Mild subclinical hypothyroidism is associated with paediatric dyslipidaemia

Background: There is a lack of consensus on the cardiometabolic consequences of mild subclinical hypothyroidism (SCH) among children. The objective of the current study was to compare lipid profiles in children with mild SCH with those of euthyroid children. Study Design: Retrospective medical record review. Patients: Children (ages 2-18 years) who had undergone simultaneous measurement of TSH, free thyroxine (T4) and lipids. Lipids in children with mild SCH (TSH 5-<10 mIU/L and normal free T4, n = 228) were compared with those in euthyroid children (n = 1215). Results: TSH level was positively associated with total cholesterol and nonhigh density lipoprotein (non-HDL) cholesterol [β 0.05(0.03-0.08), P <.0001 and β 0.05(0.03-0.08), P <.0001, respectively]. Total cholesterol was significantly higher in children and adolescents with mild SCH compared with euthyroid children (4.43 ± 1.14 mmol/L vs 4.2 ± 0.85 mmol/L, P =.0005). Similarly, non-HDL cholesterol level was also higher in children with mild SCH relative to euthyroid children (3.08 ± 1.14 mmol/L vs 2.91 ± 0.8 mmol/L, P =.001). The adjusted odds ratio of having elevated total cholesterol and elevated non-HDL cholesterol was greater in children with mild SCH compared with euthyroid children (OR 1.88, 95% CI; 1.28-2.73; P =.001 and 1.72, 95% CI 1.2-2.5; P =.003, respectively). The presence of thyroid autoimmunity was not associated with higher rates of dyslipidaemia. Conclusions: Mild SCH in children and adolescents was associated with higher rates of elevated total cholesterol and elevated non-HDL cholesterol. Randomized placebo controlled studies are warranted to determine if treatment of mild SCH in children leads to improvement in lipid profile.