Post-thyroidectomy hypocalcemia is related to parathyroid dysfunction even in patients with normal parathyroid hormone concentrations early after surgery

Incidence of post-surgical hypoparathyroidism (POSH) after total thyroidectomy

Post-surgical hypoparathyroidism (POSH) is a recognised complication of total thyroidectomy, leading to hypocalcaemia and its associated adverse effects. This retrospective study aimed to determine the incidence of POSH and identify perioperative predictors for its development. Data from patients who underwent total or completion thyroidectomy between January 2017 and July 2022 were retrospectively analysed. The incidence of POSH was assessed, and patients were categorised into transient or prolonged POSH at six months postoperatively. Potential predictors for POSH were investigated including gender, histological diagnosis, and preoperative thyroid function. A total of 133 adult patients were included in the study. The incidence of patients recovering from transient POSH within six months was 15%, and 5% had prolonged POSH beyond six months of surgery. Parathyroid hormone (PTH) levels normalised in 83% of prolonged POSH patients within 14-33 months, reducing the incidence of persistent POSH to 0.75%. Despite normal PTH levels, overall, 3% had persistent marginally low calcium levels (mean 2.11 mmol/L) in keeping with relative parathyroid insufficiency. Histological diagnosis of malignancy was the only significant risk factor for both transient and prolonged POSH (RR 2.95, CI 1.54 to 5.67, p = 0.001) in this cohort. Cautious capsular dissection during thyroidectomy and protection of the parathyroid glands and vascular supply produce a low incidence of POSH. Although the vast majority of patients with POSH recover after six months, hypocalcaemia may persist due to relative parathyroid insufficiency, requiring long-term calcium supplementation. Further research is needed to determine the best strategies for preventing and treating this condition.

Incidence and risk factors of hypoparathyroidism and hypocalcemia after hemithyroidectomy

PURPOSE

The incidence and risk factors for hypoparathyroidism after total thyroidectomy is well-known. However, the characteristics of hypoparathyroidism and hypocalcemia after hemithyroidectomy have not been investigated well. In this study, we aimed to evaluate the incidence, characteristics, and risk factors of hypoparathyroidism and hypocalcemia after hemithyroidectomy.

METHOD

We retrospectively analyzed the medical data of 321 patients who underwent hemithyroidectomy, with or without central neck dissection, from January 2012 to April 2019. We analyzed the serum intact parathyroid hormone (iPTH), calcium, and ionized calcium (iCa) levels serially (preoperatively and postoperatively on the operation day; days 1 and 3; and months 1, 3, 6, and 12) and evaluated risk factors for postoperative hypoparathyroidism and hypocalcemia.

RESULTS

The mean iPTH and calcium levels decreased significantly after hemithyroidectomy on the operation day and postoperative days 1 and 3, and returned to the preoperative level at the postoperative 1-month follow-up. The mean iCa level decreased significantly on the operation day and postoperative day 1. Transient hypoparathyroidism and transient hypocalcemia occurred in 16 (5%) and 250 (78%) participants, and they recovered to normal levels postoperatively by 1 month. Eight (2.5%) patients had mild symptoms of hypocalcemia necessitating oral calcium supplementation. No permanent hypoparathyroidism or hypocalcemia was observed. Preoperatively low serum iPTH and calcium levels were associated with transient hypoparathyroidism and hypocalcemia after hemithyroidectomy.

CONCLUSION

Approximately 5% and 2.5% of participants showed transient hypoparathyroidism and mild symptomatic hypocalcemia after hemithyroidectomy. The risk factors for transient hypoparathyroidism and hypocalcemia include preoperative low serum iPTH and calcium levels.

Definition and diagnosis of postsurgical hypoparathyroidism after thyroid surgery: meta-analysis

Background

Postsurgical hypoparathyroidism (PH) is the most frequent complication after thyroid surgery. The aim of this systematic review and meta-analysis is to summarize a unifying definition of PH and to elucidate the best possible approach for early detection of PH.

Methods

A systematic review of the literature according to the PICO framework using Embase, PUBMED and the Cochrane library was carried out on 1 December 2021 followed by analysis for risk of bias, data extraction and meta-analysis. All studies addressing the definition of postoperative hypoparathyroidism and/or diagnostic approaches for early detection and diagnosis were included. Case reports, commentaries, non-English articles, book chapters and pilot studies and reviews were excluded.

Results

From 13 704 articles, 188 articles were eligible for inclusion and further analysis. These articles provided heterogeneous definitions of PH. Meta-analysis revealed that postoperative measurements of parathormone (PTH) levels have a higher sensitivity and specificity than intraoperative PTH measurements to predict PH after thyroid surgery. None of the timeframes analysed after surgery within the first postoperative day (POD1) was superior to predict the onset of PH. PTH levels of less than 15 pg/ml and less than 10 pg/ml are both reliable threshold levels to predict the postoperative onset of PH. A relative reduction of mean(s.d.) PTH levels from pre- to postoperative values of 73 (standard deviation 11) per cent may also be predictive for the development of PH. The estimation of calcium levels on POD1 are recommended.

Conclusion

PH is best defined as an undetectable or inappropriately low postoperative PTH level in the context of hypocalcaemia with or without hypocalcaemic symptoms. PTH levels should be measured after surgery within 24 h. Both threshold levels below 10 and 15 pg/ml or relative loss of PTH before/after thyroid surgery are reliable to predict the onset of PH.

Improving safety in paediatric thyroidectomy by PTH measurements

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.

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.

