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Endocr Pract. 2008 Jul-Aug;14(5):570-5.

Increased atherogenic low-density lipoprotein cholesterol in untreated subclinical hypothyroidism.

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Endocrinology Unit, Jahra Hospital, Ministry of Health, Alsalmyia, Kuwait, Kuwait.



To evaluate the effects of physiologic doses of levothyroxine replacement on the lipoprotein profile in patients with subclinical hypothyroidism (SCH).


In a prospective, double-blind, placebo-controlled study, we enrolled 120 patients--mostly, but not exclusively, premenopausal women--with SCH. Patients were randomly assigned to either a levothyroxine-treated group (n = 60) or a placebo (control) group (n = 60). Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) were measured before and 52 weeks after assignment to either group.


In the levothyroxine-treated group, the lipoprotein mean values before and after the 52-week study were as follows: TC, 5.05 +/- 0.98 mmol/L versus 4.74 +/- 0.87 mmol/L (P<.0001); LDL-C, 3.30 +/- 0.90 mmol/L versus 2.89 +/- 0.59 mmol/L (P<.01); TG, 1.18 +/- 0.71 mmol/L versus 0.95 +/- 0.53 mmol/L (P<.002); and HDL-C, 1.20 +/- 0.33 mmol/L versus 1.19 +/- 0.32 mmol/L (P = .29). In the control group, TC, HDL-C, and TG values remained unchanged after 52 weeks in comparison with baseline, but LDL-C mean values increased from 2.79 +/- 0.60 mmol/L to 3.11 +/- 0.77 mmol/L, a change that was statistically significant (P<.001). At the end of the study, the lipid profile changes between levothyroxine-treated and control groups were compared. Total cholesterol and LDL-C were significantly lower in the levothyroxine-receiving group (P<.029 and P<.0001, respectively) in comparison with the control group. The difference did not reach statistical significance for TG and HDL-C values.


In premenopausal women, SCH has a negative effect on the lipoprotein profile and may translate into a sizable cardiovascular risk if left untreated.

[Indexed for MEDLINE]

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