Effect of rhTSH on Lipids

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 I-131 (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.