Predictors of post-thyroidectomy hypocalcaemia: a systematic and narrative review

Autofluorescence-Guided Total Thyroidectomy in Low-Volume, Nonparathyroid Institutions

Importance

Hypoparathyroidism following thyroid surgery is a serious complication that occurs frequently when surgery is performed by low-volume thyroid surgeons without experience in parathyroid surgery.

Objective

To evaluate the occurrence of hypoparathyroidism following total thyroidectomy after the introduction of autofluorescence in low-volume, nonparathyroid institutions.

Design, Setting, and Participants

This prospective, multicenter cohort study, with a follow-up period of up to 1 year, was conducted in Denmark at 2 low-volume nonparathyroid institutions between January 2021 and November 2023. All adult patients referred for total thyroidectomy were assessed for eligibility (n = 90). Only patients with no history of thyroid surgery were considered (n = 89). Patients who only underwent lobectomy (n = 6) or declined to participate (n = 5) were excluded. All included patients completed follow-up. The prospective cohort was compared with a historical cohort of successive patients undergoing primary total thyroidectomy from 2016 to 2020 (before autofluorescence was available).

Intervention

Included patients underwent autofluorescence-guided total thyroidectomy.

Main outcomes and Measures

Rate of hypoparathyroidism. Immediate hypoparathyroidism was defined as the need for active vitamin D postoperatively, whereas permanent hypoparathyroidism was considered when there still was a need for active vitamin D 1 year after surgery.

Results

Seventy-eight patients underwent autofluorescence-guided surgery (mean [SD] age, 55.6 [13.1] years; 67 [86%] female) and were compared with 89 patients in the historical cohort (mean [SD] age, 49.7 [12.8] years; 78 [88%] female). The rate of immediate hypoparathyroidism decreased from 37% (95% CI, 27%-48%) to 19% (95% CI, 11%-30%) after the introduction of autofluorescence (P = .02). Permanent hypoparathyroidism rates decreased from 32% (95% CI, 22%-42%) to 6% (95% CI, 2%-14%) (P < .001), reaching 0% at the end of the study. More parathyroid glands were identified with autofluorescence (75% [95% CI, 70%-80%] vs 61% [95% CI, 56%-66%]) (P < .001) and less parathyroid glands were inadvertently excised (4% [95% CI, 1%-11%] vs 21% [95% CI, 13%-31%]) (P = .001).

Conclusions and Relevance

In this cohort study of autofluorescence-guided thyroid surgery in low-volume, nonparathyroid institutions, the use of autofluorescence was associated with a significant decrease in both immediate and permanent hypoparathyroidism. When autofluorescence was used, hypoparathyroidism rates were comparable with those of high-volume surgeons who also perform parathyroid surgery.

Incidence of Post-Thyroidectomy Hypoparathyroidism and Associated Preoperative and Intraoperative Risk Factors

INTRODUCTION

Thyroidectomy technique and extent are related to parathyroid injury and hypoparathyroidism. Total thyroidectomy is one of the most commonly performed endocrine surgeries, and the majority of patients recover completely without any complications. However, persistent hypoparathyroidism is the most prevalent long-term consequence following total thyroidectomy. While it is seldom deadly, it can cause severe morbidity for the patient and raise healthcare expenses.

METHODS

This retrospective cohort study was conducted at King Abdulaziz Medical City, Jeddah, Saudi Arabia. We included all confirmed thyroid cancer cases that underwent thyroidectomy with or without neck dissection between July 2016 and August 2022. The data was collected from a chart review of the electronic medical record system (BEST-care), and a data collection sheet was utilized. SPSS version 26 was used to analyze the data.

RESULTS

A total of 192 patients undergoing thyroid surgery were enrolled. One hundred forty-three (74.5%) were females and the mean age of participants was 45.29 ± 16.88 years. Most patients, 170 (88.5%), had a papillary histological type, and total thyroidectomy was performed in 150 (78.1%). A significant association was found between the type of surgery and postoperative hypoparathyroidism (p=<0.05*). In addition, hypocalcemia was seen in 147 (76.6%) of the patients. Postoperative hypoparathyroidism was significantly higher among patients who had asymptomatic postoperative hypocalcemia and those who received IV calcium gluconate (p=<0.05*). Moreover, postoperative hypocalcemia, hypomagnesemia, and hyperphosphatemia were significantly associated with postoperative hypoparathyroidism (p=<0.05*).

