Endocrine aspects of obesity

Genetic polymorphisms and plasma concentrations of leptin (rs7799039) and adiponectin (rs17300539) are associated with obesity in children and adolescents

Objective:

The aim of this study was to compare the anthropometric, biochemical, and hormonal characteristics and the presence of genetic polymorphisms of leptin, adiponectin, and tumor necrosis factor alpha (TNF-α) between eutrophic and obese children and adolescents.

Methods:

This is a case–control study involving 104 children and adolescents. All subjects were assessed for anthropometric characteristics and clinical, laboratory, and genetic polymorphism parameters. The sample was selected from the pediatric endocrinology outpatient clinic specialized in the treatment of obesity in children and adolescents according to the Centers for Disease Control and Prevention (CDC) classification, and controls were selected from the same location in the general pediatric outpatient clinic.

Results:

As a result, the parameters, such as black color, obese parents, hypertensive parents, and early weaning, were found to be associated with obesity. Increased levels of insulin, triglyceride, total cholesterol, LDL cholesterol, CRP-U, AST, ALT, GGT, free T4, IGF-1, and uric acid and low levels of HDL cholesterol are found to be associated with a higher chance of obesity. The presence of AG/AA polymorphisms in the leptin is associated with a 290% (OR 3.9) higher chance of obesity, and for adiponectin genes, the chances are 740% (OR 8.4) higher. In these obese children and adolescents with AG/AA haplotypes, serum leptin levels were increased and adiponectin levels were decreased in eutrophic individuals, whereas serum TNF-α levels did not change.

Conclusions:

The AG/AA polymorphisms in the leptin and adiponectin genes alter the serum levels of these adipokines and predispose them to obesity, and many anthropometric, biochemical, and hormonal markers are altered, demonstrating early consequences for the health of these obese children and adolescents.

Polimorfismos genéticos e concentrações plasmáticas de leptina (rs7799039) e adiponectina (rs17300539) associados à obesidade em crianças e adolescentes

RESUMO Objetivo: Comparar as características antropométricas, bioquímicas, hormonais e a presença de polimorfismos genéticos de leptina, adiponectina e fator de necrose tumoral alfa (TNF-α) entre crianças e adolescentes eutróficos e obesos. Métodos: Trata-se de um estudo caso-controle conduzido com 104 crianças e adolescentes. Todos os indivíduos foram avaliados quanto às características antropométricas e parâmetros clínicos, laboratoriais e de polimorfismo genético. A amostra foi selecionada no ambulatório de endocrinologia pediátrica especializado no tratamento da obesidade em crianças e adolescentes de acordo com a classificação do Centers for Disease Control and Prevention (CDC), e os controles foram selecionados no mesmo local, porém no ambulatório de pediatria geral. Resultados: Alguns parâmetros foram associados à obesidade em nosso estudo: cor preta, pais obesos, pais hipertensos e desmame precoce. Níveis aumentados de insulina, triglicerídeos, colesterol total, colesterol LDL, PCR-U, AST, ALT, GGT, T4 Livre, IGF-1, ácido úrico e níveis baixos de colesterol HDL estão associados a uma chance maior de obesidade. A presença de polimorfismos AG/AA na leptina está associada a uma chance 290% (OR 3,9) maior de obesidade, enquanto para os genes da adiponectina as chances são 740% (OR 8,4) maiores. Nessas crianças e adolescentes obesos com haplótipos AG/AA, os níveis séricos de leptina aumentaram e os níveis de adiponectina diminuíram em relação aos eutróficos, já os níveis séricos de TNF-α não se alteraram. Conclusões: Concluiu-se que os polimorfismos AG/AA nos genes da leptina e adiponectina alteram os níveis séricos dessas adipocinas e predispõem à obesidade precoce, e muitos marcadores antropométricos, bioquímicos e hormonais ficam alterados, trazendo consequências para a saúde dessas crianças e adolescentes.

Growth of surgically confirmed leiomyomas in postmenopausal women: analysis of the influencing factors

OBJECTIVES

The aim of this study was to examine the growth of uterine leiomyomas in postmenopausal women and evaluate the influencing factors associated with fibroid growth.

METHODS

We retrospectively analyzed the medical records of postmenopausal women with fibroids between 2015 and 2020. All women received at least 2 transvaginal ultrasound examinations within a 6-month interval. All fibroids were verified via surgery. The postoperative pathology of all tumors was uterine fibroid. We calculated the fibroid volume using the ellipsoid volume formula and evaluated the growth rate of fibroids within 6 months simultaneously. Univariable analysis and a linear mixed-effects model were used to assess the factors influencing fibroid growth.

RESULTS

A total of 102 postmenopausal women with a total of 132 fibroids were assessed. The median growth rate of surgically confirmed fibroids in postmenopausal women was 12.9% every 6 months (from -61.4% to 184.1%). Obesity was associated with fibroid growth (P < 0.05). Notably, the estimated growth rates of fibroids in obese and overweight women were 26.6% (95% confidence interval [CI]: 2.3-50.9) and 15.9% (95% CI: 0.4-31.4) higher than those in women of normal weight, respectively. The growth of fibroids varied by the initial tumor size (P < 0.05). The estimated growth rate of larger fibroids (≥5.0 cm diameter) was reduced 30.0% (95% CI: -52.4 to -7.5) compared with that of small fibroids (<3.0 cm diameter).

CONCLUSIONS

Uterine fibroids continually grow in some postmenopausal women. Obesity and small fibroids (<3.0 cm diameter) may contribute to higher growth rates of fibroids.

Lipectomy associated to obesity produces greater fat accumulation in the visceral white adipose tissue of female compared to male rats

BACKGROUND

Mobility of fat deposited in adipocytes among different fatty territories can play a crucial role in the pathogenesis of obesity-related diseases. Our goal was to investigate which of the remaining fat pads assume the role of accumulating lipids after surgical removal of parietal WAT (lipectomy; LIPEC) in rats of both sexes displaying MSG-induced obesity.

METHODS

The animals entered the study straight after birth, being separated according to gender and randomly divided into CON (control, saline-treated) and MSG (monosodium glutamate-treated) groups. Next, the animals underwent LIPEC or sham-operated surgery (SHAM). Obesity was induced by the injection of MSG (4 mg/g/day) during neonatal stage (2nd to 11th day from birth). LIPEC was performed on the 12th week, consisting in the withdrawal of parietal WAT. On the 16th week, the following WATs were isolated and collected: peri-epididymal-WAT (EP-WAT); parametrial-WAT (PM-WAT); omental-WAT (OM-WAT); perirenal-WAT (PR-WAT) and retroperitoneal-WAT (RP-WAT).

RESULTS

The adiposity index was significantly increased in both male (3.2 ± 0.2** vs 1.8 ± 0.1) and female (4.9 ± 0.7* vs 2.6 ± 0.3) obese rats compared to their respective control groups. LIPEC in obese animals produced fat accumulation in visceral fat sites in a more accentuated manner in female (3.6 ± 0.3** vs 2.8 ± 0.3 g/100 g) rather than in male (1.8 ± 0.2* vs 1.5 ± 0.1 g/100 g) rats compared to obese non-lipectomized animals. Among the visceral WATs, the greater differences were observed between gonadal WATs of obese lipectomized rats, with higher accumulation having been observed in PM-WAT (2.8 ± 0.3* vs 2.1 ± 0.2 g/100 g) rather than in EP-WAT (1.0 ± 0.1 ± 0.9 ± 0.1 g/100 g) when compared to obese non-lipectomized animals.

CONCLUSIONS

The results of the present study led us to conclude that obesity induced by MSG treatment occurs differently in male and female rats. When associated with parietal LIPEC, there was a significant increase in the deposition of visceral fat, which was significantly higher in obese female rats than in males, indicating that fat mobility among WATs in lipectomized-obese rats can occur more expressively in particular sites of remaining WATs.

IGF-1R mRNA expression is increased in obese children

OBJECTIVES

Obese children are often taller than age-matched subjects. Reports on GH and IGF-I levels in obese individuals are controversial, with normal and reduced GH-IGF-I levels having been reported in this group of patients. Thus, the aim of this study was to analyse insulin-like growth factor type 1 receptor (IGF-IR) mRNA expression in obese children.

METHODS

Forty-seven pre-pubertal children were included in this study: 29 were obese and taller than their target height, and 18 were normal eutrophic controls. Fasting blood samples were collected for IGF-IR mRNA expression in isolated lymphocytes and serum IGF-I, ALS, IGFBP-3, and IGFBP-1 concentration analysis.

