6 office tests to assess ovarian reserve, and what they tell you
Several tests of ovarian reserve are at your disposal. The help is welcome—but they’re not equally informative or reliable.
IN THIS ARTICLE
The University of Medicine and Dentistry of New Jersey (UMDNJ) owns a patent relating to the use of anti-Müllerian hormone/Müllerian inhibiting substance for predicting ovarian response in women with infertility. The patent is based in part on work that Dr. Seifer carried out while employed at UMDNJ. In accordance with UMDNJ policy, Dr. Seifer, a named inventor on this patent, assigned his interest in the invention to UMDNJ. UMDNJ has a licensing agreement with Diagnostic Systems Laboratory for the use of the claimed invention. Dr. Seifer receives a portion of the royalties, as determined by UMDNJ policy, that UMDNJ gains from this licensing agreement.
CASE: Borderline test result prompts referral
A 36-year-old nulliparous woman is seen in your office for evaluation after 6 months of infertility. She is ovulatory, and has been using an ovulation-prediction kit to time intercourse. You learn that she had Chlamydia trachomatis infection in the distant past, but elicit no other significant medical or surgical history. She reports that she smoked approximately one pack of cigarettes a day for 15 years but gave up smoking 5 years ago.
You order a hysterosalpingogram, followed by day 3 testing of follicle-stimulating hormone (FSH). The hysterosalpingogram is normal; the FSH level is 7.5 mIU/mL and the estradiol level is 30 pg/mL—both in the normal range.
The patient asks for testing of anti-Müllerian hormone (AMH; also known as Müllerian-inhibiting substance) because she has read that it is a new marker of fertility. The result is 0.5 ng/mL, a borderline value. After reviewing these results, you refer her to a reproductive endocrinologist for further management.
Was the test for AMH indicated? And is this referral appropriate?
The referral is entirely appropriate, even though the patient has not been trying to conceive for a full year. Why? The AMH value suggests that her ovarian reserve is in early decline. She would benefit from evaluation by a subspecialist who can review the entire spectrum of treatments, including aggressive options such as ovulation induction and in vitro fertilization (IVF), to optimize her reproductive success.
This article reviews the various biomarkers available to assess ovarian reserve in women who experience infertility:
- day 3 (basal) FSH
- clomiphene citrate challenge
- gonadotropin-releasing hormone (GnRH) agonist stimulation
- antral follicle count (AFC)
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The AFC and AMH tend to detect the earliest changes in ovarian reserve, followed, sequentially, by inhibin-B, the clomiphene citrate challenge test (CCCT), and basal FSH.
The tests we describe are used primarily to assess treatment prognosis in infertile women. In time, however, appropriate population screening of ovarian reserve may be feasible to provide many more women with information about their reproductive potential and help them shape their life plan.
What makes a test valuable?
Ovarian reserve describes a woman’s reproductive potential—specifically, the number and quality of oocytes she possesses. 1 Biochemical tests of ovarian reserve emerged during the rise of assisted reproductive technologies (ART) in the late 1980s to predict both responsiveness to superovulation drugs and the odds of pregnancy with treatment.
Ideally, a test that assesses ovarian reserve should be affordable, straightforward, rapidly interpretable, and minimally invasive. It also should be able to detect changes that begin early in reproductive life. To be applicable to large populations of reproductive-age women, it should be of use anytime in the menstrual cycle, and should provide reproducible and highly accurate assessment of the reproductive aging process.
Our ability to offer tests that accurately measure ovarian reserve has a significant impact on women at risk of infertility and early menopause and on those who choose to delay childbearing for personal (nonmedical) reasons. These tests have become increasingly relevant because women are choosing to have their first child at a later age than their counterparts did 20 years ago:
- In 1980, 40% of women having their first baby were younger than 25 years, and only 5% were older than 35
- In 2000, 25% of women were younger than 25 when their first child was born, and 15% were older than 35.
Who should be tested?
Ovarian reserve is a complex clinical phenomenon that is influenced by age, genetics, and environmental variables. The decline in a woman’s ovarian reserve over time is irreversible; the trajectory of this decline is fundamental to the odds of fertility with age and the timing of the menopausal transition. At present, the markers used most often in clinical practice have some utility but also suffer from several drawbacks ( TABLE ).
For the general practitioner performing an infertility evaluation, we recommend focusing on the following groups of women for ovarian reserve testing:
- women over 30 years of age
- women with a history of exposure to a confirmed gonadotoxin, i.e., tobacco smoke, chemotherapy, radiation therapy
- women with a strong family history of early menopause or premature ovarian failure
- women who have had extensive ovarian surgery, i.e., cystectomy and unilateral oophorectomy.
Testing tends to have the highest yield in these groups. Women who have abnormal results should be referred to a reproductive endocrinologist for further evaluation and treatment.
The six tests are described below.
