Obesity Surgery

, Volume 24, Issue 10, pp 1686–1692

Effects of Bariatric Surgery on Male Obesity-Associated Secondary Hypogonadism: Comparison of Laparoscopic Gastric Bypass with Restrictive Procedures

Authors

  • Berniza Calderón
    • Department of Endocrinology and NutritionHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
  • Alba Galdón
    • Department of Endocrinology and NutritionHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
  • Alfonso Calañas
    • Department of Endocrinology and NutritionHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
  • Roberto Peromingo
    • Department of Digestive and General SurgeryHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
  • Julio Galindo
    • Department of Digestive and General SurgeryHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
  • Francisca García-Moreno
    • Department of Digestive and General SurgeryHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
  • Gloria Rodriguez-Velasco
    • Department of Digestive and General SurgeryHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
  • Antonia Martín-Hidalgo
    • Department of Biochemistry-ResearchHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
    • Centro de Investigación Biomédica en Red-Fisiopatología de Obesidad y Nutrición (CIBERobn)
  • Clotilde Vazquez
    • Department of Endocrinology and NutritionHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
    • Centro de Investigación Biomédica en Red-Fisiopatología de Obesidad y Nutrición (CIBERobn)
  • Héctor F. Escobar-Morreale
    • Department of Endocrinology and NutritionHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
    • Centro de Investigación Biomédica en Red Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM)
    • Department of Endocrinology and NutritionHospital Universitario Ramón y Cajal & Universidad de Alcalá & Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS)
    • Centro de Investigación Biomédica en Red-Fisiopatología de Obesidad y Nutrición (CIBERobn)
Original Contributions

DOI: 10.1007/s11695-014-1233-y

Cite this article as:
Calderón, B., Galdón, A., Calañas, A. et al. OBES SURG (2014) 24: 1686. doi:10.1007/s11695-014-1233-y

Abstract

Bariatric surgery results in the complete resolution of male obesity-associated secondary hypogonadism (MOSH) in many patients. However, the effects of different bariatric surgical procedures on male sexual hormone profiles and sexual dysfunction have not been compared to date. We compared the pre- and post-operative (at least 6 months after initial surgery) sex hormone profiles of 20 severely obese men submitted to laparoscopic gastric bypass (LGB) with 15 similar patients submitted to restrictive techniques (sleeve gastrectomy in 10 and adjustable gastric banding in 5). We calculated free testosterone (FT) levels from total testosterone (TT) and sex hormone binding globulin (SHBG) concentrations. Fasting glucose and insulin levels served for homeostatic model assessment of insulin resistance (HOMAIR). MOSH was present in 25 and 16 of the 35 patients when considering TT and FT concentrations respectively, resolving after surgery in all but one of them. When considering all obese men as a whole, patients submitted to LGB or restrictive procedures did not differ in terms of excess weight loss, in the decrease of fasting glucose and insulin, HOMAIR and waist circumference, or in the increase of serum 25-hydroxyvitamin D, TT and FT levels. The improvement in TT correlated with the decrease in fasting glucose (r = −0.390, P = 0.021), insulin (r = −0.425, P = 0.015) and HOMAIR (r = −0.380, P = 0.029), and with the increase in SHBG (r = 0.692, P < 0.001). The increase in FT correlated with the decrease in fasting glucose (r = −0.360, P = 0.034). LGB and restrictive techniques are equally effective in producing a remission of MOSH.

Keywords

Laparoscopic gastric bypassSleeve gastrectomyBand lapObesitySurgeryHypogonadismAndrogensInsulin resistance

Introduction

Obesity is a major public health problem with increasing prevalence [1] and is associated with an increased all cause mortality and medical co-morbidity [2]. The use of bariatric surgery has increased because it offers more successful weight loss and long-term weight maintenance than life style modification [3]. Even though modern bariatric surgical techniques are not entirely free of long-term nutritional and metabolic issues [47], the success and safety of current bariatric procedures clearly compensate the very important health risks associated with severe obesity.

Long-term outcomes after bariatric surgery have shown resolution of many complications associated with obesity. Overall, bariatric surgery results in the resolution of diabetes mellitus, hypertension, dyslipidemia, and sleep apnea that occur in more than 70, 60, 60, and 85 % of severely obese patients, respectively [8, 9]. Obesity-associated sexual dysfunction, including polycystic ovary syndrome in women and male obesity-associated secondary hypogonadism (MOSH) in men, may also achieve complete remission after bariatric surgery [10, 11].

