Incidence of toxic goiters, pyramidal lobe, antithyroid antibodies and preference of fixed doses of I-131 for ablation of various toxic goiters in Karachiites

Abstract

Background: Hyperthyroidism has variable incidences depending upon the regional iodine status and thyroid imaging is used to ascertain type of toxic goiters. Radioioidine-131 (RAI) therapy is considered an effective therapeutic option with variable utilization in different parts of world. Aim of this study was to find out the incidence of toxic goiters, various clinical and scintigraphic parameters and preference of RAI treatment in different types of toxic goiters. Materials and Methods: This was a retrospective observational study conducted at Nuclear Medicine sections of Aga Khan University Hospital (January 2012 till August 2014) and Dr Ziauddin Hospital Karachi (April 2013 till August 2014). Records of all patients who were referred for thyroid scan during the study period were reviewed. Patients who were diagnosed with toxic goiters and later on had had RAI were reviewed for demographic data, type of toxic goiters, scintigraphic patterns (% uptake and pyramidal lobe), thyroid antibodies and administered dose of RAI. Results: The overall incidence of toxic goiter was found to be 27% (370/1365). The mean age of the patients with toxic goiters was 46 years with female: male ratio of 69%: 31%. Graves’ disease was found in 317 (86%) patients followed by autonomous toxic nodule   in 44 (12%) and toxic MNG in 09 (02%). Pyramidal lobe was seen in 156 (42%) predominantly with GD. Thyroid antibodies was positive in 250/370 (68%) and negative in 120/370 (32%) and mean dose of RAI administered was 15± 3.51 mCi. Conclusion: We conclude that incidence of toxic goiters was in accordance with published data and GD was found to be the most common cause while the TMNG as the least common despite Pakistan lies in iodine deplete region. Antithyroid antibodies as an indicator of autoimmunity were found positive in majority of patients with GD and presence of pyramidal lobe has strong correlation with GD. Fixed doses of RAI was used for ablation of toxic goiters but outcome  of this approach needs to be evaluated.

Key Words: Toxic goiter; incidence; Graves’ disease; Pyramidal lobe; Antithyroid antibodies