Growth hormone status in morbidly obese subjects and correlation with body composition

Comparison of bioelectrical impedance analysis-derived phase angle in individuals with different weight status

OBJECTIVE

Obesity is characterized not only by an increase of fat mass but also by alterations in skeletal muscle. Bioimpedance analysis (BIA)-derived phase angle (PhA) may provide specific information on the inherent characteristics of fat-free mass, and is widely used as an index of poor nutritional status. The aim of this study was to describe whether and to what extent PhA varies depending on age, sex, and body mass index (BMI) in individuals with different weight status.

METHODS

We selected 1877 participants for this retrospective study (two weight status groups): 983 individuals with obesity (age 40 ± 13.9 y; BMI 39.5 ± 7.2 kg/m²) and 894 controls (age 40 ± 13.3 y; BMI 24.6 ± 2.7 kg/m²). Anthropometry and PhA at 50 kHz for the whole body were performed in all participants.

RESULTS

PhA was greater in men than in women, although a decline of PhA was observed with age, which was linear in women and occurred in men after 40 y of age. On the other hand, no significant differences were observed with increasing BMI in either sex; lower values might be observed when BMI >50 kg/m².

CONCLUSIONS

A more detailed appraisal of BIA-derived PhA in obesity is reported in the present study, providing basic data that might be taken into consideration in prevention and clinical nutrition. Further studies are needed to explore differences of PhA in individuals with different weight status.

Does Childhood Obesity Trigger Neuroinflammation?

Childhood obesity is constantly increasing around the world, and it has become a major public health issue. Considerable evidence indicates that overweight and obesity are important risk factors for the development of comorbidities such as cognitive decline, neuroinflammation and neurodegenerative diseases. It is known that during obesity, adipose tissue undergoes immune, metabolic and functional changes which could induce a neuroinflammatory response of the central nervous system (CNS). In this context, to inspect if obesity can start to trigger the neuroinflammation from a pediatric age, we surgically collected and analyzed adipose tissue from the periumbilical area of three obese children (AT-OB) and two normal-weight children (AT-Ctrl). We considered the transcriptomic profile of our samples to detect alterations in different biological processes that might be also involved in the inflammatory and neuroinflammatory response. Our results show alterations of lipid and fatty acids metabolism in AT-OB compared to the AT-Ctrl. We also observed an onset of inflammatory response in AT-OB. Interestingly, among the genes involved in neuroinflammation, GRN and SMO were upregulated, while IFNGR1 and SNCA were downregulated. Our study highlights that obesity may trigger inflammation and neuroinflammation from a pediatric age.

Bioelectrical impedance (BIA)-derived phase angle in adults with obesity: A systematic review

BACKGROUND & AIMS

Bioimpedance analysis-derived phase angle (PhA), as marker of body cell mass and cell integrity, might be altered in obesity, a condition which is characterized by alterations in muscle structure and function. The aim of this systematic review was to evaluate whether and to which extent PhA varies in individuals/patients with excess body weight focusing on: a) changes in PhA due to obesity; b) changes in PhA after bariatric interventions or training programs.

METHODS

According to PRISMA criteria, a systematic literature search until February 2021 using PubMed, Embase, Scopus, and Web of Science was performed. Selection criteria included studies on patients with obesity without comorbidities other than metabolic diseases.

RESULTS

A total of 278 articles were first identified. After removing duplicates and excluding studies that did not fulfil the inclusion criteria, the full text of the remaining 80 potentially relevant studies was examined to finally retrieve 11 cross-sectional and 10 longitudinal studies. Few studies have shown that PhA is lower in individuals/patients with obesity than in controls. The only study on the matter showed a decrease with age after the fourth decade of life. Four out of five studies reported consistently greater mean values in men than in women. In two studies PhA was lower in patients with severe obesity; in addition, Patients with low PhA had higher BMI and PhA was inversely correlated with fat mass. Longitudinal studies showed that PhA markedly decreased after bariatric surgery and slightly increased after training programs.

CONCLUSIONS

Thus, a relatively low number of studies have evaluated PhA in individuals/patients with obesity with sometimes contradictory and preliminary results. PhA might be useful to evaluate muscle quality in individuals/patients with obesity but further studies are needed to more accurately associate this variable with changes in muscle structure and strength, as well as in metabolic functions.

Discriminatory performance of insulin-like growth factor 1 and insulin-like growth factor binding protein-3 by correlating values to chronological age, bone age, and pubertal status for diagnosis of isolated growth hormone deficiency

PURPOSE

The discriminatory performance of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) was investigated by correlating their values with chronological age (CA), bone age (BA), and pubertal status (PS) for diagnosis of isolated growth hormone deficiency (IGHD).

METHODS

We evaluated IGF-1 and IGFBP-3 levels in 310 short-stature subjects subdivided into 2 groups: IGHD (n=31) and non-IGHD (n=279). IGF-1 and IGFBP-3 were assayed using immune-radiometric assay and transformed into standard deviation score (SDS) according to CA, BA, and PS.

RESULTS

The highest sensitivity was found in IGF-1-SDS for CA and IGFBP-3-SDS for CA (22.6% and 30.0%, respectively). The highest specificity was found in IGF-1-SDS for PS and IGFBP-3-SDS for PS (98.2% and 94.4%, respectively). Groups with the highest positive predictive values were IGF-1-SDS for BA and IGFBP-3-SDS for BA (10.9% and 5.1%, respectively). Highest negative predictive values were seen in IGF-1-SDS for CA and IGFBP-3-SDS for CA (98.4% and 98.4%, respectively).

