Original Articles

By Dr. Geetika , Dr. Sunita Gupta , Dr. Shweta Sikarwar
Corresponding Author Dr. Geetika
Obstetrics and Gynaecology, Subharti Medical College, - India 250001
Submitting Author Dr. Geetika Tomar
Other Authors Dr. Sunita Gupta
Obstetrics and Gynaecology, Subharti Medical College , - India

Dr. Shweta Sikarwar
Obstetrics and Gynaecology, Subharti Medical College , - India


Non obstructive male infertility, Serum inhibin B, Testicular volume, Testicular fine needle aspiration

G, Gupta S, Sikarwar S. Role Of Serum Hormone Indices Including Inhibin B And Scrotal Ultrasound In Evaluation Of Non Obstructive Male Factor Infertility. WebmedCentral REPRODUCTION 2011;2(1):WMC001510
doi: 10.9754/journal.wmc.2011.001510
Submitted on: 25 Jan 2011 07:45:11 PM GMT
Published on: 26 Jan 2011 08:35:14 PM GMT


Objective: To evaluate the efficacy of serum hormone indices and testicular volume in men with non obstructive male factor infertility and to correlate testicular histology with serum inhibin B.

Design: prospective study.

50 patients with nonobstructive infertility problems and 50 controls with proven fertility were enrolled. semen analysis was done according to WHO guidelines. Serum hormonal concentration were evaluated by enzyme immuno assay. Testicular histology and testicular volume were estimated.

Results: men with obstructive pathology, retrograde ejaculation and seminal infection proven by semen culture were excluded. The mean plasma levels of FSH, LH, testosterone and inhibin B were 34.06±15.81mIU/ml, 14.41±5.62mIU/ml, 17.75±10.26mIU/ml & 49.60±46.29pg/ml respectively in azoospermic men. Serum inhibin B was undetectable (<15pg/ml) in 10, detectable but low in 11 and normal in 28 non obstructive infertile males, with a mean concentration of 74.65±58.76 pg/ml. Serum FSH was inversely correlated with serum inhibin B (r=-0.389). Mean testicular volume in study and control group was 11.3±6.58ml & 22.2±4.59ml respectively and had positive correlation with serum inhibin B (r=0.59).

Conclusion: Serum inhibin B level and its correlation with FSH is the best available endocrine marker of spermatogenesis but serum inhibin B cannot be considered superior to FSH.


Semen samples are difficult to obtain within sampling frames that allow comparisons. Blood samples are easier to obtain than ejaculates or biopsy. An advantage of inhibin B measurement is that it reflects the function of the total testicular tissue, whereas a biopsy may not be representative for the entire testis. Hence, it is necessary to see whether inhibin B can demonstrate the presence of focal spermatogenesis and could reduce the need for invasive testicular biopsies. Therefore, serum biomarkers of spermatogenesis are of major interest for population studies. FSH has previously been used as a marker of spermatogenesis, although it is also influenced by the hypothalamus. Serum inhibin B is a more direct serum marker of spermatogenesis in men with testicular disorders. The development of mature spermatozoa from spermatogonia, through primary and secondary spermatocytes and spermatids takes 70 ± 4 days(1). This period is neither altered by hormones nor by physical agents. The transit time of spermatozoa from testis into ejaculate is 12-21 days. Thus, sperm count will be less sensitively correlated to testicular histology then serum markers. Inhibin, a glycoprotein hormone produced by the testes as well as the ovaries, is responsible for the selective negative feedback control of FSH secretion, and may function as an intratesticular regulator. Inhibin decreases FSH-β mRNA levels by blocking activin signaling. Inhibin is a 32-kDa heterodimer composed of an α, and one of two β subunits, β A or β B. Inhibin-B (α-β B) is the form produced by testicular Sertoli cells(2), whereas inhibin-A, a product of the corpus luteum and placenta, is undetectable in the circulation in men(3,4). Inhibin α-subunit is produced and released into the circulation in excess of dimeric inhibin-B. Early double antibody immunoassays detected both the bioactive dimer and the seemingly inactive uncombined α-subunit, and therefore did not identify the decrease in inhibin secretion in hypogonadal men with elevated FSH levels.


315 male partners of infertile couples (infertility of more than 1 year) were subjected to 2 semen analysis at 3 months apart. The average of the two reports was considered while categorizing them between oligo/ astheno/ terato/ azoospermic (95) by WHO criteria. Men with obstructive pathology (10 azoospermic with absent semen fructose levels), retrograde ejaculation (7) and seminal infection proven by semen culture (27) were excluded. Seven were lost to follow up. Serum hormonal concentration of FSH, LH, testosterone and inhibin B were evaluated by enzyme linked immuno assay in study group (n=50) & control fertile men (n=20) using morning samples of serum. In ELISA assay used in the study, microtiter plates were coated with an antibody to inhibin βB that functions as the capture antibody. The indicator antibody was specific for the inhibin α-subunit, and was coupled to alkaline phosphatase. Thus, measuring dimeric forms of inhibin B. Although there is no remarkable pulsatile fluctuation in circulating inhibin-B levels, there is a diurnal variation in normal adult men with the highest values in the morning, and nadir values are approximately 35% lower in the early evening. This diurnal pattern of secretion parallels that of testosterone. So, mornings samples of serum were used for all hormonal estimations. Testicular volumes of both the testis were determined by transperineal ultrasonography using a 7.5-Mhz sector scan with an emphasis on the course of the proximal genital duct. Testicular volumes were calculated by using the formula:- Length x height x width x 0.71. Testicular histology was estimated by fine needle aspiration cytology and / or biopsy. Biopsy was performed under local anesthesia. A tissue wedge (~25 mg) from each testis was placed in phosphate-buffered saline and immediately transported to the laboratory. The testicular tissue was fixed in Bouin’s solution/Stieve’s fixative and embedded in paraffin Tissue samples were stained with hematoxylin and eosin stain and viewed under microscope x100-1000 magnification.
Mean and standard deviation as well as linear regression of different parameter values were calculated. Descriptive statistics were given as the mean ± SD. Pearson’s coefficient of correlation was used for regression analysis. The differences of means were tested for significance by student’s t test.


