|Year : 2017 | Volume
| Issue : 1 | Page : 3-8
Association of levels of serum inhibin b and follicle-stimulating hormone with testicular vascularity, volume, and echotexture in children with undescended testes
Abhishek Chinya1, Simmi K Ratan1, Satish K Aggarwal1, Anju Garg2, TK Mishra3
1 Department of Pediatric Surgery, Maulana Azad Medical College, New Delhi, India
2 Department of Radiodiagnosis, Maulana Azad Medical College, New Delhi, India
3 Department of Biochemistry, Maulana Azad Medical College, New Delhi, India
|Date of Web Publication||23-Nov-2016|
Simmi K Ratan
Department of Pediatric Surgery, Maulana Azad Medical College, New Delhi
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aims: The aim of our study was to assess the association between reproductive hormones (inhibin B [inh B], follicle-stimulating hormone [FSH]) with testicular volume, echogenicity, and blood flow (resistive index [RI]) in children with undescended testis (UDT).
Settings and Design: This was a prospective study of 1-year study duration.
Materials and Methods: A total of 33 patients (16 unilateral and 17 bilateral) UDTs aged 5-12 years with palpable UDT were included in the study. Morning fasting blood samples were taken for estimation of serum inh B and FSH as well as inh B/FSH ratio. Testicular ultrasound was done to compute testicular volume, testicular echogenicity, and testicular vascularity in terms of RI.
Results: The mean age of patients enrolled in the study was 8.29 years for unilateral UDT and 7.97 years in bilateral UDT and it was comparable. The study groups were further subdivided into two age-wise subgroups school goers (5-8 years) and prepubertal (9-12 years). The values of inh B, FSH, and inh B/FSH ratios as well as mean testicular volume were comparable between both groups and subgroups. Overall mean testicular volume had a positive correlation with FSH, inh B, and inh B/FSH, but statistical significance was reached only for inh B (P < 0.001) in children with both unilateral and bilateral UDT. Apart from five patients with hypoechogenicity within the testis, all remaining testes were of homogenous echotexture with no instances of irregular echogenicity or tumor. Children with RI >0.6 were separately studied. The incidence of high RI (>0.6) was also comparable in unilateral or bilateral disease. These subjects had unfavorable biochemical parameters in terms of low inh B levels and high FSH levels.
Conclusions: Our findings hint to the fact that palpable UDT forms a homogenous group, whether unilateral or bilateral, whereas impalpable testes may form a separate category and need further studies to substantiate this hypothesis.
Keywords: Echogenicity, follicle-stimulating hormone, inhibin B, resistive index, testicular volume
|How to cite this article:|
Chinya A, Ratan SK, Aggarwal SK, Garg A, Mishra T K. Association of levels of serum inhibin b and follicle-stimulating hormone with testicular vascularity, volume, and echotexture in children with undescended testes. J Indian Assoc Pediatr Surg 2017;22:3-8
|How to cite this URL:|
Chinya A, Ratan SK, Aggarwal SK, Garg A, Mishra T K. Association of levels of serum inhibin b and follicle-stimulating hormone with testicular vascularity, volume, and echotexture in children with undescended testes. J Indian Assoc Pediatr Surg [serial online] 2017 [cited 2017 Nov 21];22:3-8. Available from: http://www.jiaps.com/text.asp?2017/22/1/3/194609
First author of this paper was awarded Dr. U C Chakraborty award
| Introduction|| |
The most frequently asked question by the apprehensive parents of a child presenting with undescended testes (UDTs) is the fertility potential of the child once he grows up into adulthood which depends both on the spermatogenic function of the testis and its conducting system. However, in children with UDT, it is the former that is more frequently compromised. 
The bulk of testis is constituted by the Sertoli cells More Details and larger testes are associated with better sperm counts.  Ultrasonography is a better modality to evaluate testicular volume.  The levels of inhibin B (inh B), a glycoprotein dimer consisting of α and β subunits secreted by Sertoli cells, correlated significantly with sperm concentration, sperm count, and testicular volume.  Currently, its levels are known to correlate best with potential for fertility. In fact, inh B surpasses follicle-stimulating hormone (FSH) in terms of predicting the fertility potential. Negative correlation between inh B and FSH is known.  However, the cutoff value for serum inhibin in relation to spermatogenic function has not been well-established, and studies in literature have given variable results as to the significant difference between levels among normal versus infertile men and those with subfertile men with descended or UDT. 