RESULTS

Relative IGF-IR gene expression (2^-ΔΔCT) was significantly (P=0.025) higher in obese children (median 1.87) than in controls (1.15). Fourteen of the 29 obese subjects showed 2^-ΔΔCT values greater than or equal to 2, while only 2 individuals in the control group showed values above 2 (P=0.01). Obese children showed significantly (P=0.01) higher IGF-I concentrations than the control group (237ng/ml and 144ng/ml, respectively). Among obese patients, 65.5% had IGF-I values above the 75 percentile of the control group (P=0.02). ALS concentration was significantly (P=0.04) higher in the obese group, while IGFBP-3 levels were similar in obese and control children. IGFBP-1 concentration was lower in obese children, while insulin levels and HOMA-IR index were higher than in controls.

CONCLUSIONS

The higher IGF-IR mRNA expression observed in obese children, associated with the higher IGF-I and ALS and the lower IGFBP-1 levels, suggest that the higher stature observed in these children may be due to increased IGF-I bioactivity.

Factors associated with uterine fibroid in Ghanaian women undergoing pelvic scans with suspected uterine fibroid

Background

Uterine fibroids are the most common benign tumours affecting premenopausal women and are often associated with considerable hospitalization and morbidity. Literature shows virtually no study concerning the quantification of the main factors associated with uterine fibroids in Ghanaian women. The purpose of this study was to assess the main factors associated with uterine fibroid among Ghanaian women presenting for ultrasound.

Method

A prospective cross-sectional study design was employed in this study. A total of two hundred and forty-four (244) women were consecutively evaluated from November 2011 to February 2012 using a 2–5 MHz curvilinear probe of Philips HD3 ultrasound machines at three centres in Accra using a trans-abdominal pelvic approach. Data was analysed with (SPSS) version 20.0 for windows, 2010; Chicago. The Pearson’s Chi-square test was used to determine associations between selected demographic and gynaecological characteristics and uterine fibroid appearance. All tests were two-tailed and p-value of less than 0.05 was interpreted as significant.

Results

The range, mean and standard deviation (SD) of the patients’ age were 14–54 years, 31.89 years and ± 7.92 respectively. Factors that associated significantly with uterine fibroid in Ghanaian women included obesity (X² = 17.3, p-value = 0.001), participant’s age range (X² = 47.4, p-value = 0.001), parity (X² = −10.169, p-value = 0.001), and age at last delivery (X² = 34.579, p-value = 0.001).

Conclusion

Uterine fibroid was mainly associated with women of older age group of the reproductive age than the younger age categories and also associated more with women with without children compared to those with more children. Moreover, it associated more with obese patients and patient with late age at last delivery.

Effects of obesity and hormone therapy on surgically-confirmed fibroids in postmenopausal women

To examine the association between body mass index (BMI), use of menopausal hormone therapy (HT), and incidence of uterine fibroids in postmenopausal women, 610,604 postmenopausal women without prior hysterectomy or diagnosis of fibroids were followed as part of a large United Kingdom prospective cohort study. We used Cox regression models to calculate adjusted relative risks (RRs) of surgically-confirmed fibroids (defined as a hospital admission with uterine fibroids as a primary diagnosis with a related surgical procedure), in relation to BMI and use of HT. During an average of 11.4 years of follow-up, 3561 women were admitted to hospital with surgically-confirmed fibroids. Five-year incidence rates decreased with age, from 0.50% (1 in 200 women) at age 50-54, to 0.11% (1 in 1000 women) at age 75-79. The 5-year rate in postmenopausal women aged 50-54 was about a quarter that seen in premenopausal women of the same age (1 in 200 vs. 1 in 50). Compared with normal weight women, obese women had a RR of surgically-detected fibroids of 1.46 (95% CI 1.33-1.59; p < 0.0001). HT use was associated with a RR of 2.33 (95% CI 2.18-2.49; p < 0.0001) in ever versus never users. When we analysed HT use and BMI together, obese vs. normal weight never users had a RR of 2.00 (95% CI 1.77-2.26): the highest risks were seen in women who were obese and had ever used HT, RR = 3.30 (95% CI 2.88-3.79). Uterine fibroids continue to occur in postmenopausal women; obesity and hormone therapy use are important modifiable risk factors.

Determinants of bone microarchitecture and mechanical properties in obese men

CONTEXT

Recent studies have suggested that obesity in men is associated with increased fracture risk. Obesity in men is also associated with dysregulation of the GH/IGF-I and gonadal steroid axes, important regulators of bone homeostasis.

OBJECTIVE

The aim of the study was to investigate body composition and endocrine determinants of bone microarchitecture and mechanical properties in obese men.

DESIGN AND SETTING

We conducted a cross-sectional study at a clinical research center.

PARTICIPANTS

Thirty-five obese men (mean age, 33.8 ± 6.4 yr; mean body mass index, 36.5 ± 5.8 kg/m(2)) participated in the study.

OUTCOME MEASURES

Distal radius microarchitecture and mechanical properties were measured by three-dimensional high-resolution peripheral quantitative computed tomography and microfinite element analysis; body composition by computed tomography; bone marrow fat by proton magnetic resonance spectroscopy; total and free estradiol and testosterone; IGF-I; peak glucagon-stimulated GH; 25-hydroxyvitamin D.

RESULTS

Men with high visceral adipose tissue (VAT) had impaired mechanical properties compared to men with low VAT (P < 0.05), despite comparable body mass index. VAT was inversely associated and thigh muscle was positively associated with mechanical properties (P < 0.05). Bone marrow fat was inversely associated with cortical parameters (P ≤ 0.02). Free estradiol was positively associated with total density (P = 0.05). Free testosterone was positively associated with trabecular thickness and inversely with trabecular number (P ≤ 0.05). Peak stimulated GH was positively associated with trabecular thickness, as was IGF-I with cortical area (P ≤ 0.04).

CONCLUSION

VAT and bone marrow fat are negative predictors and muscle mass is a positive predictor of microarchitecture and mechanical properties in obese men. Testosterone, estradiol, and GH are positive determinants of trabecular microarchitecture, and IGF-I is a positive determinant of cortical microarchitecture. This supports the notion that VAT is detrimental to bone and that decreased GH and testosterone, characteristic of male obesity, may exert deleterious effects on microarchitecture, whereas higher estradiol may be protective.

The serum level of fibroblast growth factor-23 and calcium-phosphate homeostasis in obese perimenopausal women

Plasma FGF-23 concentrations and its relationship with calcium-phosphate homeostasis were evaluated in 48 perimenopausal obese women and in 29 nonobese controls. Serum parathyroid hormone, 25-hydroxyvitamin D(3), CTX1, osteocalcin, total calcium, phosphorus, creatinine, and plasma intact FGF-23 concentrations were assessed. DXA of lumbar spine and femoral neck was performed to determine bone mineral density (BMD). Plasma iFGF-23 concentration was significantly higher in obese patients (by 42%) and correlated with age and BMD of proximal femur (R = -0.346; R = 0.285, resp.) but not with markers of bone turnover. However, serum phosphorus level in obese subjects was significantly lower. iFGF-23 concentration correlated significantly with body mass index (R = 0.292) and fat content (R = 0.259) in all study subjects. Moreover, a significant correlation between iFGF-23 and iPTH (R = 0.254) was found. No correlation between serum phosphorus or eGFR and plasma iFGF-23 and between eGFR and serum phosphorus was found. Elevated serum iFGF-23 concentration may partially explain lower phosphorus levels in the obese and seems not to reflect bone turnover.

Comparison of 1 mg and 2 mg overnight dexamethasone suppression tests for the screening of Cushing's syndrome in obese patients

OBJECTIVE

Obesity is currently a major public health problem and one of the potential underlying causes of obesity in a minority of patients is Cushing's syndrome (CS). Traditionally, the gold standard screening test for CS is 1 mg dexamethasone overnight suppression test. However, it is known that obese subjects have high false positive results with this test.

DESIGN

We have therefore compared the 1 mg and 2 mg overnight dexamethasone suppression tests in obese subjects. Patients whose serum cortisol after ODST was >50 nM underwent and a low-dose dexamethasone suppression test (LDDST); 24-hour urine cortisol was collected for basal urinary free cortisol (UFC). For positive results after overnight 1-mg dexamethasone suppression test we also performed the overnight 2-mg dexamethasone suppression test.

PATIENTS

We prospectively evaluated 100 patients (22 men and 78 women, ranging in age from 17 to 73 years with a body mass index (BMI) >30 kg/m2 who had been referred to our hospital-affiliated endocrine clinic because of simple obesity. Suppression of serum cortisol to <50 nM (1.8 microg/dL) after dexamethasone administration was chosen as the cut-off point for normal suppression.

MEASUREMENTS

Thyroid function tests, lipid profiles, homocysteine, antithyroglobulin, anti-thyroid peroxidase antibody levels, vitamin B12, folate levels, insulin resistance [by homeostasis model assessment (HOMA)] and 1.0 mg postdexamethasone (postdex) suppression cortisol levels were measured.

