Short-term effect on parathyroid function after ¹³¹I treatment for differentiated thyroid carcinoma

Objective: To investigate the short-term effect on parathyroid function after ¹³¹I treatment for DTC. Methods: Seventy-three patients (15 males, 58 females, mean age (44.59 ± 12.89) y) who underwent ¹³¹I treatment for thyroid remnant ablation were enrolled in the study. Serum PTH and Ca²⁺ levels were evaluated at baseline and at 5 d after ¹³¹I administration. PTH levels were compared based on gender, age and residual thyroid mass. The t-test, analysis of variance and χ² test were used for statistical analysis. Results: Fifty-eight patients showed decreased PTH (79.45%), and 8 patients (10.95%) were below normal levels. Serum PTH levels significantly decreased at 5 d from baseline at (37.33 ± 17.71) ng/L to (27.19 ± 11.58) ng/L, respectively (t=6.76, P<0.01), but serum Ca²⁺ levels were within the normal range. There were statistically significant differences between gender (χ²=4.37, P=0.036), but no differences in age and quantity of residual thyroid mass (F=0.58, 0.61, 0.46, 0.76, all P>0.05). Conclusions: ¹³¹I treatment for DTC may induce decreased PTH levels in the short-term,particularly for female patients; though, serum Ca²⁺ concentration shows no statistically significant decrease. These changes are irrelevant to age and quantity of residual thyroid mass. (authors)