Thyroid function in children with different lipoprotein profiles: observations in a biracial (black/white) population--the Bogalusa Heart Study.

Abnormalities of thyroid function are associated with hyperlipidemia, a risk factor for coronary artery disease that starts in childhood. We investigated the age-, race-, and sex-related differences in thyroid function and its relation to serum lipoprotein levels in children (n = 363) aged 6 to 18 years from the biracial (black/white) community of Bogalusa, Louisiana, using an ultrasensitive thyroid-stimulating hormone (TSH) assay. Serum levels of lipoprotein cholesterol fractions, triglycerides, triiodothyronine (T3), thyroxine (T4), and the Tanner stage of sexual development were determined. Serum T3 (P < 0.0001), T4 (P < 0.0001), and TSH (P < 0.0020) levels decreased significantly with Tanner stage. Serum T4 levels were significantly higher (P < 0.0001) in both black and white females than their male counterparts. An unexpected finding was a significantly increased mean serum TSH in whites (2.09 + 0.91; mean + standard error of mean) when compared to blacks (1.74 + 0.10; P = 0.0185). Overall, no significant correlation was noted between serum lipoprotein variables and TSH. However, those with the highest low-density lipoprotein to very low-density lipoprotein cholesterol fractions had a higher T4 and a T4/TSH ratio than those with the lowest low-density lipoprotein to very low-density lipoprotein cholesterol fractions. In summary, it is concluded that there is no simple relationship between lipoproteins and TSH or thyroid hormone levels in children.