Parathyroid Hormone Assays following Total Thyroidectomy: Is There a Predictive Value?

Area of Science:

• Endocrinology
• Surgical Oncology
• Clinical Chemistry

Background:

• Hypoparathyroidism (hypoPTH) is a common complication after total thyroidectomy.
• Parathyroid hormone (PTH) levels are a known risk marker for hypoPTH.
• Current practices for predicting and managing postoperative hypoPTH lack consensus.

Purpose of the Study:

• To determine the predictive value of early serum PTH assays at skin closure (PTH SC) for hypoPTH.
• To establish treatment algorithm thresholds for postoperative PTH SC levels.
• To assess the reproducibility of PTH SC testing using different immunoassay kits.

Main Methods:

• Prospective descriptive study of 257 patients undergoing total thyroidectomy.
• Collection of postoperative PTH SC levels, corrected calcium, and hypoPTH symptoms.
• Analysis of predictive values using two different immunoassay kits (Roche and Beckman-Coulter).

Main Results:

• The incidence of hypoPTH was 20% in the study cohort.
• Specific PTH SC thresholds demonstrated 100% positive and negative predictive values for hypoPTH.
• Thresholds varied by immunoassay kit: Roche (<7 ng/L for certainty of hypoPTH, ≥19 ng/L for certainty of no hypoPTH); Beckman-Coulter (<4 ng/L for certainty of hypoPTH, ≥9 ng/L for certainty of no hypoPTH).

Conclusions:

• A single PTH SC measurement is a reliable predictor of hypoPTH post-thyroidectomy.
• Utilizing 100% negative predictive value thresholds allows safe 24-hour postoperative discharge for at-risk patients.
• Prompt PTH-guided treatment can effectively limit hypocalcemia in high-risk patients.