We evaluated inh B and FSH levels and correlated them with testicular vascularity, size, and echotexture. We tried to establish an association between these factors in a more objective manner and deduce whether these hormonal estimations could help in indicating the spermatogenic potential.
| Materials and Methods|| |
The study was conducted in the Department of Pediatric Surgery in association with Departments of Radiodiagnosis and Biochemistry. It was a prospective study of 1-year duration. From the previous study by Pierik et al.,  the correlation between inh B and total testicular volume (r value) was found to be 0.63 and the sample size based on this finding came out to be 11 at 95% correlation levels.  A total of 33 patients (16 unilateral and 17 bilateral) UDT in the age group 5-12 years were included in the study. The inclusion criteria were at least 12 weeks postsurgical treatment and not on any hormonal treatment currently or within the past 3 months. Syndromic children and children with impalpable testes were excluded from the study. Informed consent of the parent/s was taken for study subjects. Pro forma was maintained for each patient. Morning fasting blood samples (2 ml preferably between 9 and 11 A.M.) from patients and controls were collected and stored in plain tubes for estimation of serum inh B and FSH in the Department of Biochemistry. Serum inh B (pg/ml) was measured by Human Inhibin B ELISA kit (Ansh Labs, USA). Serum FSH (IU/L) was measured by FSH ELISA kit (Calbiotech, USA). Inh B/FSH ratio was then calculated. All patients underwent an ultrasound evaluation of the testes on an ACUSON S2000 Ultrasound System (Siemens Medical Solutions) using a linear 9L4 (frequency bandwidth 4-9 MHz) multifrequency transducer. Testicular volume was measured by the formula described by Sakamoto et al. (volume = length × width × height × 0.71).  Right and left testicular volume was noted separately and mean testicular volume was computed for each subject (R + L/2). Echogenicity of both testes was noted as isoechoic, hypoechoic, or hyperechoic. Using Doppler study, the blood flow of right and left intratesticular vessels was measured in terms of resistive index [RI]. RI = systolic flow − diastolic flow/systolic flow.
The data were tabulated into two major groups: Unilateral UDT and bilateral UDT. The data were fed into Microsoft Excel. Mann-Whitney U-test was used to test the difference in hormone levels between the two groups. The quantitative variables such as inh B or FSH were correlated with testicular volume, testicular vascularity, and testicular echotexture using Spearman correlation test. The values of study variables were entered. The entire data were further categorized into two age-wise subgroups, i.e., 5-8 years and 9-12 years. In case of two group comparison of quantitative variable, Student's t-test was used. All tests were accepted statistical significant when alpha error <5%, i.e., P < 0.05. Correlation coefficient of the quantitative variables was computed using regression analysis.
| Results|| |
There were 17 patients with bilateral UDT and 16 patients with unilateral UDT. Of these, 21 (10 unilateral UDT and 11 bilateral UDT) were in the early school goers age group 5-8 years and 12 (6 each in unilateral and bilateral UDT) were in the prepubertal age group 9-12 years. The mean age of patients involved in the study in unilateral UDT was 8.29 years (standard deviation [SD] 2.64) and in bilateral UDT was 7.97 years (SD 2.16). There was no statistical significance in the age groups (P = 0.5). This might be because consecutive patients were not taken in the study.
[Table 1]a shows the description statistics of serum inh B, FSH, and inh B/FSH ratio and testicular volume in subjects with unilateral and bilateral UDT along with values of statistical difference. The mean inh B in bilateral group (137.38 pg/ml) was higher than that of unilateral group (111.85 pg/ml). Mean FSH value was also more in bilateral group (1.33 IU/L) as compared to that of unilateral group (0.92 IU/L). The mean testicular volume however was more in the unilateral group (1.31 ml) as compared to the bilateral group (1.07 ml). The mean inh B/FSH ratio was significantly low in bilateral group (292.02 ng/IU) as compared to the unilateral group (414.21 ng/IU). However, none of the study variables was found to be statistically significant in any age group.
We further analyzed data by dividing them into school goers 5-8 years and prepubertal 9-12 years. The descriptive statistics for these two age-wise subgroups for unilateral and bilateral UDT are shown in [Table 1]b. In the 5-8 years age group, the mean inh B value was more in bilateral group (123.76 pg/ml) as compared to unilateral group (90.95 pg/ml). The mean FSH was however more in unilateral group (1.01 IU/L) than that of bilateral group (0.94 IU/L). The mean testicular volume was more in children with unilateral UDT (1.04 ml) as compared to children with bilateral UDT (0.91 ml). The mean inh B/FSH ratio was lower in unilateral group (169.79 ng/IU) as compared to bilateral group (251.49 ng/IU). Statistical significance was not reached in any of the above parameters, except the P value being close to statistical significance (0.066) in case of inh B/FSH ratio. In the 9-12 years age group, the mean inh B was more in the bilateral group (162.35 pg/ml) as compared to unilateral group (146.69 pg/ml). The mean FSH was also higher in bilateral group (2.03 IU/L) than unilateral group (0.76 IU/L). Children with unilateral UDT had higher mean testicular volume (1.75 ml) as compared to children with bilateral UDT (1.36 ml). The mean inh B/FSH ratio was lower in bilateral group (124.11 ng/IU) as compared to the unilateral group (821.51 ng/IU). Statistical significance was not reached in any of the above parameters, except the P value being close to statistical significance (0.051) in inh B/FSH ratio. Overall, in our study, the inh B levels were always more in children with bilateral UDT than their unilateral counterparts, whereas FSH values were higher in children with bilateral UDT. Except in age group of 5-8 years, the mean FSH value was higher in the unilateral group, while in the 9-12 years age group, mean FSH value was always more in the bilateral group. Mean testicular volume was always more in children with unilateral UDT as compared to that with bilateral UDT and this was true for age-wise comparisons and overall. The inh B/FSH ratio was found to be lower in children with bilateral UDT in the prepubertal age group as compared to children with unilateral UDT. However, none of these reached statistical significance when age-wise subgroups were compared.
