Hypothyroidism, new nodule formation and increase in nodule size in patients who have undergone hemithyroidectomy Statistical analysis Differences in the test results between the two visits were compared using the Wilcoxon signed rank test by presence of HT, by gender, and by LT4 use. Factors found in bivariate analyses to be asso- ciated with hypothyroidism (increase in nodule number and volume, increase in thyroid volume) were evaluated by multivariate logistic regression analysis, using the program SPSS 16.0. Two-sided statistical significance was considered if the p val- ue was < 0.05. For evaluation of increase in nod- ule size we compared the size of each nodule (there were 4 nodules maximum) between the two visits. Results Among 140 patients 27 (19.3%) were male, 113 (80.7%) were female, and mean age (± SD) was 52.7 (±11.9) years. Postoperative pathological exam- ination revealed HT in 40 patients (28.6%). Inci- dence of HT (p = 0.018) and the anti-TPO antibody levels (p = 0.004 at first visit and p = 0.035 at sec- ond visit) were higher in women (Table I). Thyroid tests and ultrasonography in HT and non-HT groups Comparison of thyroid tests and ultrasono- graphic evaluation between the two visits in HT and non-HT patients are summarized in Table II. There were no differences between the two visits among patients with HT, whereas in patients without HT, TSH was higher at the second visit (p = 0.042), free T4 was lower (p = 0.001), number of nodules was higher (p = 0.005) and nodule sizes were increased with a slight statistically significant difference (p = 0.043) (Figures 1 and 2). However, when we compared the two visits using the clinical signifi- cance definitions (i.e. > 20% increase in nodule vol- ume and > 10% increase in remaining lobe volume) those differences were not significant (for nodule size p = 0.523 and for lobe size p = 0.329). Among these patients with HT 11 (27.5%) were having LT4 treatment, and among the patients with- out HT, 39 (39%) were taking LT4. Thyroid tests and ultrasonography in patients with and without LT4 use Ultrasonography findings and thyroid tests of patients were compared separately between the two visits by LT4 use (Table III). There was no sig- nificant difference between the two visits in patients on LT4 treatment, but in patients not on LT4, free T4 was significantly lower at the second visit (p = 0.001) and nodule size had increased in one nodule slightly (p = 0.043). There was an increase in nodule number but statistical tests did not reveal significance (p = 0.055). For clinical sig- Table I. Comparison of thyroid tests and ultrasonographic findings in men and women for two different visits Parameter Age [years] Hashimoto thyroiditis [%] LT4 use [%] 1st visit TSH [mIU/ml] 1st visit sT3 [pmol/l] 1st visit sT4 [pmol/l] 1st visit anti-TG 1st visit anti-TPO 2nd visit TSH 2nd visit sT3 2nd visit T4 2nd visit anti-TG 2nd visit anti-TPO 1st visit nodule no. 2nd visit nodule no. 1st visit remaining lobe volume [ml] 2nd visit remaining lobe volume [ml] SD – standard deviation, *statistically significant (p < 0.05) Arch Med Sci 2, April / 2012 Female (mean ± SD) 51.5 ±11.36 32.7 83.8 3.2 ±3.19 3.67 ±1.04 16.03 ±3.72 69.18 ±63.31 56.30 ±42.5 4.29 ±3.45 3.71 ±1.49 14.62 ±4.34 78.30 ±76.12 63.74 ±60.21 0.89 ±0.79 1.15 ±1.18 9.8 ±8.2 9.2 ±9.1 Male (mean ± SD) 57.2 ±13.4 11.1 16.2 1.42 ±1.16 4.33 ±1.35 16.74 ±4.15 20.88 ±16.04 11.97 ±8.50 2.15 ±1.95 3.73 ±0.94 14.92 ±3.41 21.46 ±19.70 13.17 ±14.10 1.00 ±0.97 1.00 ±1.33 12.0 ±9.11 11.95 ±8.22 All patients (mean ± SD) 52.6 ±11.96 28.6 48.6 2.85 ±2.62 3.80 ±1.13 16.17 ±3.81 60.25 ±53.44 47.06 ±28.05 3.88 ±2.92 3.71 ±1.39 14.68 ±4.17 68.13 ±64.01 53.85 ±45.03 0.91 ±0.89 1.12 ±1.20 10.2 ±8.4 9.78 ±9.07 Difference (value of p)* 0.712 0.018* 0.245 0.063 0.172 0.623 0.246 0.004* 0.583 0.587 0.697 0.865 0.035* 0.685 0.784 0.816 0.017* 265