Determinants of sex hormone-binding globulin concentrations in a cross-sectional study of healthy men randomly selected

Sex-hormone binding globulin (SHBG) is a glycoprotein synthesised in the liver and it is a transport protein which is primary modulator of the androgen signal. This cross-sectional study prompted us to investigate the relati-onship between SHBG and, age, anthropometric, body composition variables, the IGF-I system and leptin in a group of healthy adult men randomly selected. Included 134 men, aged 41.6 years, range 15-70 years. Body mass index (BMI) was calculated, and body composition was determined by a bioelectrical impedance analyser. Serum total IGF-I concentrations after acid-ethanol extraction, free IGF-I concentrations, IGFBP3, leptin, testosterone and SHBG were determined. Testosterone concentrations increased in the 2th decade and SHBG concentrations increased in the 4th decade. We observed an increase in leptin in the 4th decade with a decrease in IGF-I, free IGF-I and IGFBP3 throughout the decades. Total IGF-I correlated with waist/hip ratio; free IGF-I with BMI and waist/hip ratio and IGFBP3 did not correlated with any variable. As expected, there was a positive correlation between leptin and BMI, waist/hip ratio, fat free mass and fat mass. On the other hand, SHBG was negatively correlated with BMI, fat mass, total IGF-I, free IGF-I, IGFBP3 and leptin. Testosterone did not correlated with any anthropometric or body composition variable, IGF-I system components, leptin or SHBG. The multiple linear regression analysis produced a model that explained the 40.5% of SHBG variability; only fat mass and IGFBP3 brought an independent significant contribution to SHBG variability. In conclusion, in this population of healthy men randomly selected, we found that they had significant negative correlation between SHBG concentrations and anthropometric, body composition variables, the IGF-I system and leptin levels, and that fat mass and IGFBP3 may be the main determinants of SHBG changes.

Reference values of thyroid volume in a healthy, non-iodine-deficient Spanish population

Our aim was to assess reference values of thyroid volume by ultrasonography in healthy adult subjects. We conducted an epidemiological cross-sectional study where 880 subjects were randomly selected from the town census of L'Hospitalet de Llobregat after being invited to participate in our study directly by mail and phone call. We made a clinical history of each subject and determined serum thyrotropin, antiperoxidase antibodies, urinary iodine excretion and thyroid volume by ultrasonography. Subjects with thyroid disease were excluded. We finally studied 268 representative subjects. The reference thyroid volume was median 7.31 ml, mean 8.22 ml (Confidence Interval: 7.75 - 8.69 ml). In men: median 9.19 ml, mean 9.87 ml (CI: 9.09 - 10.65 ml); in women: median 6.19 ml, mean 6.57 ml (CI: 6.22 - 9.92 ml) (p < 0.0001). We grouped the subjects into decades, and found that thyroid volume was different (p = 0.0034) in males because the younger group had lower volume. We did not find any differences among age groups in women. The mean of the urinary iodine excretion was 154.23 microg/l. We have determined reference values of thyroid volume measured by ultrasonography in our iodine non-deficient population and prepared tables that distribute thyroid volume by sex and age.

Relationship between 25-(OH) D3, the IGF-I system, leptin, anthropometric and body composition variables in a healthy, randomly selected population

OBJECTIVE

This study prompted us to investigate the relationship between 25-(OH) D (3) and the IGF-I system, leptin, sex, age, anthropometric and body composition variables in healthy adults. We hypothesised that these variables would regulate 25-(OH) D (3) concentrations.

DESIGN

We included 253 subjects--126 men and 127 women. Body mass index (BMI) and body composition was determined, along with serum leptin, total IGF-I, free IGF-I, IGFBP3 and plasma 25-(OH) D (3) concentrations.

RESULTS

25-(OH) D (3) deficiency was observed in 69 subjects. There was a difference between 25-(OH) D (3) values and season (summer vs. winter). We observed similar 25-(OH) D (3) concentrations in men to those in women. The differential characteristics in subjects without 25-(OH) D (3) deficiency were lower BMI, fat mass and body fat and higher free IGF-I. We observed that leptin increased in the last decades and IGF-I system decreased by decade in both men and women. In subjects without 25-(OH) D (3) deficiency, there was a correlation between free IGF-I and 25-(OH) D (3) in men, and a negative correlation between 25-(OH) D (3) and age, BMI, fat mass and leptin and a positive correlation with total IGF-I in women. The multivariate linear regression analysis explained 37.8 % of 25-(OH) D (3) variability in men and 39 % in women, and only season and free IGF-I made an independent contribution to 25-(OH) D (3) in men, and season and fat mass in women.

