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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Effects of thyroid hormones in individual tissues are determined by many factors beyond their serum levels, including local deiodination and expression and activity of thyroid hormone transporters. These effects are difficult to examine by traditional techniques, but a novel approach that exploits the existence of common genetic variants has yielded new and surprising insights. Convincing evidence indicates a role of type 1 iodothyronine deiodinase (D1) in determining the serum T(4):T(3) ratio and a role of phosphodiesterase 8B in determining TSH levels. In addition, studies of type 2 iodothyronine deiodinase (D2) variants have shown that thyroid hormones contribute to osteoarthritis and these variants influence Intelligence quotient alterations associated with iodine deficiency. Preliminary evidence suggests associations between TSH-receptor variants and fasting glucose level, D1 variants and insulin-like growth factor I production, and D2 variants and hypertension, psychological well-being and response to T(3) or T(4) treatment. Intriguingly, most of these associations are independent of serum thyroid hormone levels, which highlights the importance of local regulation of thyroid hormones in tissues. Future research might reveal novel roles for thyroid hormones in obesity, cardiovascular disease, osteoporosis and depression and could have implications for interpretation of thyroid function tests and individualization of thyroid hormone replacement therapy.
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PMID:Novel insights into thyroid hormones from the study of common genetic variation. 1935 19

The multifactorial mechanisms promoting weight loss and improved metabolism following Roux-en-Y gastric bypass (GB) surgery remain incompletely understood. Recent rodent studies suggest that bile acids can mediate energy homeostasis by activating the G-protein coupled receptor TGR5 and the type 2 thyroid hormone deiodinase. Altered gastrointestinal anatomy following GB could affect enterohepatic recirculation of bile acids. We assessed whether circulating bile acid concentrations differ in patients who previously underwent GB, which might then contribute to improved metabolic homeostasis. We performed cross-sectional analysis of fasting serum bile acid composition and both fasting and post-meal metabolic variables, in three subject groups: (i) post-GB surgery (n = 9), (ii) without GB matched to preoperative BMI of the index cohort (n = 5), and (iii) without GB matched to current BMI of the index cohort (n = 10). Total serum bile acid concentrations were higher in GB (8.90 +/- 4.84 micromol/l) than in both overweight (3.59 +/- 1.95, P = 0.005, Ov) and severely obese (3.86 +/- 1.51, P = 0.045, MOb). Bile acid subfractions taurochenodeoxycholic, taurodeoxycholic, glycocholic, glycochenodeoxycholic, and glycodeoxycholic acids were all significantly higher in GB compared to Ov (P < 0.05). Total bile acids were inversely correlated with 2-h post-meal glucose (r = -0.59, P < 0.003) and fasting triglycerides (r = -0.40, P = 0.05), and positively correlated with adiponectin (r = -0.48, P < 0.02) and peak glucagon-like peptide-1 (GLP-1) (r = 0.58, P < 0.003). Total bile acids strongly correlated inversely with thyrotropic hormone (TSH) (r = -0.57, P = 0.004). Together, our data suggest that altered bile acid levels and composition may contribute to improved glucose and lipid metabolism in patients who have had GB.
Obesity (Silver Spring) 2009 Sep
PMID:Serum bile acids are higher in humans with prior gastric bypass: potential contribution to improved glucose and lipid metabolism. 1936 6

A moderate elevation of thyrotropin (TSH) concentrations, which is associated with triiodothyronine (T3) values in or slightly above the upper normal range, is frequently found in obese humans. These alterations seem rather a consequence than a cause of obesity since weight loss leads to a normalization of elevated thyroid hormone levels. Elevated thyroid hormone concentrations increase the resting energy expenditure (REE). The underlying pathways are not fully understood. As a consequence of the increased REE, the availability of accumulated energy for conversion into fat is diminished. In conclusion, the alterations of thyroid hormones in obesity suggest an adaptation process. Since rapid weight loss is associated with a decrease of TSH and T3, the resulting decrease in REE may contribute towards the difficulties maintaining weight loss. Leptin seems to be a promising link between obesity and alterations of thyroid hormones since leptin concentrations influence TSH release.
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PMID:Obesity and thyroid function. 1954 Mar 3