RESULTS

We found an 8% false-positive rate in 1 mg overnight test and 2% in 2 mg overnight test (p=0.001). There was no correlation between the cortisol levels after ODST and other parameters.

CONCLUSIONS

Our results indicate that the 2 mg overnight dexamethasone suppression test (ODST) is more convenient and accurate than 1-mg ODST as a screening test for excluding CS in subjects with simple obesity.

[Hormonal axes in obesity: cause or effect?]

Several endocrine changes have been described in the obesity state. The corticotropic axis is hyperresponsive and there is enhancement of hormonal clearance, but cortisol levels are within the normal range. It is important to characterize a pseudo-Cushing in obesity. Leptin seems to be a permissive hormone for the beginning of puberty. In adults, gonadotropines are normal, and hyperandrogenism and hyperestrogenism are found. In women, insulin resistance has a central role in polycystic ovarian syndrome (POS), which is associated to ovarian hyperandrogenemia. In obese subjects, growth hormone (GH) is generally low and IGF1 is normal. Thyroid function is commonly normal in obese subjects.

The influence of weight loss on serum osteoprotegerin concentration in obese perimenopausal women

OBJECTIVE

To assess the influence of weight reduction therapy on serum osteoprotegerin (OPG) concentration in obese patients and compare these results with normal-weight controls.

RESEARCH METHODS AND PROCEDURES

Forty-three obese women (BMI, 36.7 +/- 4.1 kg/m2; mean age, 50.1 +/- 4.5 years) were studied. The control group consisted of 19 normal-weight women (BMI, 24.2 +/- 2.1 kg/m2; mean age, 53.8 +/- 5.2 years). In all patients, serum concentrations of OPG, C telopeptide of type I collagen containing the cross-linking site (CTX), osteocalcin, parathormone, 25-(OH)-D3 (vitamin D), and total calcium and phosphorus were assessed before and after a 3-month weight reduction therapy.

RESULTS

In obese subjects, serum concentrations of OPG, 25-(OH)-D3, osteocalcin, total calcium, and phosphorus were significantly lower, and serum concentration of parathormone was significantly higher, before weight reduction therapy in comparison with normal-weight controls. After weight reduction, a significantly higher serum concentration of 25-(OH)-D3 and CTX and significantly lower concentration of OPG were found.

DISCUSSION

Serum concentration of OPG was significantly lower in obese patients in comparison with normal-weight controls. Weight reduction therapy resulted in further decrease in OPG serum concentrations. Therefore, OPG cannot be treated as a protective factor from bone loss in obese patients.

Risk of secondary hyperparathyroidism after laparoscopic gastric bypass surgery in obese women

BACKGROUND

Metabolic bone disease is a potential complication of bariatric surgery. The aims of our study were to evaluate the effects of laparoscopic gastric bypass on calcium and vitamin D metabolism, and to identify patients at high risk to develop secondary hyperparathyroidism (HPT).

METHODS

Serum calcium, alkaline phosphatase, intact parathyroid hormone (PTH), and 25-hydroxy (OH) vitamin D were measured at 3, 6, 12, and 24 months after laparoscopic gastric bypass in a cohort of morbidly obese women. Logistic regression was used in both univariate and multivariate models to identify independent preoperative variables associated with secondary HPT.

RESULTS

The study enrolled 193 morbidly obese women. During the 2-year follow-up period, the incidence of elevated PTH levels (>65 pg/ml) was 53.3%. The mean time elapsed between surgery and detection of secondary HPT was 9.1 months (range, 3-24 months). Vitamin D deficiency was observed in 39 patients (20.2%). On univariate analysis, the preoperative factors associated with secondary HPT were race (high PTH levels were detected in 70% of African Americans versus 50% of Caucasians; p < 0.05), preoperative body mass index (BMI; high PTH: 52.5 +/- 10.8 versus normal PTH: 48.9 +/- 7.5 kg/m2; p < 0.01), and age (high PTH: 44.9 +/- 9.2 versus normal PTH: 42.3 +/- 9 years, p < 0.05). Race and age remained independent risk factors for secondary HPT in the multivariate logistic regression model after adjusting for the covariate Roux-limb length. African Americans were at more than 2.5 times greater risk to develop secondary HPT as Caucasian (RR 2.5; 95% CI: 1.03-6.17, p < 0.05). Patients older than 45 years were at 1.8 times higher risk of developing secondary HPT as their younger counterparts (RR 1.8; 95% CI: 1.01-3.32, p < 0.05).

CONCLUSIONS

Morbidly obese women have a high incidence of elevated PTH levels after gastric bypass surgery. Low vitamin D levels did not constitute the only reason behind this finding. African-American women and women older than 45 years of age were at significantly higher risk of developing secondary HPT. In these populations, aggressive supplementation with calcium citrate and vitamin D should be implemented.

Mild androgen phenotypes

Mild androgen phenotypes are found in 30-40% of patients referred to an endocrine clinic because of suspected hyperandrogenic syndrome. These disorders are characterized by clinical or biological signs of hyperandrogenism in women with normal ovulatory menstrual cycles. Three main mild androgen disorders may be distinguished: ovulatory polycystic ovarian syndrome (PCOS), idiopathic hyperandrogenism, and idiopathic hirsutism. Ovulatory PCOS includes ovulatory hyperandrogenic patients presenting with polycystic ovaries. Using ESHRE/ASRM criteria for diagnosis of PCOS, this disorder is now part of PCOS spectrum. While in vivo and in vitro studies have confirmed the similarities between the two forms of PCOS, ovulatory PCOS presents clinicians with some unique problems. In fact, fertility is not a problem, but insulin resistance is present, and although milder than in classic PCOS it may be associated with an increased cardiovascular and metabolic risk. Because of this, an ovarian sonography should be performed in all ovulatory hyperandrogenic patients, and when polycystic ovaries are found cardiovascular and metabolic risk should be carefully evaluated. Ovulatory PCOS patients with altered glucose tolerance and/or with dyslipidaemia may need treatment with insulin-sensitizing agents. Idiopathic hyperandrogenism regroups ovulatory patients with increased androgen levels and normal ovaries, while idiopathic hirsutism includes ovulatory patients presenting with hirsutism but normal circulating androgens and normal ovaries. The differentiation between these two disorders may be difficult because commercial assays of androgen levels are generally unreliable. While idiopathic hyperandrogenism may be associated with insulin resistance, neither disorder is associated with an increased cardiovascular risk. The main clinical problem is hirsutism, and this may be approached by aesthetic or pharmacological therapies.

Obesity and androgens: facts and perspectives

OBJECTIVE

This review discusses androgen status in male and female obesity, according to their specific phenotype, and the main mechanisms responsible.

DESIGN

Published data in the literature of the last 20 years represented the basis of most of the data and concepts incorporated in the review.

RESULT(S)

Obesity is associated with profound alterations in androgen secretion, transport, metabolism, and action, according to a dichotomous behavior depending on sex. Obese men are characterized by a progressive decrease of testosterone levels with increasing body weight, whereas obese women, particularly those with the abdominal phenotype, tend to develop a condition of functional hyperandrogenism. Reduced sex hormone-binding globulin synthesis and circulating blood levels represent the sole common mechanism which is responsible in both sexes. Among other still partially undefined factors, mechanisms potentially responsible for the sex dichotomy in androgen levels involve specific alterations of gonadotropin secretion, estrogens, the hypothalamic-pituitary-adrenal axis, leptin, androgen receptors, specific steroidogenic enzymes in the peripheral tissues, and, possibly, ghrelin. In both sexes, androgens play an important role in determining the sex-dependent pattern of body fat distribution. Moreover there are theoretical possibilities that low testosterone in men and high free testosterone fraction in women may play a role in the development of the metabolic syndrome. This is exemplified by the well defined association between obesity and other features of the metabolic syndrome in women with polycystic ovary syndrome and in hypogonadal men. The effects of androgen and antiandrogens in obese men and women also represent arguments in favor of this association.

CONCLUSION(S)

Given the fundamental role of sex hormones in the regulation of body composition, fuel homeostasis, and reproduction in humans, more emphasis should be placed on the potential role of androgen dysregulation in the pathophysiology of different obesity phenotypes and the metabolic syndrome.