CONCLUSION

The incidence of postoperative hypoparathyroidism is significantly higher among patients who underwent total thyroidectomy and had a normal level of preoperative parathyroid hormone (PTH) and magnesium (Mg) levels. Identifying these factors is a crucial step to minimize the occurrence of such complications.

How to Manage Advanced Differentiated Thyroid Cancer: Step-by-Step Analysis from Two Italian Tertiary Referral Centers

BACKGROUND

Differentiated thyroid carcinoma (DTC) has an excellent prognosis; however, advanced disease is associated with a worse prognosis and is relatively common. Surgery followed by RAI treatment remains the mainstream treatment for a large majority of patients with high- and intermediate-risk DTC, but its benefits should be carefully weighed against the potential for harm. The aim of this paper is to critically review the experience in treating advanced DTC at two tertiary referral centers in Italy.

METHODS

Retrospective analysis of 300 patients who underwent surgery for ADTC over 30 years.

RESULTS

The complication rate was 50.33%. A total of 135 patients (45%) remained at regular follow-up, 118 (87.4%) were alive, while 17 (12.6%) were deceased. The mean overall survival at 12 years was 84.8% with a mean of 238 months. Eleven patients (8.1%) experienced a relapse after a median of 13 months.

CONCLUSIONS

ADTC patients adequately treated can achieve prolonged survival even in the case of metastasis or disease relapse. Patients with ADTC should be referred to high-volume centers with the availability of an extended multidisciplinary team to receive tailored treatment.

Hypoparathyroidism following total thyroidectomy: high rates at a low-volume, non-parathyroid institution

Background

Hypoparathyroidism following total thyroidectomy is globally the most common complication to thyroid surgery. The reported complication rates vary widely and might be highly dependent on the surgical experience. In this study we aimed to evaluate the rate of hypoparathyroidism following primary total thyroidectomy at a low-volume institution that only performs thyroid surgery and does not have any experience with parathyroid surgery.

Methods

Retrospective cohort study. All patients undergoing primary total thyroidectomy at the ENT-Department, Goedstrup Hospital, Denmark, over a 5-year period (2016-2020) were identified through the procedure codes for total thyroidectomy. Medical records, pathology reports, biochemical and medical histories were fully assessed for each patient. The primary endpoint was the rate of hypoparathyroidism- both immediate and permanent. Secondary outcomes were parathyroid gland identification rates, rates of parathyroid gland autotransplantation, and rates of inadvertent parathyroid gland excision.

Results

A total of 89 patients were included in the final analysis. A total of 33 patients (37.1%) experienced immediate hypoparathyroidism following surgery, while 30 patients (33.7%) still were on active vitamin D two months postoperatively. One year following surgery, 28 patients (31.5%) were still on active vitamin D and were considered as having permanent hypoparathyroidism. Sixty-one percent of the parathyroid glands were identified intraoperatively, and 19% of the patients experienced parathyroid autotransplantation. Inadvertent parathyroid gland excision occurred for 21% of the patients and was associated with a significantly increased risk of permanent hypoparathyroidism (RR = 2.99; 95% CI: 1.36 - 6.62, p = 0.005).

Conclusion

Both transient and permanent hypoparathyroidism following total thyroidectomy at a low-volume, non-parathyroid institution occurred with much higher frequencies than previously reported. The elevated rates were most likely due to the low-volume, non-parathyroid nature of the surgeons which in part was mirrored in low parathyroid gland identifications rates, and high rates of autotransplantation and inadvertent parathyroid gland excision.

Recent Advances in the Surgical Management of Thyroid Cancer

A growing incidence of differentiated thyroid cancer (DTC) has been reported in most developed countries, corresponding mainly to incidentally discovered small papillary thyroid carcinomas. Given the excellent prognosis of most patients with DTC, optimal therapeutic management, minimizing complications, and preserving patient quality of life are essential. Thyroid surgery has a central role in both the diagnosis, staging, and treatment of patients with DTC. Thyroid surgery should be integrated into the global and multidisciplinary management of patients with DTC. However, the optimal surgical management of DTC patients is still controversial. In this review article, we discuss the recent advances and current debates in DTC surgery, including preoperative molecular testing, risk stratification, the extent of thyroid surgery, innovative surgical tools, and new surgical approaches.

