Relevance analysis of thyroid hormone, serum creatase enzymes and lipids in patients with differentiated thyroid cancer under and withdrawal of levothyroxine treatment

Abstract

Objective To investigate the changes in the thyroid hormone, serum creatase enzymes, lipids, and clinical manifestations of differentiated thyroid cancer patients with levothyroxine withdrawal. Methods Forty-six differentiated thyroid carcinoma (DTC) patients were enrolled. The serial thyroid function [free triiodothyronine (FT3), free thyroxine (FT4), and thyroid stimulating hormone (TSH)], serum creatase enzymes [aspartate aminotransferase (AST), lactate dehydrogenase (LDH), alpha-hydroxybutyric dehydrogenase (α-HBD), creatine kinase (CK), and isoenzymes of creatine kinase (CKMB)], lipids [triglyceride (TG), total cholesterol (TC), high density lipoprotein (HDL), and low density lipoprotein (LDL)] levels of these patients were tested during a four-week levothyroxine withdrawal. These levels were then retested after 4, 8, and 12 weeks. The time-change curve was acquired and the clinical symptoms were recorded. Fifty patients with a normal thyroid function were included in the control group. A rank-sum test and a correlation analysis were performed to analyze the relationship among the FT3, FT4, and serum creatase enzymes of patients undergoing a four-week levothyroxine withdrawal. Results ① A statistically significant relationship was observed between those patients with DTC withdrawal and those in the control group in terms of their serum creatase enzymes and lipids [AST(t=3.888, P<0.05), LDH(Z=-3.372, P<0.05), CK(Z=-5.913, P<0.05), TG(Z=-2.787, P<0.05), TC(t=6.166, P<0.05), HDL(t=3.041, P<0.05), LDL(t=5.372, P<0.05)]. ② CK, TG, TC, and LDL returned to their normal levels after reusing levothyroxine for four weeks. ③ FT3 is negatively related to CK and TC, while FT4 is negatively related to LDH, α-HBD, CK, CKMB, and TG. ④86.96 percent of the major clinical manifestation are muscular soreness, hypodynamia and tumidness in DTC patients undergoing a four-week levothyroxine withdrawal. Conclusions ① Levothyroxine withdrawal can lead to abnormal AST, LDH, CK, TG, TC, HDL, and LDL levels. ② The changes in the serum creatase enzymes and lipids of patients with DTC withdrawal were reversible. ③ The FT3 and FT4 levels influenced CK abnormality. ④Hypothyroid myopathy occurred in DTC patients undergoing a four-week levothyroxine withdrawal, and the clinical manifestation was improved by reusing levothyroxine. Key words: Thyroid neoplasms; Thyroxine; Serum creatase enzymes; Lipids