CONCLUSION

IGF-1-SDS for CA, instead of IGF-1-SDS for BA or PS, could be used as a standard variable for IGHD screening. The sufficiently high specificity of IGF-1-SDS for PS suggests that this value is a useful tool for identification of IGHD.

Somatotropic Axis and Obesity: Is There Any Role for the Mediterranean Diet?

Obesity is associated with reduced spontaneous and stimulated growth hormone (GH) secretion and basal insulin-like growth factor I (IGF-1) levels—which in turn is associated with increased prevalence of cardiovascular risk factors. The aim of this study was to investigate: (1) the association of somatotropic axis with cardiometabolic status; (2) the association of somatotropic axis with the Mediterranean diet and nutritional pattern in people with obesity. Cross-sectional observational study was carried out in 200 adult women, aged 36.98 ± 11.10 years with severe obesity (body mass index—BMI of 45.19 ± 6.30 kg/m²). The adherence to the Mediterranean diet and the total calorie intake was assessed. Anthropometric measurements, body composition and biochemical profile were determined along with Growth Hormone (GH)/Insulin like Growth Factor 1 (IGF-1) axis and insulin resistance (homeostatic model assessment for insulin resistance—HoMA-IR). The enrolled subjects were compared after being divided according to GH peak response and according to IGF-1 standard deviation scores (SDS). Derangements of GH peak were detected in 61.5% of studied patients while IGF-1 deficiency was detected in 71% of the population. Both blunted GH peak response and IGF-1 SDS were indicators of derangements of somatotropic axis and were associated with comparable results in terms of cardiometabolic sequelae. Both GH peak and IGF-1 levels were inversely associated with anthropometric and metabolic parameters. The adherence to the Mediterranean diet predicts GH peak response. Fatty liver index (FLI), fat mass (FM) and phase angle (PhA) were predictive factors of GH peak response as well. In conclusion derangements of somatotropic axis is associated with a worse cardiometabolic profile in people with obesity. A high adherence to the Mediterranean diet—and in particular protein intake—was associated with a better GH status.

Metabolic and Endocrine Consequences of Bariatric Surgery

Obesity is one of the most serious worldwide epidemics of the twenty-first century according to the World Health Organization. Frequently associated with a number of comorbidities, obesity threatens and compromises individual health and quality of life. Bariatric surgery (BS) has been demonstrated to be an effective treatment to achieve not only sustained weight loss but also significant metabolic improvement that goes beyond mere weight loss. The beneficial effects of BS on metabolic traits are so widely recognized that some authors have proposed BS as metabolic surgery that could be prescribed even for moderate obesity. However, most of the BS procedures imply malabsorption and/or gastric acid reduction which lead to nutrient deficiency and, consequently, further complications could be developed in the long term. In fact, BS not only affects metabolic homeostasis but also has pronounced effects on endocrine systems other than those exclusively involved in metabolic function. The somatotropic, corticotropic, and gonadal axes as well as bone health have also been shown to be affected by the various BS procedures. Accordingly, further consequences and complications of BS in the long term in systems other than metabolic system need to be addressed in large cohorts, taking into account each bariatric procedure before making generalized recommendations for BS. In this review, current data regarding these issues are summarized, paying special attention to the somatotropic, corticotropic, gonadal axes, and bone post-operative health.

The effect of growth hormone on bioactive IGF in overweight/obese women

OBJECTIVE

Overweight/obesity is characterized by decreased growth hormone (GH) secretion whereas circulating IGF-I levels are less severely reduced. Yet, the activity of the circulating IGF-system appears to be normal in overweight/obese subjects, as estimated by the ability of serum to activate the IGF-I receptor in vitro (bioactive IGF). We hypothesized that preservation of bioactive IGF in overweight/obese women is regulated by an insulin-mediated suppression of IGF-binding protein-1 (IGFBP-1) and IGFBP-2, and by suppression of IGFBP-3, mediated by low GH. We additionally hypothesized that increases in bioactive IGF would drive changes in body composition with low-dose GH administration.

DESIGN

Cross-sectional analysis and 3-month interim analysis of a 6-month randomized, placebo-controlled study of GH administration in 50 overweight/obese women without diabetes mellitus. Bioactive IGF (kinase receptor activation assay) and body composition (DXA) were measured.

RESULTS

Prior to treatment, IGFBP-3 (r = -0.33, p = 0.02), but neither IGFBP-1 nor IGFBP-2, associated inversely with bioactive IGF. In multivariate analysis, lower IGFBP-3 correlated with lower peak stimulated GH (r = 0.45, p = 0.05) and higher insulin sensitivity (r = -0.74, p = 0.003). GH administration resulted in an increase in mean serum IGF-I concentrations (144 ± 56 to 269 ± 66 μg/L, p < 0.0001) and bioactive IGF (1.29 ± 0.39 to 2.60 ± 1.12 μg/L, p < 0.0001). The treatment-related increase in bioactive IGF, but not total IGF-I concentration, predicted an increase in lean mass (r = 0.31, p = 0.03) and decrease in total adipose tissue/BMI (r = -0.43, p = 0.003).

CONCLUSIONS

Our data suggest that in overweight/obesity, insulin sensitivity and GH have opposing effects on IGF bioactivity through effects on IGFBP-3. Furthermore, increases in bioactive IGF, rather than IGF-I concentration, predicted GH administration-related body composition changes.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00131378.

