Abstract
Objective: To determine whether and to what extent the acute hypothyroidism induced by thyroid hormone withdrawal (THW) impairs lipid metabolism, body weight (BW), BMI and blood pressure (RR) levels in patients with differentiated thyroid cancer (DTC).
Methods: Thirty-seven patients with DTC following total thyroidectomy participated in this study. In 19 patients (Gr1) levothyroxine (LT4) suppressive therapy was withdrawn for 4 weeks in preparation for radioactive iodine ablation, whereas 18 patients (Gr2) were prepared with rhTSH while on LT4 treatment. Clinical examination, including measurement of body weight (BW), BMI and blood pressure (RR) and blood sampling to determine total cholesterol (TC), HDL-C, LDL-C and triglyceride, were performed at baseline and at 4 and 24 weeks thereafter.
Results: In Gr1 TC and LDL-C were considerably increased by 27% (p<0.01) and 48% (p><0.001), respectively at W4, whereas no significant changes were observed for HDL-C and triglyceride. At W24 TC was completely reversed to baseline levels (201±33 mg/dl), while LDL-C was found within the upper normal range, although not significantly changed, as compared to W0 (135±33 mg/dl vs. 118±29 mg/dl, n.s). BW and BMI were both increased in Gr1 at W4 by +4.1Kg (p><0.05) and +1.2 kg/m2, respectively, while they were still not completely reversed at W24 (Gr1: +2.2kg, BMI:+0.7 kg/m2). No significant change of any study parameter was registered in Gr2. Systolic and diastolic RR showed minor changes and stayed relatively stable in both groups.
Conclusions: Short-term hypothyroidism induced by THW seriously impairs lipid metabolism and BW in patients in preparation for radioiodine ablation. The changes are not completely reversed even after several months of LT4 resumption. These results should be seriously borne in mind when patients with severe comorbidities are prepared for radioiodine ablation.