Does Preoperative 25-Hydroxyvitamin D Status Significantly Affect the Calcium Kinetics after Total Thyroidectomy?

Does Vitamin D Deficiency Really Increase the Risk of Post-surgical Hypoparathyroidism?

Purpose

Postoperative hypoparathyroidism is the most frequent complication after total thyroidectomy. The identification of preoperative predictors could be helpful to identify patients at risk. The aim of this study is to determine if preoperative vitamin D levels are related to transient, protracted, and permanent hypoparathyroidism.

Method

A prospective, observational study that includes 100 patients who underwent total thyroidectomy.

Results

Transient hypoparathyroidism was present in 42% of patients, 11% developed protracted hypoparathyroidism and 5% permanent hypoparathyroidism. The median preoperative Vitamin D levels were higher in patients who developed transient hypoparathyroidism than in patients without this complication (24 ng/mL [RIQ 13-31] vs. 17 ng/mL [RIQ 10-24]; p = 0.024). Patients with preoperative vitamin D levels below 20 ng/mL had a lower percentage of transient hypoparathyroidism (31.4% vs. 53.1%; p = 0.028). The prevalence of protracted and permanent hypoparathyroidism in both groups was similar. Patients with preoperative vitamin D levels lower than 20 pg/mL had higher median PTH levels 24 h after surgery, (37.7 ± 28.2 pg/ml vs. 23.6 ± 18.6 pg/ml; p = 0.037), and suffered a lower postoperative PTH decline (46.2 ± 35.4% vs. 61 ± 29%; p = 0.026).

Conclusions

Patients with vitamin D deficiency had a lower transient hypoparathyroidism rate, higher median PTH levels 24 h after surgery and a lower postoperative PTH decline. We found no association between preoperative vitamin D and the development of protracted or permanent hypoparathyroidism.

Preoperative and postoperative optimisation of patients undergoing thyroid surgery: a multicentre quality improvement project at Barts Health NHS Trust

Hypocalcaemia following thyroid surgery can occur in up to 38% of patients. With over 7100 thyroid surgeries performed in 2018 in the UK, this is a common postoperative complication. Undertreated hypocalcaemia can result in cardiac arrhythmias and death. Preventing adverse events from hypocalcaemia requires preoperative identification and treatment of at-risk patients with vitamin D deficiency, timely recognition of postoperative hypocalcaemia and prompt appropriate treatment with calcium supplementation. This project aimed to design and implement a perioperative protocol for prevention, detection and management of post-thyroidectomy hypocalcaemia. A retrospective audit of thyroid surgeries (n=67; October 2017 to June 2018) was undertaken to establish baseline practice of (1) preoperative vitamin D levels assessment, (2) postoperative calcium checks and incidence of postoperative hypocalcaemia and (3) management of postoperative hypocalcaemia. A multidisciplinary team approach following quality improvement principles was then used to design a perioperative management protocol with all relevant stakeholders involved. After dissemination and implementation, the above measures were reassessed prospectively (n=23; April-July 2019). The percentage of patients having their preoperative vitamin D measured increased from 40.3% to 65.2%. Postoperative day-of-surgery calcium checks increased from 76.1% to 87.0%. Hypocalcaemia was detected in 26.8% of patients before and 30.43% of patients after protocol implementation. The postoperative component of the protocol was followed in 78.3% of patients. Limitations include low number of patients which precluded from analysis of the impact of the protocol on length of stay. Our protocol provides a foundation for preoperative risk stratification and prevention, early detection and subsequent management of hypocalcaemia in thyroidectomy patients. This aligns with enhanced recovery protocols. Moreover, we offer suggestions for others to build on this quality improvement project with the aim to further advance the perioperative care of thyroidectomy patients.

The Optimal Parathyroid Hormone Cut-Off Threshold for Early and Safe Management of Hypocalcemia After Total Thyroidectomy

OBJECTIVE

To define optimal intact parathyroid hormone (iPTH) cut-off threshold predictive of hypocalcemia after total thyroidectomy for safe and effective postoperative management.

