The predictive value of postoperative intact parathyroid hormone for symptomatic hypocalcemia in older patients with thyroid cancer.

Background: Due to the unique characteristics of older patients, they are more susceptible to develop symptomatic hypocalcemia (SH). This study aimed to analyze the potential relationship between the occurrence of SH and various indicators in older patients after thyroid cancer surgery, and to further discuss the predictive value of postoperative intact parathyroid hormone (iPTH) for SH, which can provide reference for clinical prevention and treatment of hypocalcemia in older patients.

Methods: A total of 137 older patients with thyroid cancer (≥60 years old) admitted to the Department of Thyroid Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School from January 2020 to December 2022 were selected. They were divided into the SH group and the asymptomatic group according to whether they developed SH. Relevant clinical data were collected and retrospectively analyzed. The measurement data of normal distribution were expressed by mean ± standard deviation (SD). Univariate and multivariate analyses were used to determine the risk factors for SH in older patients after thyroid cancer surgery. Statistical significance was set as P<0.05. Receiver operating characteristic (ROC) curve was constructed to study the predictive value of postoperative iPTH for SH occurrence in older patients with thyroid cancer.

Results: Among 137 older patients, 48 cases (35.04%) developed SH and 89 cases (64.96%) were asymptomatic. There were significant differences in preoperative iPTH (SH group: 7.00±5.25 pmol/L; asymptomatic group: 5.52±1.80 pmol/L; P=0.004) and postoperative iPTH (SH group: 0.69±0.95 pmol/L; asymptomatic group: 3.30±2.28 pmol/L; P<0.001) between the SH group and the asymptomatic group, with statistical significance (P<0.05). The area under the curve (AUC) of postoperative iPTH predicting SH occurrence in older patients with thyroid cancer was 0.855, cut-off was 0.5941 [95% confidence interval (CI): 0.794-0.917; sensitivity, 87.5%; specificity, 71.9%].

Conclusions: Postoperative iPTH is an independent risk factor for predicting SH in older patients with thyroid cancer. In order to avoid the occurrence of postoperative SH and reduce hospitalization costs and length, calcium supplementation should be given as soon as possible according to the level of postoperative iPTH.