Effect of thyroid hormone replacement on lipoprotein(a), lipids, and apolipoproteins in subjects with hypothyroidism.
OBJECTIVE
To study the effect of thyroid hormone replacement on total cholesterol, low-density lipoprotein cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), apolipoprotein A-I and B-100, and lipoprotein(a) [Lp(a)] in subjects with hypothyroidism.


METHODS
In 17 patients with clinical primary hypothyroidism, studies were done before and after thyroid hormone replacement therapy. Free thyroxine and thyrotropin were determined by chemiluminescent assay. Total cholesterol and triglycerides were measured by enzymatic methods, and HDL-C was measured after dextran sulfate-MgCl2 precipitation. Apolipoprotein A-I and B-100 were assayed by immunonephelometry. For measurement of Lp(a), we used a sequential sandwich enzyme-linked immunosorbent assay.


RESULTS
After levothyroxine treatment, the mean concentration of thyrotropin decreased from 91.4 to 3.7 microIU/mL, and free thyroxine increased from 0.5 to 1.2 ng/ dL. Total cholesterol, triglycerides, HDL-C, low-density lipoprotein cholesterol, and apolipoprotein A-I and B-100 decreased after thyroid hormone replacement therapy. Lp(a) levels also decreased significantly (P<0.05) after treatment, from a mean of 33.4 to 25.6 mg/dL.


CONCLUSIONS
Hypothyroidism is associated with an increase in total cholesterol, triglycerides, HDL-C, apolipoprotein A-I and B-100, and Lp(a). A reduction in lipid and lipoprotein levels after thyroid hormone replacement in our study cohort resulted in a less atherogenic profile.
Martínez-Triguero
M L
ML
Endocrinology and Analysis Department, Hospital Universitario Dr. Peset, Valencia, Spain.
Hernández-Mijares
A
A
Nguyen
T T
TT
Muñoz
M L
ML
Peña
H
H
Morillas
C
C
Lorente
D
D
Lluch
I
I
Molina
E
E
D001053:Apolipoproteins / Q000097:blood; D002784:Cholesterol / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000188:drug therapy; D008055:Lipids / Q000097:blood*; D017270:Lipoprotein(a) / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use*; D014280:Triglycerides / Q000097:blood
D001053:Apolipoproteins; D008055:Lipids; D017270:Lipoprotein(a); D014280:Triglycerides; D002784:Cholesterol; D013974:Thyroxine