Postoperative Parathyroid Hormone Level as a Predictor of Post-thyroidectomy Hypocalcemia

Assessing Postoperative Phosphate and Calcium/Phosphate Ratio as Surrogates for Parathyroid Hormone Following Total Thyroidectomy

OBJECTIVE

Evaluate utility of postoperative phosphate and calcium/phosphate ratio (Ca/P) as surrogates for parathyroid hormone (PTH) following total thyroidectomy.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary care hospital.

METHODS

We retrospectively reviewed patients 18 years or older who underwent total thyroidectomy in a tertiary care hospital by a single surgeon from 2015 through 2021. Patients with incomplete data, pre-existing hypoparathyroidism, vitamin D deficiency, or renal failure were excluded. All patients had PTH drawn within 4 hours of surgery and serum calcium, albumin, and phosphate levels on postoperative Day 1. Corrected calcium was used to calculate a Ca/P. Receiver operating characteristic (ROC) curves were generated to compare phosphate level or Ca/P with PTH. Each possible surrogate was assessed relative to PTH cutoffs of less than 5, 10, 15, and 20 pg/mL. A good screening test was defined as having an area under the curve (AUC) greater than 0.8.

RESULTS

A total of 185 patients underwent total thyroidectomy with 1 fellowship-trained otolaryngologist. Most patients were female (62%), median age 48 years. Most surgeries were performed for cancer (68%). Six (3.2%) patients required IV calcium supplementation and 2 (1.1%) required readmission for symptomatic hypocalcemia. ROC curves comparing phosphate and Ca/P to PTH at the listed cutoffs demonstrated AUC ranging from 0.55 to 0.66 and 0.61 to 0.79, respectively. None met the threshold for a good screening test.

CONCLUSION

Postoperative phosphate and Ca/P ratio are not surrogates for PTH levels following total thyroidectomy. More research is needed to identify cost-effective strategies for postoperative calcium monitoring in patients undergoing total thyroidectomy.

LEVEL OF EVIDENCE

Retrospective cohort study.

Early parathyroid hormone (PTH) level as a predictor of post-surgical hypoparathyroidism

INTRODUCTION

Post-operative hypocalcemia and postoperative persistent hypoparathyroidism remain the most common complications after thyroidectomy. Many approaches have been developed to prevent them, but actually, a common protocol is not yet individuated.

MATERIALS AND METHODS

We retrospectively analyzed the results of a prospectively collected database. We dosed PTH preoperatively and 4 h after surgery (PTH_4); calcium was evaluated preoperatively, on the first (I_POD) and on the second postoperative day (II_POD). Hypocalcemia was defined when calcium <8 mg/dl. PTH_4 and I_POD calcium serum levels are identified to predict postoperative hypocalcemia.

RESULTS

Three hundred and forty-eight patients were enrolled, 37 patients resulted as hypocalcemic on I_POD and 41 on the II_POD. PTH_4 is related to I_POD (p < 0.001, r = 0.45) and II_POD (p < 0.001, r = 0.44) calcemia. PTH_4-cut-off predicting I_POD hypocalcemia was 10.50 pg/ml (sensitivity: 78.7%, specificity: 72.7%). A PTH_4 value of 11.5 pg/ml is able to predict hypocalcemia during II_POD (sensitivity: 76.5%, specificity: 69.2%). We set up a combined test to predict II_POD hypocalcemia, using PTH_4 and I_POD calcium (sensitivity: 77.8%, specificity: 89.9%).

CONCLUSION

This research shows the association between PTH_4 and postoperative hypocalcemia. The PTH_4 cut-off to predict I_POD-hypocalcemia was 10.5 pg/ml. We analyzed the calcemia trend during the postoperative period and we realized a combined test using PTH_4 and I_POD-calcemia. This test improves the accuracy of the previous test. Further studies, in particular multicentric, with a larger sample are necessary to validate the combined model.

Serum Parathyroid Hormone and Vitamin D Levels as Predictors of Hypocalcemia after Total/ Near Total Thyroidectomy

BACKGROUND

Post-operative Hypocalcaemia is the most-common complication of total and near-total thyroidectomy which is a selective treatment for benign and malignant thyroid diseases. Incidence ranges from 0.5-50%.

OBJECTIVES

The role of vitamin-D and Parathyroid hormone(PTH) in incidence of Hypocalcemia after thyroidectomy has been taken into consideration.

METHODS

This is a prospective interventional study is conducted in Kasturba Medical College and hospital, Manipal after taking written informed consent from the participants. It aimed at surveying the serum level of preoperative Vitamin D, PTH and calcium before total-thyroidectomy surgery and its relationship with the incidence of postoperative hypocalcemia after the surgery. The study was done on 70 patients who were-planned for total/near total thyroidectomy. Preoperative Vitamin D, PTH, calcium and Postoperative 4 hours-PTH, Calcium were measured on POD-1, POD-2-4, the results obtained were then analysed.

RESULTS

 Considering the cut-off of calcium as 8.6mg/dl, 42 patients developed hypocalcemia on POD-1, 28 patients on POD-2. Preoperative calcium and postoperative PTH levels in people having hypocalcaemia where significantly less compared to the patients having normal calcium. 4-hours post-operative PTH measurements showed 51% sensitivity, 100% specificity and strong co-relation between postoperative hypocalcemia and drop in PTH levels- (p=<0.001). Out of 42 patients who developed hypocalcemia 28- (65%) patients had vitamin-D deficiency(p=0.5) on POD-1 and out of 51 patients with hypocalcemia on POD 2-4, 33(78%) had-vitamin-D-deficiency(p=0.3852). Which was not statically significant.

CONCLUSION

4 hours post-operative PTH level is a predictor of early postoperative hypocalcemia, by detecting this we can effectively manage postoperative hypocalcemia.

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.