Assessment of Serum Ionized Calcium in the Perioperative Period in Patients Undergoing Total Thyroidectomy

BACKGROUND: The serious complications of total and near-total thyroidectomy vary from hypocalcemia to recurrent laryngeal nerve injury to tension hematoma. Post-operative hypocalcemia is common and has an incidence of 1.3–83% in some studies. AIM: The aim of the study is to evaluate the immediate post-operative sequence of serum-ionized calcium next to entire or close entire thyroidectomy to describe the incidence degree of hypocalcemia. METHOD: One hundred and seventy-four (174) patients who underwent total and near-total thyroidectomy were investigated for serum-ionized calcium level preoperatively and on post-operative day (POD) 1 and 2, searching for difference in serum-ionized calcium level preoperatively. RESULTS: There was a significant difference between pre-operative serum-ionized calcium (Ca++) level and that in POD1. The mean pre-operative ionized Ca was 1.23 ± 0.47 mmol/l, while mean ionized Ca on POD1 was 1.175 ± 0.11 mmol/l proposing decrease in mean of ionized Ca++ in POD1 (p = 0.0001). There was also a significant difference between pre-operative serum-ionized Ca++ level and that in POD2. The mean pre-operative ionized Ca was 1.23 ± 0.47 mmol/l, while the mean of ionized calcium on POD2 was 1.177 ± 0.1 mmol/l suggesting decrease in mean concentration of Ca++ in POD2 (p = 0.0001). CONCLUSION: Significant number of patients who undergo near-total and total thyroidectomy develop decrease in the serum concentration of calcium postoperatively.

Thyroidectomy for Cancer: The Surgeon and the Parathyroid Glands Sparing

BACKGROUND

The diagnosis of thyroid cancer is continuously increasing and consequently the amount of thyroidectomy. Notwithstanding the actual surgical skill, postoperative hypoparathyroidism still represents its most frequent complication. The aims of the present study are to analyze the rate of postoperative hypoparathyroidism after thyroidectomy, performed for cancer by a single first operator, without any technological aid, and to compare the data to those obtained adopting the most recent technological adjuncts developed to reduce the postoperative hypoparathyroidism.

METHODS

During the period 1997-2020 at the Endocrine Surgery Unit of the Department of Clinical and Experimental Medicine of the University of Florence, 1648 consecutive extracapsular thyroidectomies for cancer (401 with central compartment node dissection) were performed. The percentage of hypoparathyroidism, temporary or permanent, was recorded both in the first period (Group A) and in the second, most recent period (Group B). Total thyroidectomies were compared either with those with central compartment dissection and lobectomies. Minimally invasive procedures (MIT, MIVAT, some transoral) were also compared with conventional. Fisher's exact and Chi-square tests were used for comparison of categorical variables. p < 0.01 was considered statistically significant. Furthermore, a literature research from PubMed^® has been performed, considering the most available tools to better identify parathyroid glands during thyroidectomy, in order to reduce the postoperative hypoparathyroidism. We grouped and analyzed them by technological affinity.

RESULTS

On the 1648 thyroidectomies enrolled for the study, the histotype was differentiated in 93.93 % of cases, medullary in 4% and poorly differentiated in the remaining 2.06%. Total extracapsular thyroidectomy and lobectomy were performed respectively in 95.45% and 4.55%. We recorded a total of 318 (19.29%) cases of hypocalcemia, with permanent hypoparathyroidism in 11 (0.66%). In regard to the literature, four categories of tools to facilitate the identification of the parathyroids were identified: (a) vital dye; (b) optical devices; (c) autofluorescence of parathyroids; and (d) autofluorescence enhanced by contrast media. Postoperative hypoparathyroidism had a variable range in the different groups.

CONCLUSIONS

Our data confirm that the incidence of post-surgical hypoparathyroidism is extremely low in the high volume centers. Its potential reduction adopting technological adjuncts is difficult to estimate, and their cost, together with complexity of application, do not allow immediate routine use. The trend towards increasingly unilateral surgery in thyroid carcinoma, as confirmed by our results in case of lobectomy, is expected to really contribute to a further reduction of postsurgical hypoparathyroidism.

Risks and prediction of postoperative hypoparathyroidism due to thyroid surgery

We aimed to investigate the prevalence of postoperative hypoparathyroidism (PoH), the relevant factors, and predictors of transient or permanent hypoparathyroidism. The files of 352 patients who underwent bilateral total thyroidectomy alone or with central lymph node dissection and/or lateral neck dissection between June 1, 2019, and November 30, 2019, were retrospectively evaluated. Also, calcium and parathyroid hormone levels measured preoperatively and 4–6 h after surgery, follow-up examination results, and time to resolution of transient PoH were recorded. 16.48% (n = 58) of the surgical patients developed transient PoH and 3.98% (n = 14) developed permanent PoH. Length of hospital stay increased in patients who developed PoH (p < 0.001). Transient PoH developed less in patients who underwent parathyroid autotransplantation, while permanent PoH was not detected (p = 0.001). PoH development was not significantly correlated with nodule size as measured by preoperative thyroid ultrasonography (p = 0.944). Patients who had a serum PTH level ≤ 5.95 pmol/L 4–6 h after surgery had a greater risk of developing permanent PoH (OR 134.84, 95% CI 17.25–1053.82). PoH is more common in female gender and is not significantly correlated with nodule size. Parathyroid autotransplantation can prevent the development of PoH.

