Effectiveness of Intraoperative Topical Methylene Blue Spray for Parathyroid Gland Preservation During Thyroidectomy: A Short Prospective Observational Study

Abstract

Background
Post-thyroidectomy hypocalcemia remains one of the most common complications following thyroid
surgery and is primarily related to inadvertent injury, devascularization, or failure to identify the
parathyroid glands intraoperatively. Although several advanced imaging modalities have been developed
to improve parathyroid preservation, their routine use is often limited by cost and availability. Topical
methylene blue spray has emerged as a simple, inexpensive, and readily available technique that may
facilitate intraoperative identification of parathyroid glands and improve postoperative outcomes.
Methods
A prospective observational study was conducted among 60 patients undergoing thyroidectomy for
benign and malignant thyroid disorders at a tertiary care teaching hospital. Following standard
thyroidectomy, topical methylene blue spray was applied intraoperatively to assist parathyroid gland
identification. Baseline serum calcium and parathyroid hormone (PTH) levels were measured
preoperatively and reassessed on postoperative day one (POD-1) and postoperative day three (POD-3).
The number of parathyroid glands identified, operative outcomes, postoperative biochemical changes,
preservation rates, and complications were analyzed.
Results
Females constituted 70.0% of the study population, and multinodular goiter was the most common
indication for surgery (40.0%). Complete identification of all four parathyroid glands was achieved in
66.7% of patients, while successful preservation was observed in 93.3% of cases. Mean serum calcium
decreased from 9.42 ± 0.48 mg/dL preoperatively to 8.74 ± 0.51 mg/dL on POD-1 and improved to 8.96
± 0.45 mg/dL on POD-3. Mean PTH levels declined from 48.6 ± 11.2 pg/mL to 38.2 ± 9.4 pg/mL on
POD-1 before recovering to 42.6 ± 8.8 pg/mL on POD-3. Transient hypocalcemia occurred in only 6.7%
of patients, and no cases of permanent hypocalcemia were observed. Procedure-related complications
were minimal.
Conclusion
Intraoperative topical methylene blue spray is a safe, effective, and cost-efficient adjunct for parathyroid
gland identification during thyroidectomy. The technique demonstrated high preservation rates, low
postoperative hypocalcemia, favorable biochemical recovery, and minimal complications, supporting its
use as a practical alternative for parathyroid preservation, particularly in resource-limited surgical
settings.