METHODS

This prospective single center study was done in 2 phases. In phase I, predictors of symptomatic hypocalcemia were analyzed and the receiver operating characteristic curve was used to define the optimal iPTH cut-off threshold predictive of hypocalcemia. Phase II studied giving prompt prophylactic supplemental calcium and vitamin D to all patients who had iPTH levels below the calculated threshold, while phase I patients were given prompt selective supplementation if they had postoperative hypocalcemia or symptoms.

RESULTS

Univariate analysis of patients in phase I showed that postoperative iPTH was the only significant variable that can predict symptomatic hypocalcemia. Using receiver operating characteristic curve and Youden index, the confirmed optimal cut-off threshold predictive of hypocalcemia was iPTH 19.95 pg/mL, with area under the curve of 0.903, 100% sensitivity, negative predictive value, and highest Youden index, while iPTH 15 pg/mL and iPTH 10 pg/mL were less optimal. Symptomatic hypocalcemia occurred in 30% of the phase I cohort who received selective supplementation versus 3% of those in the phase II cohort who received prophylactic supplementation. Return to emergency department and need for intravenous calcium were also significantly better in phase II.

CONCLUSION

iPTH cut-off for post-thyroidectomy hypocalcemia was 19.95 pg/mL. Low-risk patients were discharged with no supplementation while all high-risk patients received prompt calcium and vitamin D supplementation, which led to effective hypocalcemia management and safe 24-hour discharge.

The use of vitamin D in preventing post-thyroidectomy hypocalcemia: An endocrinologist survey study

OBJECTIVE

To evaluate the use of preoperative vitamin D levels and postoperative vitamin D supplementation among endocrinologists for the prevention of post-thyroidectomy hypocalcaemia.

METHODS

Endocrinologist members of the American Thyroid Association (ATA) were contacted via email to complete a 21-question survey, which included both questions about demographic information, and preventing and managing postoperative hypocalcaemia after thyroidectomy. Univariate and multivariate analysis was performed to determine the respondents' use of preoperative vitamin D levels, dose and duration of preoperative vitamin D repletion, decision to delay surgery for low vitamin D levels in the case of a benign or malignant disease, and routine prescription of postoperative calcium or vitamin D supplementation.

RESULTS

225 endocrinologists who were ATA members responded to the questionnaire. When compared to endocrinologists practicing in other countries, those that practice in the United States were 2.5 times more likely to check preoperative vitamin D levels (95% CI[1.404, 4.535], P = .002), significantly more likely to replete vitamin D deficient patients with high-dose vitamin D (ie ≥50K IU/week), 4.458 times more likely to prescribe prophylactic supplemental calcium (95% CI[2.446, 8.126]; P < .0001) and 3.48 more likely to prescribe supplemental vitamin D (95% CI [1.906, 6.355]; P < .0001). Endocrinologists who have been in practice for >10 years were also 1.915 times more likely to prescribe supplemental vitamin D (95% CI (1.080, 3.395); P = .0263). Physicians that treat >50 thyroidectomy cases/year were 2.083 more likely to recommend a vitamin D repletion duration of >1 month than those that treat ≤50 cases/year ([1.036, 4.190], P = .0395). Lastly, if the patient has low preoperative vitamin D levels, 47.05% of respondents chose to delay surgery in a benign disease, while only 11.61% of respondents would do so in a case of malignant disease.

CONCLUSIONS

Approximately one-half of surveyed endocrinologists reported using preoperative vitamin D levels to assess a patient's risk for post-thyroidectomy hypocalcaemia. Endocrinologists practicing in the United States, compared to those practicing in other countries, were more likely to both test for preoperative vitamin D levels and to recommend prophylactic post-thyroidectomy calcium and vitamin D supplementation.

Preoperative Vitamin D Levels as a Predictor of Transient Hypocalcemia and Hypoparathyroidism After Parathyroidectomy

