NVS- 2025
Biochemistry & Nutrition
Easy
The precursor for the synthesis of steroid hormone:
Appeared in: NVS- 2025
Explanation
- Cholesterol is the primary structural backbone and initial substrate for the synthesis of all steroid hormones.
- Steroidogenic tissues, such as the adrenal glands and gonads, utilize cholesterol from circulating lipoproteins or synthesize it de novo to initiate hormone production.
- The conversion of cholesterol to pregnenolone is the first and rate-limiting step in the entire steroidogenesis pathway.
- All major steroid hormones, including glucocorticoids, mineralocorticoids, and sex steroids, are ultimately derivatives of the cholesterol molecule.
Why Other Options Were Wrong
- Option A: Pregnenolone is a crucial intermediate in steroid synthesis, but it is not the initial precursor. It is the first steroid hormone formed from cholesterol.
- Option C: Thyroglobulin is a large glycoprotein produced in the thyroid gland. It acts as a scaffold for the synthesis and storage of thyroid hormones (T3 and T4), not steroid hormones.
- Option D: Tyrosine is an amino acid. It serves as the precursor for the synthesis of amine hormones, specifically catecholamines (like epinephrine and dopamine) and thyroid hormones.
Related Visual
Clinical Relevance
- Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormone Synthesis Precursors as background academic context rather than a clinical decision trigger.
- Understanding that cholesterol is the precursor to steroid hormones is vital for nurses, as cholesterol-lowering drugs (statins) can potentially impact hormone levels, although this is not typically a major clinical concern.
- Patients with genetic disorders affecting steroidogenic enzymes (e.g., Congenital Adrenal Hyperplasia) have disrupted hormone production, leading to serious health issues that require lifelong management.
- Nurses monitor patients for signs of hormonal imbalance, which can be related to issues in the steroid synthesis pathway, such as adrenal insufficiency or excess.
How to Approach the Question
- First, identify the key terms in the question: 'precursor' and 'steroid hormone'.
- Recall the major biochemical classes of hormones: steroids (lipid-derived), peptides/proteins, and amines (amino acid-derived).
- Recognize that steroid hormones are synthesized from a lipid base. This helps eliminate amino acid-based options like Tyrosine.
- Differentiate between the initial precursor and intermediate products. Cholesterol is the foundational molecule for the entire steroid ring structure.
- Evaluate the options: Cholesterol is a well-known lipid. Pregnenolone is also part of the pathway, but it's a step after cholesterol. Thyroglobulin and Tyrosine are related to thyroid and amine hormones, respectively, not steroids.
- Select Cholesterol as the most fundamental starting material for all steroid hormones.
Concept Tested & Keywords
- Concept Tested: Hormone Synthesis Precursors
- Stem keywords: precursor, synthesis, steroid hormone
- Lead-in keywords: BEST, MOST RELEVANT CLUE
- Negative lead-in flag: false
Question ID
QaHSgi86Aa2nEH7NEUsvoe
Reference Book
E6 Gynecology Williams p. 353-421
E6 Robert Boland, Marcia L. Verduin - Kaplan and Sadock's Comprehensive Text of Psychiatry-Wolters Kluwer Health (2024) (pp 1-16525 of 16525) p. 11098-11100
E6 Harper's Illustrated Biochemistry2023 (pp 26-793 of 813) p. 484-486
Practise the full NVS- 2025
Attempt every question from this paper in a timed mock, then review the full solution for each one.
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