| Thyroid hormone (TH) is one of the most important hormone in human body because it influences metabolism of carbohydrate, protein and lipids. And the relation between TH and lipid metabolism was research focus during recent years. TH may has impact on lipid from many aspects including synthesis, mobilization and catabolism, etc, and the regulation mechanism is very complex. Hypothyroidism is an important reason for dyslipidemia clinically. High cholesterol is the most common phenomenon, and triglyceride (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C) and lipoprotein(a) will change accordingly. Relation between subclinical hypothyroid and dyslipidemia also leads to attention recently. Some research indicated that serum lipid would change to the direction which more likely to cause atherosclerosis. People may pay more attention to the relation of subclinical hypothyroidism and cardiovascular disease for the reason of high prevanlecce of these two diseases. At the same time, prevalence of type 2 diabetes mellitus become higher and higher, and dyslipidemia is very common among these patients, so the relation between thyroid function and serum lipid in type 2 diabetes also becomes a new problem. And there's still no big sample and systematic clinical research about those questions in our country.Objective:1. To study changes of serum lipid, glucose and uric acid under different thyroid function, and analyse correlation among FT3,FT4,TSH and serum lipid, glucose and uric acid.2. To study correlation between TSH and lipid in subclinical hypothyroid group.3. To explore relationship of thyroid function and serum lipid in type 2 diabetes mellitus with subclinical hypothyroidism and with normal thyroid function.Material and methods:1. Subjects:(1) This cross-sectional study includes 439 subjects whose thyroid function tests revealed abnormal results who were out-patients and in-patients at endocrinology department in Shandong Provincial Hospital, and were devided into four groups including hyperthyroid group, subclinical hyperthyroid group, hypothyroid group and subclinical hypothyroid group by their thyroid function status. And we also collected 79 cases with normal thyroid function as control group. Those with liver function abnormality, abnormal renal function, malignant tumor, diabetes mellitus and diseases which may cause dyslipidemia were exclude. They didn't smoke or prohibit smoking for at least 6 months and they didn't use any drugs which may affect serum lipid and thyroid function for the recent 3 months. (2) We analyzed 198 subjects in subclinical group and control group after TSH graded. (3) 102 diabetic subjects without thyroid disease history were collected who were in-patients at endocrinology department in Shandong Provincial Hospital, and were divided into two groups by thyoid function which were diabetes with subclinical hypothyroid and diabetes with normal thyroid function, and we also collected 79 cases with normal thyroid function as control group.2. Detected index:Fasting venous blood samples were obtained under normal dietary, and the samples were divided into 2 tubes, and seperated serum immediately. One for detection of thyroid function, including TSH,FT3,FT4,TGAb和TPOAb, and another for TC,TG,HDL-C,LDL-C,ApoA,ApoB,Lp(a),glucose and uric acid.3. Statistical analysis:TSH was log transferred for the reason that it didn't obey normal distribution at first. Numeric data were expressed as X±S, one-way ANOVA test was used for comparison means among groups. And post-hoc analysis (LSD method) was used for comparison between each group. Pearson correlation, partial correlation and multiple linear regression analyses were used to determine the correlation between the levels of serum thyroid hormone, serum lipid, glucose and uric acid. SPSS-PC 17.0 (Statistical package for the social sciences, SPSS Inc., Chicago, IL, USA) for MS Windows was used for statistical analyses. P values<0.05 were considered statistically significant. Results:1. Comparation of general data (1) 256 cases in hyperthyroid group (167 female),39.85±12.42y old, BMI 21.71±2.96 kg/m2.12 cases in subclinical hyperthyroid group (8 female), 27.33±3.79y old, BMI 22.45±1.40 kg/m2,52 cases in hypothyroid group (35 female), 49.45±15.57y old, BMI 25.55±1.99 kg/m2,119 cases in subclinical hypothyroid group (72 female),50.10±11.40y old, BMI 24.44±3.22kg/m2,79 cases in control group (50 female),41.39±21.07y old, BMI 22.24±4.41 kg/m2. There was no difference in sex distribution, but age in hypothyroid and subclinical hypothyroid group were older than others(P<0.005), and which in hyperthyroid and subclinical hyperthyroid group were same as control group. BMI had difference between groups, which in hypothyroid and subclinical hypothyroid group were higher than control group (P<0.05). (2) Comparation of general data between subclinical hypothyroid and control group see (1). (3) Type 2 diabetes mellitus with subclinical hypothyroid group 12(female 9),45.67±16.07y old, BMI 27.24±4.24 kg/m2, type 2 diabetes mellitus with normal thyroid function 90(42 female),55.40±13.30y old, BMI 25.73±4.38 kg/m2. Data of control group was same as former. Ages in T2DM with normal thyroid function was older than control group(P<0.001), and BMI in T2DM with SCH and normal thyroid function were higher than control group(P<0.05).2. Comparation of thyroid function (1) FT3, FT4, TSH, TGAb and TPOAb had significant difference in groups. FT3, FT4 were higher in hyperthyroid group than subclinical hyperthyroid group, hypothyroid group, SCH group and control group(all P<0.005), TSH in hypothyroid group and SCH group were higher than hyperthyroid, subclinical hyperthyroid group and control group(all P<0.005), TGAb was lower in hyperthyroid group than hypothyroid group(P=0.017) but a little higher than control group(P=0.049), TGAb in hypothyroid group was much higher than SCH and control group(P=0.014,0.001), TPOAb in hyperthyroid, subclinical hyperthyroid, hypothyroid and SCH group were all much higher than control group(all P<0.002).