Hypocalcemia is a common problem after parathyroidectomy and/or thyroidectomy. The complication may be transient or permanent. Most cases occur as a result of removal of the parathyroid glands or damage to the glands during neck surgery. The purpose of this study was to evaluate the effect of preoperative vitamin D deficiency in predicting transient hypocalcemia and hypoparathyroidism after parathyroidectomy.Retrospective evaluation was made of 180 patients with primary hyperparathyroidism in respect of serum 25(OH)D, calcium and parathyroid hormone before and after parathyroidectomy. Transient hypocalcemia was defined as corrected calcium ≤ 8.4 mg/dL, and these cases were then evaluated for preoperative 25(OH)D values. Transient hypoparathyroidism has been described as low PTH level immediately after surgery before beginning any supplementation. Permanent hypoparathyroidism is accepted as the need for medical treatment is necessary over 12 months.Both transient hypocalcemia and hypoparathyroidism developed at statistically significantly higher rates in patients with preoperative vitamin D deficiency and vitamin D insufficiency.Vitamin D deficiency is an independent contributor to transient hypocalcemia and hypoparathyroidism following parathyroidectomy.

Effect of Preoperative Vitamin D Deficiency on Hypocalcemia in Patients with Acute Hypoparathyroidism after Thyroidectomy

Postoperative hypoparathyroidism is a common complication of total or completion thyroidectomy. The association between preoperative vitamin D deficiency (VDD) and the development of more severe postoperative hypocalcemia is still unclear. Objectives. To evaluate the effect of preoperative VDD on severity of hypocalcemia in patients with hypoparathyroidism following thyroidectomy. Methods. Patients who developed acute hypoparathyroidism after total or completion thyroidectomy, defined as postoperative parathyroid hormone (PTH) level <15 pg/mL and albumin-adjusted calcium level <8.6 mg/dL, were prospectively recruited. Patients were divided into two groups according to their preoperative vitamin D status (VDD group: 25-hydroxyvitamin D (25(OH)D) level <20 ng/mL; non-VDD group: 25(OH) level ≥20 ng/mL). The primary outcome was severity of hypocalcemia in postoperative hypoparathyroidism. Significant hypocalcemia was defined as calcium level ≤7.5 mg/dL. Results. Forty-three patients (21 VDD, 22 non-VDD) were enrolled. Serum total albumin-adjusted calcium level was significantly lower in the VDD group (7.71 ± 0.5 vs. 8.16 ± 0.4 mg/dL, p < 0.01), and the incidence of symptomatic hypocalcemia was significantly higher in the VDD group (43% vs. 9%, p=0.01). The median maximal daily supplementary dose of elemental calcium was significantly higher in the VDD group (2,400 vs. 1,500 mg/day, p=0.02). Length of hospital stay was nonsignificantly longer in the VDD group (p=0.06). Preoperative vitamin D level <19.6 ng/mL could predict significant and symptomatic hypocalcemia in postoperative hypoparathyroidism with sensitivity of 90% and 82% and specificity of 70% and 69%, respectively. Conclusion. VDD is an independent risk factor for both significant and symptomatic hypocalcemia in hypoparathyroidism patients after thyroid surgery.

Preoperative vitamin D level as a post-total thyroidectomy hypocalcemia predictor: a prospective study

Introduction

Hypocalcemia is one of the most common complications after total thyroidectomy. Preoperative serum vitamin D concentration has been postulated as a risk factor for this complication. However, the subject is still controversial and the role of vitamin D in the occurrence of hypocalcemia remains uncertain.

Objective

To evaluate the capability of preoperative vitamin D concentrations in predicting post-total thyroidectomy hypocalcemia.

Methods

Forty-seven total thyroidectomy patients were prospectively evaluated for serum 25(OH) vitamin D, calcium and parathyroid hormone before surgery, Calcium every 6 hours, and parathyroid hormone 8 hours post-operatively. Patients were divided according to postoperative corrected calcium into groups without (corrected calcium ≥8.5 mg/dL) and with hypocalcemia (corrected calcium <8.5 mg/dL), who were then evaluated for preoperative 25(OH) vitamin D values.

Results

A total of 72.3% of cases presented altered 25(OH) vitamin D preoperative serum concentrations and 51% evolved with postoperative hypocalcemia. The with and without hypocalcemia groups did not differ for preoperative 25(OH) vitamin D (p = 0.62). Univariate analysis showed that age (p = 0.03), postoperative PTH concentration (p = 0.02), and anatomopathological diagnosis of malignancy (p = 0.002) were predictors of postoperative hypocalcemia. In multivariate analysis only parathyroid hormone in postoperative (p = 0.02) was associated with post-total thyroidectomy hypocalcemia.

