Category Archives: Screening Test

Screening Test

Preimplantation Genetic Diagnosis and Screening


BlastocystPreimplantation genetic testing is a way of examining the genetic features of a developing embryo during the process of in vitro fertilization, before pregnancy. After the egg is fertilized with sperm, the embryos develop to the cleavage-stage. On day 3 after fertilization, a single blastomere is removed from the embryo for genetic evaluation using techniques such as PCR, FISH, or comparative genomic hybridization.

Preimplantation genetic diagnosis (PGD) is used to select embryos without certain genetic disorders. This testing including three major groups of disease: sex-linked disorders, single gene defects, and chromosomal disorders.

Preimplantation genetic screening (PGS), is not used to detect disease, but as a screen to select embryos for such things as: matching HLA type in order to be a tissue donor for an affected sibling, selecting gender, selecting embryos with the least predisposition for developing certain cancers, and selecting embryos with a higher chance of implantation and therefore increase the likelihood of achieving pregnancy. Medscape has an excellent overview of PGD and PGS.

For women of advanced maternal age or couples with known genetic mutations, the ability to screen for embryos free of certain genetic mutations is reassuring. However, as with many medical interventions associated with human reproduction, PGS has raised ethical questions. For instance, as stated earlier, PGS can be used to select for a preferred gender. In some cases this is to avoid a sex-specific disease. Other times this is done for so-called "family planning" or "gender balance." In other words, selecting a gender because of personal preference. Some feel this is discriminatory and should not be allowed. In other cases, embryos have been tested so that the resulting child would be compatible to serve as a stem cell donor for a sick sibling (much like the popular fiction book "My Sister's Keeper").   There have also been cases where parents have requested the selection of affected embryos so that the child has the same minor disability, such as deafness or dwarfism, as the parents. Some preimplantation genetics laboratories agree to do this type of testing and some do not.

The New York Times recently ran an article discussing this issue. The article states that:

"In the United States, there are no regulations that limit the method’s use. The Society for Assisted Reproductive Technology, whose members provide preimplantation diagnosis, says it is 'ethically justified' to prevent serious adult diseases for which 'no safe, effective interventions are available.' The method is 'ethically allowed' for conditions 'of lesser severity' or for which the gene increases risk but does not guarantee a disease."

The January issue of Clinical Chemistry published a Question and Answer piece entitled "The Ethical Implications of Preimplantation Genetic Diagnosis." A podcast interview with two of the authors is also available.

The paper summarized the opinions of an ethicist, an attorney, and the director of a preimplantation genetics laboratory. The ethicist indicated that in the past, PGD has focused mainly on reducing the risk of transmitting serious diseases. In the future, he sees a shift away from lifesaving interventions to more ‘eugenically’ inspired interventions. That is, looking for traits that parents do not want in their children and selecting for traits that they do want in an attempt to pass them on. The morality of eugenics is a key moral as this technology moves forward.

Indeed it will be interesting to see where the future of this technology lies. Although it is practiced routinely, the indications, utility, and outcomes of PGD and PGS are still being defined.

Screening recommendations for gestational diabetes mellitus


Green check markThis blog has covered the topic of gestational diabetes mellitus several times. Recent big news in this arena is the recommendation from the U.S. Preventative Services Task Force (USPSTF) that all pregnant women be screened for gestational diabetes mellitus (GDM) after 24 weeks of gestation.

The USPSTF is an "independent panel of non-Federal experts in prevention and evidence-based medicine and is composed of primary care providers." Their job is to "conduct scientific evidence reviews of a broad range of clinical preventive health care services and develop recommendations for primary care clinicians and health systems." For the USPSTF to "recommend" a practice means that there is evidence to suggest that the benefits of that practice outweigh the harms.

