Question

The laboratory report shows values of gonadotropin and ovarian hormone levels of the blood sample taken on day 20 of the menstrual cycle of a young woman. Whether her cycle was ovulatory or not may be validly assessed by the reported serum levels of

• A. FSH
• B. LH
• C. Oestradiol
• D. Progesterone

Hint:

Mid luteal serum progesterone, around day 20 to 22, is the standard test to confirm ovulation.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks which hormone level, measured from blood drawn on day 20 of the cycle, confirms whether ovulation actually took place.

Step 2: Key Formula or Approach:
In a normal 28 day cycle, ovulation happens around day 14. Day 20 falls in the mid luteal phase, the phase that follows ovulation and is marked by the corpus luteum, the structure left behind after the egg is released, actively secreting progesterone.

Step 3: Detailed Explanation:
Progesterone is secreted almost only by the corpus luteum, so a clearly raised serum progesterone in the mid luteal phase, around day 20 to 22 of a 28 day cycle, is direct proof that a follicle ruptured and released an egg, forming a functioning corpus luteum. If the cycle was anovulatory, no corpus luteum forms and progesterone stays low throughout, this is exactly why a mid luteal progesterone test is the standard clinical way to confirm ovulation.
FSH does rise before ovulation to drive follicle growth, but by day 20 it has already settled to a low, non specific level and does not by itself prove that ovulation occurred.
LH shows a sharp surge just before ovulation, around day 13 to 14, but by day 20 this surge is long over, so a day 20 LH level does not reliably confirm that ovulation actually happened.
Oestradiol peaks just before the LH surge to trigger ovulation, but its luteal phase level is a less reliable single marker of ovulation compared to progesterone, since oestradiol is produced by growing follicles in general, not only by a functioning corpus luteum.

Step 4: Final Answer:
A mid luteal serum progesterone level, drawn on day 20, is the valid way to confirm that a cycle was ovulatory, so the correct option is (D).