Parathyroid Changes After RAI in Patients With Differentiated Thyroid Carcinoma

Area of Science:

• Endocrinology
• Oncology
• Nuclear Medicine

Background:

• Differentiated thyroid carcinoma (DTC) is often treated with radioactive iodine (RAI).
• RAI therapy can impact calcium-regulating hormones and minerals.
• Monitoring these changes is crucial for patient management.

Purpose of the Study:

• To investigate changes in parathyroid hormone (PTH), serum calcium, phosphorus, and 25-hydroxyvitamin D (25-OH-VD) levels before and after RAI in DTC patients.
• To identify risk factors for hypocalcemia following RAI treatment.

Main Methods:

• Prospective enrollment of 259 DTC patients undergoing RAI.
• Measurement of PTH, serum calcium, phosphorus, and 25-OH-VD at baseline, 5 days, 6 weeks, and 6 months post-RAI.
• Multivariate regression analysis to determine risk factors for hypocalcemia.

Main Results:

• A statistically significant decrease in mean PTH, serum calcium, and phosphorus was observed 5 days post-RAI compared to baseline.
• 21.2% of patients developed hypocalcemia at 5 days post-RAI.
• Lower baseline serum calcium (< 2.27 mmol/L), lower baseline PTH (< 4.18 pmol/L), and negative 99mTcO4- thyroid imaging were identified as risk factors for hypocalcemia.

Conclusions:

• DTC patients treated with RAI experience transient decreases in PTH, calcium, and phosphorus.
• Hypocalcemia is a common complication, occurring in approximately one-fifth of patients within 5 days post-RAI.
• Pre-treatment hypocalcemia and specific imaging findings predict the risk of developing hypocalcemia after RAI.