Comparison of parathyroid hormone kinetics in endoscopic thyroidectomy via bilateral areola with open thyroidectomy

Background

In this study, we aimed to compare the kinetics of intact parathyroid hormone (iPTH) during the perioperative period of endoscopic thyroidectomy via bilateral areola approach (ETBAA) in the same period, following a traditional open thyroidectomy approach (OTA).

Methods

We conducted a prospective observational study of patients who were undergoing thyroidectomy and level VI clearance. Patients who had been affected by papillary thyroid cancer (PTC) were stratified into three groups: those eligible for endoscopic treatment (ETBAA); patients who were eligible for ETBAA but had opted for OTA (OTA-L); and patients who were not suitable for endoscopic intervention (OTA-H). A process for locating parathyroid glands was utilized to stratify gland dissection laboriousness. In Type A, the gland is firmly fixed to thyroid gland. This type can be sub-classified into three subtypes. A1: the parathyroid gland is attached to the inherent thyroid capsule. A2: the gland is partially embedded in the thyroid gland. A3: the gland is located in the thyroid tissue. Type B is defined as a gland which is separated from the thyroid gland. The iPTH was sampled at wound closure.

Results

There were 100 patients in each group. We found a significant difference between the ETBAA and OTA-H groups for type A2, as well as a loss of parathyroid glands and a number of parathyroid transplantation procedures. The endoscopic group was treated during an earlier stage of thyroid cancer. The iPTH profile of each group decreased, although this was the most consistent in the OTA-H group. A comparison of ETBAA with OTA-L demonstrates that the iPTH level change is similar.

Conclusion

There is no advantage of endoscopic treatment for preserving parathyroid function.

FIRST DAY SERUM CALCIUM AND PARATHYROID HORMONE LEVELS AS PREDICTIVE FACTORS FOR SAFE DISCHARGE AFTER THYROIDECTOMY

Context

Permanent hypocalcemia is a rare but significant complication of thyroid surgery.

Objective

The aim of this study was to identify predictive factors of hypocalcemia and hypoparathyroidism after thyroidectomy.

Design

Study included 134 total patients submitted to thyroidectomy from two endocrine units (January 2015 - August 2016).

Methods

We measured total serum calcium (sCa) and intact PTH (iPTH) on postoperative day one and 1 month after surgery.

Results

118 patients were women with F/M ratio of 7.3/1 and a mean age of 51.8 years. 64 patients were included in group A (iPTH <12 pg/mL) and 70 patients in group B (iPTH >12 pg/mL). sCa and hypocalcemia symptoms were correlated with iPTH, measured 24 hours after surgery. The cut-off value was for sCa 8.05 mg/dL with a sensitivity of 85.29% and a specificity of 88.0% and for iPTH 11.2 pg/mL, with a sensitivity of 82.3% and a specificity of 71.0%. SCa (< 8.05 mg/dL) was a predictive factor with a 99 (IC95%:12.86-761.58) and iPTH (<11.2 pg/mL) with a 10.77 higher risk (CI95%: 3.83-30.30) to be associated with symptoms.

Conclusion

SCa and iPTH represent good predictive factors of early and safe hospital discharge and can predict the risk of prolonged and permanent hypoparathyroidism.

Role of Preoperative Administration of Vitamin D and Calcium in Postoperative Transient Hypocalcemia after Total Thyroidectomy

Introduction Thyroid surgery is one of the most frequently performed surgical procedures worldwide. Total thyroidectomy is a recommended procedure for most of the thyroid diseases. The most common complication resulting after this surgery is transient hypocalcemia - the incidence is 24% - which increases the morbidity rate and increases the length of stay in the hospital. The objective of our study was to compare the frequency of transient hypocalcemia after vitamin D and calcium supplementation with the control group for patients undergoing total thyroidectomy. Patients and methods It was a randomized controlled trial conducted at Department of Surgery, Pakistan Atomic Energy Commission General Hospital, Islamabad, Pakistan from January 2017 to July 2017. A total of 92 patients of both genders undergoing total thyroidectomy were included in the study. Patients undergoing reoperation for thyroid disease, American Society of Anesthesiologists (ASA) grade 3 or above, patients with chronic renal failure, preoperative hypocalcemia or hypercalcemia were excluded. The patients were sorted into two groups by lottery method; Group 1 in which Vitamin D (2,00,000 IU) and calcium (1 gm) was given 24 hours preoperatively. Group 2 was the control group. Total thyroidectomy was done and serum calcium levels were evaluated immediately after surgery on day two, seven and on the 30th day. The final outcome was measured at one month. Data was analyzed via the Statistical Package for Social Sciences version 22.0 (IBM Corp, Armonk, NY, USA). P value ≤ 0.05 was considered significant. Results The age ranged from 18 to 65 years with the mean age of 38.673 ± 8.63 years in group 1 while 41.217 ± 9.52 years in group 2, mean preoperative calcium level was 9.482 ± 0.49 mg/dl in group 1 and 9.678 ± 0.54 mg/dl in group 2. Hypocalcemia was seen in 3 (6.5%) in group 1 as compared to 12 (26.1%) patients in group 2 (p = 0.011). Conclusion Preoperative oral calcium and vitamin D supplements may prevent postoperative hypocalcemia, allowing a safe and early discharge. This will ultimately lead to improved patient satisfaction and significant cost savings.

One-Hour Postoperative Parathyroid Hormone Levels Do Not Reliably Predict Hypocalcemia After Thyroidectomy

INTRODUCTION

Hypocalcemia is a well-known complication after total thyroidectomy. Studies have indicated that the presence of low postoperative parathyroid hormone (PTH) levels can predict hypocalcemia. However, definitive study designs are lacking. The aim of this study was to determine whether postoperative PTH alone can accurately predict postoperative biochemical hypocalcemia.