There were 270 (85.71%) cases of primary infertility and rest 45 (14.29%) cases were of secondary infertility. Among men with abnormal semen analysis 95(30.16%) reports, 23 (24.21%) were of secondary infertility and rest 72 (75.78%) were of primary infertility.
We categorized the subfertile men as oligo/ astheno/ terato spermic (60; 63.15%) or azoospermic (35; 36.84%) according to WHO criteria. Maximum numbers of patients in both the groups belonged to age group 26-30 years.
Maximum numbers of cases (52%) were not addicted to smoking or alcohol intake (p<0.001). Cigarette smoking has already been implicated as a cause of low sperm count and sperm abnormalities (5).
Maximum cases had heat exposure and recent febrile illness (58%). So, importance of loose fitting undergarments and avoidance of sauna bath must be told to every case. Acute viremia of recent origin may depress spermatogenesis (6) and should not be overlooked. Recent febrile illness, addiction, smoking (passive and active), genital trauma, heat exposure, mumps orchitis were significantly associated (p<0.001) with subfertility. Family history of infertility was present in only 20% of subfertile males and was found to be highly statistically significant (p<0.001).
The mean plasma levels of FSH, LH, testosterone and inhibin B were 20.91±16.7mIU/ml, 11.17±5.06mIU/ml, 14.47±7.37mIU/ml &74.65±58.76pg/ml respectively in sub fertile men and 34.06±15.81mIU/ml, 14.41±5.62mIU/ml, 17.75±10.26mIU/ml & 49.60±46.29pg/ml respectively in azoospermic men. Serum inhibin B was undetectable (<15pg/ml) in 10, detectable but low in 11 and normal in 28 non obstructive infertile males, with a mean concentration of 74.65±58.76 pg/ml. LH and testosterone values were insignificant. Serum FSH was inversely correlated with serum inhibin B (r=-0.389). Mean testicular volume in study and control group was 11.3±6.58ml & 22.2±4.59ml respectively and had positive correlation with serum inhibin B (r=0.59). The sperm concentration was negatively correlated with serum FSH concentration (r= -0.527, p<0.001 & r = -0.37, p<0.017).
Table 1 shows the detailed distribution of serum hormone parameters in study and control group. Serum inhibin B and testicular volume were significantly (p<0.001) and positively correlated (r=0.539) in the study group. Except one, all cases of undetectable serum inhibin B had testicular volume <10 ml. 44.82% (13/29) cases of normal inhibin B levels had >20ml testicular volume.
Damage to germ cells, with anatomical preservation of Sertoli cells, as occurs following chemotherapy or testicular irradiation, results in low levels of inhibin-B. Thus Sertoli cell number, circulating gonadotropins and a germ cell factor all influence inhibin-B production (table 2). This might be the reason of low serum inhibin B in men with sertoli cell only syndrome.
Individual serum inhibin B level were found to correlate positively with sperm concentration in all infertile men [(r=0.70, p<0.0001(7)) (r=0.75, p=0.001(8)) & (r= 0.576, p=0.0001, our study, 2009)].
All men with normal spermatogenesis had inhibin B levels well within the normal range, as determined in men with proven fertility. Our data confirm previous observations that inhibin B concentrations are significantly correlated to testicular volume. On the other hand, testicular volume is positively correlated to total sperm output in the ejaculate and has been suggested as a reliable marker of the testicular capacity to produce sperm.
Serum inhibin B was significantly (p<0.0001) low in all except five cases of nonobstructive azoospermia. Inhibin B level decreased (p<0.001) in azoospermic men and serum FSH levels increased (p<0.001) when compared with observations of fertile group (table 3).
All cases of non-obstructive azoospermic males had increased levels of s.FSH whereas 72.2% males had decreased levels of s.inhibin B levels as five cases had normal inhibin B levels (table 4). Among them, there were three cases of known abnormal histologies with normal inhibin B and increased s.FSH levels. Although mean inhibin-B levels are lower than normal in men with impaired spermatogenesis, there is substantial overlap between values in normospermic and oligospermic men in different studies (table 5).


Serum inhibin B level and its correlation with FSH is the best available serum endocrine marker of spermatogenesis in sub fertile men.
Values of serum inhibin B were undetectable in men with Klinefelter's syndrome, in whom germ cells are generally absent and many tubules are hyalinised, as well as in men with germinal aplasia in whom Sertoli cells were present. These results imply a role for germ cells in activin/inhibin βB gene expression. Inhibin B may not be a better marker for spermatogenesis although we know that more cases and multiple sites sampling are necessary for assessment that is more accurate. However, it is very unlikely that spermatogenesis may be present in other non analyzed sites because of high FSH and prolonged infertility.
Serum inhibin B though is a direct marker of spermatogenesis and more strongly associated with sperm count, testicular volume but its measurement did not add much to FSH, semen analysis and clinical evaluation for male infertility.
Further evaluation to know any cut off value of serum hormone levels in differentiation of testicular pathologies and success of procedures like TESE is still required.


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