Effect of Levo-Thyroxine Replacement on Non-High-Density Lipoprotein Cholesterol in Hypothyroid Patients

• Published in: The journal of clinical endocrinology and metabolism Vol. 92; no. 2; pp. 608 - 611
• Main Authors: Ito, Mitsuru, Arishima, Takeshi, Kudo, Takumi, Nishihara, Eijun, Ohye, Hidemi, Kubota, Sumihisa, Fukata, Shuji, Amino, Nobuyuki, Kuma, Kanji, Sasaki, Ichiro, Hiraiwa, Tetsuya, Hanafusa, Toshiaki, Takamatsu, Junta, Miyauchi, Akira
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01-02-2007
• Subjects: Adult; Aged; Apolipoprotein A-I - blood; Apolipoproteins B - blood; Biological and medical sciences; Cardiovascular Diseases - epidemiology; Cholesterol - blood; Cholesterol, HDL; Cholesterol, LDL - blood; Endocrinopathies; Fundamental and applied biological sciences. Psychology; Humans; Hypothyroidism - drug therapy; Hypothyroidism - epidemiology; Hypothyroidism - metabolism; Lipoprotein(a) - blood; Lipoproteins - blood; Medical sciences; Middle Aged; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Risk Factors; Thyroid. Thyroid axis (diseases); Thyroxine - administration & dosage; Triglycerides - blood; Vertebrates: endocrinology; Endocrinopathy; Human; Cholesterol HDL; Thyroid diseases; Thyroxine; Thyroid hormone; Replacement; Hypothyroidism; Endocrinology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2006-1605

Context: Recently, non-high-density lipoprotein cholesterol (non-HDL-C), a measure of total cholesterol minus HDL-C, has emerged as a predictor of cardiovascular disease.
Objective: We evaluated the effect of l-T4 replacement on non-HDL-C levels in patients with primary hypothyroidism.
Methods: Thirteen patients with overt hypothyroidism and 26 patients with subclinical hypothyroidism participated in the study. The lipid profiles, including non-HDL-C, were measured in patients with hypothyroidism before and 3 months after l-T4 replacement was started.
Results: After l-T4 replacement, the serum concentrations of all lipoproteins, exclusive of lipoprotein (a) [Lp(a)], were significantly decreased in patients with overt hypothyroidism. In patients with subclinical hypothyroidism, the serum concentrations of total cholesterol, non-HDL-C, remnant-like particle cholesterol, and apolipoprotein B (Apo B) were significantly decreased, whereas no significant changes in the serum concentrations of low-density lipoprotein cholesterol, HDL-C, triglycerides, apolipoprotein A-I, and Lp(a) were observed. In all 39 patients, the reduction in the non-HDL-C levels correlated with the reduction in the low-density lipoprotein cholesterol, remnant-like particle cholesterol, and Apo B levels. However, the reduction in the non-HDL-C levels did not correlate with the reduction in the HDL-C, Lp(a), and apolipoprotein A-I levels.
Conclusions: This study is the first to show that l-T4 replacement may reduce serum concentrations of non-HDL-C in patients with hypothyroidism. The study also suggests that such altered serum concentrations of non-HDL-C in hypothyroidism may be related to the disturbed metabolism of low-density lipoprotein, remnant lipoprotein, and Apo B.