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Mild thyroid dysfunction in childhood increases dyslipidemia risk
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Children with mild subclinical hypothyroidism are nearly twice as likely to have elevated total and non-HDL cholesterol levels when compared with euthyroid children, according to findings published in Clinical Endocrinology.
“Children with mild subclinical hypothyroidism were found to have higher rates of high total cholesterol and high non-HDL cholesterol in comparison to children with normal thyroid function test results,” Seema Kumar, MD, consultant in the division of pediatric endocrinology and associate professor of pediatrics at Mayo Clinic in Rochester, Minnesota, told Endocrine Today. “Currently, there is no consensus on whether children with mild subclinical hypothyroidism should be treated with levothyroxine. The findings of our study raise the question whether mild subclinical hypothyroidism increases the risk for development of cardiovascular disease in children and adolescents by its impact on levels of total cholesterol and non-HDL cholesterol.”
Kumar and colleagues analyzed medical records data from 1,443 children without familial hyperlipidemia syndromes who underwent measurements of TSH, free T4 and lipid panel in primary or specialty care at Mayo Clinic between 2007 and 2015 (41.9% boys; 82.2% white). Mild subclinical hypothyroidism was defined as TSH between 5 mIU/L and 10 mIU/L in the presence of free T4. Abnormal lipids were defined as total cholesterol at least 5.17 mmol/L, HDL cholesterol less than 1.03 mmol/L and non-HDL cholesterol at least 3.75 mmol/L. Researchers used linear regression analyses to evaluate the relationship between TSH and lipid parameters in children with subclinical hypothyroidism and euthyroidism.
Within the cohort, 228 children had mild subclinical hypothyroidism, and 1,215 children were euthyroid.
Researchers found that TSH level was associated with total cholesterol (beta = 0.05; P < .0001) and non-HDL cholesterol (beta = 0.05; P < .0001), with the relationship persisting after adjustment for sex, age and BMI z score (P < .0001). No association was observed between TSH level and HDL cholesterol.
Researchers also found that total cholesterol levels were higher in children with subclinical hypothyroidism vs. euthyroid children (mean, 4.43 mmol/L vs. 4.2 mmol/L; P = .0005), with results persisting after adjustment for age, sex and BMI z score. Similarly, non-HDL cholesterol levels were also higher in children with subclinical hypothyroidism vs. euthyroid children (mean, 3.08 mmol/L vs. 2.91 mmol/L; P = .001). When stratified by age groups, the differences persisted only among children aged 12 to 18 years, according to researchers.
Additionally, researchers found that children with mild subclinical hypothyroidism were nearly twice as likely to have elevated total cholesterol (OR = 1.88; 95% CI, 1.28-2.73) and elevated non-HDL cholesterol (OR = 1.72; 95% CI, 1.19-2.48) vs. euthyroid children. When again stratified by age groups, ORs were higher among children aged 12 to 18 years. The presence or absence of thyroid autoimmunity did not change the results.
“Randomized, placebo-controlled studies are needed to determine if the treatment of mild subclinical hypothyroidism in children will lead to improvement in their cholesterol levels and thereby decrease their risk for development of cardiovascular disease,” Kumar said. – by Regina Schaffer
For more information:
Seema Kumar, MD, can be reached at the Mayo Clinic Department of Internal Medicine, 200 First St. SW, Rochester, MN 55905; email: kumar.seema@mayo.edu.
Disclosures: The authors report no relevant financial disclosures.
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