METHODS

Under IRB approval, a prospective study of 218 consecutive patients who underwent total or completion thyroidectomy by two surgeons between June 2014 and June 2016 was performed. Biochemical hypocalcemia was defined as ionized calcium <1.13 mmol/L or serum calcium <8.4 mg/dL at any time postoperatively. Three PTH thresholds, <10, <20 pg/mL, and >50% drop in PTH 1 h postoperatively from baseline were examined.

RESULTS

Postoperative PTH < 10 pg/mL had a sensitivity of 36.5% (95% CI 27.4-46.3%) and a specificity of 89.2% (95% CI 81.9-94.3%). Postoperative PTH < 20 pg/mL had a sensitivity of 66.4% (95% CI 56.6-75.2%) and a specificity of 67.6% (95% CI 58.0-76.2%). Postoperative PTH decrease >50% had a sensitivity of 63.4% (95% CI 53.2-72.7%) and a specificity of 72.5% (95% CI 62.5-81.0%). Across all PTH thresholds, the false-negative rate was 33.6-63.5% indicating that up to 64% of patients with a normal PTH level could have been discharged without appropriate calcium supplementation. The false-positive rate was 10.8-32.4% indicating that up to 32.4% of patients with low PTH could have been treated with calcium supplementation unnecessarily.

CONCLUSION

Following total thyroidectomy, PTH levels are unreliable in predicting hypocalcemia. Additional prospective studies are needed to understand the true utility of PTH levels post-thyroidectomy.

Parathyroid hormone and serum calcium levels measurements as predictors of postoperative hypocalcemia in total thyroidectomy

Background

The rules of quantitative measures such as parathyroid hormone (PTH) levels in the first hours following total thyroidectomy have since been validated repeatedly. Such measures play an integral rule in identifying patients at significant risk for hypocalcaemia and have allowed for earlier supplementation of these patients with calcium with or without vitamin D.

Methods

A retrospective analysis was conducted of 40 consecutive patients with well differentiated thyroid cancer (WDTC) who underwent total thyroidectomy without central neck dissection (CND) as an initial surgery and no comorbidity at King Abdulaziz Medical City (National Guard hospital), between July 2011 and July 2012. A blood testing protocol was applied for all patients that measured serum calcium PTH at 6 hours postoperatively.

Results

Following total thyroidectomy, women were found to experience transient hypocalcaemia in 12.5% of cases (4/32), whereas no men cases encountered this postoperative complication (0/8). However, most probably due to small sample size, this difference was not statistically significant. PTH level was significantly associated with post thyroidectomy hypocalcaemia (43.7±39.3 versus 13.40±24.9 ng/L), P=0.014. Only negligible differences in the length of hospital stay were observed with and without post-thyroidectomy hypocalcaemia.

Conclusions

Using post-thyroidectomy PTH levels to predict hypocalcaemia has been confirmed in the current study. So, the use of PTH levels allows for early risk stratification of our patients and we feel this has resulted in better patient satisfaction.

Postoperative IPTH compared with IPTH gradient as predictors of post-thyroidectomy hypocalcemia

OBJECTIVES/HYPOTHESIS

Predicting patients' risk for hypocalcemia after thyroidectomy may allow for same-day discharge. This study was designed to compare postoperative intact parathyroid hormone (IPTH) alone with percentage change in IPTH (IPTH gradient) in predicting post-thyroidectomy hypocalcemia.

STUDY DESIGN

Retrospective cohort study.

METHODS

Patients undergoing total thyroidectomy by the senior author from May 2015 to May 2016 were included. Serum IPTH was measured preoperatively and 1 hour postoperatively, and IPTH gradient was calculated. Postoperative hypocalcemia was mild (≥8.0, <8.4) or severe (<8.0 and/or hypocalcemic symptoms). Postoperative IPTH and IPTH gradient were compared with hypocalcemia using logistic regression. Receiver operating characteristic analysis of IPTH measures as predictors of hypocalcemia was performed, and the area under the curve (AUC) was calculated.

RESULTS

Overall, 119 patients were included. Forty-seven percent of the patients developed postoperative hypocalcemia, including 26 (22%) with mild and 30 (25%) with severe hypocalcemia. Thirteen patients had hypocalcemic symptoms. Median IPTH gradient and postoperative IPTH each differed significantly by category of hypocalcemia (P < .001). Higher IPTH gradient was significantly associated with odds of severe and symptomatic hypocalcemia (adjusted odds ratio [aOR]: 1.21, 95% confidence interval [CI]: 1.06-1.39 and aOR: 1.34, 95% CI: 1.05-1.71 per 10% increase), whereas lower postoperative IPTH was not (aOR: 1.27, 95% CI: 0.95-1.68 and aOR: 1.44, 95% CI: 0.90-2.31 per 10 pg/mL decrease). The AUC for predicting severe hypocalcemia was nonsignificantly higher for IPTH gradient than postoperative IPTH (AUC = 0.77 vs. 0.69, P = .10). The AUC for predicting symptomatic hypocalcemia was significantly higher for IPTH gradient (AUC = 0.75 vs. 0.72, P = .03).

CONCLUSIONS

Our results suggest that the IPTH gradient may be more useful than postoperative IPTH alone in predicting risk of post-thyroidectomy hypocalcemia.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:769-774, 2018.

Benefits Resulting from 1-and 6-Hour Parathyroid Hormone and Calcium Levels After Thyroidectomy

OBJECTIVE: Previous studies have established the efficacy of post-thyroidectomy hypocalcemia monitoring using parathyroid hormone (PTH) and corrected calcium levels at 1 and 6 hours. The goal of this study was to measure the impact of managing patients based on the above findings with respect to: duration of hospital stays, rates of transient hypocalcemia, number of blood tests, cost savings, and discharge from the hospital as early as 8 hours post-thyroidectomy without compromising safety.

STUDY DESIGN AND SETTING: This is a prospective study involving 95 total thyroidectomy patients using historical data as controls. The previous protocol was modified in that all blood tests ceased for patients meeting the 6-hour critical level of PTH ≥ 28 ng/L and simultaneous corrected calcium ≥ 2.14 mmol/L (8.56 mg/dL). Furthermore, patients with 1-hour PTH levels ≤ 8 ng/L were prophylactically treated with calcium and vitamin D supplementation.

