ACTH MCQs With Answer

ACTH MCQs With Answer

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ACTH MCQs With Answer provides B. Pharm students a focused, practical review of adrenocorticotropic hormone (ACTH): its synthesis from POMC, regulation by CRH, receptor (MC2R) signaling via cAMP/PKA, and actions on the adrenal cortex to stimulate cortisol, androgens, and adrenal growth. This set emphasizes clinical correlations—Cushing’s disease, Addison’s disease, ectopic ACTH, diagnostic tests (ACTH stimulation, dexamethasone suppression, metyrapone), laboratory handling, and pharmacologic agents like cosyntropin. Questions blend molecular mechanisms, physiology, pathology, and therapeutics to deepen understanding and exam readiness. Key terms include ACTH, POMC, CRH, cortisol, MC2R, cosyntropin, Cushing’s, and adrenal insufficiency. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which pituitary cell type secretes ACTH?

  • Somatotrophs
  • Lactotrophs
  • Corticotrophs
  • Thyrotrophs

Correct Answer: Corticotrophs

Q2. ACTH is derived from which precursor polypeptide?

  • Proinsulin
  • Proopiomelanocortin (POMC)
  • Preprosomatostatin
  • Prolactin

Correct Answer: Proopiomelanocortin (POMC)

Q3. The primary hypothalamic hormone that stimulates ACTH release is:

  • GHRH
  • TRH
  • CRH (corticotropin-releasing hormone)
  • Somatostatin

Correct Answer: CRH (corticotropin-releasing hormone)

Q4. The main target tissue of ACTH is the:

  • Adrenal medulla
  • Adrenal cortex
  • Thyroid gland
  • Pancreas

Correct Answer: Adrenal cortex

Q5. Which receptor mediates ACTH action on adrenal cortical cells?

  • MC1R
  • MC2R
  • GLP-1 receptor
  • Beta-2 adrenergic receptor

Correct Answer: MC2R

Q6. ACTH primarily activates which intracellular signaling pathway in the adrenal cortex?

  • cGMP/PKG
  • JAK/STAT
  • cAMP/PKA
  • PLC/IP3/DAG

Correct Answer: cAMP/PKA

Q7. A direct effect of ACTH on steroidogenesis is to:

  • Inhibit 21-hydroxylase activity
  • Increase expression of steroidogenic enzymes and StAR protein
  • Block cholesterol transport into mitochondria
  • Decrease cortisol synthesis

Correct Answer: Increase expression of steroidogenic enzymes and StAR protein

Q8. Which adrenal cortical zone is most responsive to ACTH for cortisol production?

  • Zona glomerulosa
  • Zona fasciculata
  • Zona reticularis
  • Adrenal medulla

Correct Answer: Zona fasciculata

Q9. Elevated ACTH can cause hyperpigmentation because of increased production of:

  • Thyroxine
  • Alpha-MSH derived from POMC
  • Insulin
  • Renin

Correct Answer: Alpha-MSH derived from POMC

Q10. ACTH secretion follows a circadian rhythm with peak levels typically:

  • At midnight
  • In the late afternoon
  • Early morning around wakening
  • Uniform throughout the day

Correct Answer: Early morning around wakening

Q11. In primary adrenal insufficiency (Addison’s disease), ACTH and cortisol changes are typically:

  • Low ACTH, low cortisol
  • High ACTH, low cortisol
  • High ACTH, high cortisol
  • Low ACTH, high cortisol

Correct Answer: High ACTH, low cortisol

Q12. A common cause of ectopic ACTH production is:

  • Small cell lung carcinoma
  • Prostate adenocarcinoma
  • Basal cell carcinoma
  • Pancreatic beta-cell tumor

Correct Answer: Small cell lung carcinoma

Q13. Which statement differentiates Cushing’s disease from ectopic ACTH syndrome?

  • Pituitary adenomas produce ectopic ACTH
  • Cushing’s disease refers to pituitary ACTH-secreting adenoma
  • Ectopic ACTH always responds to low-dose dexamethasone
  • Cushing’s syndrome only results from adrenal tumors

Correct Answer: Cushing’s disease refers to pituitary ACTH-secreting adenoma

Q14. A diagnostic feature of primary adrenal failure on ACTH stimulation test is:

  • Marked increase in cortisol after ACTH
  • No significant rise in cortisol after ACTH
  • Immediate suppression of ACTH secretion
  • Normalization of cortisol within 5 minutes

Correct Answer: No significant rise in cortisol after ACTH

Q15. The synthetic ACTH preparation commonly used for diagnostic testing is:

  • Dexamethasone
  • Cosyntropin (tetracosactide)
  • Metyrapone
  • Hydrocortisone acetate

Correct Answer: Cosyntropin (tetracosactide)

Q16. Chronic overstimulation by ACTH typically leads to which adrenal change?