First, a few facts about GDM:

  • Each year, about 4 million women give birth and about 240,000 of these women (6%) develop diabetes during their pregnancy. The actual number of women identified as having GDM depends on the screening test that is used.
  • Over the last 2 decades, GDM has become more common because more women are at risk of developing diabetes. Risk factors include being overweight or obese or having a family history of diabetes.
  • Even though GDM usually goes away after pregnancy ends, it still puts the mother and the fetus at risk of serious health issues. For the mother these include preeclampsia and an increased chance for the development of type 2 diabetes after pregnancy. For the fetus these include macrosomia (a high birth weight which makes delivery difficult and Cesarean section more likely), shoulder dystocia, and an increased risk of becoming obese during childhood.

The USPSTF recommended screening for GDM after 24 weeks of pregnancy in all women who do not already have symptoms of diabetes. They gave this recommendation a grade of "B," meaning that there is a high certainty that there is moderate certainty that the net benefit of GDM screening is moderate to substantial.

Women benefit from GDM screening because it:

  • Identifies those who have GDM and who should be treated (usually with diet modifications, glucose monitoring, and, if needed, insulin therapy).
  • Lowers the risk of preeclampsia, fetal macrosomia, and shoulder dystocia.

The harms of screening were minimal and included:

  • Anxiety in some women.
  • The use of unnecessary tests and services.

The Task Force did not find sufficient evidence to support screening for GDM before 24 weeks of pregnancy and gave that statement a grade of "I," meaning was insufficient evidence to assess the balance of the benefits and harms of GDM screening.

The USPSTF did not make any recommendations regarding what GDM screening test to use. As this blog has noted before, there is no universally accepted method for diagnosing GDM and this has resulted in 5 different approaches (and considerable debate).

More on noninvasive prenatal testing for fetal aneuploidy


We have written about nonivasive prenatal testing (NIPT) on this blog several times.  Because they are so new, the landscape around these tests is continually evolving.  The American College of Obstetricians and Gynecologists (ACOG) published guidelines on these tests in December of last year.  Just this week, the American College of Medical Genetics and Genomics (ACMG) released its policy statement on the same topic.  Note that the ACMG refers to these tests as "noninvasive prenatal screening" (NIPS) tests to emphasize that this is what they are: screening, not diagnostic tests.

The ACMG calls for caution before these tests become widely integrated into prenatal care due to the current lack of data obtained from prospective clinical trials.  While they acknowledge that NIPS tests have high sensitivity and specificity there are limitations to the technology and false-positive and false-negative results do occur.

A particular concern, and one that doesn't get as much attention as it should, is that most of the fetal DNA in the mother's blood sample originates from the placenta and not the fetus and it may not accurately reflect the fetal karyotype.  They emphasize (as have others), that abnormal NIPS test results must be confirmed by invasive diagnostic tests such as amniocentesis.

The policy statement also lists several limitations to NIPS tests.  Among them:

  • They only detect aneuploidies (and some detect sex chromosome abnormalities).
  • Certain chromosome abnormalities are not detected.
  • The tests take longer to perform and result than more well-established tests.
  • Data on the performance of the tests in twin and triplet pregnancies is not well established.

A recent paper published in the journal Obstetrics and Gynecology has a similar ring to it.  The authors make several interesting observations:

  • First, they point out that well-established tests were developed in academic settings and came into use gradually and only after independent clinical studies generated data to support their use.  In contrast, NIPT (also developed in academic settings) was quickly licensed to commercial enterprises that have brought them to market without FDA review (as these are "lab-developed tests," FDA appoval is not required).
  • From the analytical perspective, there are currently no guidelines regarding quality control and quality assurance for NIPT; a vital component of any lab test.
  • The performance of NIPT in actual clinical practice settings (i.e. not a clinical study) is currently not well known or documented.  This is especially true for populations of women that have not been represented in the clinical studies (e.g. woman at low risk for having a fetus with an aneuploidy).
  • The more well-established tests are able to detect fetal anomalies besides aneuploidy (e.g. open neural tube defects).

The authors also reflect on how NIPT should be incorporated into clinical care.  They agree with the ACOG recommendations that the tests should not be offered to low-risk women but they go a bit further and state that the most appropriate use of NIPT is as a second screening test used for those who have an abnormal result from convential, more well-established screening tests.  The latter point is something I have commented on before and I could not be in more complete agreement.

