Improving Safety in Paediatric Thyroidectomy by PTH Measurements

Analía V. Freire; María G. Ropelato; Patricia Papendieck; Ana Vieites; Eugenia Elías; Maria G. Ballerini; María E. Rodriguez; Ignacio Bergadá; Ana Chiesa


Clin Endocrinol. 2021;95(5):760-765. 

In This Article

Abstract and Introduction


Objetive: We followed our previously reported algorithm based on intra and postoperative parathyroid hormone (PTH) levels to predict postthyroidectomy hypoparathyroid hypocalcemia. The objective of the study was to assess if this strategy is useful and safe to reduce hypocalcemia, hospitalisation length and postsurgery calcium sampling.

Design, Patients, Meassurements: We classified our series of 66 patients according to their risk of hypoparathyroidism based on PTH determinations. We treated high-risk patients with calcium and vitamin D1–25 supplementation and obtained routine daily calcium samples to control low-risk patients until 48 h postsurgery. We compared the outcomes and overall results of this new approach with those of a historical control group of patients with equivalent PTH measurements who were treated only if they presented hypocalcemia.

Results: In the high-risk subgroup (n = 30), five patients had hypocalcemia within the first 24 h. Compared with the high-risk control subgroup, the incidence of hypocalcemia fell from 100% to 17% (p < .001), and the median hospitalisation length from 6 to 3 days (p < .001). In the low-risk subgroup (n = 36), 28 patients remained normocalcemic with significantly less calcium sampling (p < .001). Eight patients had hypocalcemia; seven of them required neck dissection, which was the only risk factor related to postsurgical hypoparathyroidism (RR: 2.1 [confidence interval 95%: 1.4–3.1]; p < .001). The overall incidence of hypocalcemia decreased by 58% in our patients compared to the control group.

Conclusions: Assessing PTH levels to classify the risk of hypoparathyroidism and to initiate preventive therapy was an effective approach that improved the safety of our paediatric patients by reducing the incidence of hypocalcemia and the length of hospitalisation after thyroidectomy in paediatric patients.


Reported hypocalcemia postthyroidectomy in paediatric series ranges from 26% to 63% and is generally transitory[1–5] and due to the hypoparathyroidism secondary to surgical manipulation of the parathyroid glands and the consequent trauma, devascularization or accidental gland removal. Hypocalcemia is the most common complication of thyroidectomy. It often leads to prolonged hospitalisation and demands many and frequent blood samples to monitor total serum calcium (TCa).

The classical postsurgical approaches to manage hypocalcemia are either (a) to indicate calcium (Ca) and vitamin D 1–25 supplement to all patients, or (b) to monitor inpatients with peripheral venipuncture calcium sampling (CaS) every 6 h for 48 h after surgery. The first approach may imply unnecessarily treating euparathyroid patients leading to over-supplementation and potential hypercalcemia or suppression of their normal parathyroid function.[2] In the second classical postsurgical approach, which was the standard care at our hospital, treatment was started only when TCa levels dropped below normal values. This approach allows hypocalcemia and its unpleasant symptoms to happen, and usually delays interventions and extends hospitalisations. The lack of symptoms' awareness, both by the patients and their parents, also delays interventions.[6] Although patients with intact parathyroid function should not require frequent CaS to monitor their TCa levels, these controls are necessary to confirm normocalcemia in patients under standard care.

The short half-life of parathyroid hormone (PTH; 3–5 min) and the availability of automated assays, which render results in less than 30 min, allowed us to identify and report a PTH cut-off value predictive of hypoparathyroid hypocalcemia, and also to develop an algorithm for the postsurgical management of these patients.[1] The algorithm includes PTH determinations obtained 5 min after thyroid gland removal, combined with an additional measurement 60 min after thyroidectomy (Figure 1), and predict hypocalcemia with 93% sensitivity (95% confidence interval [CI]: 68–100) and 100% specificity (95,% CI: 80–100). The positive predictive value, negative predictive value and diagnostic efficiency were 100%, 94% and 97%, respectively.[1] High-risk patients were preventively treated with calcium and vitamin D1–25 supplementation and low-risk patients were clinically controlled with one routine daily CaS until 48 h postsurgery.

Figure 1.

Algorithm proposed based on parathyroid hormone (PTH) determination and patient's assignment at each subgroup

The objective of this study was to assess if this strategy might reduce the incidence of hypocalcemia and the length of hospitalisation in postthyroidectomy patients at high risk of hypoparathyroidism, comparing the outcomes with a control group (CG) of patients who had been managed with the standard approach: Serum calcium monitored every 6 h and treated only if presenting hypocalcemia. We also evaluated the safety of reducing the number of CaS in low-risk patients.