What is the role of inhibin measurement in the workup of granulosa cell tumors (GCTs) of the ovaries?

Updated: Aug 30, 2018
  • Author: David C Starks, MD, MPH; Chief Editor: Warner K Huh, MD  more...
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Answer

Inhibin has been studied in women with granulosa cell tumors. It is a peptide hormone produced by ovarian granulosa cells that plays a role in regulation of FSH secretion by the pituitary. It is composed of an alpha subunit and 1 of 2 beta subunits (BA or BB). Although inhibin A and inhibin B levels can both be elevated in patients with granulosa cell tumors, inhibin B level is usually elevated in a higher proportion of these tumors. Furthermore, this increase in serum levels from baseline is often higher as well. Typical cutoffs for normal inhibin levels in postmenopausal or oophorectomized women are less than or equal to 5 ng/L and 15 ng/L for inhibin A and B, respectively.

Studies of inhibin in patients with GCTs have shown that levels are elevated preoperatively and return to the reference range postoperatively in both adult and juvenile types of tumors. In a 2002 study by Robertson et al, total serum inhibin level was elevated in 100% of GCTs and 100% of thecomas. [5] Additionally, 84% of patients with mucinous ovarian carcinomas had elevated inhibin levels. However, only 18% of patients with serous and 54% of patients with endometrioid ovarian cancers had elevation of total serum inhibin level. Current inhibin assays allow us to distinguish between inhibin A and inhibin B.

Mom et al evaluated the use of serum inhibin levels in 30 women with granulosa cell tumors. The sensitivities and specificities for inhibin A were 67 and 100% and for inhibin B were 89 and 100%, respectively. They also noted that inhibin A level was elevated before or at the time of first clinical recurrence in 58% of patients while inhibin B level was elevated in 85%. Lead time from elevation of inhibin levels to clinical recurrence was estimated to be 11 months. Inhibin A and B levels were not elevated in any of the 17 patients who were postoperatively disease free. Serum inhibin levels are currently available for diagnosis and clinical follow-up of women with granulosa cell tumors of the ovary. [6]


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