Regarding MOSH, a recent meta-analysis concluded that weight loss attained after bariatric surgery is associated with an increase in both total testosterone (TT) and free testosterone (FT) and the normalization of serum sex hormone-binding globulin (SHBG), resulting in the complete resolution of MOSH in most patients [12]. Since the different bariatric procedures may result in different rates of remission of obesity-related complications such as diabetes mellitus [13, 14], the same could happen with MOSH. However, to our best knowledge, a direct comparison of the different bariatric techniques on the beneficial effects on MOSH has not been conducted to date. Therefore, we aimed to compare laparoscopic gastric bypass (LGB) with restrictive bariatric surgical procedures in terms of improvement of serum androgen concentrations and resolution of MOSH.

Patients and Methods

Patients

We studied thirty-five patients who underwent bariatric surgery at the Metabolic Surgery Unit of the Department of Endocrinology and Nutrition of the Hospital Universitario Ramón y Cajal. Indication for surgery was based on the recommendations of the National Institutes of Health [15]. Inclusion criteria needed attending the scheduled follow-up visits at the unit and not presenting heart disease, kidney, or liver failure. Previous diagnoses of hypogonadism or treatment for sexual dysfunction, thyroid disease, hyperprolactinemia or any other condition, or drug that could interfere with normal gonadal function were considered exclusion criteria.

Twenty patients were treated by LGB, 10 by sleeve gastrectomy (SG), and 5 by adjustable gastric banding (AGB) according to the hospital’s established protocols and after the evaluation and choice of the surgeon. For this reason, patients were not randomized to each of the surgical techniques. Patients were re-evaluated after surgery at different time intervals always after the initial 6 post-operative months (mean ± SD, 12.3 ± 5.6 months) and only when a significant weight loss of at least 10 % of initial weight was achieved. We compared the pre-and post-operative hormone profiles of the 20 patients submitted to LGB with the 15 patients submitted to restrictive techniques (considering those submitted to SG and those treated with AGB as a whole).

Ten healthy controls were matched with patients in terms of age for the purpose of establishing reference ranges for some hormonal determinations. Written informed consent was obtained from every participant, and the study was approved by the institutional review board of our institution.

Anthropometric parameters were recorded, and body mass index (BMI) was calculated both before operation and during follow-up, and the percentage of BMI lost was also determined. The same applied to waist circumference, which was measured as the smallest perimeter between the costal border and the anterior suprailiac spines. Excess weight loss (EWL) was calculated in our study as the percentage of the ratio between weight loss attained at revaluation from the time immediately before operation and ideal weight. The latter was calculated as the weight corresponding for a BMI of 25, given previous lack of consensus for the precise definition of EWL [16, 17]. Excess body weight (EBW) at baseline was calculated as the difference between baseline body weight and ideal weight.

Analytical Procedures and Reference Ranges

Serum creatinine, alanine amino-transferase, aspartic amino-transferase, and serum glucose levels were measured by standard colorimetric methods, using the Architect ci8200 analyzer (Abbot Diagnostics, Berkshire, UK). Levels of HDL cholesterol were measured in supernatant after plasma precipitation with phosphotungstic acid and Mg2+ (Boehringer Mannheim GmbH, Mannheim, Germany). Levels of total cholesterol and triglycerides were measured by enzymatic methods (Menarini Diagnostica, Florence, Italy). The LDL cholesterol level was calculated by using Friedewald’s formula.

Fasting insulin, TT, sex hormone-binding globulin (SHBG), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol were also assayed. Briefly, TT was measured by radioimmunoassay (Spectria, Orion Diagnostica, Espoo, Finland) with a coefficient of variation (CV) <10 %. The FT concentration was calculated from total testosterone and SHBG concentrations [18]. Serum insulin was measured by immunochemiluminescence (Immulite 2000, Siemens Healthcare Diagnostics Inc., Gwynedd, UK), with a CV <10 %. Insulin resistance in the fasting state was estimated by the homeostasis model assessment method (HOMAIR). A commercial enzyme-linked immunosorbent assay (ELISA) was employed for the measurement of 25-hydroxyvitamin D concentrations (IDS Ltd., Boldon, UK). The specificity of this assay is 100 % for 25-hydroxyvitamin D3 and 75 % for 25-hydroxyvitamin D2, with negligible cross-reactivities with vitamin D3 and vitamin D2 (<0.01 and <0.30 %, respectively).