  • Adrenal cortical atrophy
  • Adrenal cortical hyperplasia
  • Medullary hypertrophy
  • Decrease in adrenal androgen synthesis

Correct Answer: Adrenal cortical hyperplasia

Q17. The primary negative feedback on ACTH secretion is exerted by:

  • Aldosterone
  • Cortisol
  • Catecholamines
  • Insulin

Correct Answer: Cortisol

Q18. Which melanocortin receptor is primarily responsible for adrenal responsiveness to ACTH?

  • MC1R (skin pigmentation)
  • MC2R (adrenal)
  • MC3R (energy homeostasis)
  • MC4R (appetite regulation)

Correct Answer: MC2R (adrenal)

Q19. The metyrapone test assesses the integrity of the HPA axis by blocking which enzyme?

  • Aromatase
  • 11β-hydroxylase
  • 17α-hydroxylase
  • 21-hydroxylase

Correct Answer: 11β-hydroxylase

Q20. Human ACTH peptide consists of how many amino acids?

  • 20 amino acids
  • 39 amino acids
  • 85 amino acids
  • 112 amino acids

Correct Answer: 39 amino acids

Q21. The approximate plasma half-life of ACTH is closest to:

  • 30 seconds
  • 10 minutes
  • 2 hours
  • 24 hours

Correct Answer: 10 minutes

Q22. Processing of POMC in pituitary corticotrophs yields which peptides?

  • Insulin and glucagon
  • Alpha-MSH and beta-endorphin
  • TSH and LH
  • Prolactin and GH

Correct Answer: Alpha-MSH and beta-endorphin

Q23. ACTH primarily increases which class of adrenal steroids?

  • Mineralocorticoids (aldosterone) predominantly
  • Glucocorticoids (cortisol) predominantly
  • Thyroid hormones
  • Catecholamines

Correct Answer: Glucocorticoids (cortisol) predominantly

Q24. Proper laboratory handling for plasma ACTH measurement requires:

  • Serum collected in plain tube at room temperature
  • EDTA plasma kept cold and rapid processing
  • Heparinized plasma left at 37°C for 2 hours
  • Whole blood stored at room temperature for 24 hours

Correct Answer: EDTA plasma kept cold and rapid processing

Q25. Which of the following is true regarding clinically available ACTH receptor antagonists?

  • Several selective MC2R antagonists are widely used in practice
  • No specific MC2R antagonist is routinely approved for clinical use
  • Beta-blockers act as effective MC2R antagonists
  • Spiro compounds are standard MC2R blockers

Correct Answer: No specific MC2R antagonist is routinely approved for clinical use

Q26. In classic 21-hydroxylase deficiency (congenital adrenal hyperplasia), expected ACTH levels are:

  • Low due to excess cortisol
  • Normal due to intact feedback
  • Elevated because of decreased cortisol synthesis
  • Undetectable because of pituitary failure

Correct Answer: Elevated because of decreased cortisol synthesis

Q27. A high-dose dexamethasone suppression test that suppresses cortisol suggests:

  • Ectopic ACTH production
  • Pituitary ACTH-secreting adenoma
  • Primary adrenal carcinoma
  • Exogenous cortisol use

Correct Answer: Pituitary ACTH-secreting adenoma

Q28. ACTH promotes acute steroidogenesis primarily by facilitating transport of cholesterol into mitochondria via:

  • StAR protein (steroidogenic acute regulatory protein)
  • HMG-CoA reductase
  • Low-density lipoprotein receptor degradation
  • CYP11B1 enzyme inhibition

Correct Answer: StAR protein (steroidogenic acute regulatory protein)

Q29. Which adrenal zone contributes most to androgen (DHEA) production stimulated by ACTH?

  • Zona glomerulosa
  • Zona fasciculata
  • Zona reticularis
  • Adrenal medulla

Correct Answer: Zona reticularis

Q30. The principal clinical use of synthetic ACTH (cosyntropin) is to:

  • Treat chronic Cushing’s syndrome
  • Diagnose adrenal insufficiency via stimulation testing
  • Suppress pituitary ACTH secretion
  • Replace aldosterone in Addison’s disease

Correct Answer: Diagnose adrenal insufficiency via stimulation testing

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