J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website https://jocmr.elmerjournals.com

Original Article

Volume 17, Number 12, December 2025, pages 716-725

Atrial Fibrillation in the Context of Thyrotoxicosis: Prevalence and Clinical Determinants

↓ Figure 1. Flow diagram of patient selection. A total of 1,160 patients with thyrotoxicosis were screened, exceeding the minimum required sample size, and 801 were included in the final analysis.

↓ Figure 2. Forest plot of prognostic factors associated with atrial fibrillation among patients with thyrotoxicosis. Adjusted odds ratios with 95% confidence intervals were estimated using generalized linear models with logistic regression. Increasing age, male sex, heart failure, and thyroid crisis were independently associated with atrial fibrillation, whereas thyroid hormone levels were not significant predictors.

↓ **Table 1.** Clinical Characteristics of Patients With Thyrotoxicosis, Stratified by Atrial Fibrillation Status
Baseline characteristics	AF (n = 65)	Non-AF (n = 736)	P-value
AF: atrial fibrillation; SD: standard deviation.
Sex, n (%)			< 0.001
Female	34 (52.31)	592 (80.43)
Male	31 (47.69)	144 (19.57)
Age at thyrotoxicosis diagnosis (years), mean ± SD	52 ± 15.35	36 ± 15.38	< 0.001
Body mass index, n (%)			0.177
Underweight (< 18.5 kg/m²)	7 (10.77)	119 (16.21)
Normal (18.5 - 22.9 kg/m²)	26 (40.00)	347 (47.28)
Overweight (23.0 - 27.4 kg/m²)	22 (33.85)	199 (27.11)
Obese (> 27.5 kg/m²)	10 (15.38)	69 (9.40)
Systolic pressure at diagnosis, mean ± SD	132 ± 20.51	128 ± 15.95	0.054
Diastolic pressure at diagnosis, mean ± SD	76 ± 13.34	73 ± 11.42	0.023
Heart rate at diagnosis, mean ± SD	97 ± 24.19	100 ± 20.58	0.179
Coronary artery disease, n (%)	2 (3.08)	8 (1.09)	0.192
Chronic kidney disease, n (%)			< 0.001
Stage 1	24 (36.92)	233 (31.16)
Stage 2	16 (24.62)	93 (12.61)
Stage 3	6 (9.23)	21 (2.85)
Stage 4-5	2 (3.08)	2 (0.27)
Cerebrovascular disease, n (%)	11 (16.92)	6 (0.82)	< 0.001
Dyslipidemia, n (%)	19 (29.23)	78 (10.60)	< 0.001
Diabetes mellitus, n (%)	14 (21.54)	38 (5.16)	< 0.001
Heart failure, n (%)	10 (15.38)	4 (0.54)	< 0.001
Hypertension, n (%)	27 (41.54)	86 (11.68)	< 0.001
History of thyroid crisis, n (%)	20 (30.77)	12 (1.63)	< 0.001
Etiology			0.573
Graves’ disease	60 (92.31)	629 (85.46)
Drug-induced thyroiditis	1 (1.54)	3 (0.41)
Hashimoto thyroiditis	0 (0)	12 (1.63)
Thyroid adenoma	1 (1.54)	10 (1.36)
Thyroid cancer	0 (0)	1 (0.14)
Thyroid multinodular goiter	0 (0)	9 (1.22)
Thyroid nodule	0 (0)	23 (3.13)
TSH-producing adenoma	0 (0)	1 (0.14)
Gestational transient thyrotoxicosis	0 (0)	1 (0.14)
Unknown	3 (4.62)	47 (6.39)

↓ Table 1. Clinical Characteristics of Patients With Thyrotoxicosis, Stratified by Atrial Fibrillation Status

Baseline characteristics

AF (n = 65)

Non-AF (n = 736)

P-value

AF: atrial fibrillation; SD: standard deviation.

Sex, n (%)

< 0.001

Female

34 (52.31)

592 (80.43)

Male

31 (47.69)

144 (19.57)

Age at thyrotoxicosis diagnosis (years), mean ± SD

52 ± 15.35

36 ± 15.38

< 0.001

Body mass index, n (%)

0.177

Underweight (< 18.5 kg/m²)

7 (10.77)

119 (16.21)

Normal (18.5 - 22.9 kg/m²)

26 (40.00)

347 (47.28)

Overweight (23.0 - 27.4 kg/m²)

22 (33.85)

199 (27.11)

Obese (> 27.5 kg/m²)

10 (15.38)

69 (9.40)

Systolic pressure at diagnosis, mean ± SD

132 ± 20.51

128 ± 15.95

0.054

Diastolic pressure at diagnosis, mean ± SD

76 ± 13.34

73 ± 11.42

0.023

Heart rate at diagnosis, mean ± SD

97 ± 24.19

100 ± 20.58

0.179

Coronary artery disease, n (%)

