Cortisol
Cushing syndrome produces central obesity, purple striae, proximal weakness, hypertension and hyperglycaemia, and cortisol that is not suppressed by dexamethasone.
Cortisol
- Role During Stress : The demand for cortisol increases during stress and tissue repair (e.g., wound healing), highlighting its importance in the body's adaptive responses.
- Glucose Production : Cortisol promotes gluconeogenesis, the process of converting amino acids into glucose in the liver, ensuring that blood glucose levels are maintained, especially during fasting or stress.
- Protein Catabolism : It enhances the breakdown of proteins, releasing amino acids that can be converted into glucose, which is critical for energy production.
- Mineralocorticoid Activity : While primarily glucocorticoid in function, cortisol also exhibits some mineralocorticoid activity, contributing to sodium retention and fluid balance.
Read this in LECTURE 6: Pancreatic and Adrenal Hormones
What our notes say
- Cushing syndrome produces central obesity, purple striae, proximal weakness, hypertension and hyperglycaemia, and cortisol that is not suppressed by dexamethasone. (Endocrinology and Gastroenterology Question Bank: 12 Clinical MCQs)
- | Adrenal | Total cortisol rises; free cortisol is unchanged; aldosterone rises (salt and water retention) | (Physiological changes in pregnancy)
- Total T4 (more TBG), free cortisol, prolactin and oestradiol clearly rise. (Reproductive Health 1 End of Trimester CAT: 40 MCQs and 4 short answers)
- Severe adrenal insufficiency resulting in dangerously low serum cortisol levels (Internal Medicine 4th Year Endocrinology CAT: 30 MCQs)
- About half of patients with severe depression have a raised cortisol (a failure of dexamethasone suppression). (Psychiatry Year 4 CAT: June 2023, schizophrenia, dementia, eating disorders and )
- Central obesity, striae, proximal myopathy and hypertension, with failure of cortisol suppression after low-dose dexamethasone (Endocrinology and Gastroenterology Question Bank: 12 Clinical MCQs)
Study material on Cortisol
- Endocrine and Metabolic Pathology MCQs: Practice Questions
- LECTURE 6: Pancreatic and Adrenal Hormones
- Endocrine and Metabolic Pathology MCQs for Medical Students
- Chemical Pathology Practice Examination
- Endocrine and Metabolic Pathology MCQs
- ENDOCRINE PATHOLOGY
- Chemical Pathology MCQs: Clinical Chemistry, Endocrine & Renal
- Chemical Pathology MCQs
- Endocrine & Renal Pathology
- Renal, Liver, Cardiac & Adrenal Function Tests for Year 3
- Endocrine & Renal Pathology
- Endocrine & Renal Pathology
- Chemical Pathology MCQs
Practice questions on Cortisol
Which is true regarding cortisol?
- Its production results in lowering of blood glucose
- Its level is highest just before sunrise
- It stimulates production of ACTH
- It’s not involved in the fight-or-flight response ✅ Answer: B. Its level is highest just before sunrise
Answer: A. Its level is highest just before sunrise is the physiologically correct answer per standard MBChB-level teaching on this topic. ---
Which of the following options is NOT a basal level (unstressed) function of cortisol?
- Promote fetal development of brain, intestines, and lungs
- Promote an adequate amount of glucose in the plasma between meals
- Promote bone resorption
- Maintain adequate mean arterial blood pressure
- Provide an anti-inflammatory function that prevents hyper-immune responses
Answer: E. While cortisol has anti-inflammatory effects, preventing hyper-immune responses is primarily a stress response function, not a basal function. ---
A 60-year-old man presents with weight gain, moon facies, and hypertension. Labs: Cortisol remains high after low-dose dexamethasone suppression test. What is the likely diagnosis?
- Cushing's syndrome
- Addison's disease
- Hyperthyroidism
- Acromegaly Correct
Answer: A. Failure to suppress cortisol with low-dose dexamethasone confirms Cushing's syndrome. Clinical features support this diagnosis. ---
A 30-year-old woman presents with fatigue, hypotension, and hyperpigmentation. Labs: Na⁺ 129 mmol/L, K⁺ 5.8 mmol/L, Cortisol low. What is the likely diagnosis?
- Addison's disease
- Cushing's syndrome
- SIADH
- Hyperaldosteronism Correct
Answer: A. Low cortisol with hyponatremia, hyperkalemia, and hyperpigmentation are classic for primary adrenal insufficiency (Addison's disease). ---
A patient with a central lung mass develops Cushing syndrome with high urinary cortisol that fails high-dose dexamethasone suppression. Which tumour is most responsible?
- Squamous cell carcinoma producing ectopic PTH-related peptide
- Adenocarcinoma with bilateral adrenal metastases destroying cortical tissue
- Small cell carcinoma producing ectopic ACTH causing Cushing syndrome
- Large cell carcinoma with direct hypothalamic invasion altering cortisol feedback
Answer: C. SCLC produces ectopic ACTH causing Cushing syndrome that characteristically fails high-dose dexamethasone suppression — distinguishing it from pituitary-driven Cushing disease. ---
A 70-year-old man with type 2 diabetes, hypertension, and recent weight gain develops Cushingoid features. Morning cortisol is 800 nmol/L (normal <500). ACTH is low. What is the MOST likely diagnosis?
- Ectopic ACTH syndrome
- Cushing's disease (pituitary adenoma)
- Adrenal adenoma producing cortisol
- Adrenal hyperplasia
Answer: C. Low ACTH with high cortisol indicates primary adrenal pathology. A unilateral adrenal adenoma or carcinoma secreting cortisol is the most likely cause of Cushing's syndrome in this scenario. Cushing's disease (pituitary) would have high ACTH. ---