There were three patients in the unilateral group and two patients in the bilateral group with reduced echogenicity. The detailed values of testicular volumes, hormones, and inh B/FSH ratio are given in [Table 2]. No patient had hyperechoic texture or with heterogeneous texture.
|Table 2: Description of profile of subjects with undescended testis and having hypoechoic testes|
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In both the children in bilateral group with hypoechoic testis, there was no significant difference in hormonal levels in comparison to the mean values of these hormones in their respective age-wise groups. One patient had high inh B value.
The normal testicular vascularity in the subjects was taken to be between 0.4 and 0.6. Hence, those children whose RIs were more than 0.6 were separated and studied separately. There were seven such children in the bilateral age group and eight in the unilateral age group. [Table 3]a shows testicular volumes, hormones, and ratios of subjects with bilateral UDT, and [Table 3]b shows testicular volumes, hormones, and ratios of subjects with unilateral UDT. There were seven such children in the bilateral age group and eight in the unilateral age group. One child had high serum inh B (142 pg/ml) level in the unilateral group. FSH values in the group with unilateral UDT were more than the median for that age group. In the unilateral group, the mean testicular volume of every child aged 5-8 years was less than the mean testicular volume for that group. In those children aged 9-12 years, except one child, the mean testicular volume was less than that of the group.
The correlation of mean testicular volume with FSH, inh B, and inh B/FSH ratio is tabulated in [Table 4]. Overall, mean testicular volume had a positive correlation with FSH, inh B, and inh B/FSH, but statistical significance was reached only for inh B (P < 0.001). In children with bilateral UDT too, mean testicular volume showed a positive correlation with inh B, which was statistically significant (P = 0.005). In all the remaining groups, positive correlation was seen in all instances but did not reach statistical significance. There was a negative correlation between inh B and FSH (−0.502) in unilateral UDT group, which reached statistical significance (P = 0.047). Overall, there was negative correlation of FSH with inh B (−0.110), which did not reach statistical significance.
|Table 4: Correlation of mean testicular volume with follicle-stimulating hormone, inhibin B, and inhibin B/follicle-stimulating hormone ratio in subjects with undescended testis|
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| Discussion|| |
Our study is first of its kind in which almost equal numbers of subjects with unilateral and bilateral UDT were compared. For the purpose of detailed comparison, we further divided them into two subgroups 5-8 years (school goers) and 9-12 years (prepubertal). This attempt was done in view of highly active pituitary-gonadal axis in prepubertal children at time of onset of puberty in 9-12 years of age, which can lead to discrepancy in evaluation of hormone levels when compared with younger children. The number of subjects in each age-wise subgroups for unilateral or bilateral UDT was also comparable. There were 21 subjects (10 unilateral and 11 bilateral) in 5-8 years age group and 12 in 9-12 years age group (6 each in unilateral and bilateral). No earlier study has drawn comparison by taking equal or a comparable number of subjects in unilateral or bilateral UDT.
We studied only two reproductive hormone levels, i.e., serum inh B and FSH in our study group as these are the two hormones which have been quoted to directly influence or get influenced with Sertoli cell number and function. We found the levels of these hormones to be comparable between unilateral and bilateral UDT groups although mean value of FSH was found to be higher among bilateral UDT (1.33 ± 1.26) subjects in comparison to that in unilateral group (0.92 ± 0.96). It was surprising that mean levels of inh B were found to be slightly higher among bilateral UDT group (137.38 ± 75.12) in comparison to that of unilateral group (111.85 ± 54.28). Finding comparable levels of these two hormones in our study may be due to inclusion of subjects with palpable UDT which in turn may reflect a genetically and environmentally better testis in comparison to those which are nonpalpable.