    Should DNA-based tests for Down syndrome screening replace biochemical tests?


    In a previous post I described the clinical performance of DNA-based screening tests for fetal aneuploidies like Down syndrome.  Overall, these tests have excellent detection rates (~99%) with very low false-positive rates (~0.2%).  In other words, these tests are about 99.0% sensitive and 99.8% specific.

    With performance like that one might expect these to be considered diagnostic tests.  They are not! Although quite good, test results must not be interpreted as definitive evidence that a fetus does or does not have an aneuploidy.  Recent recommendations from the American College of Obstetricians and Gynecologists (ACOG) are quite clear on that issue.

    In those same recommendations, ACOG also states that DNA-based screening tests may be performed only on women who are at increased risk of having a fetus with aneuloidy.  Among the indications listed for women considered to be at increase risk are:

    • Maternal age 35 years or older at delivery
    • Fetal ultrasound findings suggesting aneuploidy
    • A previous aneuploid pregnancy
    • Abnormal biochemical screening test results
    The ACOG is right to avoid recommending that DNA-based screening tests are acceptable to use regardless of risk factors.  Unfortunately, many women who are not at increased risk are using these new tests as a primary screening test and that's not a good idea.

    To understand why, considered a population of 100,000 pregnant women from the general population and assume that the prevalence of Down syndrome is 1 in 500 pregnancies.  That means that there would be 99,800 unaffected pregnancies and 200 pregnancies with Down syndrome.  The table below compares the results of the most commonly used biochemical screening test (the Quad test) to a DNA-based screening test.

    Quad vs DNA performance
    Clearly, the DNA-based test has several advantages over the Quad test.  Its positive predictive value is nearly 17 times greater than the Quad's and a positive DNA-based test result substantially increases the odds of having an affected fetus.  So why not use the DNA-based test as a primary screening test?  For the following reasons:
    • No studies have been published that have evaluated the performance of DNA-based tests in women who are not at increased risk of having a fetus with an aneuploidy
    • DNA-based tests are not widely available
    • The time it takes to report results of DNA-based testing is about 3 times greater than it is with biochemical testing
    • DNA-based tests are considerably more expensive than biochemical tests
    • Relative lack of insurance coverage for DNA-based tests
    Until these these limitations can be resolved, it makes more sense to use DNA-based testing as a secondary screening test.  In other words, it is only done after one of the risk factors described by ACOG (above) are met.  Doing so greatly improves the performance of both tests (see figure below).  A limitation of this approach is that the detection rate is that of the biochemical test which is not as high as it is with the DNA-based test.  Still, given the current limitations of DNA-based testing, this 2-step testing approach makes the most sense.
    DNA as secondary test

    DNA-based tests for Down syndrome screening show excellent clinical performance


    The use of biochemical screening tests to identify pregnant women who are at high risk of having a fetus with Down syndrome is well established.  Biochemical screening began nearly 30 years ago and, over the years, the tests have evolved and improved.  Now there’s a new kid on the screening test block and it’s name is DNA.

    The discovery of cell-free fetal DNA in maternal plasma in 1997 opened up new possibilities for Down syndrome and other aneuploidy screening protocols.  Rather than rely on biochemical testing to determine a biochemical phenotype, DNA-based tests have been developed that can detect the molecular pathology of aneuploidies (e.g. a fetus that has more than the expected 2 copies of chromosomes 21, 18, or 13; the cause of Down syndrome, Edwards syndrome, and Patau syndrome, respectively).

    We’ve written about DNA-based screening tests before (here and here) and described the clinical performance of the Sequenom test.  Now, other clinical performance studies have been published for 3 of the 4 tests that are (or will be) commercially available.  As expected, all of them show excellent clinical performance.  As shown in the table below, the detection rates for trisomy 21 are greater than or equal to 99% with very low false-positive results.  Similar performance has been reported for trisomy 18 and 13.

