Should I obtain a thyroid ultrasound for an elevated parathyroid hormone (PTH) level?

No, thyroid ultrasound is NOT the correct imaging for elevated PTH

You need parathyroid imaging, not thyroid imaging, if you have confirmed primary hyperparathyroidism and are planning surgery. The thyroid and parathyroid glands are different organs with different functions, and elevated PTH indicates a parathyroid problem, not a thyroid problem 1, 2.

Critical Distinction: Diagnosis vs. Localization

Imaging has NO role in diagnosing hyperparathyroidism - diagnosis is purely biochemical (elevated PTH with elevated or inappropriately normal calcium) 1, 2. Imaging is only indicated after biochemical diagnosis is confirmed and surgery is planned 2.

When Parathyroid Imaging IS Indicated

Imaging should be obtained when:

• Primary hyperparathyroidism is biochemically confirmed
• AND surgery is being planned 2

The purpose is to localize the abnormal parathyroid gland(s) to enable minimally invasive parathyroidectomy rather than bilateral neck exploration 1.

Recommended First-Line Imaging Strategy

The gold standard approach combines parathyroid ultrasound PLUS functional imaging 2:

1. Parathyroid ultrasound (not thyroid ultrasound) performed by trained operators
2. PLUS one of the following functional studies:
   • 99mTc-sestamibi parathyroid scintigraphy (ideally dual-isotope 123I/99mTc with SPECT/CT) 2
   • OR 18F-choline PET/CT (excellent performance, preferred if multi-glandular disease suspected or subtraction scintigraphy unavailable) 2

When Thyroid Ultrasound May Be Relevant

While not the primary imaging for elevated PTH, thyroid ultrasound can be useful as an adjunct because:

• 57% of patients with primary hyperparathyroidism have incidental thyroid nodules 3
• 6% may have concurrent thyroid cancer 3
• Thyroid pathology can alter surgical planning in 17% of cases 3
• Thyroid disease can decrease sensitivity of parathyroid localization 4

However, this is performed in addition to parathyroid imaging, not instead of it.

Common Pitfall to Avoid

Do not confuse thyroid and parathyroid glands. The parathyroid glands are four small glands typically located behind the thyroid that regulate calcium metabolism through PTH secretion. Elevated PTH indicates parathyroid dysfunction, requiring parathyroid-specific imaging when surgery is planned 1, 2.

When NO Imaging Is Needed

If surgery is not planned, imaging is not indicated 2. This includes patients who:

• Don't meet surgical criteria
• Refuse surgery
• Are being managed medically