en Endocrinology Endocrinology Original Article Original Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background:</span></i></b> Thyroid nodules are a significant clinical concern due to their potential for malignancy. Research suggests prolactin, a known mitogen, may contribute to cancer development, and elevated thyroid peroxidase antibody (TPO-Ab) levels are linked to increased thyroid nodularity in hyperprolactinemia. This study investigates the relationship between serum prolactin levels, thyroid nodularity, and TPO-Ab presence.</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Methods:</span></i></b> Ninety patients were divided into three groups of 30: a control group without nodules, and two case groups with nodules (one TPO-Ab positive, one TPO-Ab negative). Serum prolactin, TPO-Ab, thyroid stimulating hormone, T4, and thyroid ultrasound data were analyzed. Statistical significance was set at p < 0.05.</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Results:</span></i></b> The mean age of the participants was 46.07&plusmn;12.40 years, with 16 (17.8%) males and 74 (82.2%) females. Serum TSH, prolactin, and TPO-Ab levels were significantly higher in the case group than in the control group (P=0.041, 0.050, and 0.000, respectively). The case group had more instances of hyperprolactinemia than the control group (35% vs. 13.3%) (OR = 3.5, CI 95% = 1.08-11.38, P=0.031). Furthermore, the TPO-Ab positive group demonstrated greater solidity than the TPO-Ab negative group (93.3% vs 73.3%, P=0.038). </span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusion:</span></i></b> Our study revealed a positive correlation between thyroid nodules and increased serum TSH, prolactin, and TPO-Ab levels. Furthermore, we discovered that TPO-Ab positive nodules exhibit greater solidity and elevated TSH levels. </span></span></span><br> &nbsp; Thyroid nodule, Prolactin, Antithyroid peroxidase antibody (TPO-Ab), Thyroid-stimulating hormone (TSH) 712 717 http://caspjim.com/browse.php?a_code=A-10-3199-1&slc_lang=en&sid=1 Maedeh Mataji Maedemataji@gmail.com 100319475328460054638 100319475328460054638 No Diabetes Research Center, Mazandaran University of Medical Sciences, Sari, Iran Mehran Frouzanian Frouzanian@gmail.com 100319475328460054639 100319475328460054639 No Student Research Committee, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran Zahra Kashi kashi_zahra@yahoo.com 100319475328460054640 100319475328460054640 No Department of Internal Medicine, Diabetes Research Center, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran Amirsaleh Abdollahi a.abdollahi@mazums.ac.ir 100319475328460054641 100319475328460054641 No Student Research Committee, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran Adele Bahar doctor_bahar2000@yahoo.com 100319475328460054642 100319475328460054642 Yes Department of Internal Medicine, Diabetes Research Center, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran Reza Ali Mohammadpour mohammadpour2002@yahoo.com 100319475328460054643 100319475328460054643 No Department of Biostatistics, Faculty of Health, Diabetes Research Center, Mazandaran University of Medical Sciences, Sari, Iran