Influence of nutrition on somatotropic axis: Milk consumption in adult individuals with moderate-severe obesity

BACKGROUND & AIMS

Nutrition is the major environmental factor that influences the risk of developing pathologies, such as obesity. Although a number of recent reviews pinpoint a protective effects of milk on body weight and obesity related co-morbidities, an inaccurate estimate of milk might contribute to hamper its beneficial effects on health outcomes. Seven-day food records provide prospective food intake data, reducing recall bias and providing extra details about specific food items. Milk intake stimulates the somatotropic axis at multiple levels by increasing both growth hormone (GH) and insulin-like growth factor-1 (IGF-1) secretion. On the other hand, obesity is associated with reduced spontaneous and stimulated GH secretion and basal IGF-1 levels. Aim of this study was to evaluate the milk consumption by using the 7-days food record in obese individuals and to investigate the association between milk intake and GH secretory status in these subjects.

METHODS

Cross-sectional observational study carried out on 281 adult individuals (200 women and 81 men, aged 18-74 years) with moderate-severe obesity (BMI 35.2-69.4 kg/m²). Baseline milk intake data were collected using a 7 day food record. Anthropometric measurements and biochemical profile were determined. The GH/IGF-1 axis was evaluated by peak GH response after GHRH + ARGININE and IGF-1 standard deviation score (SDS).

RESULTS

The majority of individuals (72.2%) reported consuming milk; 250 mL low-fat milk was the most frequently serving of milk consumed, while no subjects reported to consume whole milk. Milk consumers vs no milk consumers presented the better anthropometric measurements and metabolic profile. At the bivariate proportional odds ratio model, after adjusting for BMI, age and gender, milk consumption was associated the better GH status (OR = 0.60; p < 0.001). Among milk consumers, subjects consuming 250 mL reduced-fat milk vs 250 mL low-fat milk presented the better anthropometric measurements and metabolic profile. At the bivariate proportional odds ratio model, after adjusting for BMI, age and gender, the consume of 250 mL reduced-fat milk was associated better GH status (OR = 0.54; p = 0.003).

CONCLUSIONS

A novel positive association between milk consumption, GH status, and metabolic profile in obese individuals was evidenced. Regardless of the pathogenetic mechanisms, this novel association might be relevant in a context where commonly obese individuals skip breakfast, and suggests the need of a growing cooperation between Nutritionists and Endocrinologists in the management of the obese patients.

Post-diagnosis adiposity and survival among breast cancer patients: influence of breast cancer subtype

PURPOSE

Adiposity has been linked with increased breast cancer risk and mortality. It is established that etiologic associations for adiposity vary by tumor subtype, but the influence of adiposity on subtype-specific survival is unknown.

METHODS

Study participants were 1,109 invasive breast cancer participants in the population-based Carolina Breast Cancer Study, diagnosed between 1993 and 2001, and with tissue blocks available for immunohistochemical subtyping. General and central adiposities were assessed by body mass index (BMI) and waist-to-hip ratio (WHR), respectively, based on in-person measurements after diagnosis. Vital status as of 2011 was determined using the National Death Index (median follow-up = 13.5 years). Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for breast cancer (BC)-specific and all-cause mortalities.

RESULTS

Among all patients, high WHR (≥0.84), but not BMI, was associated with all-cause mortality (adjusted HR 1.50, 95% CI 1.11-2.05, <0.77 as reference). No significant association between adiposity and BC-specific mortality was detected, although there was a suggestion of increased mortality risk among high-BMI (≥30 kg/m(2)) patients with basal-like tumors (adjusted HR 2.44, 95% CI 0.97-6.12, <25 kg/m(2) as reference). Quantitative differences in all-cause mortality were observed by subtype, with BMI associated with basal-like mortality and WHR associated with luminal mortality. The associations were attenuated by tumor characteristics.

CONCLUSIONS

Our study confirms the association of adiposity and unfavorable overall survival in breast cancer patients and suggests that this association may vary by intrinsic subtype and adiposity measure.

Preliminary data on the relationship between circulating levels of Sirtuin 4, anthropometric and metabolic parameters in obese subjects according to growth hormone/insulin-like growth factor-1 status

BACKGROUND

The main components of GH/insulin-like growth factor (IGF)-1 axis and Sirtuin 4 (Sirt4), highly expressed in liver and skeletal muscle mitochondria, serve as active regulators of mitochondrial oxidative capacity with opposite functions. In obesity both GH/IGF-1 status and serum Sirt4 levels, likely mirroring its reduced mitochondrial expression, might be altered.

OBJECTIVE

To evaluate the association between circulating levels of Sirt4, body composition, metabolic parameters and cardio-metabolic risk profile in obese patients according to their different GH/IGF-1 status.

DESIGN

Cross-sectional study with measurement of serum Sirt4, GH after GH releasing hormone (GHRH)+Arginine test, IGF-1 and assessment of body composition, glucose and lipid metabolism in 50 class II-III obese subjects (BMI 35.6 to 62.1 kg/m(2)) and 15 normal weight subjects. Low GH secretion and IGF-1 were defined using pre-determined cutoff-points. The Homeostatic Metabolic Assessment of insulin resistance index and Visceral adiposity index were also calculated. The association of Sirt4 with peak stimulated GH and IGF-1, body composition, metabolic parameters and cardio-metabolic risk profile was assessed.

RESULTS

Serum Sirt4 was inversely related to anthropometric and metabolic parameters and positively related to peak GH and IGF-1. After adjusting for peak GH and IGF-1, the relationships between Sirt4 and BMI became not significant. At multiple regression analysis IGF-1 (p<0.001) was the independent predictor for Sirt4.

CONCLUSION

There was a close relationship between low IGF-1 and low serum Sirt4. This observation suggested that in obese patients, low GH/IGF-1 status was likely associated with a major compensatory decrease in circulating levels of Sirt4 to oppose to its negative regulator effect on mitochondrial oxidative capacity.