The Relationship of Magnesium Level with the Recovery of Parathyroid Function in Post-thyroidectomy Hypoparathyroidism

Objectives

Hypocalcemia is the most common complication and acute parathyroid gland insufficiency is the main cause of it after thyroidectomy. In this study, we aimed to evaluate the relationship between the recovery time of parathyroid gland function and patient characteristics, preoperative and postoperative electrolyte changes, and intraoperative parathyroid findings in patients with postoperative hypoparathyroidism.

Methods

Patients who underwent total thyroidectomy (TT) with or without central neck dissection ± lateral neck dissection with a parathyroid hormone (PTH) value of <15 pg/mL within the postoperative 4th hour were included in this study. Postoperative calcium level of <8mg/dL was defined as biochemical hypocalcemia and a PTH value of <15 pg/mL was defined as hypoparathyroidism. The patients were divided into three groups according to the time of PTH recovery (>15 pg/mL); within the first 24 hours, between one day and 30 days, after 30 days, respectively.

Results

One hundred eleven patients (mean age, 49.3±14.4 years) consisted of Groups 1, 2 and 3, including 19 (16F, 3M), 67 (54F, 13M) and 25 (19F, 6M), respectively. Vitamin D deficiency rates for Groups 1, 2, 3 were 41.7%, 53.1% and 88.2%, respectively (p=0.018). Postoperative day 0 PTH values were 11.69±2.79pg/mL, 6.92±3.45 pg/mL, 4.99±2.36 pg/mL, (p<0.001). Biochemical hypocalcemia rates of Groups 1, 2, 3 on postoperative day 1 were 15.8%, 53.7%, 64%, (p=004) respectively, and calcium values were 8.68±0.67 mg/dL, 8.15±0.66 mg/dL, 7.75±1 mg/dL, (p=0.014), respectively. Magnesium values on postoperative day 1 and 7 for Groups 1, 2, 3 were 1.85±0.1 mg/dL, 1.77±0.17 mg/dL, 1.64±0.17 mg/dL, (p=0.005), and 1.86±0.16mg/dL, 1.82±0.21mg/dL, 1.59±0.15mg/dL (p=0.001), respectively. PTH values on postoperative day 1 and 7 in Groups 1, 2, 3 were 20.5±6.4 pg/mL, 7.06±4.35 pg/mL, 4.66±3.26 pg/mL (p<0.001), and 31.04±10.54pg/mL, 18.72±13.84pg/mL, 4.55±4.9pg/mL (p<0.0001), respectively. Parathyroid function improved in 106 patients, and permanent hypoparathyroidism developed in five patients (4.5%).

Conclusion

Hypoparathyroidism can recover rapidly in the first 24 hours in patients with a PTH value of around 10 pg/mL at postoperative 4th hour. As the number of preserved parathyroids increased, recovery time decreased. In patients with postoperative hypoparathyroidism, postoperative low magnesium levels may be associated with delayed recovery of parathyroid function.

Case for staged thyroidectomy

Recent modifications in the management of well-differentiated thyroid cancer have resulted in significant alterations in clinical approach. Utilizing a series of preoperative and postoperative risk factors involving both the patient and the disease pathology, we offer the term "staged thyroidectomy" to help organize these risk factors for patients and the endocrine team to optimize management. This approach is intended to incorporate our latest nuanced understanding of certain endocrine pathology and may serve to optimize patient outcomes.

Predicting Postthyroidectomy Hypocalcemia: Improving Predictive Ability of Parathyroid Hormone Level

We performed a retrospective study of our large patient cohort aiming to examine the ability to predict postthyroidectomy hypocalcemia. A retrospective review of patients who underwent total or near-total thyroidectomy at our institution between 2008 and 2018 was performed. Postoperative hypocalcemia was defined as Ca level <8.0 mg/dL (reference range: 8.9–10.1 mg/dL) within 30 days of operation. Logistic regression was used to develop models for prediction of the occurrence of postoperative hypocalcemia. Inclusion criteria were met by 1463 patients. Hypocalcemia was documented in 223 patients (15%). Models based on parathyroid hormone (PTH) levels alone had an associated receiver operator characteristic with an areas under the curve (AUC) of 0.79. There was an inverse relationship between time of measurement and PTH levels within the first two hours after thyroidectomy ( P < 0.01). When measured two to six hours after closure, the predictive ability of PTH compared favorably (AUC = 0.82) with either earlier (within the first two hours after closure, AUC = 0.79) or later measurement (6–24 hours after closure, AUC = 0.77). When measured between two and six hours postoperatively, PTH < 19 pg/mL had a sensitivity of 90 per cent and negative predictive value of 96 per cent for postoperative hypocalcemia. The model that included the PTH level, concurrently measured total blood calcium level, and time of measurement had an improved predictive ability with an AUC of 0.87. PTH level of 19 pg/mL measured two to six hours after thyroidectomy had a sensitivity of 90 per cent and a negative predictive value of 96 per cent in our cohort. The model including postoperative PTH level, calcium level, and time of measurement may further improve the ability to predict postthyroidectomy hypocalcemia.

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

OBJECTIVE

Hypocalcaemia is the most common complication after total or completion thyroidectomy. This study assesses recent evidence on predictive factors for post-thyroidectomy hypocalcaemia in order to identify the patients affected and aid prevention.

METHOD

Two authors independently assessed articles and extracted data to provide a narrative synthesis. This study was an updated systematic search and narrative review regarding predictors of post-thyroidectomy hypocalcaemia using the Ovid Medline, Embase, Cochrane and Cinahl databases. Results were limited to papers published from January 2012 to August 2019.