Case-control study of anthropometric measures and prostate cancer risk

A population-based case-control study of 988 stage T2 or greater prostate cancer cases and 1063 controls was conducted in Alberta from November 1997 to December 2000 to examine the influence of anthropometric risk factors on the risk of prostate cancer using several different measures. An in-person interview was conducted, and all anthropometric measurements were taken using standardized methods. Respondents also recalled their body weight at each decade from age 20 to the referent year. Several anthropometric variables were derived, and unconditional logistic regression analyses were performed. The multivariable odds ratios, when comparing the highest to the lowest quartile were: for body mass index, OR = 1.12 (95% CI 0.85-1.47); for waist-hip ratio, OR = 1.07 (0.83-1.38); for height, OR = 0.78 (0.60-1.02); for weight, OR = 0.91 (0.70-1.18); for weight gain since age 20, OR = 0.91 (0.70-1.19); and for difference between minimum and maximum adult weight, OR = 0.89 (0.69-1.16). Our study provides evidence for no association between any measures of anthropometry including several derived measures of changes in weight over lifetime and prostate cancer risk.

Obesity and endocrine disease

Several endocrine abnormalities are reported in obesity. Some of these abnormalities are considered as causative factors for the development of obesity, whereas others are considered to be secondary effects of obesity and usually are restored after weight loss. Thyroid hormones usually are normal in obesity, with the exception of T3 which is elevated. Prolactin is normal but prolactin response to different stimuli is blunted. GH is low and GH response to stimuli is blunted. IGF-I levels are normal or elevated. Cortisol, ACTH, and urine free cortisol levels are usually normal; however, a hyperresponsiveness of the HPA axis with increased cortisol and ACTH response to stimulatory tests is observed in centrally obese individuals. Total testosterone and SHBG levels are low, but free testosterone levels are usually normal in obese men. LH and FSH levels usually are normal and estrogens are elevated. Norepinephrine levels are elevated, whereas epinephrine levels are low or normal. Aldosterone levels are elevated but renin activity is usually normal. Parathyroid hormone levels are elevated with normal serum calcium levels and increased urine calcium levels. Monogenic mutations that result in severe obesity have been described in several individuals. Also, several endocrine diseases have obesity as one their clinical manifestations. Hypothyroidism, Cushing's syndrome, GH and testosterone deficiency, polycystic ovarian syndrome, insulinoma, hypothalamic lesions, and genetic syndromes often present with obesity. In most of these conditions, appropriate treatment of the primary disease results in weight loss. In addition, the fat cell has been found to be an endocrine organ that produces several peptides that are bioactive and participate in the regulation of adipocyte function.

Endocrine effects of nasal continuous positive airway pressure in male patients with obstructive sleep apnoea

OBJECTIVE

Obstructive sleep apnoea (OSA) is a relatively common condition producing disabling somnolence and profound physiological responses to hypoxaemic episodes during sleep, including significant oscillations in blood pressure. This study aimed to provide controlled data on the interaction between OSA and endocrine axes to establish whether overrepresentation of pathology such as hypertension and hypogonadism in OSA subjects might have an endocrine basis.

DESIGN, SETTING AND SUBJECTS

Parallel randomized sham placebo controlled 1-month trial of nasal continuous positive airway pressure (nCPAP) in 101 male subjects with OSA presenting to a respiratory sleep clinic.

METHODS

Analysis of gonadotrophins, testosterone, sex hormone binding protein (SHBG), prolactin, cortisol, thyroid stimulating hormone (TSH), free thyroxine (free T4), insulin-like growth factor-1 (IGF-1), renin and aldosterone were performed at baseline and after 1 month's active or placebo nCPAP intervention. Quality of life questionnaire scoring was also recorded over the same time period.

RESULTS

Testosterone and SHBG showed significant negative correlations with baseline OSA severity. Active treatment of OSA produced SHBG elevation and TSH reduction (P< or =0.03). Both groups showed an increase in aldosterone (P<0.001) and IGF-1 (P< or =0.03), associated with a large improvement in subjective quality of life scoring.

CONCLUSIONS

These findings demonstrate significant changes in endocrine axes not previously reported in a placebo-controlled trial. OSA is a recognized reversible cause of testosterone reduction; SHBG suppression correlating to baseline OSA severity supports a diagnosis of secondary hypogonadism. Significant rises in aldosterone and IGF-1 on treatment coincide with increased physical activity and an improved quality of life score.

Genetic and environmental aspect of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a heterogeneous syndrome determined in most patients by the association of two main factors: hyperandrogenism and insulin resistance. These characters are probably independent of each other and seem to be inherited by several different mechanisms. In some patients homozygous gene alteration has been found but in most patients PCOS seems to be determined by the association of gene polymorphisms that are common in the general population but alone are unable to determine phenotypic consequences. Alteration of genes that regulate the initial steps of ovarian steroidogenesis is probably the main causal factor of hyperandrogenism. Insulin resistance may be the result of many different gene alterations including insulin receptor substrate (IRS)-1 and 2, calpain-10 and peroxisome proliferator-activated receptor gamma(PPARgamma). Some polymorphisms may be protective against other gene alterations. Insulin sensitivity is also modified by socioeconomic and cultural factors that influence quantity and quality of food and energy expenditure. However, even eating behavior and weight response to food intake may be under genetic regulation. Different combinations of multiple gene polymorphisms and of environmental factors explain the heterogeneity of PCOS.

Leptin activation of corticosterone production in hepatocytes may contribute to the reversal of obesity and hyperglycemia in leptin-deficient ob/ob mice

Glucocorticoids have been implicated as pathophysiological mediators of obesity and insulin resistance and are regulated by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). This enzyme regenerates active corticosterone from inactive 11-keto forms. To assess the role of 11beta-HSD1-mediated synthesis of active corticosterone in leptin-related obesity and diabetes, we examined the peripheral effect of leptin on 11beta-HSD1 activity and gene expression in vivo and in vitro in hepatocytes from ob/ob mice and in liver of streptozotocin (STZ)-treated ob/ob mice. We observed an inverse relationship between hepatic 11beta-HSD1 expression and body weight in ob/ob mice and lean littermates. Leptin treatment of ob/ob mice markedly increased hepatic 11beta-HSD1 activity and mRNA expression. This induction of 11beta-HSD1 expression corresponded to reduced levels of circulating corticosterone and weight loss in ob/ob mice treated with leptin, indicating that impaired hepatic 11beta-HSD1 expression may contribute to the pathogenesis of obesity in ob/ob mice. In addition, leptin treatment of STZ-treated ob/ob mice caused marked increases in hepatic 11beta-HSD1 levels associated with decreased body weight and a significant reduction in hyperglycemia due to pancreatic beta-cell damage. Addition of leptin to ob/ob mouse primary hepatocytes led to a dose-dependent increase in 11beta-HSD1 mRNA expression. In contrast, leptin did not influence 11beta-HSD1 expression in primary hepatocytes from db/db mice, indicating that leptin regulation of 11beta-HSD1 expression is probably mediated by the functional leptin receptor. Thus, leptin appears to be an important metabolic signal that directly activates intrahepatic corticosterone production. These findings suggest that the liver-specific interaction of leptin with 11beta-HSD1 is involved in the development of obesity and insulin resistance in ob/ob mice.

Etiology and pathogenesis of uterine leiomyomas: a review

Uterine leiomyomas, or fibroids, represent a major public health problem. It is believed that these tumors develop in the majority of American women and become symptomatic in one-third of these women. They are the most frequent indication for hysterectomy in the United States. Although the initiator or initiators of fibroids are unknown, several predisposing factors have been identified, including age (late reproductive years), African-American ethnicity, nulliparity, and obesity. Nonrandom cytogenetic abnormalities have been found in about 40% of tumors examined. Estrogen and progesterone are recognized as promoters of tumor growth, and the potential role of environmental estrogens has only recently been explored. Growth factors with mitogenic activity, such as transforming growth factor- (subscript)3(/subscript), basic fibroblast growth factor, epidermal growth factor, and insulin-like growth factor-I, are elevated in fibroids and may be the effectors of estrogen and progesterone promotion. These data offer clues to the etiology and pathogenesis of this common condition, which we have analyzed and summarized in this review.

Lack of pleiotropic genetic effects between adiposity and sex hormone-binding globulin concentrations before and after 20 weeks of exercise training: the HERITAGE family study

The relationship between sex hormone-binding globulin (SHBG) concentrations and body fat accumulation and distribution is governed by complex dynamic factors, which may involve common genetic and/or environmental factors. The current study investigated the genetic and environmental basis for the correlation between SHBG and body fat. Several measures of adiposity were investigated including body mass index (BMI) and a trunk to extremity skinfold thickness ratio (TER) assessed by anthropometry, body composition measured by hydrostatic weighing (total body fat mass [FM], fat-free mass [FFM], and percent body fat [%BF]), and abdominal fat measured by computerized tomography scanning (abdominal visceral fat [AVF]). The study comprised 501 white subjects from 99 families and 277 black subjects from 117 families participating in the HERITAGE Family Study. Familial correlations between traits and their cosegregation were investigated both at baseline and in response to endurance exercise training. Significant inverse phenotypic correlations were detected in both races between SHBG and adiposity measures at baseline and also in response to training. Significant cross-trait familial resemblance was found between SHBG and both BMI and FFM at baseline that accounted for 11% and 4% of maximal heritability, respectively, in white families. However, a joint segregation analysis of the traits failed to implicate shared genetic effects. Specifically, neither a pleiotropic major locus nor pleiotropic polygenic effects were detected between SHBG and BMI or FFM. A maximal cross-trait heritability of 45% was obtained for SHBG and TER at baseline in black families. However, no firm conclusions as to the etiology of this relationship could be drawn because of the limitations of small sample size. For the training response phenotypes, there was no significant cross-trait correlation between SHBG and any adiposity measures studied here, suggesting that their correlation may have an environmental basis. Therefore, this study fails to support the hypothesis of genetic pleiotropy between SHBG concentrations and body fat phenotypes, and suggests an environmental basis for the correlation, ie, SHBG concentrations are genetically independent of body composition and abdominal adiposity phenotypes.

