Analysis On Risk Factors Of Symptomatic Hypocalcemia After Total Thyroidectomy And Prediction Of Calcium Supplement Dose By IPTH

ObjectiveTo observe the occurrence of symptomatic hypocalcemia(SH)in patients after total thyroidectomy and the relationship between the level of calcium supplementation dose and various potential influencing factors when hypoparathyroidism(HP)symptoms are relieved,and explore the predictive value of intact parathyroid hormone(iPTH)in the occurrence of postoperative SH and the dose of calcium supplement.MethodsThe patients who underwent total thyroidectomy in thyroid surgery of the First Affiliated Hospital of Zhengzhou University from January 2020 to March 2021 were selected retrospectively,and 101 patients with postoperative SH were set as SH group.100 patients without SH were selected by systematic sampling method and set as the Control Group.Pearson correlation analysis was used to evaluate the potential influencing factors such as age,gender,preoperative and postoperative calcium,preoperative and postoperative iPTH,number of lymph nodes in the central region,blood loss,operation duration,lymph node dissection methods,postoperative pathological types and others,and Mean±SD was used for the measurement data of normal distribution.t-test was used for the comparison between groups,and χ2-test was used for the counting data.Preoperative/postoperative iPTH levels in SH group and Control Group were studied by drawing Receiver Operating Characteristic Curve(ROC),and the diagnostic threshold,sensitivity and specificity of iPTH for SH were predicted.According to the total dose of calcium supplementation(Ca>4g/Ca≤4 g)when the HP symptoms of patients were relieved,101 patients in SH group were divided into mild group(n=62 cases)and severe group(n=39 cases).The potential influencing factors such as age,preoperative calcium,postoperative calcium,preoperative iPTH,postoperative iPTH,number of lymph nodes in the central region,blood loss,operation duration,gender,lymph node dissection method,postoperative pathological type and others were evaluated in the two groups.Logistic multivariate regression analysis was performed,and the residual statistical method was the same as above.By drawing ROC,the preoperative/postoperative iPTH levels of mild and severe patients were studied,and the critical value,sensitivity and specificity of iPTH diagnosis were predicted after SH.ResultsThere were significant differences in gender(SH Group:5 males and 96 females;Control Group:16 males and 84 females),whether lateral area dissection was performed(SH Group:53 cases,non-dissection 48 cases;Control Group:9 cases,non-dissection 91 cases),blood loss(23.5 mL vs 12.8 mL),operation duration(1.7 h vs 1.0 h),postoperative iPTH(16.0 pg/mL vs 33.0 pg/mL),preoperative iPTH(39.5 pg/mL vs 44.8 pg/mL)and postoperative calcium level(1.9 mmol/L vs 2.2 mmol/L)between SH Group and Control Group(P<0.05).However,there were no significant differences in age(40.0 vs 37.7 years,P=0.21),postoperative pathological types(SH Group:1 case with thyroid follicular carcinoma,100 cases with thyroid papillary carcinoma;Control Group:3 cases with thyroid follicular carcinoma,97 cases with thyroid papillary carcinoma,P=0.19),number of central lymph node dissection(9.4 vs 9.4,P=0.98),preoperative calcium(2.3 mmol/L vs 2.3 mmol/L,P=0.10)between the two Groups.If the postoperative iPTH of patients after total thyroidectomy was less than 20.80 pg/mL,SH was easy to occur,and its sensitivity was 74.07%,and its specificity was 96.30%;compared with postoperative iPTH(AUC=0.84),preoperative iPTH(AUC=0.56)has lower diagnostic efficiency.The patients in the SH Group were divided into Mild Group(62 cases)and Severe Group(39 cases)according to the dose of calcium supplement.There were significant differences in the gender of the Mild Group(3 males and 59 females)and Severe Group(2 males and 37 cases),the amount of calcium supplement(3.2 g vs 6.6 g),postoperative iPTH(19.3 pg/ml vs 10.6 pg/ml),preoperative iPTH(36.0 pg/ml vs 42.3 pg/ml),ΔiPTH(19.6 pg/ml vs 29.8 pg/ml),blood loss(18.9 mL vs 27.9 mL),and operation duration(1.6 h vs 2.1 h)were statistically significant(P<0.05).There were no significant differences in the age of patients in the two groups(40.4 years vs 39.2 years,P=0.63)and postoperative pathological types(Mild Group:1 case with thyroid follicular carcinoma and 61 cases with thyroid papillary carcinoma;Severe Group:39 cases with papillary thyroid carcinoma,P=0.21),whether to perform lateral area dissection(Mild Group:31 cases with dissection,31 cases with non-dissection;There was no significant difference between preoperative calcium(2.3 mmol/L vs 2.3 mmol/L,P=0.54),postoperative calcium level(1.9 mmol/L vs 1.9 mmol/L,P=0.23)and the number of central lymph nodes(8.3 vs 11.1,P=0.09).Logistic multivariate analysis showed preoperative iPTH and postoperative iPTH were independent risk factors betweenMild Group and Severe Group.For patients with SH,if the postoperative iPTH is less than 18.03 pg/mL,calcium gluconate should be added to more than 6g,and the rest patients can be supplemented with 3～4g calcium gluconate.Conclusion1.Gender,age,postoperative calcium,preoperative iPTH,postoperative iPTH,number of lymph nodes in the central region,bleeding volume,length of surgery,mode of lymph node dissection,and extent of thyroidectomy were important influencing factors for the occurrence of SH after thyroid surgery.2.The main factors influencing the high or low dose of calcium supplementation for symptom relief in patients with postoperative occurrence of SH were gender,amount of calcium supplementation,preoperative iPTH,postoperative iPTH,iPTH difference,length of surgery,bleeding,and postoperative calcium level,with preoperative or postoperative low iPTH being the independent risk factor.3.Using postoperative iPTH to predict the occurrence of SH in patients after total thyroidectomy may help to relieve the clinical symptoms of patients with SH in time.The stratified prediction of calcium supplementation is helpful for dose-specific calcium supplementation for patients with SH.4.The causes of SH after total thyroidectomy are multi-factorial.Postoperative monitoring of related indicators of SH occurrence and appropriate calcium supplementation can alleviate HP symptoms,and may be beneficial to the recovery of parathyroid function and reduce HP.occur.