Name of the Test:
Inhibin B, sensitive
Alias Names :
dimeric inhibin B
Inhibin B determination is useful in :
-The diagnosis and management of granulosa cell tumors of ovaries
-The diagnosis of issues with spermatogenesis in subfertile men
Clinical Applications:
Inhibins are protein hormones secreted by the granulosa cells of the ovary in the female and the Sertoli cells of the testis in males. Inhibin-B is a dimeric hormone that is composed of alpha and beta subunits. The free alpha subunits do not have any physiological effect. The bioactivity of the inhibin depends on the formation of a dimeric alpha, beta structure and only dimeric forms of inhibin are biologically active. Inhibin B is the major circulating inhibin in males and can be used as an endocrine marker of spermatogenesis in subfertile men. In the female, Inhibin-B selectively suppresses the secretion of pituitary follicle stimulating hormone and also has local paracrine action in gonads. Inhibin B decreases to undetectable levels after normal menopause. Certain ovarian cancers (such as mucinous carcinomas and granulosa cell tumors) produce inhibin-B and could be used as one of the tumor markers for ovaries.
Method:
Ihibin B is quantitated using an immunochemiluminometric assay. It is a three step sandwich type immunoassayusing two monoclonal antibodies to Inhibin B; one is coated to the microtiter plate as capture antibody and the other isbiotinylated as labeled antibody. Strepavidin HRP conjugate is used for light generation as Relative light units (RLU). When the samples are in high concentration, RLU increases proportionally. Since the assay is a chemiluminescence based , it is very sensitive (10 pg /ml).
Test Information:
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Specimen requirements: 1.0 ml (minimum 0.2 ml) of serum.
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Shipping requirements: Ship the samples frozen or in ice pack. Shipping samples at room temperatureis not recommended.
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Turnaround time: 1 day (Set up every Monday and reported the same day).
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Reference Range:
| Male ( pg /ml ) | Female ( pg / ml ) | |
|---|---|---|
| 5-10 Years | 21-166 | ≤18 pg/mL |
| 10-14 Years | 41-328 | ≤86 pg/mL |
| 14-18 Years | 54-295 | ≤123 pg/mL |
| ≥18 Years | 47-308 | Pre-menopausal = < 153 |
| Post-menopausal = < 10 |
References:
1. Kumanov et al (2006) Inhibin B is a better marker of spermatogenesis than other hormones in the evaluation of male factor infertility. Fertility Sterility 86: 332 – 338.
2. Lockwood G (2004) The diagnostic value of inhibin in infertility evaluation. Semin Reprod Med 22: 195 – 208.