Adrenal gland volume after spinal cord injury

OBJECTIVE

Spinal cord injury in adult men may result in hypothalamic-pituitary-adrenal axis dysfunction. Atrophy of adrenal glands was speculated in these patients. This study was undertaken to clarify the functional-anatomic correlation between adrenal volume and body surface area in subjects with spinal cord injury with impaired adrenal reserve.

DESIGN

Twenty male subjects with chronic spinal cord injury with impaired adrenal reserve were identified by adrenocorticotropic hormone stimulation test from a group of 42 subjects. All subjects with spinal cord injury and healthy volunteers underwent computed tomographic imaging with contiguous 3-mm section over adrenal glands for volumetric measurements. Ten pairs of subjects with spinal cord injury and controls with matched height and weight were included in the statistical analysis.

RESULTS

Significantly increased relative adrenal volumes were noted among subjects with chronic spinal cord injury and impaired adrenal reserve as compared with the body weight-matched and height-matched control group.

CONCLUSIONS

Increased relative adrenal volumes were found after chronic spinal cord injury. Hyperplasia of the zona glomerulosa may be the cause of increased relative adrenal volume after chronic spinal cord injury.

Increased glucocorticoid receptor expression in human skeletal muscle cells may contribute to the pathogenesis of the metabolic syndrome

Altered glucocorticoid hormone action may contribute to the etiology of the metabolic syndrome, but the molecular mechanisms are poorly defined. Tissue sensitivity to glucocorticoid is regulated by expression of the glucocorticoid receptor (GR)-alpha and 11beta-hydroxysteroid dehydrogenase type I (11beta-HSD1)-mediated intracellular synthesis of active cortisol from inactive cortisone. We have analyzed GRalpha and 11beta-HSD1 expression in skeletal myoblasts from men (n = 14) with contrasting levels of insulin sensitivity (euglycemic clamp measurements of insulin-dependent glucose disposal rate), blood pressure, and adiposity. Positive associations were evident between myoblast expression of GRalpha under basal conditions and levels of insulin resistance (r(2) = 0.34, P < 0.05), BMI (r(2) = 0.49, P < 0.01), percent body fat (r(2) = 0.34, P < 0.02), and blood pressure (r(2) = 0.86, P < 0.001). Similar associations were evident when myoblasts were incubated with physiological levels of cortisol (P < 0.01 for all). Importantly, GRalpha expression was unaffected by variations in in vivo concentrations of insulin, IGF-1, or glucose concentrations. In common with the GR, 11beta-HSD1 expression in myoblasts incubated with physiological concentrations of cortisol in vitro was positively associated with levels of insulin resistance (r(2) = 0.68, P < 0.001), BMI (r(2) = 0.63, P < 0.005), and blood pressure (r(2) = 0.27, P < 0.05). Regulation of GRalpha and 11beta-HSD1 by cortisol was abolished by the GR antagonist RU38486. In summary, our data suggest that raised skeletal muscle cell expression of GRalpha and 11beta -HSD1-mediated regulation of intracellular cortisol may play a fundamental role in mechanisms contributing to the pathogenesis of the metabolic syndrome.

Effect of obesity and starvation on thyroid hormone, growth hormone, and cortisol secretion

Obesity and starvation have opposing affects on normal physiology and are associated with adaptive changes in hormone secretion. The effects of obesity and starvation on thyroid hormone, GH, and cortisol secretion are summarized in Table 1. Although hypothyroidism is associated with some weight gain, surveys of obese individuals show that less than 10% are hypothyroid. Discrepancies have been reported in some studies, but in untreated obesity, total and free T4, total and free T3, TSH levels, and the TSH response to TRH are normal. Some reports suggest an increase in total T3 and decrease in rT3 induced by overfeeding. Treatment of obesity with hypocaloric diets causes changes in thyroid function that resemble sick euthyroid syndrome. Changes consist of a decrease in total T4 and total and free T3 with a corresponding increase in rT3. untreated obesity is also associated with low GH levels; however, levels of IGF-1 are normal. GH-binding protein levels are increased and the GH response to GHRH is decreased. These changes are reversed by drastic weight reduction. Cortisol levels are abnormal in people with abdominal obesity who exhibit an increase in urinary free cortisol but exhibit normal or decreased serum cortisol and normal ACTH levels. These changes are explained by an increase in cortisol clearance. There is also an increased response to CRH. Treatment of obesity with very low calorie diets causes a decrease in serum cortisol explained by a decrease in cortisol-binding proteins. The increase in cortisol secretion seen in patients with abdominal obesity may contribute to the metabolic syndrome (insulin resistance, glucose intolerance, dyslipidemia, and hypertension). States of chronic starvation such as seen in anorexia nervosa are also associated with changes in thyroid hormone, GH, and cortisol secretion. There is a decrease in total and free T4 and T3, and an increase in rT3 similar to findings in sick euthyroid syndrome. The TSH response to TRH is diminished and, in severe cases, thyroid-binding protein levels are decreased. In regards to GH, there is an increase in GH secretion with a decrease in IGF-1 levels. GH responses to GHRH are increased. The [table: see text] changes in cortisol secretion in patients with anorexia nervosa resemble depression. They present with increased urinary free cortisol and serum cortisol levels but without changes in ACTH levels. In contrast to the findings observed in obesity, the ACTH response to CRH is suppressed, suggesting an increased secretion of CRH. The endocrine changes observed in obesity and starvation may complicate the diagnosis of primary endocrine diseases. The increase in cortisol secretion in obesity needs to be distinguished from Cushing's syndrome, the decrease in thyroid hormone levels in anorexia nervosa needs to be distinguished from secondary hypothyroidism, and the increase in cortisol secretion observed in anorexia nervosa requires a differential diagnosis with primary depressive disorder.

Utility of insulin-like growth factor-I and its binding protein assays

Insulin-like growth factor-I circulates in serum either in free form or bound to insulin-like growth factor-binding proteins that modulate its bioavailability. Insulin-like growth factor-binding proteins interfere with insulin-like growth factor-I assay, which remains technically difficult. Many assays have been developed, but their results are somewhat discordant. The choice of separation method, standard and tracer considerably influences the results. The circulating concentration of insulin-like growth factor-I, however, is clearly dependent on nutritional status, and total levels are a valuable marker of nutritional status. The clinical utility of free insulin-like growth factor-I assay and simultaneous assay, in the same sample, of total insulin-like growth factor-I and its binding proteins (reflecting the bioavailable insulin-like growth factor-I fraction), remains to be evaluated.

Testosterone and oestradiol in relation to tobacco smoking, body mass index, energy consumption and nutrient intake among adult men

There is substantial evidence linking steroid hormones and diet to cancer aetiology. The evidence on lifestyle determinants of steroid hormones, however, is limited. We have conducted a study to identify dietary and other lifestyle predictors of testosterone and oestradiol among adult men. Subjects were 112 healthy Greek men, recruited as controls in a case-control study on the aetiology of liver cancer. Demographic data and detailed histories of smoking habits and alcohol consumption were recorded. Diet was assessed through an interviewer-administered validated food-frequency questionnaire. Serologic measurements of oestradiol, testosterone and sex hormone binding globulin were also conducted. We developed linear regression models to evaluate the associations of smoking and dietary factors with serum testosterone and oestradiol. The results indicate that, among men, both testosterone and oestradiol serum levels decline with age, whereas body mass index may be inversely related with testosterone and positively with oestradiol. The evidence concerning alcohol in relation to these hormones is inconclusive. Emerging evidence concerning smoking suggests positive associations with both hormones in the blood. The principal nutritional findings are a positive association of carbohydrate intake with testosterone levels and a set of inverse associations of vitamins with oestradiol.