RESULTS: This study demonstrates lower rates of transient hypocalcemia from 28% to 9% (OR = 4.13, P = 0.016), a 10-hour reduction in mean hospital stay, and fewer blood tests (23 vs 15) for patients undergoing total thyroidectomy since the implementation of the new protocol. Furthermore, the experimental protocol resulted in an average cost savings of $766 per patient.

CONCLUSIONS: The new algorithm resulting from PTH and corrected calcium monitoring at 1 and 6 hours post-thyroidectomy has led to significant cost savings for our institution. It has also translated into greater patient satisfaction as a result of fewer blood tests, a lower incidence of transient hypocalcemia, and significantly shorter hospital stays.

Association between decreased serum parathyroid hormone after total thyroidectomy and persistent hypoparathyroidism

Background

Postoperative hypocalcemia caused by hypoparathyroidism is one of the most common morbidities of total thyroidectomy. The aim of this study was to analyze the kinetics and factors affecting PTH levels after total thyroidectomy and central neck dissection (CND).

Material/Methods

We performed a retrospective study in 438 consecutive patients who underwent total thyroidectomy between January 2007 and December 2010. No patient had a history of thyroid or neck surgery. PTH and calcium levels were recorded 1 day before the operation, during the first 5 days, and during follow-up (2 weeks and 2, 6, and 12 months).

Results

PTH levels declined to 41.90% of its initial value on the first day after the operation. After surgery, PTH was correlated positively with calcium and inversely with phosphate levels from postoperative day 1 to 14. Based on clinical observation, using a PTH threshold of <7 ng/L on postoperative day 1 was predictive of persistent hypoparathyroidism, with sensitivity and negative predictive value 100%, but poor specificity (70.19%). CND increased the risk of transient hypoparathyroidism compared with total thyroidectomy alone. Patients with thyroiditis had an increased risk of permanent hypoparathyroidism compared with those without thyroiditis. Iatrogenic removal of the parathyroid glands increased the risk of permanent hypoparathyroidism compared with those without iatrogenic parathyroidectomy.

Conclusions

PTH declined on the first day after thyroidectomy. PTH levels <7 ng/L on the first day after surgery might be associated with persistent hypoparathyroidism. CND, thyroiditis, and iatrogenic parathyroidectomy increased the risk of hypoparathyroidism.

Defining the syndromes of parathyroid failure after total thyroidectomy

Acute and chronic parathyroid insufficiency syndromes are the most common complication after total thyroidectomy. Permanent hypoparathyroidism imposes an important medical burden on patient lifestyle due to the need for lifetime medication, regular visits and significant long-term costs. Its true prevalence has been underestimated due to lack of clear definitions, inadequate follow-up and conflicts of interest when reporting individual patient series. The aim of this review is to propose precise definitions for the different syndromes associated to parathyroid failure based on the follow-up and management of patients developing hypocalcemia (<8 mg/dL at 24 hours) after first-time total thyroidectomy for cancer or goiter at our unit. Short and long-term post-thyroidectomy parathyroid failure presents as three different metabolic syndromes: (I) postoperative hypocalcemia is defined as a s-Ca <8 mg/dL (<2 mmol/L) within 24 hours after surgery requiring calcium/vit D replacement therapy at the time of hospital discharge; (II) protracted hypoparathyroidism as a subnormal iPTH concentration (<13 pg/mL) and/or need for calcium/vit D replacement at 4-6 weeks; and (III) permanent hypoparathyroidism as a subnormal iPTH concentration (<13 pg/mL) and/or need for calcium/vit D replacement 1 year after total thyroidectomy. Each of these syndromes has its own pattern of recovery and should be approached with different therapeutic strategies.

Postoperative PTH measurement is not a reliable predictor for hypocalcemia after total thyroidectomy in vitamin D deficiency: prospective study of 203 cases

BACKGROUND

Several factors have been used to predict post total thyroidectomy (TT) hypocalcemia. Serum intact PTH (PTH) levels <10 pg/mL after TT is considered to be the most accurate predictor. The aim of the present study was to evaluate the accuracy of PTH as a predictor of post-TT hypocalcemia in patients with vitamin D deficiency.

MATERIALS AND METHODS

The present prospective study was conducted from 2009 to 2011 and included patients undergoing TT for benign goiter. The PTH levels 8 h after TT in patients who were vitamin D sufficient (group A; S Vit D >20 ng/mL) versus those who were vitamin D deficient (group B) were compared. Comparison was also performed between patients belonging to group A and group B who developed hypocalcemia. Appropriate statistical tests were applied.

RESULTS

A total of 203 patients (19 males, 184 females) underwent TT; 58.6 % (n = 119) belonged to group A and 41.4 % (n = 84) to group B. Their mean age was 36.81 ± 12.9 years, and the mean duration of goiter was 45.35 ± 54.6 months. Hypocalcemia occurred in 41 patients (20.2 %). Among them 15 belonged to group A and 26 to group B (p = 0.002). The mean PTH in patients who developed hypocalcemia was 12.75 ± 8.91 versus 22.58 ± 15.38 in those who did not develop hypocalcemia (p = 0.00). Furthermore it was seen that the mean PTH in vitamin D sufficient hypocalcemic patients (n = 15) was 7.12 ± 1.79 and that in vitamin D deficient hypocalcemic patients (n = 26) was 16 ± 9.77 (p = 0.001) CONCLUSIONS: Our findings suggest that the fall in PTH after TT in vitamin D deficient patients is unreliable in predicting hypocalcemia and should not be relied on to plan early postoperative discharge.