CONCLUSION

These data suggest that free IGF-I in men and fat mass in women could regulate 25-(OH) D (3) concentrations.

Thyroid volume as measured by ultrasonography in patients With type 1 diabetes mellitus without thyroid dysfunction

The aim of this cross-sectional study was to assess and compare thyroid volume and its derminants in a cohort of type 1 diabetes mellitus (DM1) and compare the results to a healthy control group. We studied 65 DM1 patients treated with an intensive insulin regimen and 65 matched controls. In all participants we evaluated weight, height, BMI, waist-hip ratio, body surface area and body composition variables determined by using a bioelectrical impedance analyser. Thyroid size was estimated by ultrasonography. We determined basal TSH, anti-thyroid antibodies and urinary iodine excretion. Body weight, height, BMI and body surface area were similar in DM1 patients and in controls. Fat-free mass was higher in both male and female DM1 patients than in controls (64.4 +/- 6.9 vs. 60.4 +/- 8.2 kg, p=0.03 and 48.3 +/- 5.7 vs. 45.4 +/- 6, p=0.04, respectively), and fat mass was lower in male DM1 patients than in controls (9.7 +/- 7 vs. 14.2 +/- 8.1 kg, p=0.01). Thyroid volume was greater in both male and female DM1 patients than in controls (11.12 +/- 2.87 vs. 9.63 +/- 2.27 ml, p=0.0001 and 9.5 +/- 2.3 vs. 7.7 +/- 2 ml, p=0.002, respectively). Urinary iodine excretion was similar in the two groups. In both DM1 patients and controls, thyroid volume correlated with weight, height, BMI, waist-hip ratio, body surface area, fat-free mass and the multivariate linear regression analysis with thyroid volume as the dependent variable showed that fat-free mass in either group was the only significant determinant of thyroid volume. We conclude that DM1 patients had larger thyroid volume compared with healthy controls with similar anthropometry; body composition is different in DM1 patients and that the anthropometric and body composition variables, especially fat-free mass and body surface area, predict thyroid volume either in DM1 patients or in healthy controls.

Pituitary-thyroid axis, thyroid volume and leptin in healthy adults

OBJECTIVE

Patients with thyroid diseases usually have disturbances relating to body weight and thermogenesis. On the other hand, leptin is involved in the regulation of body weight, food intake and thermogenesis. Some studies have investigated the relationship between leptin and dysthyroid states, but the complex interactions between leptin and pituitary-thyroid axis have led to controversial results.

DESIGN

The aims of this cross-sectional study were to investigate the relationship among basal TSH, ultrasonographic thyroid volume and leptin in a group of 268 healthy adults randomly selected from our city, L'Hospitalet de Llobregat, Barcelona, an area free of iodine deficiency. In this euthyroid group, we determined basal TSH, thyroid autoantibodies, leptin concentrations, and thyroid volume by ultrasonography, body anthropometry, and body composition.

RESULTS

All subjects were free of goitre and were negative for anti-thyroid antibodies. Basal TSH concentrations were 1.49 +/- 0.8 mU/l in males and 1.67 +/- 0.83 mU/l in females (p = 0.6). Anti-thyroid antibodies were negative in all cases; leptin concentrations were 6.1 +/- 4 ng/ml in males and 16.8 +/- 11.7 ng/ml in females (p = 0.0001). Thyroid volume was 9.8 +/- 4.6 ml in males and 6.5 +/- 2 ml in females (p = 0.001). There were significant correlations among leptin concentrations and anthropometric and body composition variables in both sexes, without correlation with TSH concentrations. There was no significant correlation between anthropometric and body composition variables and thyroid volume in males but there was a correlation in females. In females, there was a positive correlation between leptin and thyroid volume (r = 0.181, p = 0.038). In males, there was a negative correlation between TSH concentrations and thyroid volume (r = - 0.271, p = 0.002).

CONCLUSIONS

We did not find any correlation between leptin levels and pituitary-thyroid axis in this control population. The correlation between leptin and thyroid volume in females is probably a consequence that leptin and thyroid volume are regulated in parallel by variables relating to anthropometry and body composition.

Body composition assessment in type 1 diabetes mellitus patients over 15 years old

BACKGROUND

The aim of the present study was to assess the anthropometric characteristics and body composition in type 1 diabetic patients and compare the results with a randomly selected control population.

MATERIAL AND METHODS

We studied 75 type 1 diabetic patients, 43 male and 32 female, recruited from consecutive diagnosed type 1 diabetic patients attending the Endocrine Unit and treated with a intensive insulin regimen, and 93 control subjects, 44 males and 49 females representative of the census of this city. We performed a dietary recall in patients and determined anthropometric characteristics, both in patients and controls, body weight, height, body-mass index, waist-hip ratio and body composition parameters: total body water, free-fat mass, body free-fat mass, fat mass and body fat by bioelectrical impedance analyser.