Subcutaneous and visceral adipose tissue: their relation to the metabolic syndrome

Methods for assessment, e.g., anthropometric indicators and imaging techniques, of several phenotypes of human obesity, with special reference to abdominal fat content, have been evaluated. The correlation of fat distribution with age, gender, total body fat, energy balance, adipose tissue lipoprotein lipase and lipolytic activity, adipose tissue receptors, and genetic characteristics are discussed. Several secreted or expressed factors in the adipocyte are evaluated in the context of fat tissue localization. The body fat distribution and the metabolic profile in nonobese and obese individuals is discussed relative to lipolysis, antilypolysis and lipogenesis, insulin sensitivity, and glucose, lipid, and protein metabolism. Finally, the endocrine regulation of abdominal visceral fat in comparison with the adipose tissue localized in other areas is presented.

Adrenal responsiveness to high, low and very low ACTH 1-24 doses in obesity

OBJECTIVE

To investigate adrenal activity in visceral obesity in which adrenal hyperactivity has been hypothesized. This could reflect hypothalamus-pituitary alterations leading to slight hyperfunction of the adrenal. Primary adrenal hypersensitivity to ACTH drive in obesity has also been suggested. However, it has also been reported that dehydroepiondrosterone (DHEA) levels in obesity are reduced and it has been hypothesized that this could play a role in the increased cardiovascular risk in obese patients.

SUBJECTS

We have studied seven obese women with visceral adiposity (OB, age: 33.6+/-3.3 years, BMI: 33.8+/-1.3 kg/m2, WHR: 0.88+/-0.01). The results in OB were compared with those recorded in a group of age-matched normal women (NS, age: 30+/-1.3 years, BMI: 19.9+/-0.4 kg/m2, WHR: 0.76+/-0.02).

METHODS

We have studied the cortisol (F), aldosterone (A) and DHEA responses to ACTH 1-24 administered at low (LD, 0.5 microg/m2) or very low (VLD, 0.125 microg/m2) dose followed by a second challenge with supramaximal dose (HD, 250 microg).

RESULTS

Basal F, A and DHEA levels in OB were similar to those in NS. The peak F responses to ACTH were dose-related in both groups. At each dose the F peaks in OB (VLD: 495.6+/-43.9 nmol/l, HD: 722.3+/-67.7 nmol/l; LD: 519.2+/-46.0 nmol/l, HD: 729.6+/-44.7 nmol/l) were similar to those in NS (VLD: 556.7+/-45.9 nmol/l, HD: 704.8+/-20.7 nmol/l; LD: 511.8+/-22.8 nmol/l, HD: 726.7+/-26.5 nmol/l). The peak A responses to ACTH were dose-related in both groups. At each dose, the A peaks in OB (VLD: 0.55+/-0.03 pmol/l, HD: 0.79+/-0.09 pmol/l; LD: 0.63+/-0.04 pmol/l, HD: 0.78+/-0.09 pmol/l) were similar to those in NS (VLD: 0.8+/-0.10 pmol/l, HD: 0.86+/-0.09 pmol/l; LD: 0.8+/-0.10 pmol/l, HD: 0.95+/-0.12 pmol/l). The peak DHEA responses to ACTH were dose-related in both groups. At each dose the DHEA peaks in OB (VLD: 58.6+/-13.3 nmol/l, HD: 61.9+/-13.1 nmol/l; LD: 55.18+/-6.4 nmol/l, HD: 72.3+/-9.8 nmol/l) were similar to those in NS (VLD: 54.3+/-8.2 nmol/l, HD: 57.8+/-8.2 nmol/l; LD: 42.2+/-3.7 nmol/l, HD: 56.9+/-4.3 nmol/l).

CONCLUSIONS

This study shows that the cortisol, aldosterone and dehydroepiondrosterone responses to high, low and very low ACTH doses in obese women overlap with those in age-matched lean controls; these findings suggest normal sensitivity of the different zones of the adrenal cortex to ACTH in obesity.

Adult patients with Prader-Willi syndrome: clinical characteristics, life circumstances and growth hormone secretion

Prader-Willi syndrome is characterized by a typical clinical phenotype and by a complex genetic basis that includes large deletions, uniparental disomy and imprinting mutations of chromosome region 15q11-q13. This report delineates the clinical characteristics, morbidity and growth hormone secretory status of 19 adults with Prader-Willi syndrome. The patients were 18-34 years of age. Morbidity included marked obesity with body mass index in excess of 30 kg/m2 (grade 1-3 according to WHO), metabolic diseases, sleep apnoea and lipolymphoedema. Severe growth hormone deficiency (GHD) was seen in 38% of the patients, and levels of insulin-like growth factor I were decreased in 87%. Thus, GHD is seen, not only in children with Prader-Willi syndrome, but also in adults with the syndrome.

Relationship between serum leptin and the insulin-like growth factor-I system in humans

The growth hormone (GH)/insulin-like growth factor-I (IGF-I) system and leptin both play an important role in the regulation of body composition. Although the regulation of these two hormonal systems by insulin has been under intense investigation, the physiologic interactions between leptin and the GH/IGF-I system remain unknown. In this study, we examined the relationships among circulating leptin and key elements of the IGF-I system in 60 subjects (27 nondiabetic lean, 21 nondiabetic obese, and 12 type 1 diabetic subjects) with a wide range of insulin secretory capacity. Leptin, glucose, insulin, free IGF-I, total IGF-I, IGF-binding protein-1 (IGFBP-1), and IGFBP-3 levels were measured in the basal state after an overnight fast, and the acute insulin response to glucose (AIRG) was determined after intravenous glucose injection. AIRG was significantly higher (P < .01) in the obese (3,365+/-562 pmol/L x min) versus lean subjects (1,624+/-155 pmol/L x min). In simple regression analysis, the serum leptin concentration was positively correlated with the body mass index ([BMI] men, r = .51, P = .005; women, r = .71, P < .001), IGFBP-3 (men, r = .20, P = nonsignificant; women, r = .41, P < .025), and AIRG (men, r = .73, P < .001; women, r = .62, P < .01). There was a nonlinear correlation between leptin and IGFBP-1, but there was no correlation between leptin and free or total IGF-I. In multiple regression analysis with leptin as the dependent variable, gender, BMI, and IGFBP-3 entered the equations at a statistically significant level. The correlation of leptin with IGFBP-3 was independent of obesity and persisted after correction for AIRG, suggesting a link between leptin and GH action.

High-affinity growth hormone (GH)-binding protein (GHBP), body fat mass, and insulin-like growth factor-binding protein-3 predict the GHBP response to GH therapy in adult GH deficiency syndrome

The study objective was to investigate which baseline factors can accurately predict plasma high-affinity growth hormone (GH)-binding protein (GHBP) levels after GH replacement therapy in patients with GH deficiency (GHD). The study group consisted of 36 GHD patients (22 men and 14 women; mean age, 43.1 years; (range, 21 to 60) known to have adult-onset GHD for many years (range, 4 to 22). They were randomly divided into a GH-treated group (n = 19) and a placebo group (n = 17). Body composition (assessed by bioelectrical impendance analysis [BIA]), plasma GHBP (fast protein liquid chromatography [FPLC] size-exclusion gel chromatography), insulin-like growth factor-I (IGF-I), and IGF-binding protein-3 ([IGFBP-3] radioimmunoassays) were measured before and after 6 months. A stepwise multiple linear regression analysis with the plasma GHBP level after 6 months as the dependent variable was used to unravel significant explanatory (or predictor) variables. In contrast to placebo therapy, GH replacement therapy increased the mean plasma levels of IGF-I and IGFBP-3 to the normal range, whereas a small but statistically significant increase in plasma GHBP was observed. The combination of baseline plasma GHBP, body fat mass, and IGFBP-3 predicts posttreatment GHBP levels accurately (adjusted R2 = .97), indicating that baseline variables such as age, gender, fat-free mass, and IGF-I have no contribution. Furthermore, reliability analysis showed that the observed and predicted values for GHBP fit a strict parallel model. These findings indicate that the variations in body fat mass and IGFBP-3 among adult GHD subjects explain the reported variable response of GHBP to GH replacement therapy.