RESULTS

Sixty-three observational studies with a total of 210 401 patients met the inclusion criteria. The median incidence was 27.5 per cent for transient biochemical hypocalcaemia, 12.5 per cent for symptomatic hypocalcaemia and 2.2 per cent for permanent hypocalcaemia. The most frequent statistically significant predictor of hypocalcaemia was peri-operative parathyroid hormone level. Symptomatic hypocalcaemia and permanent hypocalcaemia were seen more frequently in patients undergoing concomitant neck dissection.

CONCLUSION

Many factors have been studied for their link to post-thyroidectomy hypocalcaemia, and this study assesses the recent evidence presented in each case.

Volume, outcomes, and quality standards in thyroid surgery: an evidence-based analysis-European Society of Endocrine Surgeons (ESES) positional statement

INTRODUCTION

Continuous efforts in surgical speciality aim to improve outcome. Therefore, correlation of volume and outcome, developing subspecialization, and identification of reliable parameters to identify and measure quality in surgery gain increasing attention in the surgical community as well as in public health care systems, and by health care providers. The need to investigate these correlations in the area of endocrine surgery was identified by ESES, and thyroid surgery was chosen for this analysis of the prevalent literature with regard to outcome and volume.

MATERIALS AND METHODS

A literature search that is detailed below about correlation between volume and outcome in thyroid surgery was performed and assessed from an evidence-based perspective. Following presentation and live data discussion, a revised final positional statement was presented and consented by the ESES assembly.

RESULTS

There is a lack of prospective randomized controlled studies for all items representing quality parameters of thyroid surgery using uniform definitions. Therefore, evidence levels are low and recommendation grades are based mainly on expert and peer evaluation of the prevalent data.

CONCLUSION

In thyroid surgery a volume and outcome relationship exists with respect to the prevalence of complications. Besides volume, cumulative experience is expected to improve outcomes. In accordance with global data, a case load of < 25 thyroidectomies per surgeon per year appears to identify a low-volume surgeon, while > 50 thyroidectomies per surgeon per year identify a high-volume surgeon. A center with a case load of > 100 thyroidectomies per year is considered high-volume. Thyroid cancer and autoimmune thyroid disease predict an increased risk of surgical morbidity and should be operated by high-volume surgeons. Oncological results of thyroid cancer surgery are significantly better when performed by high-volume surgeons.

Identifying early postoperative serum parathyroid hormone levels as predictors of hypocalcaemia after total thyroidectomy: A prospective non-randomized study

OBJECTIVE

There is no clear cut-off value of serum parathyroid hormone (PTH) or calcium in which patients are at risk for hypocalcemia after total thyroidectomy. We evaluated the usefulness of serum calcium and PTH concentration measurements after total thyroidectomy in predicting late-occurring hypocalcemia.

DESIGN

A prospective, single-center, non-randomized longitudinal cohort study of 143 patients undergoing thyroidectomy between August 2019 and December 2019 with serum calcium and PTH levels sampled 1 h after surgery and on the first and fifth postoperative day. Hypocalcemia was defined as serum calcium levels < 2.14 mmol/L regardless of clinical symptoms. Normal PTH range was 1.6-6.9 pmol/L.

MEASUREMENTS

The primary outcome measure was presence of hypocalcemia on the first and fifth postoperative day, analyzed by a logistic regression model. The PTH cut-off value for prediction of hypocalcemia was identified using a ROC curve comparing all three time points using the Youden J index.

RESULTS

Out of 143 patients, 52 (36.4%) had hypocalcemia on the fifth postoperative day. Advanced age, concomitant neck dissection and serum PTH levels < 2.9 pmol/L 1 h after surgery and on the first postoperative surgery day were associated with a high risk of hypocalcemia on the first and fifth postoperative day and need for higher doses of calcium supplements (P < 0.0001, AUC 0.748, 95% CI 0.669-0.817, with 76.92% sensitivity and 71.43% specificity).

CONCLUSION

Serum PTH level measured immediately postoperatively and on the first postoperative day is a reliable predictor of postoperative hypocalcemia with important clinical implications.

A Single Parathyroid Hormone Measurement Two Hours after a Thyroidectomy Reliably Predicts Permanent Hypoparathyroidism

INTRODUCTION

Hypoparathyroidism is the most common complication following thyroidectomy, and various algorithms for early detection have been suggested. The aim of this study was to evaluate the predictive value of measuring the parathyroid hormone level 2 h after thyroidectomy and whether determination of the perioperative decline in parathyroid hormone added diagnostic value.

METHODS

Patients subjected to thyroidectomy for benign thyroid disorders were analyzed in (1) a retrospective register-based study (366 consecutive patients treated during 2015-2016) and (2) a prospective observational study (39 patients treated during 2018). Optimal cut-off values for postoperative parathyroid hormone and perioperative decline (%) in parathyroid hormone were determined by receiver operating characteristics and area under the curve. Sensitivity, specificity, positive and negative predictive values were calculated using cross tabulation.

RESULTS

The prevalence of hypoparathyroidism the first day after thyroidectomy was higher among patients treated for hyperthyroidism (30% vs 20%; P = 0.03). The optimal cut-off level for postoperative parathyroid hormone was 1.1 pmol/L (area under the curve = 0.887, 95% confidence interval: 0.839-0.934; positive predictive value: 88%, negative predictive value: 93%) for the entire cohort. When the groups were analyzed separately, the optimal cut-off was 1.05 for the non-hyperfunctioning group and 1.55 pmol/L for the group with hyperthyroidism. Twelve months after thyroidectomy, 3% were defined as having permanent hypoparathyroidism. Measurement of parathyroid hormone decline added diagnostic value for one patient with preoperative parathyroid-hormone-elevation associated with vitamin D deficiency.