RESULTS

In diabetic male patients, we observed lower waist-hip ratio than in controls, 0.84 +/- 0.06 vs. 0.88 +/- 0.07, p = 0.021, higher free-fat mass in female diabetic patients, 48.5 +/- 5.6 vs. 45.6 +/- 5.9 kg, p = 0.03, lower fat mass in male diabetic patients, 9.5 +/- 6.9 vs. 14.6 +/- 8.5 kg, p = 0.003. We did not find any correlation among the parameters of body composition and dietary macronutrient intake in patients.

CONCLUSIONS

The present study exposes the differences in anthropometric characteristics and body composition in type 1 diabetes mellitus, especially lower waist-hip ratio in male, higher free-fat mass in female and lower fat mass in male.

Determinants of thyroid volume as measured by ultrasonography in healthy adults randomly selected

OBJECTIVES

The relationship between thyroid volume and anthropometric characteristics is a matter of controversy. The aim of this study was to investigate thyroid volume and its determinants in healthy adult subjects from a noniodine-deficient area.

DESIGN AND PATIENTS

Of the 280 000 inhabitants of the city, served by L'Hospitalet de Llobregat, we randomly selected 880 subjects from the census of the city. The participation rate in the study was 44%; after application of several exclusion criteria, a further 28 subjects were excluded because of previously diagnosed thyroid disease. We finally studied 268 subjects representative of the census of the city: 134 male and 134 female, without thyroid disease. We determined the anthropometric characteristics, body mass index, waist-hip ratio, body surface area; body composition by bioelectrical impedance analyser; thyroid volume by ultrasonography; basal TSH, antithyroid antibodies and urinary iodine excretion.

RESULTS

Thyroid volume in our population was higher in males (9.19 ml, CI 9.09-10.65) than in females (6.19 ml, CI 6.02-6.92), P = 0.001. Significant correlations were found among thyroid volume and body weight (r = 0.39, P = 0.0001), height (r = 0.44, P = 0.0001), body mass index (r = 0.13, P = 0.02), waist-hip ratio (r = 0.38, P = 0.0001), body surface area (r = 0.48, P = 0.0001), total body water (r = 0.14, P = 0.02), free fat mass (r = 0.47, P = 0.0001), fat mass (r = 0.37, P = 0.001) and body fat (r = 0.32, P = 0.001). Negative correlation was found between thyroid volume and basal TSH (r = -0.26, P = 0.001). No correlations were found among thyroid volume and iodine excretion, previous pregnancies in women, cigarette smoking and alcohol consumption. In a multiple regression analysis with thyroid volume as the dependent variable, body surface area was demonstrated to account for the 44% of variation of thyroid volume (P = 0.0001).

CONCLUSION

It is important to know the reference values of the thyroid volume in a population free of iodine deficiency and its determinants. Body surface area accounts for much of the variation of thyroid volume. Age, gender, anthropometric variables, body composition variables and biological variables, do not significantly influence the thyroid volume when considered as possible additions to this baseline model.

[Anthropometry and the reference values of body composition by bioelectrical impedance in the adult population of L'Hospitalet de Llobregat]

BACKGROUND

The aim of the present study was to assess the anthropometric variables and the reference values of body composition in the adult population of L'Hospitalet de Llobregat, due to the lack of epidemiological studies on this matter in Spain.

PATIENTS AND METHODS

We studied 234 normal subjects, 134 males, mean age 41.4 years, and 134 females, mean age 40.7 years, selected from the census of L'Hospitalet de Llobregat and representative of its population in sex and age. We determined anthropometric characteristics, body weight, height, body mass index, waist-hip ratio and body composition parameters: total body water, free fat mass, fat mass and body fat by bioelectrical impedance analyzer.

RESULTS

Twenty-four males and 33 females were obese, and out of them 2 males and 4 women presented morbid obesity. The body mass index was higher either in males (p = 0.017) or in females (p = 0. 0001) in the last decades in relation to first decade, and in women was as consequence of higher fat mass (p = 0.0001). The waist-hip ratio was 0.93 (0.08) in male and 0.79 (0.07) in female, and it was high in males in the last decades.

CONCLUSION

The present study points out the high prevalence of obesity in our city and the anthropometric characteristics and reference values of body composition in the normal population of L'Hospitalet de Llobregat, remarking the high body mass index in the last decades, especially in women due to an increase of fat mass. The waist-hip ratio was high in males in the last decades.