New Rapid Test Replaces Frozen Sections in Parathyroid Surgery, Suggests Study

While previous research by Kikumori and colleagues demonstrated that assessing enzyme proportions in tissue suspensions could help distinguish parathyroid gland (PT) tissues, the persistent clinical reliance on tedious, expensive, and often inaccessible frozen sections highlighted a significant intraoperative gap. To address this challenge, Dr. Ganesh Bhat and colleagues at the Department of Endocrine Surgery at King George’s Medical University initiated an evaluation to determine if the aspartate aminotransferase to lactate dehydrogenase (AST/LDH) ratio of parathyroid extracts could effectively differentiate these vital glands from surrounding fat, thyroid, and lymph node (LN) tissues.

Therefore, in the prospective study researchers analyzed 207 tissue samples from 68 patients undergoing thyroid or parathyroid surgery by mincing small tissue fragments in saline and evaluating the resulting fluid. The primary goal was to determine the diagnostic accuracy of this biochemical test compared to standard histopathological confirmation.

Key Clinical Findings of the Study Includes:

• Elevated Enzyme Ratios: Researchers observed that the mean AST/LDH ratio for carefully preserved parathyroid tissue was significantly higher at 0.311 compared to the vastly lower baseline ratios seen in adjacent thyroid, fat, and lymph node tissues.

• Diagnostic Threshold Value: Investigators established that utilizing an optimal AST/LDH ratio cut-off of 0.165 or greater yielded an impressive overall diagnostic sensitivity of 83.8% and an overall specificity of 83.1% for accurately confirming parathyroid tissue.

• Differentiating Adipose and Thyroid Tissues: The study demonstrated that applying this specific threshold provided an 83.1% specificity against benign and malignant thyroid tissue, alongside a 74% specificity when navigating through challenging adipose tissue. Flawless

• Lymph Node Discrimination: Researchers highlighted a major surgical takeaway, noting that the established cut-off achieved a flawless 100% specificity when directly distinguishing delicate parathyroid glands from potentially tumor-laden lymph nodes.

• Parathyroid Adenoma Comparisons: Investigators found that the mean ratio for parathyroid adenomas was robust at 0.318, even though the comparative difference between these diseased glands and normal parathyroid tissue did not reach statistical significance within this specific cohort.

The results suggest that utilizing the simple AST/LDH ratio serves as a highly reliable method for confirming parathyroid tissue during surgery, successfully identifying these small glands with an accuracy rate that frequently exceeds 83%.

Implementing this straightforward biochemical assessment, potentially through the integration of rapid point-of-care testing devices directly into the operating theater, could gently assist surgical teams in preventing the inadvertent removal of healthy parathyroid glands during complex central compartment neck dissections.

While the present investigation is modestly constrained by a smaller sample size and the unpredictable fat content associated with older parathyroid glands, future research exploring larger cohorts and utilizing fine-needle aspiration cytology washouts could harmoniously expand the practical clinical utility of this technique.

Reference

Bhat G, Sooraj R, Mishra AK, Ramakant P, Rahalkar A, Rana C, et al. Intraoperative identification of parathyroid tissue using the ratio of aspartate transaminase to lactate dehydrogenase. Indian J Endocr Metab 2025;29:77-82.