Reference ranges were those provided by the Central Laboratory of Hospital Universitario Ramón y Cajal, except for free testosterone concentrations and HOMAIR which were obtained by calculating the 95 % confidence intervals of the control group’s means (since our Central Laboratory had no standard reference range for these parameters). Normal ranges were 300–900 ng/dL for TT, 117–639 μg/dL for SHBG, 6.5–18.3 ng/dL for FT, and 6.0–27.0 μU/mL for insulin.

Statistics

A priori power analysis was performed using Ene 3.0 software (http://www.e-biometria.com). To detect a difference equal or above 1.4 ng/dL in serum FT concentrations in patients before and after surgery, with a SD of 1.4 ng/dL, power = 0.8 and α = 0.05, at least 10 patients were needed for a two-tail estimate. To detect such a difference between groups with a one-tail estimate favoring LGB, at least 14 patients in each group were needed.

Results are expressed as means ± SD unless otherwise stated. The Kolmogorov–Smirnov statistic was applied to continuous variables. Logarithmic transformation was applied as needed to ensure normal distribution of the variables. Unpaired t test or Mann–Whitney U test was used to compare the central tendencies of the different groups as needed. To evaluate the association between discontinuous variables, we used the χ2 test and Fisher’s exact test as appropriate. Comparisons of continuous variables before and after bariatric surgery were performed using repeated-measures GLM analysis. Changes in selected variables after surgery were expressed as percentage of the difference between final and baseline values divided by the baseline values. Bivariate correlation was employed to study lineal association between two quantitative variables using Pearson’s or Spearman’s tests as appropriate. Finally, a backward stepwise multiple linear regression model was applied to evaluate the effects of several dependent variables on the changes of serum FT concentration. Analyses were performed using SPSS 15 (SPSS Inc, Chicago, Illinois). P < 0.05 was considered statistically significant.

Results

Baseline characteristics of the included 35 patients who underwent bariatric surgery are shown in Table 1. Patients submitted to LGB presented with higher baseline weight, BMI, EBW, and serum estradiol (Table 1). When considering TT concentrations, there were 12 patients (60 %) with hypogonadism in the LGB group and 11 (73.3 %) in the restrictive procedures group (Fisher’s test, P = 0.489). When considering FT concentrations, there were seven patients (35 %) with hypogonadism in the LGB group and nine (60 %) in the restrictive procedures group (Fisher’s test, P = 0.182). Before surgery, TT inversely correlated with BMI, systolic blood pressure, diastolic blood pressure, waist circumference, triglycerides, fasting glucose, insulin and HOMAIR, and directly with HDL and SHBG; FT showed similar associations (Table 2).
Table 1

Clinical and analytical characteristics of the severely obese men submitted to bariatric surgery

 

Laparoscopic gastric bypass (n = 20)

Restrictive surgery (n = 15)

P value

Age (year)

38 ± 9

41 ± 10

0.468

Weight (kg)

156 ± 26

132 ± 14

0.002

Body mass index (kg/m2)

50.4 ± 8.7

42.9 ± 2.7

0.001

Excess body weight (kg)

79 ± 26

55 ± 8

0.001

Waist circumference (cm)

142 ± 18

132 ± 10

0.078

Waist to hip ratio

1.0 ± 0.1

1.1 ± 0.1

0.345

Systolic blood pressure (mmHg)

147 ± 12

142 ± 19

0.361

Diastolic blood pressure (mmHg)

87 ± 9

87 ± 10

0.925

Serum creatinine (mg/dL)

1.0 ± 0.2

0.9 ± 0.2

0.166

Aspartate amino-transferase (U/L)

30 ± 18

26 ± 8

0.379

Alanine amino-transferase (U/L)

58 ± 49

47 ± 25

0.452

Total cholesterol (mg/dL)

189 ± 28

189 ± 29

0.952

HDL cholesterol (mg/dL)

40 ± 5

40 ± 9

0.989

LDL cholesterol (mg/dL)

120 ± 28

123 ± 29

0.717

Triglycerides (mg/dL)

157 ± 93

132 ± 44

0.347

Total testosterone (ng/dL)

302 ± 102

262 ± 79

0.224

Sex hormone-binding globulin (μg/dL)