Epidemiological studies show a higher prevalence of obesity in children from smoking mothers and smoking may affect human thyroid function. To evaluate the mechanism of smoking as an imprinting factor for these dysfunctions, we evaluated the programming effects of maternal nicotine (NIC) exposure during lactation. Two days after birth, osmotic minipumps were implanted in lactating rats, divided into: NIC (6 mg/kg per day s.c.) for 14 days; Control - saline. All the significant data were P<0.05 or less. Body weight was increased from 165 days old onwards in NIC offspring. Both during exposure (at 15 days old) and in adulthood (180 days old), NIC group showed higher total fat (27 and 33%). In addition, NIC offspring presented increased visceral fat and total body protein. Lipid profile was not changed in adulthood. Leptinemia was higher at 15 and 180 days old (36 and 113%), with no changes in food intake. Concerning the thyroid status, the 15-days-old NIC offspring showed lower serum-free tri-iodothyronine (FT(3)) and thyroxine (FT(4)) with higher TSH. The 180-days-old NIC offspring exhibited lower TSH, FT(3), and FT(4)). In both periods, liver type 1 deiodinase was lower (26 and 55%). We evidenced that NIC imprints a neonatal thyroid dysfunction and programs for a higher adiposity, hyperleptinemia, and secondary hypothyroidism in adulthood. Our study identifies lactation as a critical period to NIC programming for obesity, with hypothyroidism being a possible contributing factor.
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PMID:Short- and long-term effects of maternal nicotine exposure during lactation on body adiposity, lipid profile, and thyroid function of rat offspring. 1955 80

Vitamin D deficiency is a common cause of morbidity. We prospectively studied 224 consecutive female patients in order to evaluate the prevalence of vitamin D deficiency and to assess the utility of various clinical and biochemical markers in predicting the deficiency. All of them were outpatients, 30 years old or older, and were evaluated from October 2006 through March 2008. Levels of 25 OH vitamin D > 30 ng/ml were considered sufficient. Mild deficiency was considered between 20 and 30 ng/ml and severe deficiency < 20 ng/ml. The mean age was 58 +/- 12.9 years; 77% were menopausal. Twenty nine percent of the patients had mild deficit and 26.8% had severe deficit of the vitamin. Severe deficit was associated with increasing age (62 vs. 56 years, p = 0.003), absence of sun exposure (25.82 ng/ml vs. 31.7 ng/ml, p < 0.005), obesity (70 vs. 61 kg, p < 0.05), absence of physical activity (27.8 ng/ml vs. 31.04 ng/ml, p = 0.0007) and slightly low levels of serum calcium (9.26 mg/dl vs. 9.51 mg/dl, p 0.01). We did not find any association between smokers and non-smokers patients, levels of serum phosphorus, creatinine and TSH. Vitamin D deficiency is a common disorder. It correlates with older age, absence of physical activity, sun exposure, obesity and slightly low levels of serum calcium. Improving diagnosis of this condition may enable us to improve the management of this disease.
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PMID:[Vitamin D deficit in adult women living in Buenos Aires City]. 2005 3

Postmenopausal women develop often obesity which may be prevented by 20-OH-Ecdysone (Ecd). This was investigated in ovariectomized (ovx) rats. They were orally treated with 3 doses of Ecd (18, 56 or 116 mg/day/animal). Positive controls received 159 microg estradiol (E2). Quantitative computer tomography at the level of the abdomen and the metaphysis of the tibia allowed estimation of surface, fat depots and muscles. The highest dose of Ecd resulted in serum concentrations of 0.4 x 10(-6)M. Serum E2 concentrations in the positive controls were 73.3+/-24.41 pg/ml. E2 but not Ecd stimulated uterine weights. Under Ecd ovx animals gained less fat but had more muscle mass. Serum TSH, T4 and T3 levels remained unaffected while E2 treatment increases T4 but decreases T3 levels. Ecd at the lowest dose lowered serum LDL and did not result in increased serum triglycerides, an effect seen in the E2 treated rats. At the Ecd highest dose serum HDL was higher than in the controls. In conclusion Ecd has beneficial effects on fat and muscle tissue and may be able to prevent the metabolic syndrome and sarcopenia by a non-estrogenic mechanism.
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PMID:Metabolic effects of 20-OH-ecdysone in ovariectomized rats. 2009 86