The complex relationship between obesity and the somatropic axis: the long and winding road

Despite the considerable body of evidence pointing to a possible relationship between the state of the adipose tissue depots and regulation of the somatotropic axis, to date the relationship between obesity and low growth hormone (GH) status remains incompletely understood. The low GH status in obesity is mainly considered as a functional condition, largely reversible after a sustained weight loss. Moreover, due to the effects of the adiposity on the regulation of the somatotropic axis, the application of GH stimulation tests in obesity may also lead to an incorrect diagnosis of GH deficieny (GHD). On the other hand, similar to patients with GHD unrelated to obesity, the reduced GH response to stimulation testing in obese individuals is associated with increased prevalence of cardiovascular risk factors and detrimental alterations of body composition, which contribute to worsening their cardio-metabolic risk profile. In addition, the reduced GH secretion may result in reduced serum insulin-like growth factor (IGF)-1 levels, and the concordance of low peak GH and low IGF-1 identifies a subset of obese individuals with high cardiovascular risk. Furthermore, after weight loss, the normalization of the GH response and IGF-1 levels may or may not occur, and in patients undergoing bariatric surgery the persistence of a low GH status may affect the post-operative outcomes. In this review, we will provide an overview on some clinically relevant aspects of the relationship between obesity axis and the somatotropic axis in the light of the recently published research.

Bioelectrical impedance vector analysis (BIVA) for the assessment of two-compartment body composition

This review is directed to define the efficacy of bioelectrical impedance vector analysis (BIVA) for assessing two-compartment body composition. A systematic literature review using MEDLINE database up to 12 February 2014 was performed. The list of papers citing the first description of BIVA, obtained from SCOPUS, and the reference lists of included studies were also searched. Selection criteria included studies comparing the results of BIVA with those of other techniques, and studies analyzing bioelectrical vectors of obese, athletic, cachectic and lean individuals. Thirty articles met the inclusion criteria. The ability of classic BIVA for assessing two-compartment body composition has been mainly evaluated by means of indirect techniques, such as anthropometry and bioelectrical impedance analysis (BIA). Classic BIVA showed a high agreement with body mass index, that can be interpreted in relation to the greater body mass of obese and athletic individuals, whereas the comparison with BIA showed less consistent results, especially in diseased individuals. When a reference method was used, classic BIVA failed to accurately recognize FM% variations, whereas specific BIVA furnished good results. Specific BIVA is a promising alternative to classic BIVA for assessing two-compartment body composition, with potential application in nutritional, sport and geriatric medicine.

Preoperative prediction of growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis modification and postoperative changes in candidates for bariatric surgery

BACKGROUND

Several factors alter the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis in obese patients, but GH/IGF-1 correlation with anthropometric parameters and lipid metabolism is still unclear. We evaluated this relationship and the postoperative axis modifications in candidates for bariatric surgery.

METHODS

Eighty-eight patients (males/females (M/F), 34/54) scheduled for bariatric surgery (biliopancreatic diversion or laparoscopic-adjustable gastric banding) between 2008 and 2010 were included in this observational, open, prospective study.

RESULTS

Preoperative serum GH concentrations were found near the lowest limit of normal range in both sexes, with males showing the lowest values (130 vs. 1,405 pg/ml; p < 0.01). Serum concentrations of IGF-1 were within the normal range (M/F, 179/168.5 ng/ml), whereas IGF-binding protein (BP)1 and 3 values were at the lowest limits of normal range in both sexes (M/F 1.8/3.1 μg/ml and M/F 4.1/4.2 μg/ml, respectively). A statistically significant inverse correlation was found between GH, IGF-1, and IGF-BP1-3 values and total cholesterol, LDL-cholesterol, and triglycerides values in both sexes. GH and IGF-BP1-3 values were also inversely related to waist circumference and waist/hip ratio (WHR). GH, IGF-1, and IGF-BP1 and 3 values (35 cases) increased 1 year postoperatively in both sexes, mainly after malabsorptive procedures.

CONCLUSIONS

Our results support the hypothesis that GH deficiency associated with low levels of binding proteins in obese patients may be an endocrine response to visceral fat and high levels of non-esterified fatty acids, assessable in daily clinical practice by WHR, total and LDL-cholesterol, and triglycerides. In these patients, malabsorptive procedures might be the treatment of choice due to the metabolic adaptations induced.

Endocrine changes (beyond diabetes) after bariatric surgery in adult life

Bariatric surgery is nowadays an effective therapeutic option for morbid obesity. Endocrinologists may thus have a growing opportunity to diagnose and treat obese patients eligible for surgery in pre- and post-operative phase. This requires a better understanding of endocrine changes caused by either obesity or weight loss surgery. Despite the large number of studies available in literature, only limited well-designed clinical trials have been performed so far to investigate changes of endocrine axes following bariatric procedures. There are still areas of unclear results such as female and male fertility, however, weight loss after bariatric surgery is considered to be associated with favorable effects on most endocrine axes. The aim of this clinical review is to overview the available literature on the effects of weight loss after bariatric surgery on the endocrine systems to suggest the most appropriate pre- and post-operative management of obese patients undergoing bariatric surgery in terms of "endocrine" health.