182 ± 67

181 ± 85

0.982

Free testosterone (ng/dL)

7.7 ± 2.6

6.6 ± 1.8

0.194

Prolactin (ng/mL)

8.8 ± 2.6

11.7 ± 1.0

0.184

Luteinizing hormone (mU/mL)

3.4 ± 1.2

2.9 ± 1.0

0.354

Follicle-stimulating hormone (mU/mL)

4.1 ± 2.2

3.3 ± 1.3

0.380

Estradiol (pg/mL)

40.6 ± 13.0

30.8 ± 3.9

0.027

Fasting glucose (mg/dL)

120 ± 61

114 ± 22

0.720

Fasting insulin (μU/mL)

34.2 ± 22.2

39.8 ± 40.8

0.608

HOMAIR

9.8 ± 6.1

11.9 ± 14.3

0.591

Serum PTH (pg/mL)

52.4 ± 16.1

56.9 ± 17.9

0.466

25-hydroxyvitamin D (ng/mL)

18.9 ± 9.4

18.4 ± 8.0

0.866

Data are means ± SD

HOMAIR homeostasis model assessment of insulin resistance

Table 2

Correlation of total testosterone and free testosterone with other clinical and analytical variables before surgery when considering the 35 patients submitted to bariatric surgery as a whole

 

Total testosterone

Free testosterone

 

r

P

r

P

Body mass index (kg/m2)

−0.477

0.001

−0.445

0.002

Waist circumference (cm)

−0.584

<0.001

−0.540

<0.001

Systolic blood pressure (mmHg)

−0.382

0.011

−0.319

0.037

Diastolic blood pressure (mmHg)

−0.471

0.001

−0.432

0.004

HDL cholesterol (mg/dL)

0.651

<0.001

0.551

<0.001

Triglycerides (mg/dL)

−0.443

0.002

−0.436

0.003

SHBG (μg/dL)

0.633

<0.001

0.313

0.036

Fasting glucose (mg/dL)

−0.426

0.003

−0.412

0.005

Fasting insulin (μU/mL)

−0.311

0.037

−0.296

0.048

HOMAIR

−0.340

0.022

−0.334

0.025

HDL high-density lipoprotein, HOMAIR homeostasis model assessment of insulin resistance, SHBG sex hormone-binding globulin

When patients were revaluated after weight loss induced by bariatric surgery, all patient normalized their serum concentrations of TT and FT, with the exception of one patient submitted to SG who did not normalize TT concentrations (his baseline TT of 200 ng/dL increased to 253 ng/dL when revaluated 6 months after surgery). TT and FT concentrations increased after bariatric surgery irrespective of the bariatric technique applied (LGB or restrictive techniques, Table 3). The near-significant difference (P = 0.053) between surgical techniques observed in the increase in TT was probably due to the significant change in SHBG, because no differences were observed between techniques in the increase in FT (Table 3). This highlights the importance of calculating FT in these patients, as results in TT may be spuriously low due to the lowering effects of obesity on SHBG levels.
Table 3

Changes in selected variables after bariatric surgery

 

Laparoscopic gastric bypass (n = 20)

Restrictive surgery (n = 15)

P value for within subjects effect

P value for between subjects effect

P value for interaction

Weight (kg)

−51.0 ± 20.7

−31.1 ± 17.6

<0.001

0.031

0.005

Body mass index (kg/m2)

−16.4 ± 6.8

−9.9 ± 5.0

<0.001

0.042

0.004

Waist circumference (cm)

−26.0 ± 19.5

−20.2 ± 15.2

<0.001

0.455

0.410

Total testosterone (ng/dL)

251.2 ± 168.7

148.3 ± 119.5

<0.001

0.002

0.053

Sex hormone-binding globulin (μg/dL)

243 ± 207

54 ± 72

<0.001

0.010

0.002

Free testosterone (ng/dL)

2.2 ± 2.9

3.0 ± 2.8

<0.001

0.421

0.398

Luteinizing hormone (mU/mL)

1.0 ± 1.5

0.5 ± 1.6

0.078

0.146

0.549

Follicle-stimulating hormone (mU/mL)

1.0 ± 1.8

0.9 ± 1.4

0.051

0.265

0.831

Estradiol (pg/mL)

−0.2 ± 11.4

−5.8 ± 5.2

0.288

0.087

0.320

Fasting glucose (mg/dL)

