Hypogonadotropic hypogonadism in a patient with morbid obesity

Clinical characteristics of male prolactinoma patients mainly presenting with severe obesity and the metabolic response to dopamine agonist therapy

Objective

To summarize the clinical characteristics of 4 male prolactinoma patients with severe obesity.

Methods

The clinical data of all the patients were retrospectively analyzed.

Results

All the patients visited our hospital for severe obesity at the age of 16-30 years old with their body mass index (BMI) of 37.9-55.9 kg/m2. All the patients were obese since childhood, even at birth. Hyperprolactinemia (72.3-273.0 ng/ml) was found during the etiological screening of obesity and MRI revealed pituitary adenomas. Additionally, all of them had multiple obesity related complications, such as hyperinsulinemia and dyslipidemia. Treatment of dopamine agonists (DAs) effectively normalized their prolactin level and the pituitary MRI reexamination after 6 months of DAs treatment showed the shrinkage of the pituitary adenomas in 3 patients. Their weight also decreased in different degrees (2.70~19.03% lower than the baseline) with improved metabolic profiles.

Conclusion

Serum prolactin level should be screened in obese patients, especially those with severe obesity.

Functional and Phenotypic Characteristics of Human Leptin Receptor Mutations

Several case series of extreme early-onset obesity due to mutations in the human leptin receptor (LEPR) gene have been reported. In this review we summarize published functional and phenotypic data on mutations in the human LEPR gene causing severe early-onset obesity. Additionally, we included data on six new cases from our obesity center. Literature research was performed using PubMed and OMIM. Functional relevance of mutations was estimated based on reported functional analysis, mutation size, and location, as well as phenotypic characteristics of affected patients. We identified 57 cases with 38 distinct LEPR mutations. We found severe early-onset obesity, hyperphagia, and hypogonadotropic hypogonadism as cardinal features of a complete loss of LEPR function. Other features, for example, metabolic disorders and recurring infections, were variable in manifestation. Obesity degree or other manifestations did not aggregate by genotype. Few patients underwent bariatric surgery with variable success. Most mutations occurred in the fibronectin III and cytokine receptor homology II domains, whereas none was found in cytoplasmic domain. In silico data were available for 25 mutations and in vitro data were available for four mutations, revealing residual activity in one case. By assessing provided information on the clinical phenotype, functional analysis, and character of the 38 mutations, we assume residual LEPR activity for five additional mutations. Functional in vitro analysis is necessary to confirm this assumption.

Circulating free testosterone in obese men after bariatric surgery increases in parallel with insulin sensitivity

BACKGROUND AND AIM

Male hypogonadism has been linked to obesity and diabetes. We aimed to study the association of changes in insulin sensitivity and testosterone levels in severe obese patients submitted to bariatric surgery.

SUBJECTS AND METHODS

Prospective intervention study with twenty consecutive patients who underwent bariatric surgery studied before and after significant weight loss. Serum testosterone, SHBG, fasting glucose, and insulin were measured among others. Free testosterone was calculated with the Vermeulen formula and insulin sensitivity with the homeostatic model assessment (HOMA).

RESULTS

At baseline, thirteen patients had low total testosterone levels, whereas eight of these patients also had free testosterone levels below the reference range obtained from the control group. After bariatric surgery total testosterone, SHBG, and free testosterone significantly increased and achieved normal values in all evaluated patients. Insulin sensitivity improved in all of them. Multivariate linear regression showed that changes in fasting glucose (β=-1.868, p=0.001), insulin (β=-3.782, p=0.001), weight (β=-0.622, p=0.002), and SHBG (β=-0.635, p=0.022) were associated with changes in free testosterone (adjusted R2=0.936, F=26.613, p=0.001). When insulin resistance calculated by HOMA was in the model instead of insulin and glucose, it also was associated (β=-3.488, p=0.008) with free testosterone (adjusted R2=0.821, F=11.111, p=0.005).

CONCLUSIONS

Circulating tes tos terone in obese men increases after bariatric surgery in parallel with an improvement in insulin sensitivity.