CONCLUSION

For patients with vitamin D sufficiency, the diagnostic accuracy of a single measurement of parathyroid hormone 2 h after thyroidectomy is an excellent indicator for predicting transient hypoparathyroidism.

Influence of gender and women's age on the prevalence of parathyroid failure after total thyroidectomy for multinodular goiter

Background

Female gender, particularly of a young age, has been reported as a risk factor for hypocalcemia after total thyroidectomy. There are no studies, however, addressing specifically the influence of women's age and menstrual status on postoperative parathyroid function.

Methods

Cohort study of consecutive patients undergoing total thyroidectomy for benign goiter between 2000-2017, excluding those with associated hyperparathyroidism, reoperation or conservative procedures. Prevalence of postoperative hypocalcemia (s-Ca <8 mg/dL at 24 hours), protracted (1-month) and permanent hypoparathyroidism (>1 year) were the main variables studied. Complete >1-year follow-up was achieved for all patients developing post-thyroidectomy hypocalcemia. Demographic, disease-related, number of parathyroid glands remaining in situ (PGRIS), biochemical and surgical variables were recorded. The impact of menstrual status on parathyroid function was analyzed by comparing two groups of women using a cut-off age of 45 years.

Results

A total of 811 patients were included: 14 percent were males and 86 percent females with a mean age of 53.2 years. The prevalence of postoperative hypocalcemia was ten points higher in women than in men (23.7% vs. 36.4%; P=0.008). Permanent hypoparathyroidism was more common in women than in men (5% vs. 0.9%; P=0.048). Compared to females ≥45 years, young women presented higher rates of all three parathyroid failure syndromes despite similar PGRIS scores. Age <45 years and low PGRIS scores were the only independent variables predicting postoperative hypocalcemia in females.

Conclusions

Premenopausal patients presented a higher prevalence of parathyroid failure and permanent hypoparathyroidism with similar PGRIS scores suggesting the presence of a sex-hormone factor influencing post-thyroidectomy parathyroid function.

Change of surgical strategy for Graves' disease from subtotal thyroidectomy to total thyroidectomy: a single institutional experience

The extent of thyroidectomy in Graves' disease remains controversial. In our institution, long-term euthyroidism without thyroxin replacement therapy has been the aim, and it has long been the standard surgical procedure used to treat Graves' disease in many institutions, including our hospital. Based our several clinical studies, it was concluded that subtotal thyroidectomy is not suitable as a standard surgical procedure for the treatment of Graves' disease. In 2009, the surgical strategy for Graves' disease was changed from subtotal thyroidectomy to total thyroidectomy in our hospital. In this study, how surgical complications have changed after this modification was examined. The subjects were 1,476 patients with Graves' disease treated by thyroidectomy between 2006 and 2014. There were 1,119 females and 357 males with a median age of 39 years. A total of 660 patients underwent bilateral subtotal thyroidectomy (ST group), and 816 patients underwent total thyroidectomy (TT group). Both transient hypocalcemia and prolonged hypocalcemia were observed significantly more frequently in the TT group than in the ST group (p < 0.001). Total thyroidectomy was identified as risk factors for prolonged hypocalcemia on multivariate analysis. In conclusion, total thyroidectomy is a reliable and effective therapy for controlling hyperthyroidism in terms of controlling of hyperthyroidism. However, it should be noted that total thyroidectomy resulted in increased rate of prolonged hypocalcemia. Surgeons should try to reduce the surgical complication rate as much as possible.

The timing of parathyroid hormone measurement defines the cut-off values to accurately predict postoperative hypocalcemia: a prospective study

PURPOSE

Serum intact parathyroid hormone (iPTH) level is an early marker of post-thyroidectomy hypocalcemia. However, lack of methodological standardization to define timing and cut-off points of iPTH measurement limit its clinical applicability. Here, we evaluated the relationship between two distinct postoperative time sampling and iPTH accuracy on predicting hypocalcemia.

METHODS

iPTH was measured within 4 h after surgery (iPTH 4 h) and on the morning of the first postoperative day (iPTH 1st PO). Hypocalcemia was defined by levels of total calcium corrected by serum albumin ≤ 8.0 mg/dL and/or by the presence of symptoms. The most accurate iPTH cut-off point for hypocalcemia prediction was established from a ROC curve comparing both time-points.

RESULTS

The study included 101 patients. The mean age was 52.4 ± 12.9 years, 93 were women (92.1%) and 69 patients underwent total thyroidectomy (68.3%). Hypocalcemia occurred in 25 patients (24.8%), of whom 12 were symptomatic. Total thyroidectomy, longer duration of surgery, surgical complications related to parathyroid glands and lower levels of iPTH 4 h and iPTH 1st PO were associated with postoperative hypocalcaemia (all P < 0.05). Using the ROC curve, the optimal cut-off points were 19.55 pg/mL and 14.35 pg/mL for iPTH 4 h and iPTH 1st PO, respectively. The comparison of the AUC showed no significant difference between these two points of evaluation (0.935 vs. 0.940; P = 0.415).

CONCLUSIONS

Serum iPTH levels measured within 4 h or on the first morning after surgery are predictors of postoperative hypocalcemia. Notably, both time-points have the same accuracy to predict postoperative hypocalcemia (with different cutoff points).