−30.8 ± 58.0

−21.1 ± 20.8

0.002

0.901

0.542

Fasting insulin (μU/mL)

−27.0 ± 23.8

−30.9 ± 41.3

<0.001

0.477

0.742

HOMAIR

−8.0 ± 6.6

−10.1 ± 14.7

<0.001

0.378

0.587

Serum parathyroid hormone (pg/mL)

8.9 ± 30.7

−8.3 ± 14.6

0.946

0.459

0.065

25-hydroxyvitamin D (ng/mL)

9.7 ± 20.7

7.9 ± 10.2

0.009

0.879

0.776

Data are means ± SD

HOMAIR homeostasis model assessment of insulin resistance

Fasting glucose, insulin, HOMAIR, and waist circumference showed a similar decrease after surgery between groups (Table 3). Serum 25-hydroxyvitamin D levels also showed a similar increase after surgery between groups (Table 3), and EWL did not reach a significant difference between groups either (67 ± 26 % and 54 ± 26 % for LGB and restrictive procedures, respectively, t = 1.373, P = 0.179). On the other hand, total weight loss, the decrease in BMI and the increase in SHBG after surgery were higher with LGB than with restrictive techniques (Table 3). When restricting the analysis to patients presenting MOSH at baseline (defined by low FT concentrations,) only SHBG showed a higher increase with LGB compared with restrictive surgery (Fig 1).
https://static-content.springer.com/image/art%3A10.1007%2Fs11695-014-1233-y/MediaObjects/11695_2014_1233_Fig1_HTML.gif
Fig 1

Selected anthropometric and analytical variables in obese patients presenting with MOSH at baseline, showing their changes after bariatric surgery as percentage of pre-surgery values. Data are means ± SEM. Black bars correspond to restrictive techniques (considering sleeve gastrectomy and adjustable gastric banding as a whole) and gray bars correspond to laparoscopic gastric bypass (LGB). BMI body mass index, EWL excess weight loss, FT free testosterone, SHBG sex hormone-binding globulin, TT total testosterone, WC waist circumference. Only SHBG showed a significant difference between the effects of LGB and those of restrictive techniques (*P = 0.016 by Mann–Whitney U test)

The increase in TT correlated with the decrease in fasting glucose (r = −0.390, P = 0.021), insulin (r = −0.425, P = 0.015), and HOMAIR (r = −0.380, P = 0.029), and with the increase in SHBG (r = 0.692, P < 0.001). The increase in FT correlated with the decrease in fasting glucose (r = −0.360, P = 0.034). Finally, multivariate linear regression was employed to evaluate the effects of several dependent variables (EWL, waist circumference, fasting glucose, insulin, and estradiol) on the changes of serum FT concentration. The model retained only the decrease in fasting glucose (β = −0.995, P = 0.017) as predictor of the increase in serum FT (R2 = 0.467, F = 4.945, P = 0.046).

Discussion

Our present results indicate that LGB and restrictive techniques such as SG and AGB are equally effective in inducing the remission of MOSH in severely obese men. In fact, all men presenting with MOSH before surgery normalized their serum FT concentrations after all bariatric surgical procedures. The normalization of FT occurred in parallel to weight loss, to the increase in serum vitamin D, and to the decrease in waist circumference, glycemia, insulinemia, and insulin resistance. Moreover, the decrease in glycemia after surgery was the main factor associated with the increase in FT.

Decreased testosterone concentrations in men have been found not only in obesity but also in patients with type 2 diabetes mellitus and in association with the metabolic syndrome [1921]. Moreover, low testosterone concentrations have been associated with insulin resistance in non-diabetic men [22], and weight loss induced by dieting has been shown to increase testosterone levels in parallel to the improvement in insulin sensitivity [23].

Although the precise pathophysiological mechanisms linking reduced serum testosterone concentrations with insulin resistance in men are not clearly understood, it has been proposed that the increased aromatase activity characteristic of obesity, by increasing estrogen levels, may inhibit gonadotropin secretion thereby reducing androgen concentrations [24]. These changes may also downregulate GLUT4 by an augmentation of the estrogen receptor beta expression, favoring insulin resistance [25]. Other pathophysiologic pathways that link hypogonadism with obesity and insulin resistance may include adypokines such as leptin and adiponectin [26], as testosterone replacement therapy decreases leptin and increases adiponectin levels in type 2 diabetic men [27].

