retention); the adrenal medulla is a modified sympathetic ganglion releasing adrenaline; and the stress response to surgery raises cortisol, catecholamines, ADH and ACTH, producing hyperglycaemia, sodium retention and a catabolic state. Built on the semaglutide/GLP-1 study (Shahabian 2026), the PKA-insulin-secretion study (Liu 2026), the obesity-pharmacotherapy review (Bonafede 2026), the stress-axis review (Mancuso 2026), the cortisol-stress-reactivity study (Serin 2026), and the thyroid-hormone study (da Silva 2026).
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8 MCQs with explanations
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Meet the patient
A 62-year-old on prednisolone 10 mg daily for rheumatoid arthritis is admitted for a hemicolectomy. He is nil by mouth, his morning steroid is held "because he is fasting", and four hours into the operation his blood pressure drifts to 70 systolic and will not respond to fluid or metaraminol.[4]
That refractory, vasopressor-resistant hypotension in a steroid-suppressed patient under surgical stress is adrenal crisis until proven otherwise — and the treatment is empirical intravenous hydrocortisone, not a seventh litre of fluid. Hold the picture, and the whole HPA axis below becomes a tool to prevent it.[5]
You have read the opening of this topic. The complete unit — every section and its primary-source references — is part of the Anaesthesia fellowship atlas.
References6Show ledgerHide ledger
- [1]Shahabian L, et al. Semaglutide Selectively Improves Metabolic and Cognitive Function in 5xFAD Mice Int J Mol Sci, 2026.PMID 42353032
- [2]Liu Y, et al. Type IIB PKA serves as the primary effector of Gs-coupled receptor-potentiated insulin secretion in mice by orchestrating ion channels and granule phenotype Diabetologia, 2026.PMID 42337176
- [3]Bonafede M, et al. Overview of Novel Mechanisms in Obesity Pharmacotherapy and Implications for Cardiovascular Disease: A Narrative Review Curr Atheroscler Rep, 2026.PMID 42360622
- [4]Mancuso C. Carbon Monoxide: A Context-Dependent Regulator of the Stress Axis Biomolecules, 2026.PMID 42352364
- [5]Serin E, et al. Linking brain structure to stress reactivity: cingulate surface area predicts acute cortisol responses Psychol Med, 2026.PMID 41943954
- [6]da Silva WST, et al. Coat characteristics, physiological traits, serum metabolites, and thyroid hormones of Canindé and Moxotó goats in a semiarid environment Trop Anim Health Prod, 2026.PMID 42360558