Predictors of sex hormone levels among the elderly: a study in Greece

This study examines the relationship between a series of epidemiologic parameters (age, height, body mass index (BMI), smoking, alcohol consumption, and coffee drinking) and serum concentrations of testosterone, estradiol, sex hormone-binding globulin (SHBG), and dehydroepiandrosterone sulfate (DHEAS). Among 52 healthy, elderly Greek men, we observed that serum levels of DHEAS decreased with increasing age [19% decline per 5-year increase in age, 95% CI, -2.1-(-33.5)], obesity [48% decline for BMI >30 kg/m2 compared to <27 kg/m2, CI, -15.7-(-68.7)], and current smoking [37% decline compared to nonsmokers, CI, -9.5-(-57.2)]. Estradiol concentrations increased with increasing BMI [77.1% increase for BMI >30 kg/m2 compared to <27 kg/m2, CI, -12.0-256.3], alcohol drinking [66% increase for > or = 7 glasses/week compared to <7 glasses/week, CI, 4.4-164.4], and coffee drinking [59% increase for > or = 14 cups/week compared to > or = 14 cups/ week, CI, -0.5-155.9], and decreased among current smokers [40% decline compared to nonsmokers, CI, -64.9-0.8]. SHBG was marginally positively associated with increasing age [13% increase per 5 years, CI, -0.5-29.6]. Testosterone was significantly related only to current smoking [27% decline compared to nonsmokers, CI, -45.4-(-3.1)]. These findings suggest that several variables appear to be associated with sex steroid levels and the influence of these findings on the occurrence of hormone-related conditions warrants further exploration.

Reduced growth hormone (GH) responsiveness to combined GH-releasing hormone and pyridostigmine administration in the Prader-Willi syndrome

OBJECTIVE

It is unclear whether the blunted GH secretion in Prader-Willi Syndrome (PWS) is a true deficiency, or merely secondary to obesity. We have investigated the role of obesity in the blunted GH secretion in PWS.

DESIGN

We studied the GH response to a combined administration of GHRH (1 microgram/kg i.v. at 0 min) and pyridostigmine (PD) (60 and 120 mg by mouth for children and adults, respectively, at time -60 min), as well as the baseline IGF-I levels, in a group of patients with PWS. Two different control groups were studied with GHRH + PD using the same doses and methods as above: prepubertal and pubertal obese subjects, and prepubertal short normal children. Moreover, in 14 patients with PWS and in the group of short normals the GH response to at least two stimulation tests (insulin tolerance test, clonidine, L-dopa, arginine) had been previously determined.

PATIENTS

Twenty-two PWS patients (10 males and 12 females), 21 with essential obesity (11 males and 10 females), and eight short normal children (4 males and 4 females) were studied after obtaining informed consent.

MEASUREMENTS

Blood samples were taken at -60, -30 and 0 min and then 15, 30, 45, 60, 90 and 120 min after GHRH administration. Serum GH was measured in duplicate by IRMA, and IGF-I by RIA after acid ethanol extraction. Statistical analysis was performed by t-test for unpaired data, and analysis of variance for parametric or nonparametric data, where appropriate.

RESULTS

The GH response to GHRH + PD was significantly lower in PWS patients (AUC: mean +/- SE: 599 +/- 99 micrograms/l/h) if compared with either short normal children (3294 +/- 461 micrograms/l/h: P < 0.0001) or obese subjects (1445 +/- 210 micrograms/l/h: P < 0.005). Low IGF-I concentrations were found in all PWS patients, so that PWS group had mean IGF-I levels significantly lower than the other groups.

CONCLUSIONS

Our results showed that subjects with PWS had a reduced GH responsiveness to GHRH + PD associated with subnormal IGF-I levels. These findings suggested that short stature in PWS may be at least partially correlated to the presence of GH deficiency, and that impaired GH secretion is not secondary to obesity.

The activity of GH/IGF-I axis in anorexia nervosa and in obesity: a comparison with normal subjects and patients with hypopituitarism or critical illness

GH/IGF-I axis activity changes have been reported both in anorexia nervosa (AN) and in obesity (OB). AN is characterized by GH hypersecretion and very low IGF-I levels as a result of undernutrition and acquired peripheral GH resistance. On the other hand OB is a GH hyposecretory state but IGF-I levels are generally preserved. The activity of GH/IGF-I axis in AN and OB has never been directly compared with that of other pathophysiological conditions such as hypopituitarism and critical illness in which a reduction of both GH and IGF-I secretion has been demonstrated. To this aim, we evaluated IGF-I levels and both basal and GHRH (1 microgram/kg) IV-induced GH secretion in 20 female patients with anorexia nervosa (mean age: 19.1 +/- 0.8 years) and in 15 female and 5 male patients with simple obesity (mean age: 39.0 +/- 3.0 years). We then compared the results with those of hypopituitaric patients with severe GH deficiency (GHD), including 10 female and 10 patients (mean age: 32.0 +/- 2.1 years), and with 4 female and 7 male patients with critical illness (CRI) following multiple trauma 72 hours after ICU admission (mean age: 59.2 +/- 1.2 years). Twenty-six normal subjects (NS) including 14 female and 12 male patients (mean age: 37.8 +/- 3.7 years) were studied as controls. Basal IGF-I levels in AN patients (93.5 +/- 11 micrograms/L) were lower (p < 0.001) than in the NS (201.7 +/- 13.5 micrograms/L) and OB (194.5 +/- 28.6 micrograms/L), which, in turn, were similar. IGF-I levels in AN patients were lower than in CRI patients (162.8 +/- 17.4 micrograms/L) and higher than in GHD patients (76.7 +/- 13.5 micrograms/L) but these differences did not attain statistical significance. Basal GH levels in AN patients (7.6 +/- 2.5 micrograms/L) were higher (p < 0.001) than in NS (1.8 +/- 0.3 micrograms/L), OB patients (1.1 +/- 0.5 micrograms/L), CRI patients (1.8 +/- 0.5 micrograms/L) and GHD patients (0.3 +/- 0.1 microgram/L), which were the lowest (p < 0.01). The GHRH-induced GH rise in AN patients (AUC: 2032.9 +/- 253.5 micrograms/L/h) was three fold higher (p < 0.001) than in NS (662.1 +/- 80.3 micrograms/L). On the other hand in OB (332.4 +/- 74.7 micrograms/L/h) the GH response to GHRH was similar to that in CRI (199.6 +/- 98.8 micrograms/L/h); both were clearly higher (p < 0.01) than in GHD patients (25.1 +/- 5.2 micrograms/L/h) but lower (p < 0.01) than in NS. These findings demonstrate that in AN patients, in spite of a clear increase of both basal and GHRH-induced GH secretion, IGF-I synthesis and release are as markedly impaired as in patients with panhypopituitarism and severe GHD. On the other hand in OB and in CRI, IGF-I synthesis and release are preserved despite marked impairment to GHRH-induced GH secretion. These results reinforce the major role of nutrition in conditioning the activity of GH/IGF-I axis in different patho-physiological states.

Pulsatile secretion of ACTH and cortisol in premenopausal women: effect of obesity and body fat distribution

OBJECTIVE

There is emerging evidence that women with visceral obesity may have hyper-responsiveness of the hypothalamic-pituitary-adrenal axis. There are no studies on basal daily secretory pattern of ACTH and cortisol in subjects with different obesity phenotypes.

DESIGN AND PATIENTS

In this study we examined daytime pulsatile secretion of ACTH and cortisol in two groups of premenopausal obese women with visceral (V-BFD) (BMI 37.1 +/- 1.7) and subcutaneous (S-BFD) (BMI 38.8 +/- 1.5) body fat distribution (measured by CT scan) and in a group of normal weight healthy controls (BMI 21.1 +/- 0.5). After an overnight fast, blood samples were taken at 15-minute intervals for 12 h (49 samples, from 0800 h until 2000 h). All women avoided breakfast but had a normal lunch and dinner, both containing similar food, energy and nutrient composition. ACTH and cortisol responses to mixed meals at noon and in the evening were also investigated.

RESULTS

Mean values of ACTH and cortisol did not differ between the groups. However, ACTH pulse frequency was significantly higher in V-BFD (P < 0.06) and S-BFD (P < 0.02) obese women than in controls, without any significant differences between the two obese subgroups. Mean ACTH pulse amplitude was lower in the V-BFD than in S-BFD obese (P < 0.02) and control (P < 0.05) groups. Cortisol episodic characteristics did not differ between V-BFD and S-BFD obese and controls. All differences in ACTH pulsatile parameters between obese and controls and between the two obese subgroups were evident only in the morning, with no further significant differences during the early and late afternoon. There were no significant differences in cortisol parameters during the three periods of the day between the various groups, apart from late afternoon cortisol pulse frequencies, which were significantly lower in V-BFD than in controls. After lunch, ACTH and cortisol levels significantly increased in all groups, but the cortisol increase tended to be more rapid in V-BFD than in the other two groups. After dinner, ACTH significantly increased in V-BFD and controls but not in the S-BFD group, whereas cortisol rose significantly in all groups, but significantly less in S-BFD than in V-BFD and controls. CortisolAUC (but not ACTHAUC) after lunch was significantly higher than after dinner in all groups. ACTH response after each meal was similar in all groups, but cortisolAUC after dinner was significantly lower in S-BFD than in V-BFD women.

