Question:medium
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
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
Show Hint
Mid luteal serum progesterone, around day 20 to 22, is the standard test to confirm ovulation.
Updated On: Jul 8, 2026
- FSH
- LH
- Oestradiol
- Progesterone
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: Place day 20 in the cycle.
In a textbook 28 day cycle, day 20 sits about a week after ovulation, squarely in the luteal phase.
Step 2: Ask what is unique to this phase.
Once an egg is released, the empty follicle turns into the corpus luteum, and this structure is the only source of a large, sustained rise in progesterone during the cycle.
Step 3: Connect this to proof of ovulation.
Because progesterone only rises this way if a corpus luteum has formed, and a corpus luteum only forms after an egg has actually been released, a high day 20 progesterone is direct, reliable proof of ovulation. This is why clinicians order a day 21 progesterone test to check for ovulation.
Step 4: Compare with the other hormones.
FSH and LH both have their important peaks earlier in the cycle, around the time of ovulation itself, and are back to baseline by day 20, so they cannot confirm what already happened a week earlier. Oestradiol rises with follicle growth in general and is not specific to a functioning corpus luteum, so it is a weaker marker than progesterone for this purpose.
Step 5: Conclude.
The valid marker of ovulation at day 20 is serum progesterone.
\[ \boxed{\text{Progesterone}} \]
In a textbook 28 day cycle, day 20 sits about a week after ovulation, squarely in the luteal phase.
Step 2: Ask what is unique to this phase.
Once an egg is released, the empty follicle turns into the corpus luteum, and this structure is the only source of a large, sustained rise in progesterone during the cycle.
Step 3: Connect this to proof of ovulation.
Because progesterone only rises this way if a corpus luteum has formed, and a corpus luteum only forms after an egg has actually been released, a high day 20 progesterone is direct, reliable proof of ovulation. This is why clinicians order a day 21 progesterone test to check for ovulation.
Step 4: Compare with the other hormones.
FSH and LH both have their important peaks earlier in the cycle, around the time of ovulation itself, and are back to baseline by day 20, so they cannot confirm what already happened a week earlier. Oestradiol rises with follicle growth in general and is not specific to a functioning corpus luteum, so it is a weaker marker than progesterone for this purpose.
Step 5: Conclude.
The valid marker of ovulation at day 20 is serum progesterone.
\[ \boxed{\text{Progesterone}} \]
Was this answer helpful?
0