    DNA test performance

    Table References: Genet Med 2011;13:913-920Genet Med 2012;14:296-305Obstet Gynecol 2012;119:890-901

    By comparison, the detection rate of the best biochemical Down syndrome screening test (the Integrated test) is very good at 93%.  However, about 5% of all Integrated test results are false-positive.  A 5% false-positive rate may not seem very high but it is.  For example, consider a population of 100,000 pregnant women who choose Integrated testing in the second trimester.  The prevalence of Down syndrome in the second trimester is about 1 in 500 pregnancies so 200 of those 100,000 women will have a fetus with Down syndrome and 99,800 women (100,000 – 200) will have unaffected fetuses.  Of those 99,800 women with unaffected fetuses, 4,900 will have a false-positive Integrated test result.

    Because the false-positive rate of the DNA-based tests is so low (about <0.2%), then if those same 100,000 women were screened there would be only 200 false-positive results, a 96% decrease!

    Does this mean that DNA-based tests should replace biochemical screening tests?  Probably not but I’ll leave the explanation as to why for my next post.

    Screening or diagnostic test. What is the difference?


    Today was an interesting day at work.  A genetic counselor I work with emailed me that a pregnant patient wanted to have "every single Down syndrome screening test that was available."  While this was problematic in and of itself (more about that later), this patient also planned to have an amniocentsis regardless of the results of the screening test.

    Do you see a problem with this line of thinking?  If not, read on.

    Let's start with what a screening test is.  I've written about this before here, but to recap: a screening test is NOT the same as a diagnostic test.  A test that screens for Down syndrome doesn’t identify if a woman is pregnant with a baby that has Down syndrome; it identifies women who are pregnant with babies that are at increased risk of having Down syndrome.  In other words, the screening test puts tested women into one of two camps: those without increased risk and those with incrased risk.  Women who screen positive and who are at increased risk are offered a diagnostic test that can confirm if their baby does or does not have Down syndrome.  A screening test cannot do that.

    The diagnostic test for Down syndrome is determining the karyotype of the fetus in order to identify how many copies of chromosome 21 have been inherited (unaffected fetuses have 2 copies; affected fetuses have 3 copies).

    The results of a Down syndrome screening test are used to identify women who should be offered diagnostic testing (karyotype).  Women who have a positive screening test result are offered amniocentesis in order to obtain  the amniotic fluid required for karyotyping the fetus.  However, because amniocentesis is an invasive procedure, there is a small risk of miscarriage (usually less than 0.5 percent).

    The problematic request of the patient to have more than one Down syndrome screening test should now be apparent for two reasons:

    1. Her desire to have every available screening test is illogical if she has already made up her mind to have an amniocentesis and diagnostic testing.  The fetal karyotype is THE definitive (i.e. diagnostic) test and so screening for a disorder makes no medical or economic sense because, regadless of the results, the diagnostic test will still be performed.
    2. Requesting all available screening tests is a complete waste of health care resources.  Granted, the number of Down syndrome screening tests available is a source of much confusion for both physicians and patients.  That said, patients (with help from their doctors) should choose the screening test that is best for them.  Choosing multiple screening tests is not a wise idea.  Consider what might be done if the results of these tests don't agree with each other.

    Consumers of health care often (mistakenly) believe that more testing is better.  Few take the time to consider that tests may have downstream consequences that they might not be prepared for.  In this case, the patient had already decided to have the "best" test.  That is her choice and one that I support.  What I don't support is the wasted time, money, and effort required to perform tests that are, in this specific situation, meaningless.

    Screening for neural tube defects


    NeuronsA neural tube defect (NTD) is a birth defect of the spinal cord and/or brain.  The term is used to describe a group of disorders that occur very early in pregnancy and can be mild to severe or even fatal.

    During the first 3 weeks of pregnancy, specific cells fuse to form a hollow tube (the neural tube) that forms the basis of what will become the spinal cord and brain.  A NTD occurs when that neural tube fails to close completely somewhere along its length.

