Association between Lower Normal Free Thyroxine Concentrations and Obesity Phenotype in Healthy Euthyroid Subjects

Table 1

Clinical characteristics of the 6241 subjects.

	NW-IS	NW-IR	OB/OW-IS	OB/OW-IR	𝑃
𝑁	3536	595	1145	965
Male sex (%)	1649 (46.6)	279 (46.9)	809 (70.7)	667 (69.1)	<0.001
Age (years)	49.6±10.9	50.0±11.2	51.6±10.5^a,b	50.4±10.9	<0.001
FT4 (mg/dL)*	1.33±0.22	1.28±0.22^a	1.33±0.22^b	1.27±0.22^a,c	<0.001
TSH (mIU/L)*	2.20±1.14	2.20±1.11	2.08±1.08^a	2.04±1.05^a	0.001
BMI (kg/m^2)	22.1±1.7	22.9±1.5^a	26.8±1.7^a,b	28.6±3.5^a,b,c	<0.001
WC (cm)	81.0±5.8	83.5±5.7^a	92.0±6.1^a,b	97.0±9.3^a,b,c	<0.001
SBP (mmHg)	118.5±13.6	123.3±14.2^a	125.2±13.2^a	128.9±13.9^a,b,c	<0.001
DBP (mmHg)	69.5±9.7	73.0±9.9	73.7±9.4^a	76.2±9.3^a,b,c	<0.001
Heart rate (beat/min)	63.1±9.1	66.6±9.6^a	62.9±8.7^b	66.0±9.6^a,c	<0.001
TC (mg/dL)	201.1±33.9	204.0±37.7	206.6±34.3^a	209.8±37.3^a,b	<0.001
TG (mg/dL)*	85.4±55.0	129.2±85.1^a	119.6±75.9^a	155.4±93.6^a,b,c	<0.001
HDL-C (mg/dL)	56.4±13.0	52.5±12.5^a	49.5±10.8^a,b	47.0±10.2^a,b,c	<0.001
FPG (mg/dL)	85.5±10.5	95.9±10.3^a	88.1±10.1^a,b	96.4±10.7^a,c	<0.001
FPI (U/L)*	4.8±2.1	12.2±4.0^a	6.1±2.0^a,b	14.9±6.9^,b,c	<0.001
HOMA-IR*	1.0±0.5	2.9±1.0^a	1.3±0.5^a,b	3.5±1.8^a,b,c	<0.001
CRP (mg/dL)^*†	0.16±0.38	0.20±0.58^a	0.16±0.26^a	0.25±0.52^a,b,c	<0.001
Hypertension (%)	536 (15.2)	149 (24.0)	309 (27.0)	333 (34.5)	<0.001
Hyperlipidemia (%)	781 (22.1)	238 (40.0)	432 (37.7)	503 (52.1)	<0.001
Current smoker (%)^‡	636 (19.9)	103 (20.7)	272 (26.2)	199 (24.8)	<0.001
Regular exercise (%)§	870 (29.0)	131 (28.9)	251 (26.3)	163 (22.2)	0.002

Data are expressed as means ± SD or number (percentage) unless otherwise indicated.
NW: normal weight; OW/OB: overweight/obese; IS: insulin sensitive; IR: insulin resistance; BMI: body mass index; WC: waist circumference; WHR: waist-hip ratio; SBP: systolic blood pressure; DBP: diastolic blood pressure; TG: triglyceride; HDL-C: high-density lipoprotein cholesterol; LDL-C: low-density lipoprotein cholesterol; FPG: fasting plasma glucose; FPI: fasting plasma insulin; HOMA-IR; CRP: C-reactive protein.
One-way ANOVA and Tukey’s post-hoc for continuous variables. ^a𝑃<0.05 versus NW-IS; ^b𝑃<0.05 versus NW-IR; ^c𝑃<0.05 versus OW/OB-IS; *tested by log-transformed; ^†measured in 4877 subjects; ^‡measured in 5529; §regular exercise was defined as exercise for more than 30 minutes at a time more than three times a week (measured only in 5140 subjects).