Increased adiposity and insulin correlates with the progressive suppression of pulsatile GH secretion during weight gain

Pathological changes associated with obesity are thought to contribute to GH deficiency. However, recent observations suggest that impaired GH secretion relative to excess calorie consumption contributes to progressive weight gain and thus may contribute to the development of obesity. To clarify this association between adiposity and GH secretion, we investigated the relationship between pulsatile GH secretion and body weight; epididymal fat mass; and circulating levels of leptin, insulin, non-esterified free fatty acids (NEFAs), and glucose. Data were obtained from male mice maintained on a standard or high-fat diet. We confirm the suppression of pulsatile GH secretion following dietary-induced weight gain. Correlation analyses reveal an inverse relationship between measures of pulsatile GH secretion, body weight, and epididymal fat mass. Moreover, we demonstrate an inverse relationship between measures of pulsatile GH secretion and circulating levels of leptin and insulin. The secretion of GH did not change relative to circulating levels of NEFAs or glucose. We conclude that impaired pulsatile GH secretion in the mouse occurs alongside progressive weight gain and thus precedes the development of obesity. Moreover, data illustrate key interactions between GH secretion and circulating levels of insulin and reflect the potential physiological role of GH in modulation of insulin-induced lipogenesis throughout positive energy balance.

Beyond waist circumference in an adult male population of Southern Italy: Is there any role for subscapular skinfold thickness in the relationship between insulin-like growth factor-I system and metabolic parameters?

BACKGROUND

Apart from waist circumference, other adiposity measures, such as subscapular skin fold (SST), arouse growing interest due to their relationship to metabolic complications and cardiovascular risk. The IGF-I system is deregulated in obese subjects in proportion to their degree of visceral adiposity.

AIM

To examine the association among IGF-I, IGF-binding protein (BP)-1 and -3 levels and different measures of adiposity in a sample of adult male population in Southern Italy.

MATERIALS AND METHODS

A complete database for this analysis was available for 229 (age range 50-82 yr) participating at 2002-2004 Olivetti Heart Study follow-up.

RESULTS

After adjustment for age, IGF-I was inversely associated with body mass index (BMI) and waist circumference (p<0.05). IGFBP-1 was inversely associated with BMI, waist circumference, SST, homeostasis model assessment (HOMA) index, fat mass. HOMA index, age, and SST significantly predicted the IGFBP-1 plasma levels, with 24% of IGFBP-1 variability explained at a linear regression analysis.

CONCLUSIONS

IGFBP-1 inversely correlated to adiposity and HOMA index. Among adiposity indexes, SST was the best predictor of IGFBP-1 levels. The evaluation of some components of the IGF system, and simple measures of body adiposity, such as SST, may represent a further tool to better evidence phenotype profiles associated to the pathogenetic mechanism of cardiovascular risk factor clustering in male adults.

Liver-spleen axis, insulin-like growth factor-(IGF)-I axis and fat mass in overweight/obese females

BACKGROUND

Fat mass (FM) in overweight/obese subjects has a primary role in determining low-grade chronic inflammation and, in turn, insulin resistance (IR) and ectopic lipid storage within the liver. Obesity, aging, and FM influence the growth hormone/insulin-like growth factor (IGF)-I axis, and chronic inflammation might reduce IGF-I signaling. Altered IGF-I axis is frequently observed in patients with Hepatic steatosis (HS). We tested the hypothesis that FM, or spleen volume and C-reactive protein (CRP)--all indexes of chronic inflammation--could affect the IGF-I axis status in overweight/obese, independently of HS.

METHODS

The study population included 48 overweight/obese women (age 41 ± 13 years; BMI: 35.8 ± 5.8 kg/m2; range: 25.3-53.7), who underwent assessment of fasting plasma glucose and insulin, homeostasis model assessment of insulin resistance (HOMA), cholesterol and triglycerides, HDL-cholesterol, transaminases, high-sensitive CRP, uric acid, IGF-I, IGF binding protein (BP)-1, IGFBP-3, and IGF-I/IGFBP-3 ratio. Standard deviation score of IGF-I according to age (zSDS) were also calculated. FM was determined by bioelectrical impedance analysis. HS severity grading (score 0-4 according liver hyperechogenicity) and spleen longitudinal diameter (SLD) were evaluated by ultrasound.

RESULTS

Metabolic syndrome (MS) and HS were present in 33% and 85% of subjects, respectively. MS prevalence was 43% in subjects with increased SLD. IGF-I values, but not IGF-I zSDS, and IGF-I/IGFBP-3 ratio were significantly lower, while FM%, FPI, HOMA, ALT, CRP, were significantly higher in patients with severe HS than in those with mild HS. IGF-I zSDS (r = -0.42, r = -0.54, respectively; p < 0.05), and IGFBP-1 (r = -0.38, r = -0.42, respectively; p < 0.05) correlated negatively with HS severity and FM%. IGF-I/IGFBP-3 ratio correlated negatively with CRP, HS severity, and SLD (r = -0.30, r = -0.33, r = -0.43, respectively; p < 0.05). At multivariate analysis the best determinants of IGF-I were FM% (β = -0.49; p = 0.001) and IGFBP-1 (β = -0.32; p = 0.05), while SLD was in the IGF-I/IGFBP-3 ratio (β = -0.43; p = 0.004).

CONCLUSIONS

The present study suggests that lower IGF-I status in our study population is associated with higher FM, SLD, CRP and more severe HS.

Association of beta2-adrenergic receptor and insulin receptor substrate-1 polymorphisms with obesity in a Northern Indian population

BACKGROUND:

Imbalance in hormonal levels, regulated by host genetic factors, are known to be a major cause of obesity. Therefore, we aimed to evaluate association of genetic polymorphisms of β₂-adrenergic receptor (β₂-AR) and insulin receptor substrate-1 (IRS-1) with hormonal levels in northern Indian obese.