Conclusion

Preoperative serum concentrations of 25(OH) vitamin D were not predictors for post-total thyroidectomy hypocalcemia, whereas postoperative parathyroid hormone influenced the occurrence of this complication.

Preoperative vitamin D deficiency is a risk factor for postoperative hypocalcemia in patients undergoing total thyroidectomy: retrospective cohort study

BACKGROUND

The relationship between preoperative vitamin D deficiency and postoperative hypocalcemia in cases of total thyroidectomy (TT) is a matter of controversy and may vary according to geographical scenarios and populations.

OBJECTIVE

The objective here was to evaluate whether preoperative vitamin D deficiency was associated with postoperative symptomatic hypocalcemia in a population in South America.

DESIGN AND SETTING

Retrospective cohort study on data from all patients undergoing total thyroidectomy, with or without central compartment lymph node dissection, from January 2014 to December 2017, at the A. C. Camargo Cancer Center.

METHODS

Patients with benign thyroid disease (Graves' disease, multinodular goiter or hyperthyroidism) or thyroid cancer who underwent primary total thyroidectomy with or without central compartment lymph node dissection were included. The exclusion criteria were simultaneous parathyroidectomy and conditions that could affect serum calcium levels. The data collected included patient demographics, thyroid pathology, extent of the surgical procedure and complications. Information on preoperative and postoperative calcium, parathyroid hormone (PTH) and vitamin D levels were retrieved from the medical records.

RESULTS

1,347 patients were assessed and postoperative hypocalcemia was diagnosed in 284 patients (21%). The vitamin D levels were considered deficient in 243 patients (18%). Postoperative hypocalcemia was diagnosed in 357 patients (31.5%). Multivariate analysis showed that central compartment dissection and preoperative total calcium and deficient vitamin D levels were significant risk factors for postoperative hypocalcemia.

CONCLUSION

Deficient preoperative vitamin D levels were a significant risk factor for postoperative hypocalcemia. Preoperative oral supplementation should be considered, to minimize this risk.

Can preoperative vitamin D deficiency predict postoperative hypoparathyroidism following thyroid surgery?

IMPORTANCE

Postoperative hypoparathyroidism remains a relevant problem after thyroid surgery. Although the roles of vitamin D deficiency and other risk factors have been discussed in previous studies, variable results have been reported.

OBJECTIVE

Predicting the risk of postoperative hypocalcemia could be helpful for individual prognoses and medical treatment.

PATIENTS AND METHODS

Documentation and analysis of bilateral thyroid operations performed between July 2011 and May 2014 were studied. Results involving age, gender, diagnosis, surgical techniques, pre- and postoperative calcium and parathyroid hormone (PTH) levels, and especially, the role of preoperative vitamin D levels were assessed in uni- and multivariate analyses.

RESULTS

Bilateral thyroid surgery was performed in 361 patients with multinodular goiters (n = 224), Graves' disease (n = 40), or thyroid carcinoma (n = 97). In total, 124 patients (34%) with postoperative hypoparathyroidism, defined as having a PTH level ≤ 10 pg/mL, were treated with calcium and vitamin D regardless of their symptoms. The rate of permanent hypoparathyroidism was 3.6% and correlated with the extent of surgery; the highest risks were shown for total thyroidectomy and central lymph node dissection. In univariate analysis, the extent of surgery, parathyroid autotransplantation, and histopathology were the strongest predictors of hypoparathyroidism. Even severe vitamin D deficiency (< 10 ng/mL) showed a trend only towards a higher transient hypoparathyroidism risk (p = 0.0514) but failed to predict permanent hypoparathyroidism.

CONCLUSION

Postoperative PTH levels accurately identified patients at risk for hypoparathyroidism. Decreased preoperative vitamin D levels could not predict hypocalcemia, and high vitamin D levels could not prevent permanent hypoparathyroidism.

American Thyroid Association Statement on Postoperative Hypoparathyroidism: Diagnosis, Prevention, and Management in Adults

BACKGROUND

Hypoparathyroidism (hypoPT) is the most common complication following bilateral thyroid operations. Thyroid surgeons must employ strategies for minimizing and preventing post-thyroidectomy hypoPT. The objective of this American Thyroid Association Surgical Affairs Committee Statement is to provide an overview of its diagnosis, prevention, and treatment.