Risk Factors for Hypoparathyroidism after Thyroid Surgery: A Single-Center Study

BACKGROUND

Hypoparathyroidism is one of the most common complications after thyroidectomy. This study evaluated the incidence and potential risk factors for postoperative hypoparathyroidism after thyroid surgical procedures in a single high-volume center.

METHODS

In this retrospective study, in all patients undergoing thyroid surgery from 2018 to 2021, a 6 h postoperative parathyroid hormone level (PTH) was evaluated. Patients were divided into two groups based on 6 h postoperative PTH levels (≤12 and >12 pg/mL).

RESULTS

A total of 734 patients were enrolled in this study. Most patients (702, 95.6%) underwent a total thyroidectomy, while 32 patients underwent a lobectomy (4.4%). A total of 230 patients (31.3%) had a postoperative PTH level of <12 pg/mL. Postoperative temporary hypoparathyroidism was more frequently associated with female sex, age < 40 y, neck dissection, the yield of lymph node dissection, and incidental parathyroidectomy. Incidental parathyroidectomy was reported in 122 patients (16.6%) and was correlated with thyroid cancer and neck dissection.

CONCLUSIONS

Young patients undergoing neck dissection and with incidental parathyroidectomy have the highest risk of postoperative hypoparathyroidism after thyroid surgery. However, incidental parathyroidectomy did not necessarily correlate with postoperative hypocalcemia, suggesting that the pathogenesis of this complication is multifactorial and may include an impaired blood supply to parathyroid glands during thyroid surgery.

Effect of near infrared autofluorescence guided total thyroidectomy on postoperative hypoparathyroidism: a randomized clinical trial

PURPOSE

The purpose of this single-blinded, 2-centre, randomized controlled trial was to test if near-infrared (NIR) autofluorescence image guidance for parathyroid gland (PG) detection during total thyroidectomy can reduce the incidence of hypoparathyroidism in both malignant and benign cases.

METHOD

Patients admitted for primary or completion total thyroidectomy were randomized to either the NIR intervention group or the standard care NONIR (no near infrared) group. The primary endpoint was the rate of hypoparathyroidism at the 3-month follow-up, defined as hypocalcemia and inappropriately low parathyroid hormone levels and/or continuous treatment with active vitamin D. The secondary endpoint was the PG identification rate.

RESULTS

A total of 147 patients were included of whom 73 were allocated to NIR. Primary or completion thyroidectomy was conducted in 84 and 63 cases, respectively. A total of 130 completed 3 months follow-up. Postoperative hypoparathyroidism in the NIR group at 12 h, 1 month and 3 months was, respectively, 31.8, 14.1, 6.5% compared with 35.9, 18.9, 11.8% in the NONIR group (all p > 0.46). In the NIR group, the identification rate of PGs was 69.5% (146 of 210 PGs), and 9% (19 of 210 PGs) were identified only due to additional use of NIR. For 15 out of 69 patients (21.7%) additionally PGs was found.

CONCLUSION

Hypoparathyroidism was nominally less frequent in the NIR group, although not statistically significant. Further studies are needed to confirm if NIR may be a supportive PG identification tool to minimize the number of PG which would have been otherwise missed, especially during more complicated thyroid procedures.

TRIAL REGISTRY

ClinicalTrials.gov: NCT04193332. Registration date: 16.08.2019.

Hypoparathyroidism after thyroidectomy: A 20-year experience at a children's hospital

INTRODUCTION

Hypoparathyroidism (HP) is the most common complication of total thyroidectomy and can be an emergency.

OBJECTIVES

To describe the prevalence of HP after total thyroidectomy in children under 14 years of age, the variables related to its appearance and its clinical expression.

PATIENTS AND METHODS

Retrospective study at a children's hospital in the last 20 years. HP was defined by the need to supplement calcium after the intervention and was considered permanent if it could not be suspended within 12 months. Fisher's statistical method of comparison of proportions.

