Effect of levo-thyroxine replacement on non-high-density lipoprotein cholesterol in hypothyroid patients.
BACKGROUND
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.
Ito
Mitsuru
M
Kuma Hospital, Kobe 650-0011, Japan. ito02@kuma-h.or.jp
Arishima
Takeshi
T
Kudo
Takumi
T
Nishihara
Eijun
E
Ohye
Hidemi
H
Kubota
Sumihisa
S
Fukata
Shuji
S
Amino
Nobuyuki
N
Kuma
Kanji
K
Sasaki
Ichiro
I
Hiraiwa
Tetsuya
T
Hanafusa
Toshiaki
T
Takamatsu
Junta
J
Miyauchi
Akira
A
D000328:Adult; D000368:Aged; D016632:Apolipoprotein A-I / Q000097:blood; D001055:Apolipoproteins B / Q000097:blood*; D002318:Cardiovascular Diseases / Q000453:epidemiology; D002784:Cholesterol / Q000097:blood*; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL / Q000097:blood; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy* / Q000453:epidemiology / Q000378:metabolism*; D017270:Lipoprotein(a) / Q000097:blood; D008074:Lipoproteins / Q000097:blood*; D008875:Middle Aged; D012307:Risk Factors; D013974:Thyroxine / Q000008:administration & dosage*; D014280:Triglycerides / Q000097:blood*
D016632:Apolipoprotein A-I; D001055:Apolipoproteins B; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D017270:Lipoprotein(a); D008074:Lipoproteins; D014280:Triglycerides; C112017:remnant-like particle cholesterol; D002784:Cholesterol; D013974:Thyroxine