SUMMARY

HypoPT occurs when a low intact parathyroid hormone (PTH) level is accompanied by hypocalcemia. Risk factors for post-thyroidectomy hypoPT include bilateral thyroid operations, autoimmune thyroid disease, central neck dissection, substernal goiter, surgeon inexperience, and malabsorptive conditions. Medical and surgical strategies to minimize perioperative hypoPT include optimizing vitamin D levels, preserving parathyroid blood supply, and autotransplanting ischemic parathyroid glands. Measurement of intraoperative or early postoperative intact PTH levels following thyroidectomy can help guide patient management. In general, a postoperative PTH level <15 pg/mL indicates increased risk for acute hypoPT. Effective management of mild to moderate potential or actual postoperative hypoPT can be achieved by administering either empiric/prophylactic oral calcium and vitamin D, selective oral calcium, and vitamin D based on rapid postoperative PTH level(s), or serial serum calcium levels as a guide. Monitoring for rebound hypercalcemia is necessary to avoid metabolic and renal complications. For more severe hypocalcemia, inpatient management may be necessary. Permanent hypoPT has long-term consequences for both objective and subjective well-being, and should be prevented whenever possible.

Incidence, prevalence and risk factors for post-surgical hypocalcaemia and hypoparathyroidism

Hypocalcaemia following thyroid surgery is common and is associated with significant short and long term morbidity. Damage to or devascularisation of parathyroid glands is the predominant underlying mechanism; although other factors such as hungry bone syndrome may occasionally contribute to it in the immediate post-operative period. The reported incidence of post-surgical hypocalcaemia and/or hypoparathyroidism (PoSH) varies significantly in the literature; the variation thought to be at least partly due to differences in the definitions used. Figures on the prevalence of chronic or long term post-surgical hypocalcaemia in the population are unclear. Risk factors for PoSH have been extensively studied in recent years and may be classified into patient, disease and surgery related factors. Some risk factors are modifiable; but both modifiable and non-modifiable factors help in generating a risk profile that may be used to select patients for preventative measures and/or changes in surgical strategy. This narrative review discusses recent literature on the incidence, prevalence and risk factors for PoSH.

Impact of pre-operative serum 25-hydroxyvitamin D on post-operative serum calcium in patients undergoing total thyroidectomy for benign goitre: retrospective study of 246 patients

OBJECTIVE

To determine whether pre-operative serum 25-hydroxyvitamin D has an impact on post-operative parathyroid hormone and serum calcium levels in patients undergoing total thyroidectomy for benign goitre.

METHODS

This single-centre, retrospective study comprised 246 unselected surgical patients who had undergone total thyroidectomy for bilateral, benign, multinodular goitre. The correlation between pre-operative serum 25-hydroxyvitamin D and post-operative serum parathyroid hormone and serum calcium was studied to determine whether low pre-operative serum 25-hydroxyvitamin D was predictive of post-operative hypocalcaemia.

RESULTS

Seventy-nine patients (32 per cent) had post-operative hypocalcaemia. Eighteen patients (7.32 per cent) experienced unintentional parathyroidectomy (1 parathyroid gland in 15 patients, 2 parathyroid glands in 3 patients). In univariate analysis, pre-operative serum 25-hydroxyvitamin D was not correlated with post-operative serum calcium (p = 0.69) or post-operative serum parathyroid hormone (p = 0.5804). Furthermore, in multivariate analysis, which took into account unintentional parathyroidectomy, no correlation was found (p = 0.33). Bilateral unintentional parathyroidectomy was statistically associated with post-operative hypocalcaemia (p = 0.032).

CONCLUSION

Pre-operative serum 25-hydroxyvitamin D did not appear to have any impact on post-operative serum calcium in patients undergoing total thyroidectomy for benign goitre.

A Case of "Late" Postsurgical Hypoparathyroidism

INTRODUCTION

Postsurgical hypoparathyroidism normally occurs a short time after thyroid surgery in form of two clinical syndromes of different etiology and prognosis. The first is transitory and might spontaneously recover within a few weeks or months. The second is permanent and needs a definitive treatment. Only few cases of hypoparathyroidism clinically evident after many years from surgery have been reported.