Hypocalcaemia following total thyroidectomy: early post-operative parathyroid hormone assay as a risk stratification and management tool

Objective:

To develop a practical, efficient and predictive algorithm to manage potential or actual post-operative hypocalcaemia after complete thyroidectomy, using a single post-operative parathyroid hormone assay.

Methods:

This paper reports a prospective study of 59 patients who underwent total or completion thyroidectomy over a period of 24 months. Parathyroid hormone levels were checked post-operatively on the day of surgery, and all patients were evaluated for hypocalcaemia both clinically and biochemically with serial corrected calcium measurements.

Results:

No patient with an early post-operative parathyroid hormone level of 23 ng/l or more (i.e. approximately twice the lower limit of the normal range) developed hypocalcaemia. All the patients who initially had post-operative hypocalcaemia but had an early parathyroid hormone level of 8 ng/l or more (i.e. approximately two-thirds of the lower limit of the normal range) had complete resolution of their hypocalcaemia within three months.

Conclusion:

Early post-operative parathyroid hormone measurement can reliably predict patients at risk of post-thyroidectomy hypocalcaemia, and predict those patients expected to recover from temporary hypocalcaemia. A suggested post-operative management algorithm is presented.

Systematic review and meta-analysis of predictors of post-thyroidectomy hypocalcaemia

BACKGROUND

Hypocalcaemia is common after thyroidectomy. Accurate prediction and appropriate management may help reduce morbidity and hospital stay. The aim of this study was to perform a systematic literature review and meta-analysis of predictors of post-thyroidectomy hypocalcaemia.

METHODS

A systematic search of PubMed, EMBASE and the Cochrane Library databases was undertaken, and the quality of manuscripts assessed using a modified Newcastle-Ottawa Scale.

RESULTS

Some 115 observational studies were included. The median (i.q.r.) incidence of transient and permanent hypocalcaemia was 27 (19-38) and 1 (0-3) per cent respectively. Independent predictors of transient hypocalcaemia included levels of preoperative calcium, perioperative parathyroid hormone (PTH), preoperative 25-hydroxyvitamin D and postoperative magnesium. Clinical predictors included surgery for recurrent goitre and reoperation for bleeding. A calcium level lower than 1·88 mmol/l at 24 h after surgery, identification of fewer than two parathyroid glands (PTGs) at surgery, reoperation for bleeding, Graves' disease and heavier thyroid specimens were identified as independent predictors of permanent hypocalcaemia in multivariable analysis. Factors associated with transient hypocalcaemia in meta-analyses were inadvertent PTG excision (odds ratio (OR) 1·90, 95 per cent confidence interval 1·31 to 2·74), PTG autotransplantation (OR 2·03, 1·44 to 2·86), Graves' disease (OR 1·75, 1·34 to 2·28) and female sex (OR 2·28, 1·53 to 3·40).

CONCLUSION

Perioperative PTH, preoperative vitamin D and postoperative changes in calcium are biochemical predictors of post-thyroidectomy hypocalcaemia. Clinical predictors include female sex, Graves' disease, need for parathyroid autotransplantation and inadvertent excision of PTGs.

Use of Parathyroid Hormone Assay after Thyroidectomy: A Survey of US and European Surgeons

Introduction

Hypocalcemia after thyroidectomy results in prolongation of hospitalization and patient discomfort but can be predicted by PTH assays. However, there is considerable variation in their use.

Methods

This study was undertaken to document current US and European practice patterns regarding the use of this assay. Anonymous surveys were collected in 2009–2011 from members of the American Academies of Otolaryngology-Head and Neck Surgery and Endocrine Surgery and the European, Italian, French, Spanish and British Societies of Endocrine Surgery.

Results

There were 356 American (3% response) and 61 European (10% response) respondents. 105 (29.8%) American and 25 (41%) European respondents reported routine PTH assay use. Fellowship trained surgeons reported increased use of the PTH assay (P = 0.004). Shorter reported average post-operative hospital stay was associated with American physicians (P = 0.0001), community practice location (P = 0.0002) and routine calcium supplementation (P = 0.0015).

Conclusions

Surgical training was associated with routine use of the PTH assay. Average reported hospital stay was lower for American and community practice physicians and correlated with post-operative oral calcium use.

Female Gender as a Risk Factor for Transient Post-Thyroidectomy Hypocalcemia

Objectives. Transient post-thyroidectomy hypocalcemia is a common complication following thyroid surgery. Studies have identified risk factors and possible ways to help predict post-thyroidectomy hypocalcemia with the intent of ultimately limiting its incidence. This study evaluates the role of patient gender as a potential risk factor.

Study Design. A retrospective case series with chart review of 270 consecutive total thyroidectomy patients was conducted.

Setting. Jewish General Hospital, a McGill University–affiliated hospital in Montreal, Canada.

Subjects and Methods. 219 women and 51 men were included. Postoperative hypocalcemia was defined as any 1 of the following: total serum calcium 1.90 mmol/L or less, or signs and symptoms of hypocalcemia. The following were evaluated as potential confounding factors in the study: age, menopause, preoperative calcium, parathyroid hormone, magnesium and phosphate levels, presence of carcinoma in the surgical specimen, number of parathyroid glands preserved in situ, thyroid gland volume, and nodule size.

Results. Female patients experienced transient postoperative hypocalcemia in 24.7% (54/219) of cases, which was significantly greater than the 11.8% (6/51) incidence detected in men ( P < .05). This represents a female/male relative risk ratio of 2.1 (confidence interval, 1.0-4.6). There was no significant difference in rates of hypocalcemia between premenopausal and postmenopausal women (22.7% vs 26.6%).

Conclusion. These findings suggest that being female is likely a risk factor for transient post-thyroidectomy hypocalcemia. Although this association is statistically significant, its magnitude and clinical relevance are uncertain and may be trivial. Additional research is needed to ascertain the physiologic mechanisms underlying this gender difference.

