|Year : 2012 | Volume
| Issue : 2 | Page : 45-47
Relationship between hypothyroidism and carotid artery intima media thickness, and prevalence of hypothyroidism in rheumatoid arthritis patient: An observational study
Jayanta Paul1, Somnath Dasgupta1, Mrinal Kanti Ghosh2, Kishore Shaw1, Arpan Kumar Dey1, Tanmoy W Momin1
1 Department of General Medicine, Burdwan Medical College, Burdwan, West Bengal, India
2 Department of Radiology, Burdwan Medical College, Burdwan, West Bengal, India
|Date of Web Publication||12-May-2012|
Post Graduate Student, Department of General Medicine, Burdwan Medical College, C/o Jitendra Chandra Paul, J+B lodge, Santosh Sarani, Banamalipur, Barasat, Kolkata-124, West Bengal
Source of Support: None, Conflict of Interest: None
Introduction: Rheumatoid arthritis (RA) and hypothyroidism both are associated with atherosclerosis. Prevalence of hypothyroidism is higher in RA than in general population. But there is still controversy regarding relationship between carotid artery intima media thickness (CAIMT) and hypothyroidism. Aims and Objectives: This study was done to find out prevalence of hypothyroidism in RA and relationship between hypothyroidism and CAIMT in RA patients. Materials and Methods: The study subjects included 52 RA patients. Among them, 8 RA patients were suffering from hypothyroidism. CAIMT was measured by B-mode ultrasound. Statistical analysis was performed by SPSS software (17 th edition for window). Result and Analysis: 15.4% of RA patients were suffering from hypothyroidism. There was also independent correlation between CAIMT and hypothyroidism in RA (P = 0.044). CAIMT of RA with hypothyroidism was significantly higher than RA without hypothyroidism (P = 0.023). Conclusion: Prevalence of hypothyroidism is higher in RA than in general population. Hypothyroidism is an independent risk factor of atherosclerosis in RA patients.
Keywords: Carotid artery intima media thickness, hypothyroidism, prevalence, rheumatoid arthritis
|How to cite this article:|
Paul J, Dasgupta S, Ghosh MK, Shaw K, Dey AK, Momin TW. Relationship between hypothyroidism and carotid artery intima media thickness, and prevalence of hypothyroidism in rheumatoid arthritis patient: An observational study. Thyroid Res Pract 2012;9:45-7
|How to cite this URL:|
Paul J, Dasgupta S, Ghosh MK, Shaw K, Dey AK, Momin TW. Relationship between hypothyroidism and carotid artery intima media thickness, and prevalence of hypothyroidism in rheumatoid arthritis patient: An observational study. Thyroid Res Pract [serial online] 2012 [cited 2019 Dec 5];9:45-7. Available from: http://www.thetrp.net/text.asp?2012/9/2/45/96035
| Introduction|| |
Rheumatoid arthritis (RA) patients are associated with increased cardiovascular risks, and clinical hypothyroidism is observed three times more often in female RA patients than females in the general population.  RA patients show greater thickness of the common carotid artery than healthy controls.  Hypothyroidism is also associated with increase in CAIMT and presence of carotid plaques, independent of classical risk factors for atherosclerosis.  Patients with hypothyroidism are at a three times increased risk for early atherosclerosis, as shown independently for other risk factors, such as lipid profile, hypertension, and impaired endothelial function. Whether hypothyroidism has influence on the same risk factors and is associated with atherosclerosis is still under debate.  Some studies showed that there is an association,  but others did not.  Carotid artery intima media thickness (CAIMT) is increasingly used as a surrogate marker of early atherosclerosis, and in a recent review it was shown that CAIMT is a strong predictor of future vascular events such as myocardial infarction and stroke. 
This study was done to find out the prevalence of hypothyroidism in RA and relationship between hypothyroidism and CAIMT in RA patients.
| Materials and Methods|| |
The study subjects included 52 RA patients diagnosed according to the classification criteria of the RA by the American College of Rheumatology, 2010. Of which 35 (67.3%) were female and 17 (32.7%) were male; 8 (15.4%) RA patients were associated with hypothyroidism, 16 (30.7%) were smoker, 24 (46.2%) were suffering from dyslipidemia, and 23 (44.2%) were hypertensive [Table 1]. All RA patients were nondiabetic. Body mass index of all patients was below 25.All RA patients had normal body weight and waist circumference. Mean age of study population was 45.63 ± 1.12 years [Table 1].
