Ultrasound and Doppler Elastography for Predicting Levothyroxine Needs in Hypothyroid Patients: A Cross-Sectional Study

This study explored the role of Doppler ultrasound in evaluating hypothyroid patients, particularly focusing on how Doppler parameters relate to clinical characteristics like autoimmune status and levothyroxine (LT4) replacement adequacy. A cohort of 338 hypothyroid patients, primarily affected by autoimmune thyroiditis (85.2%), was examined to assess whether Doppler sonography could serve as an alternative tool for managing thyroid hormone replacement. Excluding patients with specific medical histories or thyroid nodules, the study analyzed demographics (age, sex, BMI), LT4 dosage, and thyroid hormone levels (TSH and fT4). The findings showed that patients with autoimmune thyroiditis had higher elastography ratios and increased vascularity. Among those without autoimmune disease, individuals with suboptimal LT4 replacement also had smaller thyroid volumes. Notably, in the subset with suboptimal LT4 replacement, peak systolic velocity (PSV) and end-diastolic velocity (EDV) in the inferior thyroid artery were elevated, while the resistive index (RI) was lower, suggesting altered blood flow. Additionally, a higher LT4 dose adjusted for BMI correlated with lower thyroid volume and EDV values, indicating a more severe hypothyroid state. PSV in the inferior thyroid artery was identified as a predictive marker of inadequate LT4 replacement, with 81.8% sensitivity but lower specificity (42%). This study suggests that color Doppler ultrasound can be a valuable tool for assessing vascular changes related to hypothyroidism, potentially guiding treatment adequacy and identifying patients who may benefit from further hormonal evaluation, especially in situations where blood tests are inaccessible.