Clinical research Hypothyroidism, new nodule formation and increase in nodule size in patients who have undergone hemithyroidectomy Sibel Ertek1, Reyhan Ünlü Ersoy2, Cüneyd AnIl3, Özgür Demir4, Murat Faik Erdog˘an4, Sevim Güllü4, Dilek Berker5, Kamile Gül2, Ug˘ur Ünlütürk4, Gürbüz Erdog˘an1; Ankara Thyroid Study Group 1Department of Endocrinology and Metabolic Diseases, Dr. R. Ege Hospital, Ufuk University Medical Faculty, Ankara, Turkey 2Department of Endocrinology and Metabolic Diseases, Ataturk Hospital, Ankara, Turkey 3Department of Endocrinology and Metabolic Diseases, Baskent University Hospital, Ankara, Turkey 4Department of Endocrinology and Metabolic Diseases, Ibni Sina Hospital, Ankara University Medical Faculty, Ankara, Turkey 5Department of Endocrinology and Metabolic Diseases, Numune Hospital, Ankara, Turkey Submitted: 8 October 2011 Accepted: 14 November 2011 Arch Med Sci 2012; 8, 2: 263-269 DOI: 10.5114/aoms.2012.28222 Copyright © 2012 Termedia & Banach A b s t r a c t Introduction: The current medical literature has conflicting results about fac- tors related to hypothyroidism and nodular recurrences during follow-up of hemithyroidectomized patients. We aimed to evaluate factors that may have a role in new nodule formation, hypothyroidism, increase in thyroid lobe and increase in nodule volumes in these patients with and without Hashimoto’s thy- roiditis (HT), and with and without levothyroxine (LT4) use. Material and methods: We enrolled 140 patients from five different hospitals in Ankara and evaluated their thyroid tests, autoantibody titre results and ultra- sonographic findings longitudinally between two visits with a minimum 6-month interval. Results: In patients with HT there was no significant difference between the two visits but in patients without HT, thyroid stimulating hormone (TSH) levels and nodule volume were higher, and free T4 levels were lower in the second visit. Similarly, in patients with LT4 treatment there was no difference in TSH, free T4 levels, or lobe or nodule size between the two visits, but the patients without LT4 had free T4 levels lower in the second visit. Regression analysis revealed a relationship between first visit TSH levels and hypothyroidism dur- ing follow-up. Conclusions: Patients who have undergone hemithyroidectomy without LT4 treatment and without HT diagnosis should be followed up more carefully for thyroid tests, new nodule formation and increase in nodule size. The TSH lev- els at the beginning of the follow-up may be helpful to estimate hypothyroidism in hemithyroidectomized patients. Key words: hemithyroidectomy, hypothyroidism, nodular goitre, Hashimoto’s disease, thyroid lobectomy. Introduction Thyroid nodules are one of the most frequent endocrinological problems in the adult population [1, 2]. The use of fine needle aspiration biopsy (FNA) Corresponding author: Sibel Ertek MD, PhD Endocrinology and Metabolic Diseases Department Ufuk University Medical Faculty Dr. R. Ege Hospital Mevlana Bulvari (Konya Yolu) No: 86-88 Balgat Ankara, Turkey Phone: +90 312 204 40 00 Fax: +90 312 204 40 55 E-mail: sibelertek@yahoo.it