CONCLUSION

This study demonstrates that in premenopausal women, obesity, particularly the visceral phenotype, is associated with several abnormalities of ACTH pulsatile secretion, particularly in the morning. On the contrary, no major differences were present in either blood concentrations, diurnal rhythm or secretory pattern of cortisol between obese and controls. The responses to meals seem to indicate a much more rapid cortisol response after lunch in women with visceral obesity and a reduced activation of the hypothalamic-pituitary-adrenal axis after dinner in women with subcutaneous obesity.

Sleep apnea in patients receiving growth hormone

Among 145 patients treated with recombinant human growth hormone (GH), four developed sleep apnea (two obstructive, two mixed) associated with tonsillar and adenoidal hypertrophy in three. These four patients had no local risk factors predisposing to upper airway obstruction (i.e., frequent pharyngitis or sinusitis). Clinical and/or polysomnographic features of sleep apnea improved following cessation of GH therapy in one patient, and following tonsillectomy and adenoidectomy in all patients. The present observations indicate that, albeit rarely, obstructive and/or central sleep apnea may occur in children treated with GH. Polysomnography should be considered if symptoms of snoring, interrupted sleep, daytime somnolence-particularly if associated with tonsillar hypertrophy-appear in children during GH therapy.

Associations between pituitary-adrenocortical function and abdominal obesity, hyperinsulinaemia and dyslipidaemia in normotensive males

OBJECTIVES

To examine the relationships between pituitary-adrenal cortical (PA) function, abdominal obesity, hyperinsulinaemia, and dyslipidaemia.

DESIGN

A prospective study.

SETTING

Helsinki University Central Hospital, Finland.

SUBJECTS

Seventy-one healthy males aged 30-55 years.

MAIN OUTCOME MEASURES

Insulin sensitivity was assessed by the oral glucose tolerance test (OGTT). Basal PA activity was examined by measuring urinary and serum concentrations of hormones, followed by dexamethasone suppression and corticotrophin (ACTH) stimulation tests to determine functional PA activity.

RESULTS

The means of waist-to-hip ratio (WHR), body-mass index (BMI), HDL-cholesterol and triglyceride levels, and insulin and C-peptide measurements during the OGTT were significantly different across the tertiles for insulin:glucose ratio. The ratio of 12-h urinary cortisol excretion to BMI, preceding the OGTT, and the mean basal cortisol level during the OGTT were decreased, while the net increments of cortisol and 17-hydroxyprogesterone (17-OHP) from 0 to 60 min, as well as the ratio of net 17-OHP to 11-deoxycortisol increments, after ACTH, were elevated in the upper compared with the lower tertile. The mean cortisol during the OGTT, and the ratio of urinary cortisol to BMI were negatively related, while absolute DHEA and cortisol responses to ACTH were positively related to fasting and mean insulin levels. Hormonal variables, WHR, insulin, and triglycerides were successfully integrated into a tentative mathematical model by the use of covariance structure (path) analyses.

CONCLUSIONS

Several alterations in the PA function, suggestive of decreased 21-hydroxylase activity, mild cortisol deficiency and slight adrenal hyperplasia, are associated with abdominal obesity which, in turn, appears to be an important prelude to insulin resistance and dyslipidaemia.

Effects of ovary suppression by a long-acting GnRH-agonist on circulating GH, insulin-like growth factor I and insulin levels in women with polycystic ovary syndrome

Our aim was to investigate the effect of GnRH-agonist (GnRH-a) induced suppression of plasma sex steroids on serum GH, insulin like growth factor-I (IGF-I) and insulin levels after an oral glucose load (OGTT) in women with polycystic ovary syndrome (PCOS). Serum insulin, GH and IGF-I levels during a 75-g 4-h OGTT were measured in 3 nonobese and 7 obese hyperandrogenic women with PCOS and normal glucose tolerance before and after 10 weeks of treatment with the GnRH-a triptorelin (3,75 mg im every 28 days). Basal estrogen and androgen levels were also measured at time 0 of the first and the second OGTT. After the therapy serum estrogens and androgens were significantly suppressed. Body weight remained unchanged. Basal GH significantly increased after the treatment while fasting IGF-I and insulin levels decreased from (mean +/- SE) 349.3 +/- 31.8 to 278.7 +/- 33.2 ng/mL and from 22.4 +/- 4.1 to 18.8 +/- 4.4 microU/mL, respectively. The insulin response to OGTT (area under curve) was also reduced (from 16,017 +/- 2598 to 11,736 +/- 2317 microU/mL/240 min). Our results suggest that the GnRH-a induced suppression of ovary secretion may modify the serum GH and IGF-I levels and the insulin response to an OGTT in women with PCOS.

The endocrinology of obesity

Numerous endocrine alterations are associated with obesity (Table 1). The majority of the alterations are secondary to obesity and must be considered simply associated and potentially in the pathogenesis of the complications of obesity. The discovery of new endocrine peptides such as leptin that signal body fat content will increase our understanding of the regulation of body fat content. As a result, therapies will most certainly be developed that are directly targeted at the alterations in endocrine function.

Low urinary GH levels in normal statured obese children

Urinary GH (u-GH) levels were evaluated in 240 children (age range 5-14 years; 136M, 104F) of normal height (25-90th centile); 165 children were defined as "non-obese" (body mass index (BMI) < 75th centile for their chronological age (CA)) and 75 as "obese" (BMI > 75th). U-GH levels were determined using a two-site enzyme immunometric assay and calculated as the mean obtained from the values of three consecutive first morning voidings; results were expressed as both u-GH concentration (ngl-1) and u-GH excretion (ng per night). Multiple regression analysis revealed that in all children (non-obese and obese) most of the variation in u-GH levels (ngl-1 and ng night-1) was explained by BMI (coefficient: -0.72, p < 0.0001 and coefficient: -0.10, p < 0.001, respectively) and chronological age (coefficient: 1.03, p < 0.01 and coefficient; 0.27, p < 0.001, respectively), whereas sex and pubertal stage did not add significance to the variance. In obese children, mean u-GH concentration and u-GH excretion (per night) levels were significantly lower than those recorded in non-obese children both before and during puberty. A similar trend towards higher u-GH levels at puberty was found in non-obese and obese children. In conclusion, our study shows that u-GH levels are (a) related to CA and BMI in the general population and (b) significantly lower in obese than in non-obese children, in spite of their comparable normal height. The measurement of u-GH excretion in the assessment of children with short stature needs to take into consideration the role of marked ponderal excess, which is associated "per se" with significantly lower u-GH levels.

Prevalence and significance of Acanthosis nigricans in children and adolescents

Acanthosis nigricans (AN) develops commonly in obese adults, yet its prevalence and metabolic significance in children and adolescents have not been determined. To address these issues, 100 obese children and adolescents enrolled in the obesity clinic at the Royal Hospital, Muscat, Oman, were chosen at random and examined. AN was observed in 43 of the study children (43%). The frequency and severity of AN increases and significantly with increasing body mass index (BMI) in these children. Twenty patients with obesity and AN and 20 age-matched nonacanthotic obese children, randomly selected from the study children, were investigated. Their oral glucose tolerance and serum C-peptide responses to IV glucagon were evaluated. Circulating concentrations of free thyroxine (FT4), TSH, basal and ACTH-stimulated cortisol, testosterone, leutinizing hormone, (LH), follicle-stimulating hormone (FSH), and prolactin were measured by radioimmunoassay (RIA). Children with AN exhibited higher basal and glucagon-stimulated C-peptide concentrations than the nonacanthotic obese group. Two hours after the oral load of glucose (1.75 g/kg), serum glucose concentration (6.3 +/- 1.4 mmol/L) was higher in the acanthotic group versus the nonacanthotic group (5.2 +/- 0.8 mmol/L). Impaired glucose tolerance was detected in two children with AN (10%), and in none of the nonacanthotic controls. Hypothyroidism was diagnosed in two (10%) children with AN (TSH = 109 and 18 mIU/mL and FT4 = 4.6 and 13.5 pmol/L respectively), while all the nonacanthotic children were euthyroid. Serum testosterone concentration was insignificantly lower in the acanthotic group (6.5 +/- 3.9 ng/dL) versus the nonacanthotic children (8.3 +/- 4.5 ng/dL). Basal serum LH, FSH and prolactin concentrations and basal and ACTH-stimulated cortisol levels did not differ between the two study groups. Plasma triglyceride concentration was significantly higher in the acanthotic group (1.43 +/- 0.5 mmol/L) versus the nonacanthotic group (1.05 +/- 0.45 mmol/L), and was correlated significantly with BMI (r = 0.446, P < 0.05). In conclusion, obesity is a significant risk factor for the development of AN in children. AN is a reliable skin marker of hyperinsulinemia in obese children and adolescents. The prevalence of impaired glucose tolerance (10%) and primary hypothyroidism (10%) appears to be higher in obese acanthotic children than in those without AN.