RESULTS

Thirty-nine children and adolescents (26 females) with an age range of 3.67-14.00 years. In 25 patients, the intervention was prophylactic and in 14 it was therapeutic; 14 suffered accidental excision of some parathyroid gland, but none more than two of them; 12 presented HP, of which 3 were permanent; 5 presented clinical symptoms; 1 of them was an emergency. The frequency of HP was 4/4 when 2 parathyroids were dissected, 2/10 when one was dissected, and 6/25 when none were dissected (p = 0.02). In the prophylactic interventions, it was 6/25 compared to 6/14 in the therapeutic ones (p = 0.29). The three cases of permanent HP were in children under 6 years of age, and it did not occur in any older children (p = 0.09).

CONCLUSIONS

HP is a common and sometimes serious complication in children after total thyroidectomy. It can occur, and even be permanent, even if the intervention is prophylactic and parathyroid glands remain in situ. Younger age could be a risk factor.

Incidence and predictive factors of postoperative hypocalcaemia according to type of thyroid surgery in older adults

PURPOSE

Transient hypocalcaemia after thyroid surgery and its possible predictors have not been extensively described in the elderly. This study aimed to establish the frequency of postsurgical transient hypocalcaemia according to the extent of thyroid surgery in older adults and to assess mineral metabolism biochemical parameters as its predictors.

METHODS

All patients ≥60 years undergoing thyroid surgery were prospectively included. Type of surgery (hemithyroidectomy(HT) or total thyroidectomy(TT)); and preoperative 25OH Vitamin D (25OHD) and pre and 6 (only TT), 24 h and 6 months postsurgical serum levels of calcium, magnesium, phosphate and parathormone (PTH) were considered. Postsurgical hypoparathyroidism (hPTpost) was defined at PTH levels ≤11 pg/mL.

RESULTS

Out of 46 patients (87% female), age (mean ± SD) 70.1 ± 6.2 years, 24 h postsurgical hypocalcaemia was found in ten patients (22%). In 25 (54%) TT patients, 36% and 16% had postsurgical hypocalcaemia at 6 and 24 h respectively; 28% hPTpost but no definitive hPT was recorded and 44% had 25OHD deficiency. Lower 24 h magnesium levels were found in those TT patients with 24 h hypocalcaemia (1.6 ± 0.1 vs 1.9 ± 0.1 mg/dL (p = 0.005)). Among 21 (46%) HT patients, 28.6% had 24 h postsurgical hypocalcaemia; 9.5% had hPTpost. A positive correlation was observed between preoperative 25OHD and 24 h calcaemia (r:0.51,p = 0.02). 43% of the patients were 25OHD deficient, in whom 55% had 24 h hypocalcaemia vs only 9% in the 25OHD sufficient group (p = 0.049).

CONCLUSION

Postsurgical hypocalcaemia was common in elderly thyroidectomized patients. After TT, lower magnesium levels were found in those patients with 24 h hypocalcaemia. In the HT group, preoperative 25OHD deficiency predicted lower postsurgical calcium levels.

Post-thyroidectomy hypocalcemia: Is a routine preferable over a selective supplementation?

BACKGROUND

Comparative studies among protocols for the management of post-total thyroidectomy (TT) hypocalcemia are lacking. We compared the effectiveness of PTH-driven selective supplementation (PD-SS) and routine calcium and calcitriol supplementation with preoperative calcitriol administration in preventing symptomatic hypocalcemia (SH) and readmission.

METHODS

Three-hundred consecutive patients undergoing TT were assigned to 3 groups: the PD-SS group, the high-dose routine supplementation (HD-RS) group and the low-dose routine supplementation (LD-RS) group.

RESULTS

Mean post-operative stay was shorter in HD-RS patients when compared to PD-SS and LD-RS (p < 0.001). Significantly more patients in the PD-SS group experienced SH (p = 0.042). The rate of post-operative hypocalcemia was not significantly different among the groups (p = 0.063). No readmission for SH or hypercalcemia occurred.

CONCLUSIONS

HD-RS emerged as the most effective treatment to prevent SH, without increasing the risk of readmission for calcitriol-related hypercalcemia. Basing on the present results, HD-RS should be recommended as the preferable protocol.