    The two most common NTDs are spina bifida and anencephaly.  Spina bifida is the most common.  There are different types of spina bifida and each has varying degrees of severity but it nearly always results in some nerve damage that can cause at least some paralysis of the legs.  Anencephaly is the most severe NTD and results in the lack of development of the brain and skull and is not compatible with life.  NTDs that are covered by skin are called “closed” defects while those that are not covered by skin are considered to be “open.”  Only open NTDs are detected by screening tests.

    Alpha-fetoprotein (AFP) testing is used to screen for a NTD during the second trimester of pregnancy.  Ideally it takes place between 16 and 18 weeks of gestation but between 15 and 22 weeks is acceptable.  The concentration of AFP in fetal blood is 100,000 times greater than it is in maternal blood.  Some of the fetal AFP normally enters the maternal blood and so the AFP concentration in maternal blood will begin to increase.  A fetus with an open NTD will transfer more AFP into maternal blood than an unaffected fetus and so an unusually high AFP concentration in maternal blood can indicate that the fetus has an open NTD.

    Because AFP concentrations normally increase during pregnancy (by about 15 percent each week), a statistic called the “multiple of the median” (MoM) is used to normalize the test result.  The MoM is a measure of how far an individual test result deviates from the median (middle) value of a large set of AFP results obtained from unaffected pregnancies.  For example, if the median AFP result at 16 weeks of gestation is 30 ng/mL and a pregnant woman’s AFP result at that same gestational age is 60 ng/mL, then her AFP MoM is equal to 60 divided by 30 (60/30) or 2.0.  In other words, her AFP result is 2 times higher than “normal.”

    So how is the AFP MoM interpreted?  What is considered an abnormal result?  Although the AFP MoM cutoff varies by lab, the two most commonly used are 2.0 and 2.5.  Results above the cutoff are considered to be abnormal.  A cutoff of 2.0 will detect about 85 percent of open NTD and a cutoff of 2.5 will detect about 75 percent.  Most cases of anencephaly are detected with maternal serum AFP screening.  The figure below illustrates the distribution of AFP MoM results in women with unaffected fetuses, those with spina bifida, and fetuses with anencephaly.

    Results to the right of the blue line (a cutoff of 2.5 MoM) would be interpreted as "abnormal" while an AFP MoM to the left of the line would be considered "normal."  Note that there is no single MoM cutoff that can completely separate unaffected from affected fetuses.  There will always be affected fetuses that screen normal and unaffected fetuses that screen abnormal.

    Because this is a screening test, women with an abnormal result require additional testing to confirm if the fetus has a NTD.  More about these tests in future post.

    AFP and NTD
    Lastly, it’s important to keep in mind that most abnormal NTD screening tests are false-positives.  There are several reasons why AFP might be elevated in the absence of an open NTD such as: an abnormality in the fetal kidneys, a ventral wall defect (opening in the abdomen), the death of the fetus, a twin gestation, or, most commonly, underestimated gestational age.

    The gestational diabetes mellitus debate continues


    Discussion_icon_noshadowI have just returned from the annual meeting of the AACC where I attended a very interesting debate on the diagnosis of gestational diabetes mellitus (GDM). I've written about the current controversy in diagnosing GDM before and you can read about those here and here. Basically, the controversy boils down to one issue: should recently recommended criteria for identifying pregnant women with GDM be globally implemented or not? 

    Arguing for that position was Dr. Donald Coustan from Brown University and regional principal investigator for North America of the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study. He correctly pointed out that lack of a universal testing strategy when screening for GDM makes it impossible to compare clinical studies on GDM. He reviewed how the new IADPSG glucose cutoffs came into being (they were based on risk of adverse infant outcomes) that he advocates referring to as the ADA criteria because the ADA is recommending the use of the new testing method.

    Arguing against the use of the ADA criteria was Dr. Sean Blackwell from the University of Texas Health Science Center at Houston, TX. He agreed with several of Dr. Coustan points. Among them that:

    1. The HAPO study was well conducted.
    2. There was a positive association between glucose concentration and adverse infant and maternal outcomes at lower glucose cutoffs than are currently used to diagnose GDM.
    3. There is benefit in having a single, universal screening test for GDM.
    4. There is evidence that, as currently defined, treatment of GDM improves outcomes.