Serum phosphate predicts temporary hypocalcaemia following thyroidectomy

BACKGROUND

Temporary hypocalcaemia occurs in up to 40% of patients following a total thyroidectomy. Serum calcium and parathyroid hormone (PTH) measurements are currently used to predict post-thyroidectomy hypocalcaemia. However, immediate access to PTH measurement is expensive and not widely available. Serum phosphate responds rapidly to changes in circulating PTH levels, and its measurement is readily available in all hospitals. We evaluated the use of serum phosphate to predict temporary hypocalcaemia post-thyroidectomy.

METHODS

We retrospectively assessed 111 consecutive patients who had total or completion thyroidectomy. Patients had serum calcium and phosphate measured preoperatively, on the evening of surgery (day 0), on the morning of day 1 and over the following week as clinically indicated. Serum PTH was measured on the morning of day 1. Vitamin D levels were measured preoperatively.

RESULTS

Seventy-six patients did not develop treatment-demanding hypocalcaemia. In these patients, the mean serum phosphate concentration was lower on the morning of day 1 compared to that on the evening of surgery. Seventeen patients with a vitamin D>25 nmol/l developed hypocalcaemia requiring treatment from day 1 onwards. All had an overnight rise in serum phosphate to >1.44 mmol/l (100% sensitivity and specificity for predicting hypocalcaemia). Twelve patients who had a vitamin D<25 nmol/l also developed hypocalcaemia but had an attenuated rise in serum phosphate.

CONCLUSION

Serum phosphate is a reliable biochemical predictor of post-thyroidectomy hypocalcaemia in patients without vitamin D deficiency. The use of serum phosphate may facilitate safe day 1 discharge of patients undergoing thyroidectomy.

Preoperative Parathyroid Hormone Levels as a Predictor of Postthyroidectomy Hypocalcemia

Objectives. The goal of the present study is to determine whether a decline in the 1-hour postoperative parathyroid hormone (PTH) level relative to the preoperative level is predictive of hypocalcemia.

Methods. This is a retrospective study involving 142 consecutive patients who underwent total thyroidectomy. Changes in preoperative PTH levels were then compared with the 1-hour levels.

Results. Thirty-four of 142 patients (23.9%) who underwent total thyroidectomy developed hypocalcemia. Thirty-one of the 34 patients who became hypocalcemic had a 1-hour postoperative PTH drop of 70% or more when compared with the preoperative value (sensitivity = 91%, specificity = 98%, positive predictive value = 94%, and negative predictive value = 97%).

Conclusion. A decline in the preoperative PTH level of 70% or greater at 1 hour following total thyroidectomy appears to be a reliable predictor of patients at risk of developing hypocalcemia. By allowing thyroid surgeons to identify these patients in the early postoperative period, calcium supplementation can be initiated sooner.

Prediction of hypocalcemia after using 1- to 6-hour postoperative parathyroid hormone and calcium levels: an analysis of pooled individual patient data from 3 observational studies

BACKGROUND

Parathyroid hormone (PTH) levels up to 6 hours postthyroidectomy have been shown to have excellent predictive power in determining hypocalcemia. In this study, we investigate the usefulness of combining calcium and PTH to increase the predictive power.

METHODS

Individual patient data were obtained from 3 studies (152 patients) that fulfilled our criteria (using PTH assay within hours postthyroidectomy to predict symptomatic hypocalcemia).

RESULTS

Changes in combined PTH and calcium threshold levels checked 1 to 6 hours after thyroidectomy were excellent in predicting postoperative hypocalcemia. A decrease in PTH of 60%, coupled with a simultaneous decrease in calcium of 10%, 5 to 6 hours postoperatively resulted in a sensitivity and specificity of 100%. However, combined PTH and calcium threshold changes were not significantly better than using PTH threshold changes alone.

CONCLUSIONS

Threshold changes in serum calcium and PTH, checked hours after surgery, can be used together to accurately predict whether a patient will become hypocalcemic after thyroidectomy.

The timing of calcium measurements in helping to predict temporary and permanent hypocalcaemia in patients having completion and total thyroidectomies

INTRODUCTION

Postoperative hypocalaemia commonly occurs after extensive thyroid surgery and may require calcium and/or vitamin D supplements to alleviate or prevent the symptoms. In this study, we determined the risk factors for developing hypocalcaemia and whether early serum calcium levels can predict the development of or differentiate between temporary or permanent hypocalcaemia.

PATIENTS AND METHODS

A total of 162 patients who either had a completion or total thyroidectomy formed the basis of this prospective study. Serial serum calcium measurements were recorded as well as details of the operation, pathology, indications for surgery, number of parathyroids identified at operation and any complications.

RESULTS

Eighty-four (52%) patients did not develop hypocalcaemia but 69 (43%) were found to have temporary hypocalcaemia and 9 (5%) had permanent hypocalcaemia. Hypocalcaemia was more common after total than completion thyroidectomies and the identification of parathyroids at operation appears to have a significant adverse effect on outcome. The calcium levels measured on day 1 postoperatively and the slope (serum calcium levels of day 1 postoperative minus day of operation) were statistically significant in predicting the development of hypocalcaemia and possibly to differentiate between temporary or permanent hypocalcaemia.

DISCUSSION

Although almost half the patients having extensive thyroid surgery developed hypocalcaemia (as defined by any postoperative corrected serum calcium level of < 2.12 mmol/l) only 24% had a serum calcium of < 2.12 mmol/l associated with clinical symptoms of hypocalcaemia or a calcium level of < 2.0 mmol/l. Only 5% had persistent hypocalcaemia defined as requiring exogenous supplements at 6 months' postoperatively. Patients having a completion thyroidectomy appear to be less likely to develop hypocalcaemia perhaps as a result of any iatrogenic effects on the parathyroids at the first operation being reversed before the second operation. Identification and, therefore, exposure of parathyroids at operation may have an adverse effect on the blood supply to the glands affecting their function.

