Oestrone MCQs With Answer — The following set of multiple-choice questions is designed for B.Pharm students to deepen understanding of oestrone, a key estrogen steroid hormone. Topics include oestrone structure, biosynthesis from androstenedione, interconversion with estradiol, metabolic conjugation (sulfation/glucuronidation), pharmacokinetics, estrogen receptor affinity, clinical relevance in hormone replacement therapy and breast cancer, analytical assays (immunoassay, LC-MS), and drug interactions affecting estrogen metabolism. These MCQs emphasize mechanisms, therapeutic implications, and laboratory interpretation to build applied pharmacological knowledge and exam readiness. Clear, targeted questions will help you master oestrone’s pharmacology, endocrine physiology, and clinical significance. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which biosynthetic precursor is primarily converted to oestrone in peripheral tissues?
- Testosterone
- Androstenedione
- Cholesterol
- DHEA
Correct Answer: Androstenedione
Q2. Which enzyme catalyzes the aromatization of androstenedione to oestrone?
- 17β-Hydroxysteroid dehydrogenase (17β-HSD)
- Aromatase (CYP19A1)
- Sulfotransferase (SULT1E1)
- 3β-Hydroxysteroid dehydrogenase
Correct Answer: Aromatase (CYP19A1)
Q3. Oestrone is interconverted with which more potent estrogen by 17β-HSD enzymes?
- Estriol
- Estradiol (E2)
- Progesterone
- Testosterone
Correct Answer: Estradiol (E2)
Q4. Compared to estradiol, oestrone’s intrinsic estrogen receptor affinity is generally:
- Much higher
- Similar
- Lower
- Non-existent
Correct Answer: Lower
Q5. Which conjugated form of oestrone acts as a circulating reservoir with extended half-life?
- Oestrone glucuronide
- Oestrone sulfate
- Oestrone phosphate
- Oestrone acetate
Correct Answer: Oestrone sulfate
Q6. Major hepatic phase II reactions of oestrone include:
- Oxidation and reduction
- Sulfation and glucuronidation
- Methylation and acetylation
- Hydroxylation only
Correct Answer: Sulfation and glucuronidation
Q7. Which enzyme converts oestrone to its 17β-reduced active form estradiol?
- 17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1)
- Sulfotransferase
- Aromatase
- CYP3A4
Correct Answer: 17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1)
Q8. In postmenopausal women, the primary source of circulating oestrone is:
- Ovarian granulosa cells
- Peripheral adipose tissue aromatization
- Placenta
- Hypothalamus
Correct Answer: Peripheral adipose tissue aromatization
Q9. Which clinical condition is most directly associated with elevated local oestrone production in breast tissue?
- Osteoporosis
- Breast cancer
- Type 1 diabetes
- Parkinson’s disease
Correct Answer: Breast cancer
Q10. Which analytical method provides highest specificity and sensitivity for measuring oestrone in plasma?
- Radioimmunoassay (RIA)
- Enzyme-linked immunosorbent assay (ELISA)
- Gas chromatography-mass spectrometry (GC-MS) or LC-MS/MS
- UV spectrophotometry
Correct Answer: Gas chromatography-mass spectrometry (GC-MS) or LC-MS/MS
Q11. Which drug class can increase oestrone levels by inducing aromatase activity or increasing androgen precursors?
- Aromatase inhibitors
- CYP19A1 inhibitors
- Glucocorticoids
- Certain progestins or exogenous androgens
Correct Answer: Certain progestins or exogenous androgens
Q12. Aromatase inhibitors (e.g., anastrozole) used in breast cancer act by:
- Stimulating 17β-HSD to produce estradiol
- Blocking conversion of androgens to estrogens including oestrone
- Enhancing estrogen receptor expression
- Increasing oestrone sulfation
Correct Answer: Blocking conversion of androgens to estrogens including oestrone
Q13. Oestrone sulfate can be converted back to active oestrone by which enzyme in peripheral tissues?
- Sulfotransferase (SULT)
- Sulfatase (arylsulfatase)
- UDP-glucuronosyltransferase (UGT)
- CYP1A2
Correct Answer: Sulfatase (arylsulfatase)
Q14. The majority of circulating oestrone is present in which form?
- Free (unconjugated) oestrone
- Protein-bound free oestrone
- Conjugated, primarily as oestrone sulfate
- Bound to red blood cells
Correct Answer: Conjugated, primarily as oestrone sulfate
Q15. Which statement about oestrone’s potency and clinical effects is correct?
- Oestrone is more potent than estradiol at estrogen receptors.
- Oestrone has negligible estrogenic activity in vivo.
- Oestrone is less potent than estradiol but contributes to estrogenic effects after conversion.
- Oestrone acts exclusively on ERβ with no ERα activity.
Correct Answer: Oestrone is less potent than estradiol but contributes to estrogenic effects after conversion.