(2) TSH and TPOAb in SCH group were higher than control group, and other indexes had no significant difference. (3)TSH, TGAb and TPOAb were significant different when compared T2DM with SCH group with T2DM with normal thyroid function group and control group.(P<0.002), FT3, FT4 had no difference(P>0.05). TGAb was lower (P=0.005) when compare T2DM with normal thyroid function group with control group. FT4, TSH, TGAb and TPOAb were all different in T2DM with SCH from T2DM with normal thyroid function(P≤0.001). When we compare the positive rate of TGAb and TPOAb, we found that it was higher in T2DM with SCH than T2DM with normal thyroid function and control group.3. Comparation of serum lipid(1) TC, TG, HDL-C, LDL-C and ApoB were different among groups by one-way ANOVA(all P<0.01), and ApoA, Lp(a), GLU and UA had no difference(P>0.05). TC was lower in hyperthyroid group than control group while higher in hypothyroid and subclinical hypothyroid group. TG was lower in hyperthyroid and subclinical hyperthyroid groups than control group. HDL-C was lower in both hyperthyroid and hypothyroid groups. LDL-C was lower in hyperthyroid groups than control group but higher in hypothyroid and subclinical hypothyroid groups. ApoA, Lp(a) and blood glucose had no difference in groups. ApoB was lower in hyperthyroid group than control group and higher in hypothyroid and subclinical hypothyroid groups. UA was higher in hyperthyroid and subclinical hypothyroid groups. TC, LDL-C and ApoB had significant differences after adjudgement of sex, age and BMI.(2)Our research indicated that TC was higher in SCH group no matter TSH 4.2-10μIU/ml or>10μIU/ml than control group. TC was also higher in TSH>10μIU/ml subgroup than TSH 4.2-10μIU/ml subgroup. TG had no difference among groups. The rising rate of TC was higher when TSH>10μIU/ml, and when TSH 4.2-10μIU/ml, rising rate of TC was higher than control group, but had no statistic meaning. TG was higher in SCH group than control in the subgroup younger than 20-years old. TC and TG in SCH group in male subgroup were higher than control group, TC's difference remained but TG's vanished in female subgroup. TC was also higher in SCH group in BMI<24 subgroup than control group but not in other BMI subgroup. TG showed no difference in any BMI subgroup.(3) TC, TG, LDL-C, ApoA, ApoB, Lp(a), glucose and UA were all different in T2DM with SCH to control group or T2DM with normal thyroid function to control group. But such index had no differences in T2DM with SCH and T2DM with normal thyroid function.4. Results of Pearson correlation and multiplt linear regression analysis(1) The relationship between thyroid function and lipid in each group was showed below:①hyperthyroid group. LnTSH correlated positively with Lp(a), FT4 correlated negatively with TC, HDL-C, LDL-C and Lp(a), FT3 correlated negatively with TC, HDL-C, LDL-C, ApoB and Lp(a).②hypothyroid group. LnTSH correlated positively with TC, HDL-C and LDL-C, FT4 correlated negatively with HDL-C, FT3 had no correlation with such index,③subclinical hypothyroid group. LnTSH correlated positively with TC and TG, FT3 correlated negatively with TC.④subclinical hyperthyroid group and control group. FT3, FT4 and TSH had no correlation with serum lipid, glucose and UA. Multiple linear regression showed that FT4 was predictive variables for TC, LDL-C and ApoB in hyperthyroid group, LnTSH was predictive variable for TC and HDL-C while FT3 was predictive variable for TG in hypothyroid group. LnTSH was predictive variable for TC in subclinical hyperthyroid group.(2)see(1).(3) FT3, FT4 and LnTSH had no correlation with TC, TG, HDL-C, LDL-C, ApoA, ApoB, Lp(a) and UA. They had no correlation even after adjudgement of age, sex and BMI. Segregant analysis showed that thyroid function had no correlation with serum lipid and glucose in T2DM with SCH group. LnTSH correlated positively with HDL-C and UA in T2DM with normal thyroid function. Multiple linear regression analysis showed that LnTSH,FT3,FT4 couldn't be predictive variables for serum lipid in T2DM with SCH group and T2DM with normal thyroid function group.Conclusion:1. TC, TG, HDL-C, LDL-C and ApoB were lower in hyperthyroid group than control group, and TG was lower in subclinical hyperthyroid group than control group. TC, LDL-C, ApoB were higher and HDL-C was lower in hypothyroid group than control group, while TC, LDL-C, ApoB and UA were higher in SCH group than control. ApoA, Lp(a) and glucose had no difference among groups. TC, LDL-C and ApoB were different after adjudgement of age, sex and BMI.2. Our research indicated that TC was higher in SCH group than control group no matter TSH 4.2-10μIU/ml or>10μIU/ml. TG had no difference among three groups. The rising rate of TC was higher when TSH>10μIU/ml, and when TSH 4.2-10μIU/ml, the rising rate of TC was higher than control group, but had no statistic meaning.3. TG was higher in SCH group than control group in the subgroup with ages younger than 20y. TC and TG in SCH group in male subgroup were higher than control group, TC were also higher in female subgroup but TG had no difference in SCH group. TC was also higher in SCH group in BMI<24kg/m2 subgroup than control group but not in other BMI subgroup.4. TC, TG, LDL-C, ApoA, ApoB, Lp(a), glucose and UA were all different in T2DM with SCH to control group or T2DM with normal thyroid function to control group. But such index had no differences in T2DM with SCH and T2DM with normal thyroid function.5. Correlation and regression analysis indicated that TC, LDL-C and ApoB correlated closely with thyroid function, especially TSH. But in patients with type 2 diabetes, the correlation became not so evident.
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