Biochemical tests were done after overnight (at least 12 hours) fasting at the Biochemistry Department of Burdwan Medical College. Thyroid function tests (TSH, thyroid-stimulating hormone; total T 3 , thiiodothyronine; free T 4 , thyroxine) were estimated by chemiluminscence assay. Hypothyroidism was diagnosed when TSH level was >4.5 mIU/l. 
Thyroid peroxidase antibody (TPO Ab) was also measured in all patients.
Serum total cholesterol was measured by "cholesterol oxidase-peroxidase" method. Patients who used cholesterol lowering medication or had a total serum cholesterol level ≥200 mg/dl were classified as having dyslipidemia. 
Plasma glucose was measured by a "glucose oxidase-peroxidase" method. Diabetes was diagnosed according to the American Diabetes Association when a previous or current 12 h fasting glucose level is 7 mmol/l or greater (≥126 mg %).
Participants were classified as nonsmokers if they responded that they had smoked fewer than 100 cigarettes or 5 packs of cigarettes during their lifetime. 
The average of three blood pressure measurements was used for analysis. Hypertension was diagnosed when a patient had received medicine for hypertension or had systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg after taking 5 minutes rest. 
Carotid artery intima media thickness measurement
Examination of the carotid arteries was performed with a 7 MHz B-mode ultrasound system (Philips-HD7 Diagnostic Ultrasound System, China). The B-mode scanning protocol included the scanning of the right and left common carotid arteries (3 cm before the carotid bifurcation), carotid bifurcation, as well as of the internal carotid artery 2 cm distally from the carotid bifurcation [Figure 1].  CAIMT measurements were always performed in plaque-free arterial segments.  All examinations and measurements were performed by same examiner to exclude examiner bias.
|Figure 1: The intima media thickness of right common carotid artery at 3 cm before bifurcation (1000 μm) and at right-sided carotid bifurcation (1230 μm) in RA patient with hypothyroidism|
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Independent samples t test and Linear multivariate regression analysis with 95% confidence interval were performed. P value less than 0.05 was taken as statistically significant. Data were expressed as means ± SE (Standard Error). All these analyses were performed by using a commercially available software SPSS (17 th version for window) on personal computer.
| Results|| |
Our study showed that 15.4% RA patients were also suffering from hypothyroidism.
In this study, there was significant independent positive correlation between hypothyroidism (P = 0.044) and CAIMT. There was also independent positive correlation between CAIMT and age (P = 0.000), sex (P = 0.047), dyslipidemia (P = 0.030), smoking (P = 0.046), and hypertension (P = 0.008) [Table 2].
|Table 2: Multivariate linear regression analysis of traditional risk factors correlating with carotid artery intima media thickness in rheumatoid arthritis|
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CAIMT of RA patients with hypothyroidism was significantly higher (1136.6791 ± 22.48 μm; P = 0.023) than RA patients without hypothyroidism (972.27 ± 13.72 μm).
Male RA patients with hypothyroidism had higher CAIMT (1209.99 ± 8.33 μm; P value = 0.002) than female RA patients with hypothyroidism (932.31 ± 6.45 μm).
| Discussion|| |
National Health and Nutrition Examination Survey (NHANES 1999-2002) showed that hypothyroidism prevalence (TSH > 4.5 mIU/L) in the general population was 3.7%.  Another study  demonstrated that 6.3% of RA patients had subclinical hypothyroidism. So in RA prevalence of hypothyroidism is higher than in normal population. Our study also showed higher prevalence of hypothyroidism (15.4%) in RA.
Some study  demonstrated that CAIMT is independently associated with thyroid function and increased cardiovascular risk in subjects with low normal thyroid function. Our study showed that hypothyroidism is an independent risk factor of atherosclerosis in RA patients (P = 0.044) because CAIMT is a surrogate marker of atherosclerosis.
There were some limitations in our study: 1) Small number of participants was included, 2) Premature atherosclerosis, serum homocysteine, lipoprotein (a) physical activity, atherogenic diet, proinflammatory factors, and prothrombotic factors could not be examined in this study.
| Conclusion|| |
From this study, it can be concluded that prevalence of hypothyroidism is higher in RA than in general population. Hypothyroidism is also an independent factor of atherosclerosis in RA. So, treatment of hypothyroidism along with other modifiable risk factors may halt or slow the progression of CAIMT in RA.
| Acknowledgments|| |
We acknowledge the contributions of faculty of Department of Medicine, Burdwan Medical College & Hospital for helping us to carry out this work.
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[Table 1], [Table 2]