Q16. Which pharmacokinetic property is extended for oestrone when present as oestrone sulfate?
- Volume of distribution
- Metabolic clearance
- Half-life due to circulating reservoir
- Renal excretion rate
Correct Answer: Half-life due to circulating reservoir
Q17. In HRT formulations, why is monitoring estrone levels relevant?
- Estrone indicates androgen status only
- Estrone concentrations predict thrombotic risk directly
- Estrone reflects peripheral conversion and overall estrogen exposure
- Estrone measurement is irrelevant in HRT
Correct Answer: Estrone reflects peripheral conversion and overall estrogen exposure
Q18. Which cytochrome P450 isoform contributes to estrogen hydroxylation that inactivates oestrone?
- CYP19A1
- CYP3A4 and CYP1A2
- CYP2D6 only
- CYP21A2
Correct Answer: CYP3A4 and CYP1A2
Q19. Which clinical lab interference can falsely elevate immunoassay-measured oestrone concentrations?
- Cross-reactivity with conjugated metabolites
- Hemolysis reduces measured values only
- Low albumin increases specificity
- High glucose causes suppression
Correct Answer: Cross-reactivity with conjugated metabolites
Q20. 17β-HSD type 2 primarily catalyzes which reaction relevant to oestrone/estradiol metabolism?
- Conversion of estrone to estradiol
- Conversion of estradiol to estrone (oxidation)
- Sulfation of oestrone
- Aromatization of androgens
Correct Answer: Conversion of estradiol to estrone (oxidation)
Q21. Which tissue expresses high sulfatase activity enabling local activation of oestrone sulfate?
- Adipose tissue
- Breast and endometrial tissue
- Hair follicles
- Kidney cortex only
Correct Answer: Breast and endometrial tissue
Q22. Which therapeutic strategy reduces intratumoral oestrone production in estrogen-dependent breast cancer?
- Progestin-only therapy
- Aromatase inhibition
- Sulfatase activation
- Estrogen supplementation
Correct Answer: Aromatase inhibition
Q23. Elevated circulating oestrone relative to estradiol in postmenopausal women is largely due to:
- Increased ovarian secretion of estradiol
- Peripheral aromatization of androstenedione producing more oestrone
- High dietary phytoestrogens converting to estradiol
- Enhanced 17β-HSD1 activity producing estradiol
Correct Answer: Peripheral aromatization of androstenedione producing more oestrone
Q24. Which laboratory specimen handling is preferred for accurate LC-MS measurement of oestrone?
- No special handling; room temperature storage for 72 hours
- Immediate freezing and use of proper extraction to remove conjugates
- Adding EDTA causes hydrolysis and increases signal
- Exposure to sunlight improves assay sensitivity
Correct Answer: Immediate freezing and use of proper extraction to remove conjugates
Q25. Which receptor subtype does oestrone preferentially activate compared to estradiol?
- ERα with higher potency than ERβ
- ERβ exclusively
- No strong preference; generally weaker at both ERα and ERβ
- G protein-coupled estrogen receptor (GPER) only
Correct Answer: No strong preference; generally weaker at both ERα and ERβ
Q26. Which drug interaction is most likely to lower oestrone concentrations?
- CYP3A4 inhibitors
- Strong enzyme inducers increasing hepatic metabolism (e.g., rifampicin)
- Estrogen receptor modulators like tamoxifen increasing oestrone synthesis
- Sulfonylureas
Correct Answer: Strong enzyme inducers increasing hepatic metabolism (e.g., rifampicin)
Q27. Estrone’s role in bone physiology is primarily mediated via:
- Direct androgen receptor activation
- Estrogen receptor-mediated modulation of bone resorption and formation
- Mineralocorticoid receptor binding
- Inhibition of vitamin D activation
Correct Answer: Estrogen receptor-mediated modulation of bone resorption and formation
Q28. In the context of endocrine pharmacology, oestrone glucuronide primarily indicates:
- Active free estrogen available for receptor binding
- Phase II metabolism and urinary excretion of estrogen
- Increased aromatase expression
- Adrenal estrogen synthesis
Correct Answer: Phase II metabolism and urinary excretion of estrogen
Q29. Which clinical measure would most directly reduce peripheral oestrone production?
- Weight loss to reduce adipose aromatase activity
- High-dose estrogen supplementation
- Supplemental DHEA therapy
- Administering sulfur-containing supplements
Correct Answer: Weight loss to reduce adipose aromatase activity
Q30. A selective estrogen receptor modulator (SERM) can affect oestrone action by:
- Directly inhibiting aromatase enzyme
- Altering estrogen receptor conformation to produce tissue-specific agonist/antagonist effects
- Increasing sulfatase activity to raise oestrone sulfate levels
- Converting oestrone to estriol
Correct Answer: Altering estrogen receptor conformation to produce tissue-specific agonist/antagonist effects
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com