CONCLUSIONS

Serum calcium levels measured 6 hours' post-surgery and on day 1 postoperatively can be useful in predicting if the patient will develop hypocalcaemia and the slope may indicate whether the hypocalcaemia will be temporary or permanent. Patients with toxic goitres and those having a one-stage total thyroidectomy are most at risk of developing hypocalcaemia.

Evidence for the role of perioperative PTH measurement after total thyroidectomy as a predictor of hypocalcemia

BACKGROUND

Total thyroidectomy is now accepted worldwide as the standard surgical procedure for the management of benign bilateral nodular thyroid disease. Hypocalcemia is the most common complication of that procedure and a variety of strategies for diagnosing and managing post-thyroidectomy hypocalcemia have been advocated. Increasingly, the use of intact parathyroid hormone (PTH) has been utilized to try to predict those patients at risk of developing post-thyroidectomy hypocalcemia.

METHODS

A Medline search of English language literature was performed and we reviewed the evidence in relation to the following three issues: the accuracy of PTH in predicting hypocalcemia, the optimal timing for measuring PTH, and the routine use of oral calcium supplements.

RESULTS

Post-thyroidectomy PTH levels accurately predict hypocalcemia but lack 100% accuracy. Progressive and severe hypocalcemia is unlikely in the setting of a normal PTH level and hence PTH can be cautiously used to facilitate discharge within 24 h for many patients. In addition, PTH levels can be used to implement early treatment with calcium and/or vitamin D supplements to reduce the incidence and severity of hypocalcemia. A single PTH measurement taken any time from 10 min to several hours postoperative will provide equally accurate results for predicting post-thyroidectomy hypocalcemia. Routine use of oral calcium supplements may reduce the incidence and severity of post-thyroidectomy hypocalcemia.

CONCLUSION

Postoperative PTH can be used to stratify the risk of patients developing hypocalcemia after thyroidectomy. In addition, the routine use of oral calcium supplements can lead to decreased incidence and severity of post-thyroidectomy hypocalcemia. Protocols based on PTH and the routine use of oral calcium supplements can lead to improved patient outcomes after thyroidectomy.

Kinetics of serum parathyroid hormone during and after thyroid surgery

Background

Hypocalcaemia after thyroidectomy is thought to result from surgical damage to the parathyroid glands. This study analysed postoperative outcomes related to perioperative parathyroid hormone (PTH) levels.

Methods

Some 402 consecutive patients undergoing thyroid surgery were studied prospectively to monitor perioperative changes in serum PTH and Ca2+ levels, and clinical symptoms of hypocalcaemia.

Results

Transient symptomatic hypocalcaemia and persistent hypoparathyroidism occurred in 61 (15 per cent) and six (1·5 per cent) of 402 patients respectively. The intraoperative decline in PTH was 20·2 per cent; the trough (63·8 per cent of preoperative value) was reached 3 h after surgery. Before surgery, PTH levels were correlated inversely with serum Ca2+ concentration. The correlation remained positive from 3 h after surgery until postoperative day 14. Thus, PTH secretion was reduced, but remained sufficient to prevent symptomatic hypocalcaemia in most patients. A low serum PTH level was predictive of persistent hypoparathyroidism (sensitivity and negative predictive value 100 per cent, but poor specificity of 54·1 per cent).

Conclusion

Thyroid surgery impairs hormone secretion by the parathyroid glands resulting in postoperative latent parathyroid insufficiency. Normal PTH levels 3 h after surgery and a normal serum calcium level on the first postoperative day rule out persistent hypoparathyroidism.

Accuracy of PTH assay and corrected calcium in early prediction of hypoparathyroidism after thyroid surgery

Objective

To evaluate the accuracy of the intraoperative parathyroid hormone (ioPTH) and 6-hour PTH (6hPTH) assay in predicting transient hypoparathyroidism after thyroidectomy.

Study Design

A nonrandomized prospective study was conducted on patients undergoing thyroid surgery.

Subjects and Methods

Of 138 patients undergoing thyroid surgery, intraoperative PTH was measured 10 minutes after gland removal. Serum calcium, magnesium, inorganic phosphorus, albumin, and PTH levels were assayed 6 and 16 hours after surgery and daily until patient discharge.

Results

The development of postoperative hypocalcemia was associated with low ioPTH ( P < 0.0001) and 6hPTH ( P < 0.0001) values, and the decline of PTH from baseline ( P < 0.0001). The cutoff for percentage decline of ioPTH and 6hPTH (55.7% and 379%, respectively) was more accurate than an absolute value. Accuracy, and positive and negative predictive values were 88 percent, 63 percent, and 100 percent for ioPTH and 75 percent, 46 percent, and 100 percent for 6hPTH, respectively.

Conclusion

With the use of ioPTH decline in association with 16-hour corrected calcium, it is possible to distinguish early normocalcemic patients from hypocalcemic ones in most cases.

Cost savings associated with post-thyroidectomy parathyroid hormone levels

OBJECTIVES: A 1-hour post-thyroidectomy parathyroid hormone (PTH) level of ≤8 ng/L is predictive of patients who will develop hypocalcemia and guides early supplementation with calcium and vitamin D. However, most hypocalcemic patients fail to meet this criterion. The goal of this study was to determine whether PTH ≤ 15 ng/L could be used as a better predictor of hypocalcemia.

STUDY DESIGN, SUBJECTS, AND METHODS: This retrospective study involved 270 thyroidectomy patients (2004-2006). PTH and calcium levels, length of admission, supplementation, and rates of hypocalcemia were recorded.

RESULTS: Forty-three percent (26/60) of patients developing hypocalcemia met the PTH ≤ 8 ng/L cut-off. In contrast, 80% (48/60) of patients developing hypocalcemia had a PTH ≤ 15 ng/L. Two point two percent of patients had a 1-hour PTH ≤ 15 ng/L and failed to develop hypocalcemia, for a specificity of 97%.