METHODS:

A total of 111 obese and 89 age matched non-obese subjects were studied after taking detailed clinical profile. Hormonal assays in serum/plasma for different hormones were done using IRMA and RIA kits. Genetic analysis of β₂-AR (-47 and -20, T to C) and IRS-1 (Arg972Gly) was done using PCR-RFLP.

STATISTICAL ANALYSIS:

Statistical analysis was performed by SPSS (version 11.5) software. All continuous variables were expressed as mean ± SD and tested by ANOVA test. Comparisons of categorical variables were assessed using X² tests or Fisher's exact test. P-value <0.05 was considered as significant.

RESULTS:

Analysis showed that obese subjects had significantly higher value of blood pressure (systolic), WHR, leptin insulin and glucagon and lower value of GH. In β₂-AR (-47) T/C and IRS-1 Gly972Arg gene polymorphisms we did not found significant differences in genotype or allele frequencies. Moreover, none of the studied hormonal or metabolic parameters showed any association with the gene polymorphisms.

CONCLUSIONS:

Study reveals no significant association of β₂-AR (-47 and -20, T to C) and IRS-1 Gly 972 Arg polymorphisms with obesity in northern Indians.

Effects of short-term treatment with orlistat on growth hormone/insulin-like growth factor-I axis in obese post-menopausal women

AIM

Obesity is associated with an altered GH/IGF-I axis status, accounting for the increased cardiovascular risk in obese subjects with GH deficiency. Aim of this randomized, simple-blind, cross-over study was to verify the effectiveness of a short-term treatment with orlistat in reducing non-esterified fatty acid (NEFA) and influencing the endogenous activity of GH/IGF-I axis in obese subjects.

OUTCOME MEASURES

The primary outcome measures were post-prandial lipemia; GH peak after GHRH+arginine; IGF-I; IGF-binding protein (BP)-3, IGF-I/IGFBP-3 ratio. Secondary outcome measures were insulin resistance (IR) indexes (homeostasis model assessment of insulin resistance and Insulin Sensitivity Index).

STUDY DESIGN

Twenty obese post-menopausal women (age: 53.6 ± 6.2; body mass index: 34.1 ± 4.0) were randomized to receive normo-caloric diet plus + orlistat (Roche, UK; 120 mg tid) or normo-caloric diet without the additional treatment. The duration of follow-up was 10 days for each treatment period.

RESULTS

Orlistat induced a weight-independent reduction in post-prandial NEFA levels compared with diet alone, with higher GH peak, IGF-I, and IGF-I/IGFBP3 ratio. GH peak was correlated negatively with postprandial NEFA and positively with IGF-I and IGF-I/IGFBP-3 ratio.

CONCLUSIONS

Orlistat is effective in inducing a weight-independent higher reduction in post-prandial NEFA levels than dietary treatment alone along with increase in GH peak, IGF-I levels, and IGFI/ IGFBP-3 ratio. These results might add a new potential benefit of orlistat in the management of obese subjects.

Normal sweat secretion despite impaired growth hormone-insulin-like growth factor-I axis in obese subjects

Adults with GH deficiency are known to exhibit reduced sweating. Whether sweating capacity is impacted in obese subjects with impaired GH secretion have not previously been investigated. The main objective was to investigate sweat secretion rate and the GH-IGF-I axis in obese subjects before and after weight loss. Sixteen severely obese women (BMI, 40.6 ± 1.1 kg/m(2)) were investigated before and after a diet-induced weight loss. Sixteen age-matched nonobese women served as controls. The obese subjects presented the characteristic decreased GH release, hyperinsulinaemia, increased FFA levels, and impaired insulin sensitivity, which all were normalised after diet-induced weight loss of 30 ± 5 kg. Sweat secretion rates were similar comparing obese and nonobese subjects (78 ± 10 versus 82 ± 9 mg/30 minutes) and sweat secretion did not change after a diet-induced weight loss in obese subjects. We conclude that although obese subjects have markedly reduced GH release and impaired IGF-I levels, sweat secretion rate is found to be normal.

Serum insulin-like growth factor-I and body composition in community dwelling older people

OBJECTIVES

The decline in the growth hormone/insulin-like growth factor-I (GH/IGF-I) axis during normal aging might be involved in the changes in body composition associated with increasing age. We conducted a study to investigate serum IGF-I levels across different age categories and a possible association between serum IGF-I and measurements of body composition in older people.

DESIGN

A cross-sectional analysis of community dwelling older people, which participated in a large longitudinal cohort study (Longitudinal Aging Study Amsterdam).

SUBJECTS

1319 subjects, 644 men, mean age 75.6 +/- 6.6 years and 675 women, mean age 75.4 +/- 6.6 years.

MAIN OUTCOME MEASUREMENTS

IGF-I, body mass index (BMI), waist, waist-hip ratio (WHR), fat mass, lean body mass and total bone mineral density.

RESULTS

IGF-I levels were significantly lower in the highest age categories. BMI and biceps skinfold measurements were lower in the lowest IGF-I quartile in men aged > or =75.5 years. In men with a low total physical activity score (<131 min/day), BMI, WHR and skinfolds were significantly lower in the lowest IGF-I quartile. In women with a high total physical activity score (>174 min/day), WHR was lower in the lowest IGF-I quartiles.

CONCLUSION

In this large cohort of community dwelling older people, we observed lower serum IGF-I levels in the higher age categories. A low serum IGF-I was associated with significantly lower measurements of body composition, such as BMI, skinfolds and WHR. These results do not support previous findings that high IGF-I levels are favourable for a healthy body composition in community dwelling older people.

