Abstract
Background: Subclinical hypothyroidism is associated with increased blood lipid levels. However, the exact role of thyrotropin (TSH) alone is not clear. In order to clarify this point, we analysed the acute effect of recombinant human TSH (rhTSH) administration on lipid levels. Methods: Sera of 27 premenopausal women with well-differentiated thyroid cancer were analysed. Patients that underwent a total thyroidectomy, ablation with 131I (Iodine 131) and rhTSH administration as a part of routine follow-up American Thyroid Association guidelines were included. The protocol consists of 2 intramuscular injections of 0.9 mg of rhTSH, performed on day 1 day and day 2, with blood collection on day 1 (before rhTSH administration), and day 5. TSH, free thyroxine, total cholesterol, low-density lipoprotein cholesterol (LDLc), high density lipoprotein cholesterol (HDLc), and triglycerides were assessed in all the samples, before and four days after the first administration of rhTSH. Results: Total cholesterol and triglycerides significantly increased after stimulation of rhTSH (respectively, 192 ± 33 vs. 207 ± 26, p = 0.036 and 72 ± 23 vs. 85 ± 23, p = 0.016). LDLc and HDLc showed comparable concentrations before and after the test (respectively, 115 ± 27 vs. 126 ± 22, p = 0.066, and 62 ± 15 vs. 64 ± 15, p = 0.339), while non-HDLc increased after stimulation (130 ± 30 vs. 143 ± 25, p = 0.045). Conclusion: TSH has a direct effect on total cholesterol, triglycerides, and nonHDLc. Explanation of these phenomena will require additional studies.
Highlights
Thyroid hormones regulate different processes in the human body and the effects of their action are more evident during dysfunction of the thyroid gland, affecting processes from the cardiovascular system to cognition level [1,2,3]
We aimed to investigate the role of recombinant human TSH (rhTSH) on lipids by using a sample of pre-menopausal women with well-differentiated thyroid cancer, treated with total thyroidectomy and 131I remnant ablation
Total cholesterol and triglycerides significantly increased after stimulation of rhTSH
Summary
Thyroid hormones regulate different processes in the human body and the effects of their action are more evident during dysfunction of the thyroid gland, affecting processes from the cardiovascular system to cognition level [1,2,3]. Subclinical hypothyroidism, defined as increased thyrotropin (TSH) level and free hormones within the normal range, is associated with atherosclerosis and worse lipid metabolism [6]. While the serious effects of overt hypothyroidism (increased TSH and low free hormones) are well acknowledged, different studies were focused on the association between subclinical hypothyroidism and increased serum lipid concentration. Some studies found and association between thyroid hormone and total cholesterol [10], while others reported with total cholesterol, low density lipoprotein cholesterol (LDLc), triglycerides [11,12], and even with high density lipoprotein cholesterol (HDLc) [13]. TSH, free thyroxine, total cholesterol, low-density lipoprotein cholesterol (LDLc), high density lipoprotein cholesterol (HDLc), and triglycerides were assessed in all the samples, before and four days after the first administration of rhTSH.
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