How six markers of ovarian reserve stack up
Test (year described)
Intracycle and intercycle variability
Reflects changes in ovarian reserve
Basal follicle-stimulating hormone (FSH) (1988)
Day 3 of menstrual cycle
• Early follicular phase FSH level <10 mIU/mL
• High estradiol level (decreases)
Clomiphene challenge test (1989)
Days 3 and 10 of menstrual cycle
• Day 3 FSH level <10 mIU/mL; day 3 estradiol level <80 pg/mL
• High day 3 estradiol level (decreases day 3 FSH)
GnRH agonist (1988)
Early follicular phase of menstrual cycle
• Oral contraceptives (decrease estradiol levels)
Early follicular phase of menstrual cycle
Variable in the literature; normal cutoffs range from ≥45–80 pg/mL
• Obesity (decreases)
Antral follicle count (1997)
Early follicular phase of menstrual cycle
Clinically significant (includes interobserver variability)
≥5–10 total antral follicles
• Oral contraceptive use (decreases)
Anti–Müllerian hormone/Müllerian-inhibiting substance (2002)
At any time; not cycle-dependent
• PCOS (increases)
1 | Basal FSH—widely used but only moderately informative
Day 3 FSH and the CCCT are the most widely used measures of ovarian reserve in ART practice. The use of early follicular-phase FSH as a marker of ovarian reserve and fertility was proposed 20 years ago with the emergence of IVF. 2-4 The test is an indirect assessment of ovarian reserve in that it measures pituitary production of FSH in response to feedback from ovarian hormones. Estradiol and inhibin-B reach a nadir early in the menstrual cycle; measuring FSH on day 3 offers a glimpse of the functioning of the hypothalamic–pituitary–ovarian axis before ovarian hormone levels rise later in the cycle ( FIGURE 1 ). 5,6
FIGURE 1 The HPO axis
The FSH level opens a window onto the function of the hypothalamic–pituitary–ovarian axis before ovarian hormone levels rise in the cycle. Women who have normal ovarian reserve have sufficient ovarian hormone production early in the menstrual cycle to maintain FSH levels within the normal range. Conversely, a “monotropic” elevation in FSH—one that is unaccompanied by a rise in luteinizing hormone (LH)—reflects poor hormone production from an aging pool of ovarian follicles and disinhibition of FSH production. 5,6
FSH measurements are typically combined with estradiol to enhance the sensitivity of testing ( FIGURE 2, ). Premature elevations of estradiol early in the follicular phase are driven by rising FSH levels in women with declining ovarian reserve. Abnormally elevated estrogen levels then feed back negatively on pituitary production of FSH and mask an elevation that might otherwise reveal diminished ovarian reserve. Measurement of both FSH and estradiol on cycle day 3 may therefore help decrease the incidence of false-negative testing.
Commonly cited criteria for normal ovarian reserve are:
- early follicular phase FSH, <10 mIU/mL
- estradiol, <80 pg/mL 1
It is extremely important to note, however, that these are general guidelines and that cutoffs are both laboratory- and practice-specific.
FIGURE 2 Monthly and lifetime variations in estradiol and FSH
How 17ß-estradiol and follicle-stimulating hormone levels vary over the menstrual cycle (top) and a woman’s lifetime (bottom).
2 | Clomiphene citrate—more sensitive than FSH testing
Like basal FSH testing, the CCCT is an indirect assessment of ovarian reserve. Unlike FSH testing, the CCCT is provocative. It involves administration of 100 mg of clomiphene citrate (Clomid) on days 5 through 9 of the menstrual cycle, with FSH and estradiol measured on days 3 and 10. Once clomiphene citrate is administered, FSH and LH levels rise, followed by an increase in estradiol and inhibin. Evidence suggests that the smaller follicular cohorts in women with diminished ovarian reserve produce less inhibin-B and estradiol and, therefore, less negative feedback on clomiphene-induced pituitary FSH release. 6,7 The result: persistent elevation of the day 10 FSH value and a positive screen for diminished ovarian reserve.
In some women, day 10 FSH is elevated even after a normal day 3 value. This makes the CCCT more sensitive than basal FSH testing; it can identify women who might go unrecognized if evaluated by day 3 FSH and estradiol levels alone.
More expensive and labor-intensive than the alternatives
Interpretation of the CCCT requires that FSH and estradiol both be assessed on days 3 and 10. An elevated FSH (≥10 mIU/mL) on either day indicates diminished ovarian reserve. As with basal FSH testing, elevated estradiol (≥80 pg/mL) on day 3 is considered abnormal. The day 10 estradiol value of the CCCT reflects whether or not clomiphene citrate was administered appropriately, and should be elevated. However, the significance of the day 10 estradiol level has been debated with respect to its predictive value for pregnancy in infertile populations. 8
The addition of day 10 FSH assessment improves the sensitivity of the CCCT over basal FSH measurement, but makes it a more expensive and labor-intensive test ( TABLE ). 5,6 The CCCT involves administration of clomiphene citrate, a safe drug (though it can have side effects), and two blood draws instead of one. Nevertheless, both tests are relatively noninvasive, rapid measures of ovarian reserve.
Drawbacks of the tests
Both basal FSH testing and the CCCT are widely used, although support for their ability to predict ovarian reserve in the infertile population has been challenged recently. Newer data demonstrate that these tests are limited in their ability to predict outcome (pregnancy and response to superovulation drugs) in all but a narrow group of patients undergoing IVF. Performance is particularly limited in:
Additional drawbacks of basal FSH testing and the CCCT include:
- significant variability of test results from cycle to cycle (intercycle variability)
- limited time frame within which the tests can be performed (intracycle variability).
The basal FSH test and CCCT have high specificity (98% to 99% for each) as an assessment of reproductive performance in infertile women and generate few false-positive results. 5,6 However, the high screen cutoffs that allow for such specificity come at a price: Few women will screen positive, and sensitivity of the tests is low (between 7% and 8% for basal FSH and between 25% and 40% for the CCCT). Such low sensitivity means that many women will not conceive after infertility treatment despite a normal test result. 5,11 Overall, the tests are not highly informative for many women who get tested.