    He had two major problems with use of the new ADA criteria. The first was that its use would double the number of women diagnosed with GDM (from about 7% to 16%). The second was that the HAPO study was an observational study, not a treatment trial and, as such, there is no evidence that treating these additional women for GDM is effective or safe.

    Dr. Coustan argued that the increase in the number of GDM diagnoses is not surprising given that, in the US, 31% of adult US women have either diabetes or pre-diabetes. He also argued that the Australian Carbohydrate Intolerance Study of Pregnant Women (ACHOIS) study demonstrated that treatment of women with mild GDM reduced adverse outcomes such as large for gestational age newborns, macrosomia, and preeclampsia.

    Dr. Blackwell pointed out that most of the additional 10% of women that would be diagnosed with GDM under the ADA criteria would, by definition, have "milder" GDM and would only require nutritional modification and glucose monitoring rather than drugs to control their GDM. These women would have glucose control similar to those of obese women without diabetes. Further, he added that several studies in obese women without diabetes have failed to demonstrate that nutritional interventions have any impact on any infant health outcome.

    The moderator of this debate was my co-blogger, Ann Gronowski. Prior to its start, she polled the audience of (mostly) laboratorians to see which testing strategy they currently offered at their institutions. Most indicated they offered the current ACOG criteria (advocated by Dr. Blackwell). At the end of the debate, the audience was asked if they would support switching to the new, ADA criteria. The majority response was "yes." Dr. Coustan argued his points effectively.

    It's my belief that the evidence, while not complete, is strong enough to support widespread adoption of the ADA criteria when screening for and diagnosing GDM.

    Should I get my iodine measured during pregnancy?


    Salt2

    The short answer is no, but let me explain why.

    Iodine is necessary for the production of the thyroid hormones T3 and T4. A deficiency of iodine leads to decreased production of these hormones and can cause goiter (enlargement of the thyroid) and hypothyroidism.

    During pregnancy, a number of normal changes occur that involve the thyroid gland and the need for iodine including:

    1. hCG is similar in structure to TSH, the hormone that stimulate the thyroid gland, and so hCG can also stimulate the thyroid gland;
    2. There is an increased demand for T3 and T4; and,
    3. Clearance of iodine through the kidneys is increased.

    In areas where there is iodine deficiency, pregnancy is associated with a 20-40% increase in the size of the thyroid gland. In areas where iodine is replete, like the United States, the thyroid increases in size by only around 10% during pregnancy.

    Because of these changes, dietary iodine requirements for pregnant women are higher than they are for non-pregnant women. If iodine intake was adequate before pregnancy, women should have sufficient iodine stores and therefore have no difficulty meeting the needs for iodine during pregnancy and lactation. If their iodine intake was not sufficient, it can result in overt hypothyroidism which is associated with miscarriage, stillbirth, and, in very severe cases, cretinism (characterized by severe mental retardation and deafness). Iodine deficiency is the leading cause of preventable mental retardation worldwide. According to public health experts, iodization of salt may be the world's simplest and most cost-effective measure available to improve health

    While the U.S. is an iodine replete country, some studies have suggested that women of reproductive age may be at risk of iodine deficiency.  This might make one think that iodine status should be determined in these women. Iodine status is usually assessed by measuring urine iodine concentrations. However, there is significant day-to-day variation in urine iodine excretion, such that measurement in a single individual is not useful. Urine concentrations are most useful to assess the iodine status of a whole population.

    In 2011, the American Thyroid Association (ATA) published guidelines for the diagnosis and management of thyroid disease during pregnancy and postpartum. In these guidelines, the ATA recommends that all pregnant and lactating women ingest a minimum of 250 ug of iodine daily. For U.S. women that means supplementing their diet with a daily oral supplement that contains 150 ug of iodine (optimally potassium iodide).