Risk Factors for Low Levels of Parathyroid Hormone after Surgery for Thyroid Cancer: A Single Center Study

Background: Thyroidectomy is the definitive treatment for most patients with thyroid cancer. Hypoparathyroidism is the most frequent complication of thyroidectomy, and its pathogenesis is multifactorial. The aim of this study is to evaluate the patient- and surgical-related risk factors for hypoparathyroidism after surgery for thyroid cancer. Methods: In this retrospective study, patients referred to surgery for thyroid cancer from 2016 to 2019 were enrolled. Preoperative serum calcium and parathyroid hormone (PTH) and postoperative 24 h PTH and calcium levels were evaluated. Demographic data, type of surgery, incidence of hypoparathyroidism and hypocalcemia were recorded for all the patients. Patients were divided into two groups based on post-operative PTH levels (≤12 and >12 pg/mL). Results: A total of 189 patients were enrolled in this study. There were 146 women (87.3%) and 43 men (22.7%), with a mean age of 51.3 years. A total of 79 patients (41.7%) underwent a neck dissection. A total of 59 patients (31.1%) had a postoperative PTH level < 12 pg/mL. Female sex, neck dissection, the yield of lymph node dissection and incidental parathyroidectomy were significantly associated with postoperative hypoparathyroidism. Incidental parathyroidectomy was reported in 44 (23.2%) patients and was correlated with younger age (<40 years) and neck dissection. There was no difference in the rate of post-operative hypocalcemia between patients with incidental parathyroidectomy and those without. Conclusions: Young patients undergoing neck dissection and with incidental parathyroidectomy have the highest risk of postoperative hypoparathyroidism after surgery for thyroid cancer. However, a large proportion of patients without incidental parathyroidectomy may have temporary hypocalcemia, suggesting that impaired blood supply of parathyroid glands during their identification and dissection may play a relevant role.

Morbidity following thyroid and parathyroid surgery: Results from key performance indicator assessment at a high-volume centre in New Zealand

BACKGROUND

Complications following thyroid/parathyroid surgery include recurrent laryngeal nerve (RLN) injury, hypocalcaemia and return to theatre for haematoma evacuation. Rates of these form the basis of key performance indicators (KPI). An endocrine database, containing results from 1997, was established at the North Shore Hospital in Auckland, New Zealand. We aimed to measure complication rates by procedure (thyroid and parathyroid), explore a temporal change in our unit and compare our results against international literature.

METHODS

A retrospective review of the database between July 1997 and February 2020 was performed. The results for each KPI were analysed in total and over consecutive time periods. A review of the literature was carried out to find international complication rates for comparison. A cumulative sum (CUSUM) analysis was performed to give visual feedback on performance.

RESULTS

There were 1062 thyroidectomies and 336 parathyroidectomies from July 1997 to February 2020. Thyroid surgery results found rates of temporary/permanent RLN injury of 1.9%/0.3%, temporary/permanent hypocalcaemia of 22.3/2.5%, and return to theatre for haematoma evacuation of 1.1%. Parathyroid surgery results were, temporary RLN injury of 0.8% (no permanent injury), temporary/permanent hypocalcaemia of 1.7%/0.4%, and return to theatre for haematoma evacuation of 0.3%. CUSUM analysis found KPI results to be comparable with international literature.

CONCLUSION

Our unit's KPI results are comparable to published results in the literature. The use of this clinical database will help in future monitoring of performance and help drive improvement in the service. Embedding prospective data collection as routine practice allows for continuous improvement for the unit.

Hypoparathyroidism after thyroidectomy: A 20-year experience at a children's hospital

INTRODUCTION

Hypoparathyroidism (HP) is the most common complication of total thyroidectomy and can be an emergency.

OBJECTIVES

To describe the prevalence of HP after total thyroidectomy in children under 14 years of age, the variables related to its appearance and its clinical expression.

PATIENTS AND METHODS

Retrospective study at a children's hospital in the last 20 years. HP was defined by the need to supplement calcium after the intervention and was considered permanent if it could not be suspended within 12 months. Fisher's statistical method of comparison of proportions.

RESULTS

Thirty-nine children and adolescents (26 females) with an age range of 3.67 to 14.00 years. In 25 patients, the intervention was prophylactic and in 14 it was therapeutic. Fourteen suffered accidental excision of some parathyroid gland, but none more than t2 of them. Twelve presented HP, of which 3 were permanent; 5 presented clinical symptoms; one of them was an emergency. The frequency of HP was 4/4 when 2 parathyroids were dissected, 2/10 when one was dissected, and 6/25 when none were dissected (P=.02). In the prophylactic interventions, it was 6/25 compared to 6/14 in the therapeutic ones (P=.29). The 3 cases of permanent HP were in children under 6 years of age, and it did not occur in any older children (P=.09).

