Objective
Hypocalcemia is the most common complication after thyroid surgery. It is believed that acute parathyroid failure is the main cause of hypocalcemia after bilateral interventions. In our study, we aimed to evaluate the preoperative and postoperative characteristics of parathyroid function in patients with postoperative hypoparathyroidism in reference to the time of return to normal values.
Material and Methods
Among the patients undergoing total thyroidectomy+central neck dissection between 2014 and 2018, those with PTH<15 pg/mL within the postoperative first 4 hours were included in the study. After thyroidectomy, calcium<8 mg/dL was defined as biochemical hypocalcemia and PTH<15 pg/mL was defined as hypoparathyroidism. The patients were divided into 3 groups according to the time of PTH level to exceed 15 pg/mL. Group 1 was composed of the patients whose PTH value improved in the first 24 hours, Group 2 was composed of the patients whose PTH value improved in 1–30 days, and Group 3 was composed of the patients whose PTH value improved or did not improve after 30 days.
Results
As to the distribution of 111 patients according to age groups with a mean age of 49.3+14.4; there were 19 patients (16F, 3M) in Group 1, 67 patients (54F, 13M) in Group 2, and 25 patients (19F, 6M) in Group 3. The rates of vitamin D deficiency were 41.7%, 53.1% and 88.2% in Groups 1, 2 and 3, respectively; the difference was significant (p=0.018). Ca values on the postoperative 0th day in Groups 1, 2 and 3 were 8.56+0.46, 8.16+0.66, and 8.1+0.84, respectively; the difference was significant (p=0.028). PTH values on the postoperative 0th day were 11.69+2.79, 6.92+3.45, and 4.99+2.36 and the difference was significant (p<0.001). It was significantly lower both in Group 2 and Group 3 (p<0.001) than in Group 1 (p<0.001). Biochemical hypocalcemia rates of Group 1, 2 and 3 on the first postoperative day were 15.8%, 53.7% and 64%, respectively, and there was a significant difference among the groups (p=004). Ca values on the postoperative 1st day were 8.68+0.67, 8.15+0.66, and 7.75+1 in Group 1, 2 and 3, respectively; the difference was significant (p=0.014). Mg values on the postoperative 1st day were 1.85+0.1, 1.77+0.17, and 1.64+0.17 in Group 1, 2, and 3, respectively; the difference was significant (p=0.005). PTH values on the postoperative 1st day were 20.54+6.37, 7.07+4.35 and 4.66+3.27, in Group 1, 2 and 3, respectively; the difference was significant (P<0.001). In paired comparisons, it was lower in Group 2 and Group 3 than in Group 1 (p=0.0001, p=0.0001). Mg values on the postoperative 7th day were 1.86+0.16, 1.82+0.21, and 1.59+0.15 in Group 1, 2, and 3, respectively, and the difference was significant (p=0.001). P values on the postoperative 7th day in Groups 1, 2 and 3 were 3.71+0.75, 3.88+0.76, and 4.76+0.69, respectively, and the difference was significant (p=0.002). In 106 of the patients, parathyroid function restored to normal values and permanent hypoparathyroidism developed in 5 patients (4.5%).
Conclusion
Among the patients with postoperative hypoparathyroidism, the rate of preoperative vitamin D deficiency is higher in those whose parathyroid function improves after 1 month. The rates of parathyroid autotransplantation and iatrogenic para-thyroidectomy, which are among the intraoperative factors that may affect parathyroid function, are similar. The patients whose parathyroid function improves after 24 hours have lower PTH levels on the first day. Postoperative low Mg levels may be associated with delayed recovery of parathyroid function.