Testosterone and Leydig cell function were not studied by us. However, there is ample literature that reveals that androgen depletion may be associated with UDT. In fact, Hadziselimovic et al. found that androgen deficiency is present in both unilateral and bilateral UDT. Based on their research, they found that this androgen deficiency causes delay in transformation of fetal spermatogonia to adult spermatogonia and affects the further fertility potential which may not be affected by age at orchidopexy or unilaterality or bilaterality of this disease.  On the other hand, other authors have found the incidence of infertility to be 3.5 times more than general population in unilateral UDT and 6 times more in bilateral UDT, and even among UDT, those which are impalpable are associated with greater germ cell depletion. , The risk may be 50% higher among those with impalpable testes than those with palpable.  Therefore, it seems that the prospects of germ cell loss should be lower in palpable testis.
Testicular volume is considered to be associated with fertility prospects.  An extrapolation of evidence of poorer fertility in subjects with bilateral UDT suggests that testicular volume should be much poorer in subjects with bilateral UDT. However, our results do not agree with this and we found a comparable testicular volume for both unilateral and bilateral UDT subjects overall and within age-wise and subgroup. We can attribute this difference to the fact that all subjects in our study had palpable UDT.
High variations in levels of inh B have been noted in subjects with disorder of testicular function. Some studies have found that serum FSH has got better predictive value than serum inh B toward prediction of fertility.  Although in most cases both FSH and inh B correlate well with sperm concentration and testicular volume, it has been found that concentration of sperm correlated more positively with inh B/FSH ratio. A high serum inh B level may even be seen in patients with azoospermia if the cause is obstructive. Similarly, foci of spermatogenesis lead to serum inh B concentration even in small testis.  It has been observed that idiopathic subfertile men have significantly lower inh B and significantly higher FSH as compared with reference range.  However, since these parameters were found to be comparable, we deduce that Sertoli cell function in these testes whether unilateral or bilateral would be comparable at least until prepubertal period as studied by us.
Hyperechoic areas are generally found on testicular sonography due to irregular parenchyma or hyalinized foci within the testis whereas hypoechoic foci may be due to Leydig cell hyperplasia.  Prepubertal testes are known to have low to medium echogenicity, whereas pubertal and postpubertal testes are of medium homogeneous echogenicity, reflecting how the development of germ cell elements and tubular maturation, and how it affects the echotexture of testes.  Hence, hypoechogenicity in preoperative testis may reflect that tubular maturation has not taken place in these patients. However, these testes constitute only 15% of entire study group and probably do not prognosticate poor prognosis of infertility in these children. However, the ultrasound findings of these testes were not matched with normally descended testes of growing children and form another subject of further research.
In our study also, we got a positive correlation of mean testicular volume with inh B (0.573) which reached statistical significance (P < 0.001). This is in accordance with several other studies reported in literature, showing serum inh B as a reliable marker of the testicular capacity to produce sperm which in turn is related to testicular volume. , In our study, there was a positive correlation between serum inh B and FSH, but that was not found to be statistically significant. This differs from some other studies reported. Trsinar and Muravec reported a negative correlation between inh B and FSH in their study on fertility potential after orchidopexy after cryptorchidism in 68 men with UDT aged between 25 and 30 years. 
The normal testicular RI in most studies was taken to be between 0.4 and 0.6. , Mean testicular size and total motile sperm were reduced and serum FSH was found to be raised in subjects with RI higher than 0.6. Hence, those children whose RIs were more than 0.6 were categorized and studied separately by us. One child had high serum inh B (142) level in the unilateral group. FSH values in the group with unilateral UDT were higher than the median (0.53) for that age group. In the unilateral group, the mean testicular volume of every child aged 5-8 years was less than the mean testicular volume (1.04) for that group. In those children aged 9-12 years, except one child, the mean testicular volume was less than that of the group (1.75). These data are supportive of the fact that the subjects with higher RI had unfavorable hormonal status and lower testicular volumes. Hence, calculation of RI should form an integral part of workup of children with UDT. The incidence of high RI was also comparable in unilateral or bilateral disease and this again shows that unilaterality or bilaterality may not cause difference in fertility prospects in patients with UDT.
| Conclusion|| |
We conclude that palpable UDT whether unilateral or bilateral form a homogenous group and probably separate from nonpalpable testes. Inh B and FSH both positively affect testicular volume. Not many echotextural changes are noted among prepubertal subjects in unilateral or bilateral UDT. However, a high RI (>0.6) may dictate a poor prognosis for such testes which can reflect as subfertility status in adulthood. Further research is required to compare the hormonal profile of children with palpable UDT with those of impalpable UDT. Impalpable testes may form a separate category and need further studies to substantiate this hypothesis.
We would like to thank Mrs. Anju Sharma for her contribution and help in conducting this research work.
Financial support and sponsorship
Thesis grant received from Maulana Azad Medical College (GNCT, New Delhi) for procuring inhibin B and FSH kits for the study.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]