Thyroid-stimulating hormone levels appear to have a stronger effect on total cholesterol and LDL cholesterol in older adults compared with younger adults, according to recent study findings published in Thyroid.
“The results of this study improve upon the traditional concept and suggest that [subclinical hypothyroidism] might play a role in age-related dyslipidemia,” the researchers wrote. “As aging is a non-modifiable factor for dyslipidemia, these findings have important clinical implications. Based on the results, thyroid screening and modification should be strongly considered in elderly and dyslipidemic patients. Maintaining TSH in an appropriate range might be beneficial for the primary prevention of atherosclerotic diseases.”
Jiajun Zhao, MD, PhD, of Shandong Provincial Hospital in China, and colleagues evaluated data from 17,046 adults aged 40 years and older (8,827 with dyslipidemia; 8,219 controls) from the REACTION study to determine the relationship between subclinical hypothyroidism and lipid profiles among different age groups.
Overall, 19.29% of all participants had thyroid dysfunction, with subclinical hypothyroidism the most common (11.33%). More participants with dyslipidemia compared with controls had subclinical hypothyroidism (P < .001).
A linear and significant increase with age was found for the presence of subclinical hypothyroidism among all participants (P < .001). Similarly significant increases with age were found for the prevalence of dyslipidemia, high total cholesterol, high triglycerides and high LDL cholesterol. Among participants aged 40 to 70 years, the prevalence of high total cholesterol increased by 1.61-fold, and high LDL cholesterol increased by 1.69-fold; a slight decrease was found for the group aged 70 years and older.
In participants aged 40 to 70 years, a positive significant association was found between TSH and serum total cholesterol. Positive significant associations were found between TSH and LDL cholesterol for participants aged 40 to 49 years and 50 to 59 years.
After adjustment for potential confounders and thyroid hormones, each 1 mIU/L increase in TSH increased total cholesterol by 0.0147 mmol/L in participants aged 40 to 49 years, 0.0395 mmol/L in those aged 50 to 59 years and 0.0551 mmol/L in those aged 60 to 69 years. Similar increases among the age groups were found for LDL cholesterol.
High total cholesterol increased by 6.76% in euthyroid participants aged 60 to 69 years compared with those aged 40 to 49 years. High total cholesterol in participants aged 60 to 69 years with mild subclinical hypothyroidism (4.2 mIU/L TSH 10 mIU/L) increased by 10.11%, and by 15.33% in those with significant subclinical hypothyroidism (TSH > 10 mIU/L).
“In summary, the findings of this large-scale population-based, case-control study indicate that [subclinical hypothyroidism] and dyslipidemia increase progressively with age in middle-aged and elderly Chinese subjects,” the researchers wrote. “Indeed, TSH exhibited a stronger effect on the [total cholesterol] and LDL-C level in moderately old subjects than in younger subjects. Additionally, [subclinical hypothyroidism] increased the prevalence of high [total cholesterol] and high LDL-C and augmented the concentrations of [total cholesterol] and LDL-C with age. Thus, [subclinical hypothyroidism] might worsen the age-related increase in the prevalence of dyslipidemia. Overall, [subclinical hypothyroidism] has generated interest because of its increasing prevalence, its detrimental effects and the challenging issues it raises, which must be urgently addressed.” - by Amber Cox
The researchers report no relevant financial disclosures.