CONCLUSIONS

HP is a common and sometimes serious complication in children after total thyroidectomy. It can occur, and even be permanent, even if the intervention is prophylactic and parathyroid glands remain in situ. Younger age could be a risk factor.

Preoperative Vitamin D Deficiency is a Risk Factor for Postthyroidectomy Hypoparathyroidism: A Systematic Review and Meta-Analysis of Observational Studies

CONTEXT

Whether preoperative vitamin D deficiency (VDD) contributes to postoperative hypoparathyroidism (hypoPT) risk is unknown.

OBJECTIVE

This work aimed to meta-analyze the best available evidence regarding the association between preoperative vitamin D status and hypoPT risk.

METHODS

A comprehensive literature search was conducted in PubMed, CENTRAL, and Scopus databases, up to October 31, 2020. Study selection included patients undergoing thyroidectomy with preoperative vitamin D status and postoperative hypoPT data. Two researchers independently extracted data from eligible studies. Data were expressed as risk ratio (RR) with 95% CI. The I2 index was employed for heterogeneity.

RESULTS

Thirty-nine studies were included in the quantitative analysis (61 915 cases with transient and 5712 with permanent hypoPT). Patients with VDD demonstrated a higher risk for transient hypoPT compared with those with preoperative vitamin D sufficiency (RR 1.92, 95% CI, 1.50-2.45, I2 = 85%). These results remained significant for patients with preoperative 25-hydroxyvitamin D concentrations less than or equal to 20 ng/mL (mild VDD; RR 1.46, 95% CI, 1.10-1.94, I2 = 88%) and less than or equal to 10 ng/mL (severe VDD; RR 1.98, 95% CI 1.42-2.76, I2 = 85%). The risk of permanent hypoPT was increased only in cases with severe VDD (RR 2.45, 95% CI, 1.30-4.63, I2 = 45%). No difference was evident in subgroup analysis according to study design or quality.

CONCLUSION

Patients with preoperative VDD are at increased risk of transient hypoPT following thyroidectomy. The risk for permanent hypoPT is increased only for those with severe VDD.

Development and validation of a new model for predicting hypocalcaemia after total thyroidectomy: the NuGra model

BACKGROUND

Hypocalcaemia is the most frequent complication after total thyroidectomy. Finding a method for its early detection has become a priority. A single-center prospective cohort study was conducted to identify risk factors for postoperative hypocalcaemia, develop an early detection model, and test its validity in a different group of patients.

METHODS

The sample was composed of patients who underwent a total thyroidectomy between May 2012 and September 2015. Demographic, clinical, laboratory, and surgical data were collected. The incidence of hypocalcaemia and permanent hypoparathyroidism was calculated. Bivariate and multivariate analysis identified several independent predictors of hypocalcaemia, which were used to design a predictive model. The validity of the model was subsequently tested in a different cohort. Area under the ROC curve (AUROC) was calculated to determine its predictive power.

RESULTS

The study and validation groups included 352 and 118 patients, respectively. Seventy-three patients developed laboratory-confirmed hypocalcaemia (20.7%), and symptomatic in 43 (12.2%). Multivariate analysis confirmed as independent predictors of hypocalcaemia the higher number of parathyroid glands identified [OR 1.41(0.98, 2.02); p = 0.063] and pre-to-postoperative gradient of parathormone decline [OR 1.06(1.04, 1.08); p < 0.001]. Based on these variables, the NuGra (Number of parathyroid glands identified-Gradient of decline) model was developed for predicting laboratory-confirmed hypocalcaemia. Its predictive power was high (AUROC 0.902, CI 0.857-0.947) for the study and the validation group (AUROC 0.956, CI 0.919-0.993).

CONCLUSIONS

A higher number of parathyroid glands identified and a higher gradient of parathormone decline are risk factors for post-thyroidectomy hypocalcaemia. The NuGra model is useful for early prediction of individual risk for hypocalcaemia.