Determination of the autonomously functioning volume of the thyroid

Area of Science:

• Endocrinology
• Nuclear Medicine
• Thyroidology

Background:

• Determining autonomously functioning thyroid volume is crucial for prognostic and therapeutic decisions in goiter management.
• Assessing thyroid autonomy aids in predicting and preventing hyperthyroidism.

Purpose of the Study:

• To establish a method for determining the autonomously functioning thyroid volume in euthyroid and hyperthyroid goiters.
• To identify the critical autonomous volume threshold for the onset of hyperthyroidism.
• To enable precise patient selection for definitive treatment of thyroid autonomy.

Main Methods:

• Technetium-99m thyroid uptake measurements were performed under exogenous (TcUs) and endogenous (TcU) suppression in various patient groups.
• Sonography was used to delineate and measure autonomous thyroid volume.
• A formula (TcUs/TcU x total thyroid volume) was employed to calculate autonomous volume, referencing a baseline in healthy individuals.

Main Results:

• A linear correlation was observed between TcUs/TcU values and sonographically measured autonomous volume in unifocal autonomy.
• The mean autonomous volume in healthy individuals was determined to be 2.2 +/- 1.1 ml.
• A critical autonomous volume of 16 ml was identified, predicting hyperthyroidism with high sensitivity and specificity (>0.9).

Conclusions:

• The developed method accurately quantifies autonomously functioning thyroid volume, irrespective of its distribution.
• This technique facilitates the selection of patients for preemptive treatment before hyperthyroidism develops.
• The method converts relative functional parameters into absolute functioning volume measurements for improved thyroid disorder management, particularly for radioiodine therapy.