Association Between Serum Thyroid Measurements and Hyperhomocysteinemia in Euthyroid Subjects: A Retrospective Cross-Sectional Study

Figures & data

Table 1 General Characteristics of the Subjects

	Overall	Non-HHCy	HHCy	p value
	N=775	N=677	N=98
Sex (female, %)	368 (47.5%)	329 (48.6%)	39 (39.8%)	0.10
Age (years)	43.06±16.71	40.92±15.99	57.82±13.94	<0.01
Residence (Urban, %)	518 (66.8%)	458 (67.7%)	60 (61.2%)	0.21
Smoking (N, %)	192 (24.8%)	145 (21.4%)	47 (48.0%)	<0.01
Drinking (N, %)	436 (56.3%)	371 (54.8%)	65 (66.3%)	0.03
BMI (kg/m^2)	25.27±4.03	24.84±3.92	28.25±3.51	<0.01
HR (per min)	86.93±12.76	84.16±13.49	90.45±11.87	0.03
SBP (mmHg)	134.65±19.12	133.85±18.34	140.20±23.22	<0.01
DBP (mmHg)	82.59±11.78	82.12±10.99	85.83±15.93	0.02
Hypertension (N, %)	386 (49.8%)	329 (48.6%)	57 (58.2%)	0.08
FPG (mmol/L)	5.55±2.33	5.54±2.28	5.63±2.41	0.44
TC (mmol/L)	5.02±0.95	4.96±0.91	5.15±1.04	<0.01
TG (mmol/L)	1.56±1.01	1.39±0.98	1.82±1.22	<0.01
HDL (mmol/L)	1.35±0.38	1.36±0.34	1.28±0.43	0.03
LDL (mmol/L)	3.31±0.87	3.26±0.86	3.40±0.93	0.04
Dyslipidemia (N, %)	403 (52.0%)	336 (49.6%)	67 (68.4%)	<0.01
HCy (μmol/L)	11.76±6.00	9.98±1.84	24.07±9.45	<0.01

Notes: Continuous variables are expressed as mean and standard deviation. Binary variables are expressed as numbers and percentages.

Abbreviations: BMI, body mass index; HR, heart rate; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; TC, total cholesterol; TG, total triglyceride; HDL, high-density lipoprotein; LDL, low-density lipoprotein; HCy, homocysteine; HHCy, hyperhomocysteinemia.

Table 2 Thyroid Indicators Corresponding to Subjects with or without HHCy

	Overall	Non-HHCy	HHCy	p value
	N=775	N=677	N=98
TSH (mIU/L)	1.71±0.93	1.65±0.90	2.10±1.06	<0.01
FT4 (mmol/L)	13.74±1.73	13.76±1.73	13.64±1.75	0.53
FT3 (mmol/L)	4.06±0.60	4.06±0.61	4.07±0.56	0.72
pTPOAb (N, %)	87 (11.2%)	68 (10.0%)	19 (19.4%)	<0.01
pTgAb (N, %)	130 (16.8%)	107 (15.8%)	23 (23.5%)	0.06

Abbreviations: TSH, thyroid stimulating hormone; FT4, free thyroxine; FT3, free triiodothyronine; pTPOAb, positive thyroid peroxidase; pTgAb, positive thyroglobulin antibody.

Table 3 HCy Levels in Subgroups with Different Quartiles of TSH, FT4, FT3, and Positive or Negative TPOAb and TgAb

	Q1	Q2	Q3	Q4	p for Trend
TSH	9.81±3.59	11.96±5.88	11.77±5.45	13.49±7.78	<0.01
FT4	11.90±6.60	12.21±6.29	11.79±6.17	11.16±4.80	0.17
FT3	11.77±6.86	12.07±6.11	11.30±5.15	11.92±5.82	0.86
	Negative		Positive		p value
TPOAb	11.48±5.47		14.06±8.89		<0.01
TgAb	11.59±5.63		12.63±7.55		0.12

Notes: The serum HCy levels (μmol/L) in Table 3 are presented as the mean and standard deviation.

Abbreviations: TPOAb, thyroid peroxidase antibody; TgAb, thyroglobulin antibody.

Table 4 HHCy Prevalence in Subgroups with Different Quartiles of TSH, FT4, FT3, and Positive or Negative TPOAb and TgAb

	Q1	Q2	Q3	Q4	p for Trend
TSH	11/192 (5.7%)	24/193 (12.4%)	26/196 (13.3%)	37/194 (19.1%)	<0.01
FT4	23/193 (11.9%)	28/194 (14.4%)	24/194 (12.4%)	23/194 (11.9%)	0.83
FT3	21/190 (11.1%)	29/194 (14.9%)	22/197 (11.2%)	26/194 (13.4%)	0.77
	Negative		Positive		p value
TPOAb	79/688 (11.5%)		19/87 (21.8%)		<0.01
TgAb	75/645 (11.6%)		23/130 (17.7%)		0.06

Table 5 Regression Analysis Between Serum TSH and TPOAb Measurements and Serum HCy Level or HHCy Prevalence

		Serum HCy	HHCy Prevelence
TSH	Q1	Ref	Ref
	Q2 (model 1)	2.149±0.497*	2.337 (1.111, 4.916)*
	Q2 (model 2)	1.053±0.463*	1.289 (0.561, 2.961)
	Q3 (model 1)	1.961±0.470*	2.517 (1.206, 5.250)*
	Q3 (model 2)	1.226±0.440*	1.490 (0.627, 3.543)
	Q4 (model 1)	3.685±0.618*	3.878 (1.914, 7.858)*
	Q4 (model 2)	2.855±0.550*	3.440 (1.511, 7.832)*
	Per SD increase (model 1)	1.660±0.225*	1.585 (1.288, 1.951)*
	Per SD increase (model 2)	1.414±0.199*	1.706 (1.315, 2.214)*
TPOAb	Negative	Ref	Ref
	Positive (model 1)	2.583±0.677*	2.154 (1.230, 3.771)*
	Positive (model 2)	2.229±0.598*	2.380 (1.231, 4.601)*
	Per SD increase (model 1)	0.006±0.002*	1.001 (0.999, 1.003)
	Per SD increase (model 2)	0.003±0.002	1.000 (0.999, 1.002)

Notes: Data are presented in the form of regression coefficient (β) and standard error (SE), or odds ratio (OR) and 95% confidence interval (95% CI). In Model 1, the regression analysis did not adjust for any confounding factors. In Model 2, the regression analysis adjusted for age, sex, BMI, smoking habits, hypertension, dyslipidemia, and fasting plasma glucose. *p<0.05.