Factors predicting hypocalcemia after total thyroidectomy - A retrospective cohort analysis

BACKGROUND

Hypocalcemia after total thyroidectomy is the most frequent complication resulting in prolongation of hospitalisation. Therefore we aimed to analyse clinical risk factors predictive for hypocalcemia and its long term persistence after total thyroidectomy.

METHODS

Retrospective analysis of patients undergoing total thyroidectomy from 2005 until 2013. Outcome measures were initial postoperative hypocalcemia defined as serum calcium below 2.0 mmol/l after total thyroidectomy within 48 h and persistent hypocalcemia defined as serum calcium below 2.0 mmol/l above six months and/or the need for additional calcium and vitamin D supplementation.

RESULTS

Initial postoperative hypocalcemia was present in 160 of 702 patients (22.8%) with 91 patients (13%) developing symptoms. 48 patients (6.8%) had a persistent hypocalcemia above six months. Patients with an initial symptomatic postoperative hypocalcemia showed significantly more often a persistent hypocalcemia compared to asymptomatic patients with biochemical hypocalcemia (38 patients (41.8%) vs. 10 patients (14.5%), p < 0,001). In the binary logistic regression analysis, female gender (OR 2.4; CI95% 1.5-3.8), prolonged surgery time >189 min (OR 1.8; CI95% 1.2-2.6) and parathyroid reimplantation (OR 2.4; CI95% 1.2-4.7) were associated with initial hypocalcemia while only initial symptomatic hypocalcaemia was shown to be independently associated with persistent hypocalcemia (OR 40.9; CI95% 18.5-90.4).

CONCLUSION

Prolonged surgery time seems to correlate with initial postoperative hypocalcemia independently of the underlying disease and surgical expertise but does not affect the persistence of hypocalcemia. Initial symptomatic postoperative hypocalcemia after total thyroidectomy is associated with a high rate of persistent hypocalcemia.

Modification, validation and implementation of a protocol for post-thyroidectomy hypocalcaemia

Introduction The management of post-thyroidectomy hypocalcaemia should facilitate early discharge, and reduce risks of hypocalcaemia, readmission and treatment related hypercalcaemia. This paper describes the implementation, evaluation and revision a protocol for the optimal management of this condition. Methods Day 1 parathyroid hormone (PTH) measurements in addition to calcium measurements were commenced following review of the unit's outcomes and literature on post-thyroidectomy hypocalcaemia. Outcomes from a three-year cohort of patients undergoing thyroid surgery helped amend this protocol (revision 1) to reduce biochemical tests, stipulate the need, nature and dose of vitamin D/calcium supplements, and encourage early discharge. This was further validated over seven months to assess compliance, episodes of hyper and/or hypocalcaemia after discharge, readmissions and need for treatment changes. Further revisions were made (revision 2) and implemented. Results The temporary and long-term postoperative hypocalcaemia rates were 29.1% and 3.2% respectively. Repeat calcium measurements on the first day altered management in only 1.4% of cases. The revised protocol was adhered to in 90% of cases. One patient had hypocalcaemia (due to non-compliance) and one had hypercalcaemia. Revision 2 involved reducing the dose of calcium. Conclusions This is a good example of a unit protocol for post-thyroidectomy hypocalcaemia being developed and modified on the basis of the literature and local experience. Day 1 PTH and calcium levels determine the need for treatment and frequency of follow-up visits, facilitate early discharge, reduce risk of over and/or undertreatment, and are good indicators of permanent hypocalcaemia.

The Impact of Postoperative Percent Change of Parathormone Level From Baseline Value on the Rate of Hypocalcemia After Total Thyroidectomy

Background

The purpose of this study was to investigate the impact of the percent change of postoperative parathormone (PoPTH) level from baseline value (ΔPTH) on the rate of hypocalcemia after total thyroidectomy.

Methods

Assays of serum PTH and calcium (Ca) were performed preoperatively and at 24 hours postoperatively in 222 consecutive patients who underwent total thyroidectomy. Postoperative hypocalcemia was defined as serum calcium level corrected for albumin concentration (cCa) &lt;8.5 mg/dL. Patients with postoperative hypocalcemia were classified as group 1 (n = 100) and those with normal Ca levels as group 2 (n = 122). The PoPTH levels and ΔPTH were compared between the 2 groups. Receiver operating characteristic analysis was performed to determine the cutoff values for PoPTH and ΔPTH.

Results

The mean PoPTH level was significantly lower in group 1 compared with group 2 (18.6 ± 15.3 versus 32.3 ± 15.6 pg/mL, respectively; P &lt; 0.0001). PoPTH values were within the normal range in 54% of the patients with hypocalcemia and 35% of those with symptomatic hypocalcemia. PoPTH &lt;28 pg/mL or ΔPTH &gt;45 were significantly associated with increased risk of post-thyroidectomy hypocalcemia (P = 0.0001). A ΔPTH &gt;70%, PoPTH ≤15.5 pg/mL, and postoperative serum cCa concentrations&lt;8.0 mg/dL significantly predicted symptomatic hypocalcemia (P = 0.009, P = 0.006, and P = 0.0001, respectively). The sensitivities of ΔPTH, PoPTH level, and postoperative serum cCa concentration to predict symptomatic hypocalcemia were 67%, 64%, and 100%, respectively.

Conclusion

Although PTH decline significantly correlates with symptomatic hypocalcemia, a considerable number of patients may experience hypocalcemic symptoms despite normal PoPTH levels. Analysis of serum Ca concentrations at 24 hours postoperatively help to achieve a more precise prediction of patients who bear a high risk for developing hypocalcemic symptoms.