Normal growth hormone secretion in overweight young adults with Down syndrome

Down syndrome (DS) is associated with short stature and obesity. Adults with DS have several features in common with growth hormone (GH) deficient adult subjects. The aim of this study was to investigate GH secretion in young adults with DS and its relation to body composition as well as glucose and lipid metabolism. Ten young adults with DS (aged 24-32 years; 5 F) and ten controls matched for age and sex were examined regarding spontaneous nocturnal GH secretion and body composition. Stable isotope tracers were used to study glucose and lipid metabolism in the DS subjects. There was no difference in secretion of GH between the DS subjects and controls. The DS subjects had a higher BMI, fat mass proportion and HOMA (homeostasis model assessment) index compared with the controls. The rates of production of glucose and glycerol (reflecting lipolysis) in the DS subjects were increased (15.5+/-5.07 and 3.5+/-1.68 micromol/kg/min, respectively). The DS subjects showed normal GH secretion despite increased BMI and fat mass. The increased HOMA index and high rate of glucose production indicate peripheral and hepatic insulin resistance in adult DS subjects.

Prevalence of the metabolic syndrome in moderately-severely obese subjects with and without growth hormone deficiency

BACKGROUND AND AIM

There is a considerable heterogeneity in metabolic phenotype among equally obese subjects. Impaired GH secretion is frequent in obese patients, with GH secretion reduced up to levels that are comparable to those found in adult patients with organic GH deficiency (GHD). Low GH status exerts detrimental effects onmetabolic abnormalities in organic GHD patients. The aim of this observational, retrospective study was to investigate the prevalence of the metabolic syndrome (MetS) in moderately-severely obese subjects who met criteria for GDH (GHD) and in those with normal GH status (GH sufficient: GHS).

METHODS AND RESULTS

One-hundred and ninety-five moderately-severely obese individuals partecipated, 149 women and 46 males [bodymass index (BMI) 43.0+/-4.4 kg/m2 aged 34.3+/-11.8 yr] . Main outcome measures were: GH peak after GHRH plus arginine test, IGF-I, MetS parameters according to National Cholesterol Education Program criteria. Fifty-five subjects (27.3%) were GHD (49 females and 6 males). The prevalence of MetS parameters was 70.9% in GHD subgroup vs 52.9% in GHS (chi2=5.281; p=0.02) and the likelihood of MetS was highest in GHD subgroup (odds ratio: 2.174; 95% confidence interval 1.113 to 4.248). At the multiple regression analysis either GH peak or IGF-I were the major determinants of waist circumference (beta=-0.380, t=-6.110 and beta=-0.326, t=-4.704, respectively; p<0.001), while age and IGFI were the major determinants of MetS (beta=0.255, t= 3.342, and beta=-0.282, t=-3.270; p=0.02, respectively).

CONCLUSIONS

Among moderately-severely obese individuals the prevalence of the MetS was higher in GHD than in GHS subjects. Thus, in obese subjects, GH status investigation might be considered in the clinical evaluation of their metabolic risk profile.

Relationship between growth hormone/insulin-like growth factor-1 axis integrity and voluntary weight loss after gastric banding surgery for severe obesity

BACKGROUND

The aim of this observational study was to determine, in a retrospective analysis, whether growth hormone (GH) and insulin-like growth factor-1 (IGF-1) at baseline or changes in the GH/IGF-1 axis after laparoscopic adjustable gastric banding (LAGB) is associated with weight loss and body composition changes in severely obese nondiabetic patients.

METHODS

Weight loss (expressed as percent excess weight loss [EWL%]), anthropometry, body composition by bioelectrical impedance analysis (BIA), serum IGF-1, and GH peak after GH-releasing hormone (GHRH) plus arginine (ARG) test were measured and expressed as standard deviation scores (SDS) of reference values in 104 women and 36 men, age (mean +/- SD) 34 +/- 11 and 30.2 +/- 11 years, and BMI 44 +/- 5.7 and 39 +/- 3.2, respectively, before and 6 months after LAGB.

RESULTS

After LAGB, 25% of women and 22.5% of men had GH deficiency, while 30.8% of women and 33.3% of men had IGF-1 deficiency or insufficiency. The median EWL was 36.8% in women and 40.0% in men. In both genders, percent decrease of waist circumference, EWL, and fat mass (FM) and percent increase of fat-free mass (FFM) was greater in patients with normal GH secretion and IGF-1 levels. The GH peak after GHRH + ARG, IGF-1 levels, and IGF-1 SDS were inversely correlated with EWL% (r = -0.50, r = -0.53, and r = -0.42, respectively; p < 0.0001) and percent FM (r = -0.41, r = -0.36, and r = -0.35, respectively; p < 0.0001). In stepwise linear regression analysis, the GH peak after GHRH + ARG was the major determinant of EWL% (p < 0.0001) and FM (p = 0.001).

CONCLUSIONS

The efficacy of LAGB was greater in the patients with a normal GH response to GHRH + ARG and with normal IGF-1 levels. The percent of FM, FFM, and EWL were significantly correlated with the GH response to GHRH + ARG and with IGF-1 levels.

Growth hormone treatment prevents loss of lean mass after bariatric surgery in morbidly obese patients: results of a pilot, open, prospective, randomized, controlled study

CONTEXT

The loss of lean body mass (LBM) negatively influences the outcome in bariatric surgery. Impaired GH secretion is frequent in obese patients.

OBJECTIVE

Our objective was to investigate if GH treatment prevents LBM loss in the early postoperative period.

DESIGN

This was an open, prospective, randomized, and controlled study.

