Is a thyroid ultrasound indicated in a 45-year-old female with persistently elevated Thyroid Peroxidase (TPO) antibodies, currently on 175 micrograms of levothyroxine (T4), following a gluten-free diet, and receiving selenium supplementation?

From the Guidelines

It is appropriate to get a thyroid ultrasound for a 45-year-old female with persistently elevated TPO antibodies above 900, despite being on levothyroxine 175mcg, following a gluten-free diet, and taking selenium supplements. The presence of high TPO antibody levels indicates autoimmune thyroid disease, typically Hashimoto's thyroiditis, which increases the risk of thyroid nodules and, less commonly, thyroid cancer 1. Key points to consider in this patient's management include:

• The role of TPO antibodies in identifying patients at increased risk for thyroid autoimmunity 1
• The importance of monitoring thyroid function, particularly in patients with previously normal TSH levels, every 1–2 years or when clinical thyroid dysfunction is suspected 1
• The need for comprehensive evaluation and treatment of thyroid dysfunction, including the use of thyroid hormone replacement therapy in patients with elevated TSH levels 1
• The potential benefits of thyroid ultrasound in evaluating structural abnormalities in the thyroid gland, including screening for nodules or signs of thyroiditis Given the patient's persistently elevated TPO antibodies and current management, a thyroid ultrasound can provide valuable information about thyroid size, texture, vascularity, and the presence of any suspicious nodules that might require further evaluation. This approach prioritizes the patient's morbidity, mortality, and quality of life by ensuring timely detection and management of potential thyroid complications associated with autoimmune thyroid disease.

From the Research

Thyroid Peroxidase Antibodies and Ultrasound

• The patient's TPO levels are elevated above 900, and they are already on 175mcg of levothyroxine, following a gluten-free diet, and taking selenium 2, 3.
• Studies have shown that selenium supplementation can decrease TPO antibody concentrations in patients with autoimmune thyroiditis 2.
• However, another study found that selenite supplementation in euthyroid subjects with thyroid peroxidase antibodies did not significantly decrease TPO-Ab levels 3.
• The decision to perform a thyroid ultrasound may depend on various factors, including the patient's clinical presentation, medical history, and laboratory results.
• A study on patients with chronic autoimmune thyroiditis (Hashimoto's thyroiditis) treated with levothyroxine found that TPO-Ab levels declined in most patients, but the correlation between changes in thyroid volume and changes in TPO-Ab was not significant 4.
• Another study suggested that ultrasound of the thyroid may be useful in monitoring the echogenicity of the thyroid in patients with autoimmune thyroiditis 2.

Determinants of Thyroid Peroxidase Antibodies

• Female sex and current smoking are determinants of TPO-Ab levels in the detectable and positive range 5.
• Alcohol consumption is associated with lower odds of TPO-Abs 5.
• The clinical importance of detectable TPO-Ab levels is illustrated by the association with an increased mortality risk, mainly in men 5.

Clinical Validity of Anti-TPO Assay

• The anti-TPO assay is a sensitive and specific method for detecting autoantibodies against thyroid peroxidase 6.
• Clearly elevated anti-TPO values were found in 59% of patients with thyroiditis, but in none of the controls or patients with non-thyroidal illness 6.