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Inhibin-A
Summary
Inhibins are glycoproteins that belong to the TGF-β superfamily. Their roles in reproduction have been the focus of recent research. Inhibins are heterodimers consisting of disulfide linked α and β subunits: inhibin-A (α-βA) and inhibin-B (α-αB).
Inhibin A is secreted by ovarian luteal cells during the luteal phase of the menstrual cycle and by the feto-placental unit during pregnancy. Serum concentrations of Inhibin A are lower in women with luteal phase defects than women with normal menstrual cycles and as early as 4-7 weeks gestation among women whose pregnancies are destined to fail compared with those who deliver normal infants. Early pregnancy loss and multiple gestations are common after in vitro fertilization (IVF). Therefore, there is a need for markers that can accurately detect the establishment of pregnancy and predict its outcome as early as possible. Serum inhibin-A concentrations have been shown to be significantly more accurate than hCG levels in the prediction of preclinical or chemical pregnancy losses.
Indication for Testing
Infertile women whose symptoms are suggestive of luteal phase defect or women with the diagnosis of unexplained infertility should be tested in the midluteal phase of their menstrual cycle for serum levels of inhibin A. All women achieving pregnancy after IVF should have inhibin A measurements between post-embryo transfer days 8 to 16. In addition, women with a history of recurrent pregnancy loss and women with a high risk of early pregnancy loss should be tested during the first trimester to ensure pregnancy viability.
Detection Method
Inhibin A is detected by standard ELISA procedure.
Interpretation of results
Normally cycling women midluteal phase range is 13 – 160 pg/ml.
Normal pregnancy >175pg/ml
Specimen Collection, Handling and Shipping Requirements
- Collect a sample DNA with a buccal swab.
- Ship at room temperature in prepaid FedEx mailer overnight, next day
delivery.
Turn Around Time
Processing of specimens begins immediately upon receipt at our facilities. Results are routinely available within
10 to 14 days and are initially faxed, then mailed to the requesting physician.
Cost
Included in our test are specimen collection and shipping materials, shipping
charges, telephone and written reports as well as consultations with the
referring physicians. Please call (312) 274-1928 for pricing information.
References
Kingsley DM. The TGF superfamily: new members, new receptors and new genetic tests of functions in different organisms. Gene Dev 1994;8:133-146.
Yamoto M, Imai M, Otani H, Nakano R. Serum levels of Inhibin A and Inhibin B in women with normal and abnormal luteal function. Obstet Gynecol 1997;89:773.
Illingworth PJ, Groome NP, Duncan C, Grant V, Tovanabutra S, Baird DT, McNeilly AS. Measurement of circulating Inhibin forms during the establishment of pregnancy. J Clin Endocrinol & Metabol1996;81:1471.
Lockwood CM, Ledger WL, Barlow DH, Groome NP, Multukrisha S. Measurement of inhibin and activin in early human pregnancy: demonstration of fetoplacental origin and role in prediction of early pregnancy outcome. Biol Reprod 1997;57:1490-1494.
Al-Azemi M. Ledger WL, Diejomach M, Mousa M, Makhseed M, Omu A. Measurement of inhibin A and inhibin pro-αc in early human pregnancy and their role in the prediction of pregnancy outcome in patients with recurrent pregnancy loss. Fertil Steril 2003;80:1473-1479.
Aiken DA, Wallace EM, Crossley JA, Swanston IA, van Pareren Y, van Maarle M, Groome NP, Macri JN, Connor JM. Dimeric inhibin A as a marker for Down’s Syndrome in early pregnancy. N Engl J Med 1995;334:1231-1236.
Vanderpuye OA, Goodman C, Randall HT, Roussev RG, TsaoD,CoulamCB. Aneuploidy diagnosis in the first trimester: serum PAPP-A, free beta hCG and Inhibin A. Am J Reprod Immunol 2000;43:341
Hauzman E, Fedorcsak P, Klinge K, Papp Z, Rabe T, Strowitzke T, Urbancsek J. Use of serum inhibin A and human chorionic gonadotrapin measurements to predict the outcome of in vitro fertilization pregnancies. Fertil Steril 2004;81:66-72.
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