ObjectiveTo investigate the clinical value of fine needle aspiration cytology (FNAC) combined with washout fluid detection of parathyroid hormone (PTH) in identifying parathyroid glands during thyroid cancer radical surgery. MethodsA total of 108 patients who underwent thyroid cancer radical surgery in Rizhao Central Hospital from June 2020 to December 2022 were selected as the study subjects. During the surgery, highly suspected parathyroid tissues were punctured with fine needle aspiration. FNAC and washout fluid were collected for PTH detection. Using the results of postoperative histopathological examination as the gold standard, the accuracy of different methods in identifying parathyroid glands during surgery was analyzed. ResultsAmong the 73 positive cases, the PTH level in the washout fluid was (591.20±84.30) pg/mL, while in the 35 negative cases, it was (18.69±2.53) pg/mL. The PTH level was significantly higher in the positive cases compared to the negative cases (P＜0.05). Postoperative routine histopathological examination confirmed parathyroid tissues in 91 cases, while in 17 cases, they were confirmed as adipose tissues (11 cases) or lymphoid tissues (6 cases). In the 17 cases confirmed as non-parathyroid tissues, both methods considered them as non-parathyroid tissues. The sensitivity of puncture eluent in detecting PTH was 80.22% (73/91), that of cytological smear was 70.33% (64/91), and that of puncture eluent combined with cytological smear was 94.50% (86/91). There was no significant difference between the sensitivity of puncture cytology smear and puncture eluent in detecting PTH (P＞0.05). The sensitivity of combined detection of the two methods was higher than that of individual detection, and the difference was statistically significant (P<0.05). ConclusionThe combined detection of PTH by fine needle puncture smear and eluent can improve the accuracy of identification of parathyroid gland during radical thyroidectomy, and is beneficial to the identification and protection of parathyroid gland during surgery.