2 (3.08)

8 (1.09)

0.192

Chronic kidney disease, n (%)

< 0.001

Stage 1

24 (36.92)

233 (31.16)

Stage 2

16 (24.62)

93 (12.61)

Stage 3

6 (9.23)

21 (2.85)

Stage 4-5

2 (3.08)

2 (0.27)

Cerebrovascular disease, n (%)

11 (16.92)

6 (0.82)

< 0.001

Dyslipidemia, n (%)

19 (29.23)

78 (10.60)

< 0.001

Diabetes mellitus, n (%)

14 (21.54)

38 (5.16)

< 0.001

Heart failure, n (%)

10 (15.38)

4 (0.54)

< 0.001

Hypertension, n (%)

27 (41.54)

86 (11.68)

< 0.001

History of thyroid crisis, n (%)

20 (30.77)

12 (1.63)

< 0.001

Etiology

0.573

Graves’ disease

60 (92.31)

629 (85.46)

Drug-induced thyroiditis

1 (1.54)

3 (0.41)

Hashimoto thyroiditis

0 (0)

12 (1.63)

Thyroid adenoma

1 (1.54)

10 (1.36)

Thyroid cancer

0 (0)

1 (0.14)

Thyroid multinodular goiter

0 (0)

9 (1.22)

Thyroid nodule

0 (0)

23 (3.13)

TSH-producing adenoma

0 (0)

1 (0.14)

Gestational transient thyrotoxicosis

0 (0)

1 (0.14)

Unknown

3 (4.62)

47 (6.39)

↓ **Table 2.** Laboratory Profiles of Patients With Thyrotoxicosis, Stratified by Atrial Fibrillation Status
Laboratory parameters	AF (n = 65)	Non-AF (n = 736)	P-value
AF: atrial fibrillation; BUN: blood urea nitrogen; eGFR: estimated glomerular filtration rate; FT3: free triiodothyronine; FT4: free thyroxine; HbA1c: glycated hemoglobin; TSH: thyroid-stimulating hormone; SD: standard deviation.
Hct (%), mean ± SD	40.13 ± 6.52	39.48 ± 4.15	0.3017
Hb (g/dL), mean ± SD	13.05 ± 2.28	12.80 ± 1.49	0.267
HbA1C (%), mean ± SD	5.95 ± 0.89	5.87 ± 0.97	0.660
BUN (mg/dL), mean ± SD	16.25 ± 11.28	12.32 ± 5.67	0.001
Creatinine (mg/dL), mean ± SD	1.11 ± 1.54	0.72 ± 0.25	< 0.001
eGFR (mL/min), mean ± SD	84.77 ± 29.30	101.29 ± 26.49	< 0.001
TSH (µIU/mL), mean ± SD	0.02 ± 0.08	0.03 ± 0.24	0.763
FT4 (ng/mL), mean ± SD	4.10 ± 2.09	4.19 ± 2.23	0.771
FT3 (ng/mL), mean ± SD	11.37 ± 8.48	14.16 ± 9.76	0.027
Sodium (mmol/L), mean ± SD	139.20 ± 3.66	139.10 ± 2.71	0.801
Potassium (mmol/L), mean ± SD	3.92 ± 0.61	4.12 ± 2.25	0.593
Chloride (mmol/L), mean ± SD	104.04 ± 4.45	104.35 ± 3.31	0.543
Bicarbonate (mmol/L), mean ± SD	23.39 ± 2.88	24.07 ± 3.51	0.118

↓ Table 2. Laboratory Profiles of Patients With Thyrotoxicosis, Stratified by Atrial Fibrillation Status

Laboratory parameters

AF (n = 65)

Non-AF (n = 736)

P-value

AF: atrial fibrillation; BUN: blood urea nitrogen; eGFR: estimated glomerular filtration rate; FT3: free triiodothyronine; FT4: free thyroxine; HbA1c: glycated hemoglobin; TSH: thyroid-stimulating hormone; SD: standard deviation.