This study investigated the effects of obesity induced by high-fat (HF) diet on thyroid function and whole-body energy balance. To accomplish that, we assessed the effects of 8 wk of HF diet on several parameters of hypothalamus-pituitary-thyroid axis function. Serum total T(4) and T(3), rT(3), and TSH, the activity of type 1 and type 2 deiodinases in central and peripheral tissues were determined. Also, we measured in vivo energy balance, substrate partitioning, and markers of leptin resistance. Here we provide novel evidence that prolonged positive energy balance acquired by feeding a HF diet induced hyperactivation of the hypothalamus-pituitary-thyroid axis, which was characterized by 2.24-, 1.6-, and 3.7-fold elevations in hypothalamic TRH expression, thyroid iodide uptake, and serum TSH, respectively. Serum T(4) and T(3) were normal together with augmented deiodinase type 1 activity in liver (1.3-fold) and kidney (1.2-fold) and increased (1.5-fold) serum rT3 in HF rats. Despite no increase in circulating levels of T(3) and T(4), whole-body oxygen consumption was increased, and substrate metabolism was shifted toward fat oxidation in HF rats. These in vivo metabolic adjustments were mainly driven by the fat content of the diet. Furthermore, spontaneous dark cycle physical activity was reduced by 30% in rats fed a HF diet, which limited energy expenditure and favored the development of obesity. Our findings provide new insight into the endocrine and physiological mechanisms that underlie the alterations in thyroid hormone availability, energy balance, and metabolic partitioning in HF diet-induced obesity.
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PMID:High-fat diet increases thyrotropin and oxygen consumption without altering circulating 3,5,3'-triiodothyronine (T3) and thyroxine in rats: the role of iodothyronine deiodinases, reverse T3 production, and whole-body fat oxidation. 2041 Jan 93

Both overweight and obesity have been identified as risk factors for sexual dysfunction in men, but the relationship between sexual function and amount of body fat in females is still obscure. There are few reported studies in women assessing the relationship between female sexual function index (FSFI) and body weight. The aim of this study was to identify the frequency of female sexual dysfunction (FSD) among obese and overweight women. A total of 45 obese and overweight and 30 age-matched voluntary healthy women serving as a control group were evaluated by a detailed medical and sexual history, including the FSFI questionnaire. Serum prolactin, cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), dehydroepiandrosterone-SO(4) (DHEA-S), testosterone, estradiol and sex hormone-binding globulin (SHBG) levels were measured. No significant difference was observed between controls and patients in terms of the FSH, LH, estradiol, free thyroxine and thyrotropin (TSH), testosterone and DHEA-S levels. The comparison of total FSFI scores between patients and controls showed no significant difference (P=0.74). As the FSFI score of <or=26.55 indicated FSD, 86% of obese patients and 83% of controls were considered to have sexual dysfunction. The mean total FSFI score was 22.1+/-4.3 for obese patients and 23.1+/-3.7 for healthy women. FSFI scores were not correlated with any of the anthropometric measurements (body mass index (BMI), waist-to-hip ratio (WHR) and fat percent). The levels of total testosterone and DHEA-S were not correlated with total FSFI scores. We found a significant negative correlation between BMI and orgasm (P=0.007, r=-0.413). Satisfaction was also negatively correlated with BMI (P=0.05, r=-0.305) and weight (P=0.03, r=-0.326). Testosterone levels were negatively correlated with only satisfaction domain scores of FSFI (P=0.01, r=-0.385). We found that 86% of obese women and 83% of controls had sexual dysfunction. Although obesity does not seem to be a major contributor to sexual dysfunction, it affects several aspects of sexuality.
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PMID:Sexual dysfunction in obese and overweight women. 2048 60

Subclinical hypothyroidism (SCH), defined by a normal total or free T4 level and a mildly elevated TSH (typically 5-10 mU/L), is common in children, but there is currently no consensus on management. Several recent pediatric studies indicate that progression of SCH to overt hypothyroidism (OH) is uncommon and that over a period of several years, elevated TSH usually either normalizes or persists but does not increase. The etiology appears to be multifactorial, with some cases representing minor developmental abnormalities, some related to obesity, some to mild autoimmune thyroiditis, and some associated with mutations in the gene for the TSH-receptor. There are no pediatric studies showing clinical benefit of treating these children with thyroid hormone, but additional studies in this area are needed. Since few cases of pediatric SCH progress to OH, treatment can be deferred, and periodic follow-up testing may be the preferred strategy, with elevated thyroid antibodies or a goiter being considered risk factors for eventual OH.
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PMID:Subclinical hypothyroidism in children: normal variation or sign of a failing thyroid gland? 2062 88

A relationship between thyroid function and obesity seems likely, mainly influenced by the insulin resistance. Whether variations in TSH and/or thyroid hormones, within a normal range, can influence body weight or if obesity per se can alter thyroid function has not been clarified so far. Further studies are necessary to assess the link between thyroid function and body weight, that must consider not only changes of thyroid hormones, but also body fat distribution, obesity duration and the state of low grade inflammation. It is recognized that thyroid function is linked not only to body mass index, but also to body composition and, particularly, to the amount and percentage of fat mass.
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PMID:[Thyroid function and obesity]. 2104 57


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