CASE REPORT

A case of hypoparathyroidism clinically evident only three and a half years after surgery is reported. Our findings and review of a few cases reported by medical literature suggest the existence of a third form of postsurgical hypoparathyroidism, characterized by a late beginning.

Completion thyroidectomy and total thyroidectomy for differentiated thyroid cancer: Comparison and prediction of postoperative hypoparathyroidism

BACKGROUND

Consensus regarding the difference of postoperative hypoparathyroidism following completion thyroidectomy (CT) and total thyroidectomy (TT) has yet to be reached. We compare the occurrence of postoperative hypoparathyroidism between CT and TT for differentiated thyroid cancer (DTC), and explore the predictive factors for postoperative hypoparathyroidism.

METHODS

We retrospectively reviewed 221 consecutive patients underwent CT or TT for DTC between February 2012 and March 2014. Patients' demographic and clinical data of the two groups were analyzed.

RESULTS

There were 57 CTs and 164 TTs. Temporary hypoparathyroidism occurred in 12.3% (7 of 57) and 28.0% (46 of 164) of patients in the CT and TT groups, respectively. In univariate analysis, type of surgical procedure (CT or TT) and extent of central lymph node dissection (CND) (unilateral or bilateral) were significantly associated with the postoperative temporary hypoparathyroidism (P < 0.05). Multivariate analysis showed that only the extent of CND was an independent risk factor for temporary hypoparathyroidism.

CONCLUSIONS

Although temporary hypoparathyroidism was lower in the CT group, our analysis indicates the difference is due to the extent of CND rather than type of surgical procedure (CT vs. TT). Only bilateral CND is an independent risk factor for temporary hypoparathyroidism after thyroidectomy. J. Surg. Oncol. 2016;113:522-525. © 2016 Wiley Periodicals, Inc.

[Surgical assessment of complications after thyroid gland operations]

BACKGROUND

The extent, magnitude and technical equipment used for thyroid surgery has changed considerably in Germany during the last decade. The number of thyroidectomies due to benign goiter have decreased while the extent of thyroidectomy, nowadays preferentially total thyroidectomy, has increased. Due to an increased awareness of surgical complications the number of malpractice claims is increasing.

OBJECTIVES

In contrast to surgical databases the frequency of complications in malpractice claims reflects the individual impact of complications on the quality of life. In contrast to surgical databases unilateral and bilateral vocal fold palsy are therefore at the forefront of malpractice claims. As guidelines are often not applicable for the individual surgical expert review, the question arises which are the relevant criteria for the professional expert witness assessing the severity of the individual complication.

RESULTS

While in surgical databases major complications after thyroidectomy, such as vocal fold palsy, hypoparathyroidism, hemorrhage and infections are equally frequent (1-3 %), in malpractice claims vocal fold palsy is significantly more frequent (50 %) compared to hypoparathyroidism (15 %), hemorrhage and infections (about 5 % each). To avoid bilateral nerve palsy intraoperative nerve monitoring has become of utmost importance for surgical strategy and malpractice suits alike. For surgical expert review documentation of individual risk-oriented indications, the surgical approach and postoperative management are highly important.

CONCLUSION

Guidelines only define the treatment corridors of good clinical practice. Surgical expert reviews in malpractice suits concerning quality of care and causality between surgical management, complications and sequelae of complications are therefore highly dependent on the grounds and documentation of risk-oriented indications for thyroidectomy, intraoperative and postoperative surgical management.

Vitamin D level is not a predictor of hypocalcemia after total thyroidectomy

PURPOSE

As the incidence of thyroid cancer has increased, hypocalcemia, a common complication of thyroid surgery, has become a serious problem. However, no definite predictor of postoperative hypocalcemia is known. In this study, our purpose was to investigate the potential role of vitamin D as a predictor of postoperative hypocalcemia.

METHODS

A prospective observational study was performed on patients who underwent total thyroidectomy for thyroid cancer performed by a single experienced surgeon between October 2013 and September 2014.

MEASUREMENTS

Their serum 25-OH vitamin D levels were measured preoperatively. On the day after surgery, serum calcium and intact parathyroid hormone levels were measured, and symptoms of hypocalcemia were recorded.