Aside from the decrease in glycemia, another factor which might have influenced the increase in testosterone after bariatric surgery was the increase observed in vitamin D concentrations, as it has been positively associated with TT and FT [28, 29]. Moreover, vitamin D is positively associated with semen quality apart from its association with androgen levels [30, 31]. On the other hand, to date, no trial has shown that vitamin D administration may correct androgen deficiency, so reduced vitamin D may be only a surrogate marker of ill-health in these patients and the association of increased androgen and vitamin D concentrations after bariatric surgery may only reflect the improvement in their metabolic function.

Massive weight loss after bariatric surgery is a constant finding associated with the remission of MOSH. A recent study conducted in 33 men has shown that age and the percentage of weight loss were the only independent factors associated with the increase in TT after bariatric surgery [32]. Also, a recent meta-analysis has shown that body weight loss induced by bariatric surgery was the main factor associated with a relevant increase in gonadotropins and in TT and FT, and with a decline in estrogen levels [12]. Although not thoroughly analyzed in this study, we may speculate with the possibility that weight reduction is associated with increased insulin sensitivity, and in turn with an activation of the hypothalamic-pituitary-gonadal axis, as insulin exerts a permissive role on GnRH neuron activity [33]. However, in our study, we did not find an association of excess weight loss and the increase in FT in multivariate analysis. This may have been due to the fact that all patients were revaluated at least 6 months after surgery, when extensive weight loss has already taken place. We might hypothesize that once a threshold for weight loss is reached, gonadal function is restored, the relationship between excess weight loss and remission of MOSH not being lineal.

In conceptual agreement with the beneficial effects of weight loss on the gonadal function of severely obese men observed in our study, both the Endocrine Society Guidelines and the Third International Consultation on Sexual Medicine recommend that lifestyle modification must be strongly encouraged in hypogonadal men with obesity, type 2 diabetes, and the metabolic syndrome [34, 35]. However, the increase in testosterone induced by lifestyle interventions was clearly inferior to that induced by bariatric surgery (9.8 % with diet vs 32 % with surgery).

Therefore, we suggest that bariatric surgery should be considered for the treatment of MOSH [12]. However, it is unclear which bariatric technique is the most appropriate for inducing the remission of MOSH since a direct comparison of these bariatric surgical procedures has not been conducted to date. There have been controversial results when comparing the effects of weight loss after bariatric surgery with different techniques on TT and FT. Although Bastounis et al. [36] found years ago an improvement in SHBG and TT after vertical gastroplasty without any change in FT, other authors recently found an increase in FT after gastric bypass [37] or banded gastroplasty [38]. Even the aforementioned meta-analysis [12] gives no clue on this aspect and, as far as we know, our study is the first one to report a direct comparison of the effects of LGB and restrictive techniques on sexual dysfunction and the first to include an evaluation of the changes in gonadal steroids after SG. In fact, our data indicated that changes in BMI and SHBG were the only significant ones between the different surgical techniques. This might be of interest, since SHBG produced by the liver has been shown to have important effects on insulin sensitivity and the regulation of body weight [39].

Our study, however, was not free of limitations. First, because this study was not a randomized trial, patients in the LGB group were more obese at baseline than those submitted to restrictive procedures. This difference in weight, however, does not invalidate the results because both groups were comparable in terms of total testosterone, SHBG and free testosterone levels, and age. Second, our relatively small sample size did not permit a separate comparison of LGB, SG, and AGB, explaining why we considered patients submitted to SG and AGB as a whole. Third, not all patients were revaluated at the same time intervals after bariatric surgery and, in fact, the only MOSH patient who did not normalize entirely his sex hormone profile was revaluated after only 6 months post-operatively, suggesting that a longer period is needed for MOSH to resolve. Future studies in which patients are reevaluated after bariatric surgery at fixed intervals will help in elucidating if resolution of MOSH is only a matter of weight loss or is also a time-dependent effect of bariatric surgery.

In conclusion, weight loss after bariatric surgery results in the complete remission of MOSH, with LGB and restrictive techniques being equally beneficial for male gonadal function.

Acknowledgments

We thank the nurse staff of the Department of Endocrinology and Nutrition for their help with the anthropometric and blood sampling of the patients.

Conflict of Interest

The authors declare no conflict of interest.

Copyright information

© Springer Science+Business Media New York 2014