Does diagnostic sonography alter thyroid and parathyroid hormone levels?

To investigate possible alterations in the levels of thyroid and parathyroid hormones (PTHs) and thyroglobulin (TG) in healthy individuals following diagnostic sonographic examination of the thyroid gland.

Thirty healthy women with no pathologic findings underwent sonographic examination, followed 6 weeks later by a second examination involving a probe-only application (PA) with the ultrasound scanner switched off. Duration times were identical for both examinations. Blood was drawn before and after the 2 applications. Thyroid hormone, PTH, and TG levels before and after the 2 applications were compared, and the difference between the variations for each parameter in the first and second applications was assessed. Blood samples were taken before and after the sonographic examination and the PA, and the serum concentrations of sensitive thyrotropin, total and free thyroxine, total and free tri-iodothyronine, TG, and PTH were measured. The pre- and post-examination levels of the hormones for the 2 applications were then compared and the difference between the variations for each parameter in the first and second application was then assessed.

The only significant variations observed were in the TG levels after PA and PTH levels after both sonographic examination and PA. The comparison between the 2 difference values revealed no significant difference except for PTH.

This preliminary report on the possible influence of sonographic examination of the thyroid on the serum levels of thyroid and parathyroid hormones suggests that gland secretions such as PTH may be affected by external factors, including ultrasound. Clinicians should be aware of alterations in hormone levels by external factors.