RESULTS

Of the 134 patients, laboratory and symptomatic hypocalcemia developed in 52 patients (39 %) and 25 patients (19 %), on the day after surgery. The preoperative vitamin D level was 16.5 ± 9.2 ng/mL, and this value did not differ according to laboratory or symptomatic hypocalcemia (p = 0.94). The incidence of laboratory or symptomatic hypocalcemia did not differ according to vitamin D deficiency. Only incidental parathyroidectomy was associated with symptomatic hypocalcemia (p = 0.03).

CONCLUSIONS

Vitamin D level is not a predictor of hypocalcemia after total thyroidectomy for thyroid cancer. Thus, routine preoperative screening for vitamin D is not recommended.

Severe Vitamin D Deficiency

Objective

To assess the role of preoperative serum 25 hydroxyvitamin D as predictor of hypocalcemia after total thyroidectomy.

Study Design

Retrospective cohort study.

Setting

University teaching hospital.

Subjects and Methods

All consecutively performed total and completion thyroidectomies from February 2007 to December 2013 were reviewed through a hospital database and patient charts. The relationship between postthyroidectomy laboratory hypocalcemia (serum calcium ≤2 mmol/L), clinical hypocalcemia, and preoperative serum 25 hydroxyvitamin D level was evaluated.

Results

Two hundred thirteen patients were analyzed. The incidence of postoperative laboratory and clinical hypocalcemia was 19.7% and 17.8%, respectively. The incidence of laboratory and clinical hypocalcemia among severely deficient (<25 nmol/L), deficient (<50 nmol/L), insufficient (<75 nmol/L), and sufficient (≥75 nmol/L) serum 25 hydroxyvitamin D levels was 54% versus 33.9%, 10% versus 18%, 2.9% versus 11.6%, and 3.1% versus 0%, respectively. Multiple logistic regression analysis revealed preoperative severe vitamin D deficiency as a significant independent predictor of postoperative hypocalcemia (odds ratio [OR], 7.3; 95% confidence interval [CI], 2.3-22.9; P = .001). Parathyroid hormone level was also found to be an independent predictor of postoperative hypocalcemia (OR, 0.6; 95% CI, 0.5-0.8; P = .002).

Conclusion

Postoperative clinical and laboratory hypocalcemia is significantly associated with low levels of serum 25 hydroxyvitamin D. Our findings identify severe vitamin D deficiency (<25 nmol/L) as an independent predictor of postoperative laboratory hypocalcemia. Early identification and management of patients at risk may reduce morbidity and costs.

Incidence and predictors of post-thyroidectomy hypocalcaemia in a tertiary endocrine surgical unit

BACKGROUND

Post-thyroidectomy hypocalcaemia is a common complication with significant short and long term morbidity. The aim of this study was to determine the incidence and predictors of post-thyroidectomy hypocalcaemia (as defined by a corrected calcium <2.1 mmol/l) in a tertiary endocrine surgical unit.

METHODS

A total of 238 consecutive patients who underwent completion or bilateral thyroid surgery between 2008 and 2011 were included in this retrospective study. Clinical and biochemical data were obtained from electronic and hard copy medical records.

RESULTS

The incidence of post-thyroidectomy hypocalcaemia on first postoperative day (POD1) was 29.0%. There was variation in the incidence of hypocalcaemia depending on the timing of measurement on the first postoperative day. At six months following surgery, 5.5% of patients were on calcium and/or vitamin D supplementation. Factors associated with post-thyroidectomy hypocalcaemia were lower preoperative corrected calcium (p=0.005) and parathyroid gland (PTG) auto-transplant (p=0.001). Other clinical factors such as central lymph node dissection, inadvertent PTG excision, ethnicity, preoperative diagnosis and Lugol's iodine were not associated with post-thyroidectomy hypocalcaemia.

CONCLUSION

The incidence of post-thyroidectomy hypocalcaemia was underestimated by 6% when only POD1 measurements were considered. The timing of measurement on POD1 has an impact on the incidence of post-thyroidectomy hypocalcaemia. Auto-transplantation and lower preoperative calcium were associated with post-thyroidectomy hypocalcaemia.