Subclinical hyperthyroidism in the course of autonomous nodules - clinical evaluation

Subclinical hyperthyroidism (SCH), also known as mildly symptomatic hyperthyroidism, has recently been diagnosed more frequently. One of the main endogenous causes of this disorder is autonomously functioning thyroid nodule (AFTN). Despite the fact that it is usually asymptomatic, SCH entails repercussions on the cardiovascular system and bone, and it carries a risk of progression to overt hyperthyroidism with a typical clinical picture. Treatment is still controversial, and its benefits are widely debated in literature.

From 459 patients authors selected a group of 49 patients (10.6% of all subjects with hyperthyroidism), 41 women (83.7%) with AFTN at the stage SCH treated in the Outpatient Endocrinological Clinic and the Department of Endocrinology of the Medical University of Lublin over a three-year period. The method applied in the study was a retrospective analysis of medical records with a particular account of medical history, physical examination, and additional tests obtained during the process of diagnostic and therapeutic procedures.

Forty-one patients (83.7%) suffered from typical symptoms of hyperthyroidism; only eight patients (16.3%) were asymptomatic. The most frequently reported symptoms were tachycardia in women (51.2%) and anxiety in men (50%). The type of thyrostatic drugs and the length of therapy did not affect the outcome of iodine-131 therapy. In the vast majority of the patients (87.8%) radioidodine therapy was effective; 30 patients (61.2%) reached euthyreosis and 13 patients (22.5%) developed hypothyroidism.

Most patients with SCH in the course of AFTN suffered from typical symptoms of overt hyperthyroidism; only every sixth patient was asymptomatic. The volume of autonomous adenomas did not affect the result of 131I therapy; however, the impact of AFTN volume as well as the thyroid volume on RIT efficacy requires futher investigation. In the vast majority of patients 131I therapy was an effective method of treatment, and an earlier therapeutic effect was observed more often in the patients with focal lesions located in the right lobe.