Hct (%), mean ± SD

40.13 ± 6.52

39.48 ± 4.15

0.3017

Hb (g/dL), mean ± SD

13.05 ± 2.28

12.80 ± 1.49

0.267

HbA1C (%), mean ± SD

5.95 ± 0.89

5.87 ± 0.97

0.660

BUN (mg/dL), mean ± SD

16.25 ± 11.28

12.32 ± 5.67

0.001

Creatinine (mg/dL), mean ± SD

1.11 ± 1.54

0.72 ± 0.25

< 0.001

eGFR (mL/min), mean ± SD

84.77 ± 29.30

101.29 ± 26.49

< 0.001

TSH (µIU/mL), mean ± SD

0.02 ± 0.08

0.03 ± 0.24

0.763

FT4 (ng/mL), mean ± SD

4.10 ± 2.09

4.19 ± 2.23

0.771

FT3 (ng/mL), mean ± SD

11.37 ± 8.48

14.16 ± 9.76

0.027

Sodium (mmol/L), mean ± SD

139.20 ± 3.66

139.10 ± 2.71

0.801

Potassium (mmol/L), mean ± SD

3.92 ± 0.61

4.12 ± 2.25

0.593

Chloride (mmol/L), mean ± SD

104.04 ± 4.45

104.35 ± 3.31

0.543

Bicarbonate (mmol/L), mean ± SD

23.39 ± 2.88

24.07 ± 3.51

0.118

↓ **Table 3.** Prognostic Factors Associated With AF Among Thyrotoxicosis Patients
Prognostic factors	Crude OR (95% CI)	Adjusted OR (95% CI)	P-value (adjusted model)
Adjusted odds ratios were derived from a full multivariable logistic regression model including all clinically relevant covariates (age group, sex, BMI, diabetes mellitus, hypertension, heart failure, thyroid crisis, TSH, FT4, and FT3). The final P-values presented in the table correspond to the adjusted model. BMI: body mass index; CI: confidence interval; FT3: free triiodothyronine; FT4: free thyroxine; OR: odds ratio; TSH: thyroid-stimulating hormone.
Age of diagnosis (years)
< 35	1	1
35 - 60	5.35 (2.55 - 11.24)	5.48 (2.03 - 14.83)	0.001
> 60	13.07 (5.61 - 30.47)	11.39 (3.43 - 37.76)	< 0.001
Male	3.75 (2.23 - 6.30)	3.38 (1.70 - 6.30)	< 0.001
BMI (kg/m²)
< 18.5	1	1
15.5 - 22.9	1.24 (0.53 - 2.94)	1.55 (0.42 - 5.68)	0.506
≥ 23.00	1.98 (0.85 - 4.61)	2.11 (0.59 - 7.60)	0.253
Diabetes mellitus	5.04 (2.57 - 9.91)	1.87 (0.77 - 4.55)	0.169
Hypertension	5.37 (3.12 - 9.24)	1.1.53 (0.72 - 3.26)	0.272
Heart failure	33.27 (10.10 - 109.53)	11.25 (2.85 - 44.54)	0.001
Thyroid crisis	26.81 (12.34 - 58.29)	61.84 (21.89 - 181.32)	< 0.001
TSH (µIU/mL)	0.77 (0.14 - 4.21)	0.90 (0.06 - 12.86)	0.938
FT4 (ng/mL)	0.98 (0.88 - 1.10)	1.04 (0.83 - 1.30)	0.740
FT3 (ng/mL)	0.97 (0.94 - 0.99)	0.95 (0.90 - 1.01)	0.085

↓ Table 3. Prognostic Factors Associated With AF Among Thyrotoxicosis Patients

Prognostic factors

Crude OR (95% CI)

Adjusted OR (95% CI)

P-value (adjusted model)

Adjusted odds ratios were derived from a full multivariable logistic regression model including all clinically relevant covariates (age group, sex, BMI, diabetes mellitus, hypertension, heart failure, thyroid crisis, TSH, FT4, and FT3). The final P-values presented in the table correspond to the adjusted model. BMI: body mass index; CI: confidence interval; FT3: free triiodothyronine; FT4: free thyroxine; OR: odds ratio; TSH: thyroid-stimulating hormone.

Age of diagnosis (years)

< 35

35 - 60

5.35 (2.55 - 11.24)

5.48 (2.03 - 14.83)

0.001

> 60

13.07 (5.61 - 30.47)

11.39 (3.43 - 37.76)

< 0.001

Male

3.75 (2.23 - 6.30)

3.38 (1.70 - 6.30)

< 0.001

BMI (kg/m²)

< 18.5

15.5 - 22.9

1.24 (0.53 - 2.94)

1.55 (0.42 - 5.68)

0.506

≥ 23.00

1.98 (0.85 - 4.61)

2.11 (0.59 - 7.60)

0.253

Diabetes mellitus

5.04 (2.57 - 9.91)

1.87 (0.77 - 4.55)

0.169

Hypertension

5.37 (3.12 - 9.24)

1.1.53 (0.72 - 3.26)

0.272

Heart failure

33.27 (10.10 - 109.53)

11.25 (2.85 - 44.54)

0.001

Thyroid crisis

26.81 (12.34 - 58.29)

61.84 (21.89 - 181.32)

< 0.001

TSH (µIU/mL)

0.77 (0.14 - 4.21)

0.90 (0.06 - 12.86)

0.938

FT4 (ng/mL)

0.98 (0.88 - 1.10)

1.04 (0.83 - 1.30)

0.740

FT3 (ng/mL)

0.97 (0.94 - 0.99)

0.95 (0.90 - 1.01)

0.085