Relationships between plasma thyrotropin receptor antibodies and lipid or lipoprotein parameters in Graves' disease

Abstract

Rieu M, Revue E, Bonete R, Nunez S. Relationships between plasma thyrotropin receptor antibodies and lipid or lipoprotein parameters in Graves' disease. Eur J Endocrinol 1996:135:77–81. ISSN 0804–4643 Functional thyrotropin receptors (TSH-R) have recently been detected in fat cells but not in liver cells from rat, and it seems that in infant adipocytes stimulatory TSH-R antibodies (TSH-R-ab) act through this receptor pathway, resulting in increased triglyceride catabolism. We investigated the relationships between plasma TSH-R-ab and free thyroxine (FT4) levels and plasma lipid or lipoprotein values in 49 untreated adult women with Graves' disease, all positive for these antibodies. A simple positive correlation (p < 0.01) was found between TSH-R-ab levels and FT4 values (r = 0.40). Simple positive correlations (p < 0.001) were found between triglyceride levels and FT4 (r = 0.51) or TSH-R-ab (r = 0.52) values. Multiple regression analysis confirmed that both FT4 and TSH-R-ab are strong (p < 0.005) predictors of triglyceride (FT4: partial r = 0.40; TSH: partial r = 0.39). Simple negative correlations (p < 0.05, at least) were found between FT4 levels and total cholesterol (TC) (r = −0.45), low-density lipoprotein (LDL)-C (r = -0.46), apoprotein (apo)-B (r = −0.31) or high-density lipoprotein (HDL)-C (r = −0.55) values. Among these lipid parameters, only HDL-C levels (r = −0.31, p < 0.05) correlated to TSH-R-ab values. However, multiple regression analysis revealed that while FT4 is a strong predictor (p < 0.005) of TC (partial r = −0.42), LDL-C (partial r = −0.43) or HDL-C (partial r = 0.47), TSH-R-ab are not. Thus, the apparent positive relationship between TSH-R-ab and HDL-C results from the positive correlation between TSH-R-ab and FT4. In conclusion, this study suggests that stimulating TSH-R-ab are involved in triglyceride metabolism. In contrast to thyroid hormones, these antibodies seem not to be related to cholesterol metabolism. Max Rieu, Hôpital Saint Michel, 33 rue Olivier de Serres, 75015 Paris, France