TSH-controlled L-thyroxine therapy reduces cholesterol levels and clinical symptoms in subclinical hypothyroidism: a double blind, placebo-controlled trial (Basel Thyroid Study).
This study evaluated the effect of physiological, TSH-guided, L-thyroxine treatment on serum lipids and clinical symptoms in patients with subclinical hypothyroidism. Sixty-six women with proven subclinical hypothyroidism (TSH, 11.7 +/- 0.8 mIU/liter) were randomly assigned to receive L-thyroxine or placebo for 48 wk. Individual L-thyroxine replacement (mean dose, 85.5 +/- 4.3 microg/d) was performed based on blinded TSH monitoring, resulting in euthyroid TSH levels (3.1 +/- 0.3 mIU/liter). Lipid concentrations and clinical scores were measured before and after treatment. Sixty-three of 66 patients completed the study. In the L-thyroxine group (n = 31) total cholesterol and low density lipoprotein cholesterol were significantly reduced [-0.24 mmol/liter, 3.8% (P = 0.015) and -0.33 mmol/liter, 8.2% (P = 0.004), respectively]. Low density lipoprotein cholesterol decrease was more pronounced in patients with TSH levels greater than 12 mIU/liter or elevated low density lipoprotein cholesterol levels at baseline. A significant decrease in apolipoprotein B-100 concentrations was observed (P = 0.037), whereas high density lipoprotein cholesterol, triglycerides, apolipoprotein AI, and lipoprotein(a) levels remained unchanged. Two clinical scores assessing symptoms and signs of hypothyroidism (Billewicz and Zulewski scores) improved significantly (P = 0.02). This is the first double blind study to show that physiological L-thyroxine replacement in patients with subclinical hypothyroidism has a beneficial effect on low density lipoprotein cholesterol levels and clinical symptoms of hypothyroidism. An important risk reduction of cardiovascular mortality of 9-31% can be estimated from the observed improvement in low density lipoprotein cholesterol.
Meier
C
C
Division of Endocrinology, Department of Central Laboratories, University Hospital Basel, Petersgraben 4, CH-4031 Basel, Switzerland. cmeier@uhbs.ch
Staub
J J
JJ
Roth
C B
CB
Guglielmetti
M
M
Kunz
M
M
Miserez
A R
AR
Drewe
J
J
Huber
P
P
Herzog
R
R
Müller
B
B
D002784:Cholesterol / Q000097:blood*; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D004311:Double-Blind Method; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000188:drug therapy*; D008875:Middle Aged; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use*
D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D013972:Thyrotropin; D002784:Cholesterol; D013974:Thyroxine