The impact of different surgical procedures on hypoparathyroidism after thyroidectomy: A population-based study

The main objective of this study is to investigate the outcome between surgical procedures and the risk of development of hypoparathyroidism followed by surgical procedure in patients with thyroid disorders.We analyzed the data acquired from Taiwan's Bureau of National Health Insurance (BNHI) research database from 1998 to 2011 and found 9316 patients with thyroid surgery. Cox regression model was used to calculate the hazard ratio (HR).A count of 314 cases (3.4%) of hypoparathyroidism was identified. The 9 years cumulated incidence of hypoparathyroidism was the highest in patient undergone bilateral total thyroidectomy (13.5%) and the lowest in the patient with unilateral subtotal thyroidectomy (1.2%). However, in the patients who had undergone unilateral subtotal, the risk was the highest in bilateral total (HR: 11.86), followed by radical thyroidectomy with unilateral neck lymph node dissection (HR: 8.56), unilateral total (HR, 4.39), and one side total and another side subtotal (HR: 2.80).The extent of thyroid resection determined the risk of development of hypoparathyroidism. It is suggested that the association of these factors is investigated in future studies.

[Intraoperative parathyroid hormone measurement is the best predictor of postoperative symptomatic hypocalcemia]

BACKGROUND

The goal of this study is to evaluate risk factors for transient postoperative hypocalcemia (HC) and to define cutoff values for perioperative parathyroid hormone (PTH) and calcium parameters (Ca) to reduce the morbidity of symptomatic HC.

MATERIALS AND METHODS

At our tertiary referral hospital (Luzerner Kantonsspital, Switzerland), a total of 353 patients underwent total thyroidectomy between 2006 and 2013 and were analyzed retrospectively in terms of HC risk. The serum values of calcium and PTH were measured at strictly defined time intervals, and patients' symptoms and the necessity of treatments were determined from patients' charts.

RESULTS

The prevalence of transient postoperative HC was 43%; however, only 10% of patients were symptomatic. Significant risk factors for serum and symptomatic HC were calcium values (pre-, intra-, 4 h and 1 d postoperative), PTH values (intraoperative, 4 h and 1 d postoperative), and PTH decline. Interestingly, preoperative PTH values, patient age, weight of the thyroid gland, diagnosis, and sex were not significant risk factors. In the ROC analysis ('receiver operating characteristics'), calcium measurement 4 h postoperatively showed the best predictive ability for detecting serum HC, whereas intraoperative PTH measurements were predictive for symptomatic HC.

CONCLUSION

Calcium and PTH values as well as PTH decline are significant risk factors for postoperative HC. Preoperatively, only calcium measurement is prognostically significant. Intraoperative PTH measurement is the most reasonable and sensitive factor for early recognition of temporary postoperative HC in the clinical setting.

Prolonged Duration of Surgery Predicts Postoperative Hypoparathyroidism among Patients Undergoing Total Thyroidectomy in a Tertiary Referral Centre

BACKGROUND

Postoperative hypoparathyroidism is a common complication following total thyroidectomy. The aim of this study was to investigate the incidence of both transient and permanent hypoparathyroidism in patients undergoing total thyroidectomy in a tertiary referral centre and, furthermore, to identify early predictive risk factors.

METHODS

Based on a single-institution retrospective review, we identified 582 patients who underwent total thyroidectomy between January 2010 and March 2015. Information on age, gender, pathological diagnosis, duration of surgery, autotransplantation of parathyroid glands, neck dissection, and experience and position of the surgeon was retrieved from the medical records. Furthermore, serum levels of parathyroid hormone and calcium were registered pre- and postoperatively and after 3 and 12 months.

RESULTS

The incidence of transient hypoparathyroidism during the first 24 h and 3 months after surgery was 47.8 and 17.8%, respectively. Furthermore, the incidence of permanent hypoparathyroidism 1 year after surgery was 10.7%. A prolonged duration of surgery was significantly associated with hypoparathyroidism. Moreover, autotransplantation of parathyroid glands was a significant predictor of transient hypoparathyroidism after 24 h and 3 months, but was not associated with permanent hypoparathyroidism.

CONCLUSIONS

Transient and permanent hypoparathyroidism is common among patients undergoing total thyroidectomy in a tertiary referral centre. A duration of surgery >120 min constitutes an independent risk factor due to the risk of ischaemic damage. Regain of function of devascularized parathyroid glands must be expected to last at least 1 year postoperatively. Furthermore, the recovery of autotransplanted parathyroid glands should not be evaluated within 1-3 months after surgery.

Hypomagnesemia predicts postoperative biochemical hypocalcemia after thyroidectomy

Background

To investigate the role of magnesium in biochemical and symptomatic hypocalcemia, a retrospective study was conducted.

Methods

Less-than-total thyroidectomy patients were excluded from the final analysis. Identified the risk factors of biochemical and symptomatic hypocalcemia, and investigated the correlation by logistic regression and correlation test respectively.

Results

A total of 304 patients were included in the final analysis. General incidence of hypomagnesemia was 23.36%. Logistic regression showed that gender (female) (OR = 2.238, p = 0.015) and postoperative hypomagnesemia (OR = 2.010, p = 0.017) were independent risk factors for biochemical hypocalcemia. Both Pearson and partial correlation tests indicated there was indeed significant relation between calcium and magnesium. However, relative decreasing of iPTH (>70%) (6.691, p < 0.001) and hypocalcemia (2.222, p = 0.046) were identified as risk factors of symptomatic hypocalcemia. The difference remained significant even in normoparathyroidism patients.

