Color Doppler ultrasound and real-time elastography in patients with hypothyroidism for the prediction of levothyroxine replacement: a cross-sectional study of 338 patients.

Aims: While hormonal assays are commonly used for thyroid function assessment, Doppler sonography provides valuable information on vascularization and blood flow. This study aimed to examine the potential associations between Doppler parameters and clinical characteristics of hypothyroid patients, such as the autoimmune nature of the disease and adequacy of LT4 replacement.

Methods: A total of 338 patients with hypothyroidism, primarily caused by autoimmune thyroiditis (AT), were enrolled in this study. Exclusion criteria comprised specific medical conditions, medication history, and nodular abnormalities of the thyroid gland. Patient demographics (age, sex, BMI), treatment parameters (LT4 daily dose), and thyroid hormone levels (TSH, fT4) were recorded.

Results: Among the enrolled patients, 85.2% had autoimmune thyroiditis. Suboptimal levothyroxine (LT4) replacement was observed in 20.1% of patients at the time of enrollment. Patients with autoimmune thyroiditis had increased elastography ratios compared to those without autoimmune disease and present a positive association of elastography ratios with vascularity. In patients without autoimmune thyroiditis, those with suboptimal LT4 replacement had lower total thyroid volume. Patients with suboptimal LT4 replacement had higher peak systolic velocity (PSV) and end-diastolic velocity (EDV) in the inferior thyroid artery and lower resistive index (RI). The severity of hypothyroidism, as indicated by LT4 dose/body mass index (BMI), was negatively correlated with thyroid volume and EDV values of superior and inferior thyroid arteries. PSV of the inferior thyroid artery can predict suboptimal LT4 replacement (sensitivity 81.8%, specificity 42%).

Conclusions: In situations where obtaining blood tests may be challenging, utilizing color Doppler ultrasound can serve as an alternative method to assess treatment responses and identify patients who require further hormonal examinations.