Thyroid Ultrasound

Thyroid Ultrasound is a simple test to do, but has more limited indications than are commonly realized.

The Journal of General Internal Medicine summarized the indications in 2005 as 

1. patients with a thyroid nodule and a history of head or neck irradiation; 
2. follow-up of patients with nodules not surgically removed; 
3. evaluation of patients with amiodarone-induced thyrotoxicosis.

Although they did note that thyroid ultrasound was "relatively inexpensive, usually accessible, noninvasive, accurate... and in view of the relative inaccuracy of thyroid palpation, it may supplement the physical examination," they also pointed out that the workup and/or follow-up of small, incidental thyroid nodules was controversial and that there was a very real risk of "cascade iatrogenesis." 

 

Ultrasound examination is not indicated for suspected thyroid dysfunction. Rather, history and physical examination, TSH and thyroid hormone determinations, and thyroid uptake in patients with thyrotoxicosis are the appropriate diagnostic procedures. A low uptake is indicative of subacute or “silent” thyroiditis, recent exposure to iodine or factitious thyrotoxicosis; diffuse uptake is suggestive of Graves' disease, or sometimes of the recovery phase of subacute thyroiditis, while focal uptake along with matching physical examination findings are usually diagnostic of an autonomous toxic nodular disease. Neither ultrasound nor thyroid scan/uptake is useful in the differential diagnosis of hypothyroidism.

Neck pain can result from thyroiditis, which is best diagnosed by the combination of tenderness on thyroid palpation, elevated erythrocyte sedimentation rate (ESR), and a thyroid scan revealing nonuptake. TUS is nonspecific in subacute thyroiditis.⁵ Neck pain is rarely a presenting symptom of thyroid cancer,⁶ and even when it precedes the diagnosis of thyroid cancer, it is more likely that the thyroid mass would be an incidental finding. Bleeding into a thyroid nodule (hemorrhagic cyst) may also cause neck pain and tenderness, which can be confusing. In this case, a nodule can usually be palpated and fine needle aspiration (FNA) has the advantage of being both diagnostic and palliative (as evacuation of the hemorrhagic fluid usually reduces the pain).

Finally, a review of Thyroid Nodules with an Algorithm was posted on this blog sometime ago. Enjoy.

Comments

[Thyroid Cancer]

my wife was diagnosed with thyroid cancer the same day she found out she was pregnant with our 2nd child. She had surgery to remove her thyroid in the 2nd trimester and had a complete removal of her thyroid. Thankfully the surgery, birth of my son, and radition tratments were a success and she is about 6 months away from hitting the 1 year mark.