Patients on LT4 2nd visit 5.55 ±4.84 16.51 ±4.87 3.44 ±3.11 9.83 ±9.18 1.01 ±1.01 13.2 ±4.8 9.4 ±3.5 2.9 ±2.5 1.3 ±1.1 Value of p 0.251 0.053 0.069 0.274 0.134 0.274 0.195 0.799 0.891 1st visit 2.61 ±4.46 15.31 ±2.84 3.84 ±0.95 10.53 ±7.03 0.98 ±1.05 5.8 ±1.4 2.1 ±1.1 1.4 ±1.2 2.2 ±2.3 Patients not on LT4 2nd visit Value of p* 2.31 ±1.67 13.81 ±3.10 4.03 ±1.75 9.72 ±6.55 1.22 ±1.36 6.2 ±1.6 2.0 ±1.4 1.4 ±1.6 3.1 ±1.1 0.109 0.001* 0.572 0.329 0.055 0.288 0.446 0.347 0.043* Hypothyroidism, new nodule formation and increase in nodule size in patients who have undergone hemithyroidectomy Table III. Comparison of thyroid tests and ultrasonographic findings in patients on and not on LT4 use, for two dif- ferent visits Arch Med Sci 2, April / 2012 267 Parameter TSH [mIU/ml] sT4 [pmol/l] sT3 [pmol/l] Number of nodules Nodule 1 volume** Nodule 2 volume Nodule 3 volume Nodule volume** 1st visit 3.11 ±2.86 17.07 ±4.45 3.76 ±1.31 0.83 ±0.94 12.8 ±4.7 8.9 ±2.4 2.8 ±1.4 1.3 ±1.0 Remaining lobe volume** 9.96 ±9.75 *p < 0.05, **Nodule volumes are calculated in millilitres (ml) nificance the two groups were compared (by χ2 test) and neither nodule size (p = 0.588) nor remaining lobe volume (p = 0.513) was statistical- ly or clinically different. Factors related to hypothyroidism, number of nodules, increase in nodule and remaining lobe volumes We evaluated the role of age, gender, presence of HT, LT4 use and TSH value at the first visit on hypothyroidism at the second visit. Only the TSH value at the first visit was associated with hypothy- roidism (p = 0.035, exp(B) = 1.083, 95% CI: 1.006- 1.167). The same parameters were also tested for increase in number of nodules, for nodule size and for remaining lobe volume (by logistic regression analysis) and none of them were significantly relat- ed (p > 0.05). Discussion Partial thyroidectomies provide some advantages to the patient, for example they are associated with lower incidence of hypothyroidism and lower risks of surgical complications. Risk of chronic hypothy- roidism was found to be 87% in subtotal and 46% in hemithyroidectomies compared to 100% in total thyroidectomies [4]. Hemithyroidectomy also lessens the risk of hypocalcaemia and recurrent laryngeal nerve injury, but with a risk of nodule recurrence [5, 6]. The medical literature provides conflicting findings with regard to the factors asso- ciated with hypothyroidism and formation of new nodules, and the need for LT4 use to prevent recur- rences. In the study by Niepomniszcze et al., 47 women with hemithyroidectomy due to follicular adenoma were evaluated with palpation for 7 years and they found 32% new nodule and goitre forma- tion in patients without LT4 use [7]. In another study by Bellantone et al. evaluating patients with unilateral toxic nodular goitre, LT4 use decreased the recurrence of nodules [8], whereas Waldström et al. did not find any benefit of LT4 use in multin- odular goitre patients after hemithyroidectomy [9]. In our study we did not find a relationship between number of nodules, nodule volume, lobe volume and LT4 use or HT. But when we compared patients on LT4 treatment with those not on LT4, patients not on LT4 treatment had lower free T4 and it resulted in a statistically significant (but not clini- cally important) increase in nodule volume at the second visit. Thus, we suggest that patients, par- ticularly those not on LT4 treatment, should be fol- lowed closely for nodule enlargement and new nod- ule formation. Wolmard et al. suggested the importance of starting TSH levels (> 1.6 μU/ml) and lymphocytic infiltration in thyroid parenchyma to predict risk of hypothyroidism in these patients [18]. Like Wormald et al., in our study, baseline TSH levels were significantly associated with hypothyroidism. However, in our study, patients with HT did not have a significant increase in TSH and number of nodules in the follow-up visit, while among those without HT patients had a significant increase in TSH and number of nodules. It is known that patients with nodular goitres may be predisposed to clonal or polyclonal nodular recurrence tenden- cy [19] but in HT, lymphocytic infiltration and atro- phy of the gland [20] may be the reason for the lower number of nodules. There is also a debate on LT4 use for the pre- vention of nodule formation in the remaining thy- roid lobe after a partial thyroidectomy. Alba et al. followed 223 patients and they found less nodular recurrence among patients with LT4 use [21]. Yetkin et al. reported that the nodular recurrence was associated with multinodularity, specific histopatho-