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Risk factors for cardiovascular disease in patients with subclinical hypothyroidism
Fusun Toruner1, Alev E Altinova, Ayhan Karakoc
1Department of Endocrinology and Metabolism, Gazi University, Faculty of Medicine, Ankara, Turkey.
Insights
Subclinical hypothyroidism (SCH) is linked to abnormal lipid and lipoprotein levels, impacting cardiovascular disease risk. These changes occur independently of thyroid-stimulating hormone (TSH) levels.
Area of Science:
- Endocrinology
- Cardiovascular Medicine
- Clinical Chemistry
Background:
- Subclinical hypothyroidism (SCH) is a condition where thyroid hormone levels are mildly abnormal, but its link to cardiovascular disease (CVD) risk factors remains unclear.
- Investigating the relationship between SCH and CVD risk factors like lipid profiles, lipoproteins, insulin resistance, and inflammatory markers is crucial for understanding potential health implications.
Purpose of the Study:
- To investigate cardiovascular disease risk factors in patients with subclinical hypothyroidism (SCH).
- To examine the relationship between thyroid hormones and cardiovascular disease risk factors in SCH patients and controls.
Main Methods:
- A study involving 38 SCH patients and 44 controls with no confounding medical conditions or thyroid medication.
- Assessment of cardiovascular risk factors including lipid profile, lipoproteins, insulin resistance, C-reactive protein (CRP), homocysteine (Hcy), and fibrinogen levels.
Main Results:
- Patients with SCH exhibited higher serum total cholesterol, low-density lipoprotein cholesterol, and triglycerides compared to controls.
- While serum lipoprotein(a) [Lp(a)] was higher in SCH subjects, the difference was not statistically significant.
- Free triiodothyronine (FT3) showed a negative correlation with apolipoprotein B (Apo B) and Lp(a) in SCH patients, and with Lp(a) in controls. No significant differences were found in other tested parameters or between TSH subgroups.
Conclusions:
- Subclinical hypothyroidism (SCH) is associated with specific lipid and lipoprotein abnormalities.
- The observed association between SCH and lipid/lipoprotein abnormalities does not appear to be dependent on the subject's thyroid-stimulating hormone (TSH) level.
Introduction:
The relationship between subclinical hypothyroidism (SCH) and cardiovascular disease is not fully understood. We investigated risk factors for cardiovascular disease (lipid profile, lipoproteins, insulin resistance, C-reactive protein [CRP] homocysteine [Hcy] and fibrinogen levels) and their relationships with thyroid hormones in SCH patients and controls.
Methods:
Thirty-eight SCH patients and 44 controls were enrolled in this study. No patients had any substantial confounding medical conditions (including diabetes mellitus or coronary heart disease) or were taking thyroid-related medication.
Results:
Serum total cholesterol (P<0.05), low-density lipoprotein cholesterol (P<0.05) and triglycerides (P<0.001) were higher in patients with SCH than in controls. Serum lipoprotein(a) (Lp[a]) levels were higher in SCH subjects but this difference did not reach statistical significance (P=0.07). No significant differences were noted in CRP, Hcy, fibrinogen, high-density lipoprotein cholesterol, apolipoprotein A-1, apolipoprotein B (Apo B) or insulin resistance between patients with SCH and controls (in all cases, P>0.05). Free triiodothyronine (FT3) negatively correlated with Apo B (r=.0.46, P=0.005) and Lp(a) (r=.0.31, P=0.03) in patients with SCH and negatively correlated with Lp(a) (r=.0.30, P=0.04) in controls. All of these parameters were comparable between patients with thyroid-stimulating hormone (TSH) >10 microIU/ml and TSH <10 microIU/ml (in SCH patients, P>0.05).
Conclusion:
Our results suggest that SCH is associated with some lipid and lipoprotein abnormalities. Our results also suggest that this association does not depend on the subject's TSH level.
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