    In 1924, the Morton Salt Company began distributing iodized salt nationally, which is a good source of iodine. While iodized salt is the main source of iodine in the American diet, only ~20% of the salt Americans eat contains iodine!  Reasons for this include:

    1. Increase in popular designer salts like sea salt and Kosher salts (see photo below); Salt
    2. Iodized salt is not used in most fast and processed foods or in the production of commercial breads; and,
    3. Patient concerns about salt intake & hypertension. Good dietary sources of iodine include kelp seaweed, seafood (cod, sea bass, haddock, and perch are good sources) and dairy products.

    In summary, if you are pregnant make sure you are taking a supplement that contains iodine, but do not worry about having your iodine concentration measured.

     

    Assessing Ovarian Reserve


    OvariesWomen in their mid to late 30s and early 40s with infertility constitute the largest portion of the total infertility population. These women are also at an increased risk for pregnancy loss. This reflects a decline in oocyte quality and a diminished ovarian reserve as a result of follicular depletion. Ovarian reserve is a term that is used to describe the capacity of the ovary to provide eggs that are capable of fertilization resulting in a healthy and successful pregnancy.

    While there is no gold standard for assessing the ovarian reserve of individual women, its indirect determination has been used to help direct infertility treatment.

    Serum concentrations of follicle-stimulating hormone (FSH) and estradiol on day 3 of the menstrual cycle have been the tests of choice for assessing ovarian reserve. Cycle day 3 is chosen because at this time the estrogen concentration is expected to be low, a critical feature, as FSH concentrations are subject to negative feedback from estradiol. In general, day 3 FSH concentrations >20 to 25 IU/L are considered to be elevated and associated with poor reproductive outcome.   FSH concentrations are expected to be below 10 IU/L in women with reproductive potential.  Concomitant measurement of serum estradiol adds to the predictive power of an isolated FSH determination. Basal estradiol concentrations >75-80 pg/mL are associated with poor outcome. 

    Inhibin B is produced by the developing follicles and concentrations peak during the follicular phase. Concentrations of inhibin B can be used in conjunction with serum FSH and estradiol to assess ovarian function. As women age, serum FSH concentrations in the early follicular phase begin to increase. It has been suggested that this is due to a decline in the number of small follicles secreting inhibin B.  Because inhibin is produced by the ovaries, it is thought to be a more direct marker of ovarian activity and ovarian reserve than FSH. In addition, cycle day 3 inhibin B concentrations may demonstrate a decrease before day 3 FSH concentrations. 

    Seifer et al reported that women undergoing in vitro fertilization (IVF) with day 3 inhibin B concentration <45 pg/mL had a pregnancy rate of 7% and a spontaneous abortion rate of 33% as compared to pregnancy rate of 26% and abortion rate of 3% in women with day 3 inhibin B concentrations of > 45 pg/mL. 

    In recent years, anti-Mullerian Hormone (AMH) has been suggested to be a more useful predictor of ovarian reserve. AMH is expressed by the granulosa cells of the ovary during the reproductive years, and controls the formation of primary follicles by inhibiting excessive follicular recruitment by FSH. In 2005 Tremellen reported that plasma AMH concentrations start to drop rapidly by age 30, and are ~10 pmol/L by the age of 37. David has blogged previously about the use of AMH as a predictor of IVF outcome.   

    Using a cut off value of 8.1 pmol/L, plasma AMH could predict poor ovarian reserve on a subsequent IVF cycle with a sensitivity of 80% and a specificity of 85%.     In 2008, Riggs and colleagues confirmed that AMH concentrations correlated the best with the number of retrieved oocytes relative to age, FSH, inhibin B, LH, and estradiol. 

    High concentrations of AMH can also be present in women with polycystic ovarian syndrome (PCOS), a cause of female infertility.  Therefore, in PCOS patientsAMH should not be used alone, but should be combined with transvaginal ultrasound to count the number of follicles.

    Women who are diagnosed with diminished ovarian reserve should be counseled regarding options such as oocyte donation or adoption.