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Serum biomarkers for cardiovascular inflammation in subclinical hypothyroidism
William J Hueston1, Dana E King, Mark E Geesey
1Department of Family Medicine, Medical University of South Carolina, Charleston, 29425, USA. huestowj@musc.edu
Insights
Subclinical hypothyroidism (SCH) is linked to cardiovascular disease. This study found no difference in cardiac inflammation biomarkers, high-sensitivity C-reactive protein (hsCRP) and homocysteine, between individuals with SCH and euthyroid controls.
Area of Science:
- Endocrinology
- Cardiology
- Clinical Chemistry
Background:
- Cardiovascular disease (CVD) is more prevalent in individuals with elevated thyroid-stimulating hormone (TSH) and normal thyroxine levels, a condition known as subclinical hypothyroidism (SCH).
- Inflammatory biomarkers are associated with cardiac disease, making their evaluation in SCH relevant.
Purpose of the Study:
- To investigate whether individuals with SCH exhibit higher levels of cardiac-associated inflammatory biomarkers compared to euthyroid individuals.
- To determine the association between SCH and elevated levels of C-reactive protein (CRP) and homocysteine.
Main Methods:
- Analysis of data from the National Health and Nutrition Examination Survey (NHANES) 1999-2002.
- Identification of respondents aged 40 and above meeting laboratory criteria for SCH.
- Comparison of C-reactive protein (CRP) and homocysteine levels in SCH individuals versus euthyroid controls, with adjustments for potential confounders.
Main Results:
- A total of 1608 individuals were analyzed, with 45 (2.8%) diagnosed with SCH.
- No significant differences were observed in median, mean, or elevated frequencies of CRP or homocysteine between the SCH group and euthyroid controls.
- Linear regression models, adjusted for age, gender, cardiac risk factors, and cholesterol-lowering drug use, showed no association between SCH and high-sensitivity CRP (hsCRP) or homocysteine levels (P = 0.62 and P = 0.63, respectively).
Conclusions:
- In a large, population-based sample, hsCRP and homocysteine levels do not differ between individuals with SCH and euthyroid individuals.
- These findings suggest that cardiac inflammation is not elevated in individuals with subclinical hypothyroidism.
Objective:
Cardiovascular disease has been reported to be more common in patients with elevated levels of TSH and with normal thyroxine levels, termed subclinical hypothyroidism (SCH). The aim of this study was to determine whether individuals with SCH were more likely than euthyroid controls to have elevations in inflammatory biomarkers that are associated with cardiac disease.
Methods:
From the National Health and Nutrition Examination Survey (NHANES) 1999-2002 data we identified respondents aged > or = 40 who met the laboratory criteria for SCH. We compared the average values and frequencies of elevated C-reactive protein (CRP) and homocysteine in the SCH individuals to those in euthyroid individuals. Results A total of 1608 individuals were included in the analysis of whom 45 (2.8%) met the criteria for SCH, with seven (15.6%) having TSH levels between 10 and 15 IU/l. We found no differences in median, mean or the percentage of elevated CRP or homocysteine in individuals with SCH compared to euthyroid controls. Linear regression models adjusting for age, gender, the presence of other cardiac risk factors, and whether the individual was using a cholesterol-lowering drug also failed to show any association between SCH and either high-sensitivity CRP (hsCRP) (P = 0.62) or homocysteine (P = 0.63) levels. When we examined the subset of people with TSH levels between 10 and 15 IU/l, we again found no difference in mean hsCRP or homocysteine compared to control.
Conclusions:
In this large population-based sample, hsCRP and homocysteine levels do not differ for individuals with SCH compared to euthyroid individuals. This suggests that cardiac inflammation is not greater in individuals with SCH.
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