PATIENTS

A total of 24 women (body mass index: 44.4 +/- 7.6 kg/m(2), aged 36.8 +/- 11.7 yr) undergoing laparoscopic-adjustable silicone gastric banding (LASGB) and with GH deficiency after LASGB was included in the study.

TREATMENT PROTOCOL

Group A (n = 12) included a standardized diet regimen and exercise program plus recombinant human GH (0.5 +/- 0.13 mg every day), and group B (n = 12) included a standardized diet regimen and exercise program. The follow-up duration was 6 months.

RESULTS

The excess of body weight loss did not differ between groups A and B after 3 and 6 months. At 3 months, LBM loss was lower (P < 0.0001) and fat mass (FM) loss was higher (P = 0.02) in group A than group B. At 3 and 6 months, appendicular skeletal muscle mass loss was lower (P = 0.000) in group A than group B. At 3 (P = 0.0003 and 0.0005, respectively) and 6 months (P < 0.0001 and 0.0002, respectively), the percent changes of FM and lean body mass were significantly higher in group A than group B. In both groups fasting and postglucose area under the plasma concentration-time curve insulin significantly reduced. The homeostasis model assessment of insulin and insulin sensitivity indexes and total to high-density lipoprotein cholesterol ratio improved only in group A.

CONCLUSIONS

GH treatment for 6 months after LASGB reduces loss in LBM and appendicular skeletal muscle mass during a standardized program of low-calorie diet and physical exercise program, with improvement of lipid profile and without a deterioration of glucose tolerance.

GH and IGF-I deficiency are associated with reduced loss of fat mass after laparoscopic-adjustable silicone gastric banding

CONTEXT

GH secretion is reduced in obese subjects and increases after body weight loss. It is still unclear if changes in the GH/IGF-I axis after laparoscopic-adjustable silicone gastric banding (LASGB) are associated with changes of body composition.

OBJECTIVE

To analyse the relationships between changes in the GH/IGF-I axis and those of body weight and composition before and after LASGB.

DESIGN

Observational, prospective.

SETTING

University 'Federico II' of Naples (Italy).

PATIENTS

Seventy-two severely obese females (BMI: 44.9 +/- 4.68; mean age: 33.1 +/- 11.34 years) were studied.

MAIN OUTCOME MEASURES

GH peak after GHRH plus arginine test, IGF-I, IGFBP-3 and ALS levels, fat mass (FM) and free fat mass (FFM) (by Bioelectrical Impedance Analysis) at baseline and 6 months after LASGB. The change in percentage of individual variables was calculated as well as that of excess of body weight loss (EBWL%). The FM%, FFM% and EBWL% were correlated with peak GH and IGF-I levels changes.

RESULTS

At baseline, GH deficiency (GHD) (GH peak = 4.1 microg/l) was found in 22 patients (31%), 16 of them also had IGF-I deficiency (< -2SDS). IGF-I levels were inversely correlated with waist circumference (r = -0.72, P < 0.001) and FM% (r = -0.75, P < 0.001). Post-LASGB the patients were classified as follows: group (1) GH and IGF-I sufficient (n = 44; 61.1%); group (2) GH and IGF-I deficient (n = 14; 19.4%) and group (3) GH sufficient and IGF-I deficient (n = 14; 19.4%). The percentage changes of EWBL (P < 0.05, P = 0.051, respectively) and FM (P < 0.001, P < 0.01, respectively) were lower in groups (2) and (3) than in group (1). At the stepwise linear regression analysis, postoperative IGF-I levels were the strongest determinant of percent changes of FM (P < 0.0001), of FFM (P = 0.009) and of EBWL (P < 0.0001).

CONCLUSIONS

IGF-I levels is the most sensitive to unfavourable changes in body composition 6 months after LASGB making investigation of the somatotropic axis useful in the evaluation of bariatric surgery outcomes.

Lower growth hormone and higher cortisol are associated with greater visceral adiposity, intramyocellular lipids, and insulin resistance in overweight girls

Although body composition, insulin sensitivity, and lipids are markedly altered in overweight adolescents, hormonal associations with these parameters have not been well characterized. Growth hormone (GH) deficiency and hypercortisolemia predispose to abdominal adiposity and insulin resistance, and GH secretion is decreased in obese adults. We hypothesized that low-peak GH on the GH-releasing hormone (GHRH)-arginine stimulation test and high cortisol in overweight adolescents would be associated with higher regional fat, insulin resistance, and lipids. We examined the following parameters in 15 overweight and 15 bone age-matched control 12- to 18-yr-old girls: 1) body composition using dual-energy X-ray absorptiometry and MR [visceral and subcutaneous adipose tissue at L(4)-L(5) and soleus intramyocellular lipid ((1)H-MR spectroscopy)], 2) peak GH on the GHRH-arginine stimulation test, 3) mean overnight GH and cortisol, 4) 24-h urinary free cortisol (UFC), 5) fasting lipids, and 6) an oral glucose tolerance test. Stepwise regression was the major tool employed to determine relationships between measured parameters. Log peak GH on the GHRH-arginine test was lower (P = 0.03) and log UFC was higher (P = 0.02) in overweight girls. Log mean cortisol (overnight sampling) was associated positively with subcutaneous adipose tissue and, with body mass index standard deviation score, accounted for 92% of its variability, whereas log peak GH and body mass index standard deviation score accounted for 88% of visceral adipose tissue variability and log peak GH for 34% of the intramyocellular lipid variability. Log mean cortisol was independently associated with log homeostasis model assessment of insulin resistance, LDL, and HDL and explained 49-59% of the variability. Our data indicate that lower peak GH and higher UFC in overweight girls are associated with visceral adiposity, insulin resistance, and lipids.