Original article
Lipid profile in different degrees of hypothyroidism and effects of levothyroxine replacement in mild thyroid failure

https://doi.org/10.1016/j.trsl.2007.12.006Get rights and content

The aim of this study was to evaluate the lipid profile of patients with different degrees of hypothyroidism and the effect of levothyroxine replacement in subclinical hypothyroidism (SH). Initially, a cross-sectional study was performed with 226 participants [SH = 133 participants, manifest hypothyroidism (MH) = 23 participants, and euthyroidism (EU) = 70 participants]. The mean levels of atherogenic lipid variables were greater in MH than in SH and were greater in SH than in EU, although the differences between SH and EU did not reach statistical significance. The SH subgroup with greater serum thyrotropin (TSH) levels and that with positive antithyroperoxidase antibodies (TPO-Ab) had greater levels of triglycerides and of the atherogenic index Apo B/Apo A. A positive correlation exists between serum TSH and total cholesterol (rs = 0.167; P = 0.006), triglycerides (rs = 0.219; P < 0.001), and ApoB levels (rs = 0.205; P < 0.001). Eleven patients who received levothyroxine (L-T4) treatment and 15 patients who received placebo were reevaluated 1 year after TSH adjusted intervention. A fall in atherogenic variables was observed in the L-T4–treated group, with significance for total cholesterol (−20.0 vs +16.1 mg/dL in the placebo group) and LDL-c (−21.7 vs +17.2 mg/dL). We concluded that SH leads to an intermediary lipid profile between euthyroid individuals and that found in manifest hypothyroidism and that a significant lipid profile improvement occurred 1 year after L-T4 replacement therapy.

Section snippets

Study population

Participants were recruited from the Outpatient Clinic of the Clementino Fraga Filho University Hospital (HUCFF) and Federal University of Rio de Janeiro (UFRJ) between the years 2001 and 2006. To be enrolled in the SH group, the patients had 2 laboratorial serum determinations with a minimum interval period of 6 weeks, both TSH levels above normal upper limit (4.0 μUI/mL), and free thyroxine (FT4) were in the normal range (0.9–1.8 ng/dL). Manifest hypothyroidism (MH) patients had low FT4

Results

Overall, 226 participants were included within the years of 2001 and 2006. Of those participants, 133 patients had SH (6 patients were men), 23 patients had MH (all of them were women), and 70 patients (2 men) had no thyroid dysfunction.

Spontaneous hypothyroidism was the more prevalent etiology of disease in the group, but 9 patients (SH = 8) had history of ablative therapy for Graves disease, and 7 patients had been thyroidectomized for benign nodular disease (SH = 6). The presence of TPO-Ab

Discussion

The findings of the current study suggest that SH might be an intermediate state between EU and MH. It was demonstrated that the lipid profile of SH patients did not differ significantly from EU, except in the subgroups of patients with positive TPO-Ab and TSH greater than 8.0 μUI/mL.

Although not statistically significant, when compared with the EU group, the means of all lipid variables of the study were greater in SH. In addition, the means were lesser than those of MH group, except for

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