The Changes Of Thyroid Hormones Within Normal Range In Different Metabolic Status Of Obesity

Chapter 1:The changes of thyroid hormones within normal range in metabolically healthy obesityObjective: To study the changes of thyroid hormones within normal range in metabolically healthy but obese(MHO) individuals. Compare the levels of serum FT3, FT4, TSH and ratios of FT3/FT4, FT3/TSH,FT4/TSH in different groups of MHO, obesity with metabolic syndrome(MS) and metabolically healthy normal weight(MHNW).Methods: 1479 subjects were evaluated for routine health examination in Hunan Provincial People’s Hospital from November 2014 to January2015. Those with history and family history of thyroid diseases were excluded. Blood samples were tested in 847 individuals(598 with obesity and 249 within normal weight), parameters were evaluate including height, weight and blood pressure. Serum free thyroxine(FT4), free triiodothyronine(FT3), thyroid stimulating hormone(TSH),triglyceride(TG), total cholesterol(TC), high density lipoprotein(HDL),low density lipoprotein(LDL), fasting blood glucose,FBG(FBS), blood urea nitrogen(BUN), serum creatinine(CR), blood uric acid(UA),serum alanine aminotransferase(ALT), peripheral white blood cell count(WBCC) were detected.We diagnosed obesity when the BMI is higher than 25 kg/m2, used the criteria of American Cholesterol Education program(the National Cholesterol Education Programe, NCEP) in the third report(Adult Treatment Panel III, ATP-III) in 2001 to define MS, MHO and other different metabolic status. MHO was defined as obesity without MS,MHNW was defined as 18.5 kg/m2 ≤ BMI < 25 kg/ m2 without MS,MUNW was defined as 18.5 kg/m2 ≤ BMI < 25 kg/m2 with MS. 847 individuals, 107 as abnormal thyroid function(79 with obesity and 28without). 740 euthyroid individuals, and 235 as MHO, 284 as obesity with MS(65 as obesity both with MS and T2DM), 153 as MHNW and 68 as MUNW. To Compare the levels of serum FT3, FT4, TSH and FT3/FT4,FT3/TSH, FT4/TSH in different groups of MHO, obesity with MS,MHNW and MUNW, and analyze the impact of thyroid hormones within normal range in obesity related disorder.Results:1. TSH : Compared with MHNW, the levels of TSH increased in MHO(P<0.05), compared with MHO, the levels of TSH decreased in obesity with MS and obesity with MS and T2DM(P<0.05).2. FT3 : Compared with MNHW, the levels of FT3 decreased in MHO(P < 0.05), compared with MHO, the levels of FT3 increased in obesity with MS, and was in the lowest levels in obesity with MS-3.while the levels of FT3 decreased in obesity both with MS and T2DM(P<0.05),and be the lowest.3. FT4: Compared with MNHW, the levels of FT4 decreased in MHO(P < 0.05), compared with MHO, the levels of FT4 decreased significantly in obesity with MS and obesity both with MS and T2DM(P<0.05).4. FT3/FT4: There was no differences in the ratio of FT3/FT4 between MNHW and MHO,compared with MHO, the ratios of FT3/FT4 increased in obesity with MS and was in the highest levels in obesity with MS-3, but the ratios of FT3/FT4 was decreased in obesity both with MS and T2DM(P<0.05) and be the lowest.Conclusions:1. The levels of TSH increased in MHO compared with other groups,indicate that the increased serum TSH levels within normal range can help MHO maintain healthy metabolic state.2. In metabolically healthy, the levels of FT3 decreased in MHO compared with MHNW, indicate that the obesity maybe associated with the decreases of the production of active thyroid hormone.3. The levels of FT4 decreased,while the levels of FT3 and ratios of FT3/FT4 increased in obesity, indicate that in the process of obesity related disorders, the turn over rate of serum T4 to T3 had increased.Chapter 2: The changes and significance of thyroid hormone within normal range in different body mass index subjectsObjective: Compare the differences of thyroid hormone within normal range in different body mass index(BMI) individuals. Try to explore the relationships between thyroid hormone and BMI.Methods:The subjects and methods of data collection were the same as chapter 1. 847 routine health examinations, 740(519 with obesity and221 within normal weight) as euthyroid individuals and 107 as abnormal thyroid function. To compare the differences of abnormal thyroid function in obesity and normal weight individuals. According to the levels of BMIto ivide the 740 subject into different groups, as groups of D1、D2、D3、D4. To compare the difference of thyroid hormone within normal range in different body mass index(BMI) individuals. Try to explore the relationships between thyroid hormone and BMI.Results:1. Compared with normal weight individuals, the obesity are more likely to be accompanied by subclinical hypothyroidism(6.02% vs10.36%, P<0.05).2. Compared with the normal weight individuals, the levels of FT4 decreased in the individuals with BMI≥25kg/m2(p<0.05) and be the lowest levels in those subjects with BMI between 28-30kg/m2. While in the obesity with BMI ≥30 kg/m2, the levels of FT4 was increased(p <0.05).3. The ratios of FT3/FT4 was in higher levels of the group with BMI between 28-30kg/m2 than others(p<0.05).Conclusions:1. Obesity is more likely to be accompanied by subclinical hypothyroidism compared with normal weight individuals.2. In Obesity with BMI ≥30 kg/m2, the levels of FT4 decreased,while the ratio of FT3/FT4 inceased, indicate that with the development of obesity, the thyroid function was declined, but the turn over rate of serumT4 to T3 had increased.Chapter 3: The relationships in different levels of lipid,blood pressure,blood glucose with thyroid hormone in obesityObjective: Compare the changes of thyroid hormone within normal range in different levels of lipid, blood pressure, blood glucose in obesity.Try to explore the relationships among thyroid hormone and the lipid,blood pressure, blood glucose.Methods:The subjects and methods of data collection were the same as chapter 1. 847 routine health examinations, 740(519 with obesity and221 without) as euthyroid individuals and 107 as abnormal thyroid function. Divided the 519 euthyroid obesity into different groups according to the different levels of lipid, pressure, glucose. Compare the changes of thyroid hormone within normal range in those different groups.Results:1. Compared with those with normal levels of serum TG, the levels of FT3 and ratios of FT3/FT4 increased in those with higher levels of serum TG(p<0.05).2. Compared with those with normal levels of BP, the levels of FT3 and ratios of FT3/FT4 decreased in those with higher levels of BP(p<0.05).3. Compared with those with normal levels of serum BS, The levels of FT3 and TSH decreased in those with higher levels of BS(p<0.05).Conclusions:1. The levels of serum FT3 and ratios of FT3/FT4 increased in obesity with higher levels of TG, indicate that the turn over rate of T4 to T3 had increased.2. The levels of FT3 and ratios of FT3/FT4 decreased in obesity with hypertension,indicate that the turn over rate of T4 to T3 had decreased.3. The levels of FT3 and TSH decreased in obesity with hyperclycemia, indicate that the function of pituitary-thyroid axis had decreased.