Test Background Inhibins are heterodimeric polypeptide hormones composed of alpha (α) and beta (β) subunits. The inhibin molecule has a molecular weight of approximately 32-36 kD. They suppress the secretion of pituitary follicle stimulating hormone (FSH) and also have local paracrine actions in the gonads. Inhibins are produced by the sertoli cells of the testis and the granulosa cells of the ovary.
Inhibin B consists of an α-subunit and a β-subunit. Inhibin B is used for the relapse detection in granulosa cell tumour (GCT) of the ovary. Inhibin B measurements have also been reported as markers for the assessment of sertoli cell function and ovarian reserve.
In pre-menopausal fertile woman, inhibin B levels vary throughout the menstrual cycle. Due to the paucity of studies and the variability of inhibin B levels between women throughout the cycle, reference intervals serve only as a guide. Higher follicular/ovulatory phase levels are observed in multi-follicular cycles and may indicate polycystic ovarian syndrome. Hormone replacement therapy will artificially stimulate inhibin B production in the menopause.
Clinical Indications - Assessment of male or female gonadal function
- As an adjunct test in the diagnosis and treatment monitoring for granulosa cell tumour (GCT) of the ovary
- Recurrence detection in post-oophorectomy in follow-up monitoring of GCT of the ovary
Reference Range Adult Male 25-325 ng/L
Adult Female <341 ng/L
Post-Menopause <5 ng/L
Sample Required SST (gold top) preferred, serum (red top) accepted
Sample Volume 0.5 mL
Turnaround Time 4 weeks
Notes Beckman Coulter ELISA. Higher follicular/ovulatory phase levels are observed in multi-follicular cycles and may indicate PCOS. HRT will artificially stimulate inhibin B production in the menopause.