Conclusions

Postoperative hypomagnesemia was independent risk factor of biochemical hypocalcemia. Relative decline of iPTH was predominating in predicting symptomatic hypocalcemia.

Postoperative hypomagnesaemia is not associated with hypocalcemia in thyroid cancer patients undergoing total thyroidectomy plus central compartment neck dissection

BACKGROUND

The literature remains scarce and controversial regarding the association of hypomagnesaemia and hypocalcemia after total thyroidectomy. This study aims to assess this association in thyroid cancer patients underwent total thyroidectomy (TT) plus central compartment neck dissection (CCND).

METHOD

All consecutive thyroid cancer patients who underwent TT plus CCND were retrospectively reviewed through a prospectively collected database between October 2015 and June 2016 in a tertiary referral hospital. The univariate and multivariate analysis were performed to identify the significant predictors for hypocalcemia.

RESULTS

A total of 237 patients were included. The incidence of postoperative biochemical and symptomatic hypocalcemia was 52.3% (124 patients) and 33.8% (80 patients), respectively. Multivariate analysis showed that only postoperative hypoparathyroidism was an independent predictor for biochemical hypocalcemia (HR = 14.37, 95%CI = 6.07-34.0; P < 0.000), while parathyroid gland autotansplantation (HR = 2.02, 95%CI = 1.04-3.91; P = 0.038) and hypoparathyroidism (HR = 7.47, 95%CI = 3.84-14.5; P < 0.000) were independent risk factor for symptomatic hypocalcemia. Postoperative hypomagnesaemia was not significantly associated with the development of hypocalcemia (P > 0.05).

CONCLUSION

Postoperative hypomagnesaemia was not an independent predictor of hypocalcemia after total thyroidectomy. It seems to be unnecessary to routinely monitor the magnesium levels before and after thyroid surgery.

Prophylactic oral calcium supplementation therapy to prevent early post thyroidectomy hypocalcemia and evaluation of postoperative parathyroid hormone levels to detect hypocalcemia: A prospective randomized study

BACKGROUND

Postoperative hypocalcemia is the most common complication after total thyroidectomy. Postoperative parathyroid hormone (PTH) measurement is one of the methods to detect or prevent postoperative hypocalcemia. Prophylactic oral calcium supplementation is another method to prevent early postoperative hypocalcemia. The aim of this study is to detect the accurate timing of PTH and evaluate efficacy of routine oral calcium supplementation for postoperative hypocalcemia.

METHODS

A total of 106 patients were performed total thyroidectomy. Rotuine oral calcium supplementation was given to group 1 and no treatment to group 2 according to randomization. Serum calcium and PTH level of patients in group 2 at postoperative 6, 12 and 24 h and patients in both groups at postoperative day 7 were evaluated. Patients were compared according to age, sex, operation findings, serum calcium and PTH levels and symptomatic hypocalcemia.

RESULTS

Half of the patients (50%) were in group 1. Most of the patients were female (83%). The most common etiology of thyroid disease was multinodular goiter (64.1%). Oral calcium supplementation was given to 18 (33.9%) patients in group 2. Symptomatic hypocalcemia for group 1 and 2 was found to be 1.9 and 33.9% respectively (p < 0.05). No statistical difference can be observed regarding the timing of serum biomarkers.

CONCLUSION

Serum PTH levels at postoperative 12 and 24 h can predict early post-thyroidectomy hypocalcemia. Prophylactic oral calcium supplementation therapy can prevent early post-thyroidectomy hypocalcemia with advantages of being cost effective and safe.

Outcomes of Parathyroid Autotransplantation During Total Thyroidectomy: A Comparison with Age- and Sex-Matched Controls

PURPOSE

To determine the effect of parathyroid autotransplantation (PA) on postoperative hypocalcemia in cases of total thyroidectomy.

MATERIALS AND METHODS

Cases undergoing total thyroidectomy and PA were compared with age and sex-matched controls who had not undergone PA. The postoperative percentage changes (PC) of parathyroid hormone (PTH) and calcium (Ca+2) in the first 12-24 hours (12-24hr→preop), between the 1st-3rd weeks (1-3wk→preop) and at the 6th month (6mo→preop), the rates of hypocalcemia (Ca+2< 8mg/dL) and low PTH level (PTH< 15 pg/mL), permanent hypocalcemia, inadvertent parathyroidectomy in both groups were compared.

RESULTS

The number of patients with PTH12-24hr<15 pg/mL was significantly higher (n:34,(55.7%)) than the number of patients in the control group (n:16(26.2%)), (p=0.001). The rate of decrease in the blood Ca+2 median PC (6mo→preop) was significantly higher in the PA group (4.2%) than the control group (1.1%), (p=0.008). There was no significant difference between the 2 groups in terms of the postoperative frequency of hypocalcemia (p>0.05). In the PA&age≤50 group, the rate of inadvertent parathyroidectomy was higher than that of cases over age 50 (p=0.029).

CONCLUSION

In spite of the presence of an increased postoperative hypocalcemia trend in cases requiring PA during total thyroidectomy, the rates of transient and permanent hypocalcemia were not different to the control cases. But the frequency of cases with low PTH level in cases undergoing PA was higher than that of the control cases. In cases of 50 years of age and under, who had undergone PA, the possibility of inadvertent parathyroidectomy increased.