CONCLUSIONS: A 1-hour PTH cut-off of ≤15 ng/L for prophylactic supplementation should allow the prevention of the majority of cases of hypocalcemia, leading to significant cost savings by shortening hospital stays.

Intraoperative parathormone measurement from the internal jugular vein predicts post-thyroidectomy hypocalcaemia

BACKGROUND

The most common significant complication of total thyroidectomy is hypoparathyroidism. Intraoperative prediction of which patients are likely to be affected would allow both intraoperative and postoperative interventions to be utilised in these patients. Selection of these patients is essential if we are to be successful at discharging total thyroidectomy patients on the first postoperative day. We investigated the utility of intraoperative parathormone measurement from the internal jugular vein at predicting postoperative hypocalcaemia.

MATERIALS AND METHODS

Prospective collection of data was done on 45 consecutive total thyroidectomy patients. Preoperative calcium, intraoperative parathormone and postoperative calcium and parathormone were collected. The accuracy of intraoperative parathormone in predicting those with postoperative hypocalcaemia was assessed.

RESULTS

Intraoperative parathormone of less than 2 pmol l(-1) had a sensitivity of 100% and a specificity of 95% in predicting those with postoperative hypocalcaemia. An intraoperative sample less than 2 pmol l(-1) was a highly significant predictor (p < 0.0001) of postoperative hypocalcaemia.

CONCLUSION

Intraoperative assessment of parathormone is an accurate predictor of those patients who will become hypoparathyroid in the postoperative period. Intraoperative prediction allows for targeted autotransplantation of glands in those at risk and selected early institution of postoperative supplementation in these patients. Patients not identified as at risk can be safely discharged.

Parathyroid Hormone as a Predictor of Hypocalcemia after Thyroidectomy

OBJECTIVES

The aims of this study are to ascertain whether parathyroid hormone (PTH) assay before total/completion thyroidectomy followed by levels immediately thereafter in the recovery room and the morning after surgery are a reliable predictor of hypocalcemia at our institution. In addition, to determine the feasibility of early discharge home from hospital after total thyroidectomy on the basis of postoperative PTH levels.

STUDY DESIGN

Prospective clinical study.

METHODS

Two hundred one patients undergoing total thyroidectomy at our institution were enrolled in the study. Preoperative levels of PTH, serum calcium, ionized calcium, and albumin were drawn. In the postoperative phase, the same biochemical markers were taken in the recovery room within 1 hour of the procedure and at a standard time the morning after the procedure. Discharge planning took place as per existing standards.

RESULTS

Two hundred and one patients were reviewed. PTH levels below 1.1 pmol/L within 1 hour of completion or total thyroidectomy were predictive of risk for developing hypocalcemia, requiring calcium replacement therapy. PTH levels above 1.6 pmol/L were predictive of patients who would remain normocalcemic. Patients who fell in between these two values require further monitoring with conventional calcium levels.

CONCLUSIONS

At our institution, PTH assays drawn postoperatively are predictive of patients who are at risk for developing hypocalcemia. Early identification of at-risk patients will facilitate prompt calcium replacement therapy and potential safe early discharge from hospital.

Randomized study on oral administration of calcitriol to prevent symptomatic hypocalcemia after total thyroidectomy

BACKGROUND

Symptomatic hypocalcemia remains the main postoperative complication after total thyroidectomy. The aim of the present study was to evaluate the role of oral supplementation of calcitriol and calcium salts in preventing severe postoperative hypocalcemia after total thyroidectomy.

METHODS

A consecutive series of patients undergoing total thyroidectomy followed by administration of 500 mg of calcium salts 3 times per day were randomized to 3 different postoperative medical treatments: in group A, .5 microg of calcitriol twice per day was administered to 104 patients; in group B, 1 mmicrog of calcitriol twice per day was administered to 111 patients; and in group C, 202 patients did not receive calcitriol.

RESULTS

The rate of postoperative tetany in group A was 2.9%, in group B was 0%, and in group C was 7.4% (P=.03) and the rate of paresthesias was 28.8%, 17.1%, and 22.3%, respectively (P=.19). At discontinuation of calcitriol/calcium salts treatment, intact parathyroid hormone levels did not significantly differ from the preoperative levels. Receiver operating characteristic (ROC) curve analysis showed that the area under the curve for serum concentration of calcium in predicting postoperative tetany was .749, .858 and .862 on the first, second, and third postoperative day, respectively. The best cut-off value of calcemia for prediction tetany was 7.5 mg/dL, and the rate of severe hypocalcemia on the third postoperative day was 23.1% in group A, 9.9% in group B, and 27.2% in group C (P=.001).

CONCLUSIONS

Oral administration of 1 microg of calcitriol twice per day and 500 mg of calcium salts 3 times per day after total thyroidectomy significantly decreases the risk of severe postoperative hypocalcemia.

Perioperative Parathyroid Hormone Assay for Diagnosis and Management of Postthyroidectomy Hypocalcemia

OBJECTIVES/HYPOTHESIS

The purpose of this study was to assess the relationship between perioperative changes in parathyroid hormone (PTH) level and the likelihood of postthyroidectomy hypocalcemia.

STUDY DESIGN

In a series of 78 patients undergoing total or completion thyroidectomy, PTH levels were measured before surgery and at 10 minutes after removal of the thyroid gland.

METHODS

A prospective, nonrandomized collection of serum from 78 consecutive total or completion thyroidectomy procedures performed by a single surgeon was carried out over 18 months. Analysis is made of PTH levels, serum calcium values, need for calcium supplementation, and symptoms of hypocalcemia.

RESULTS

Both a PTH change of 75% and an absolute postoperative PTH of 7 pg/mL are accurate standards for predicting symptomatic hypocalcemia after total or completion thyroid surgery.

CONCLUSIONS

Perioperative PTH levels are a tool for the prediction of postoperative symptomatic hypocalcemia after thyroidectomy. A PTH level drawn 10 minutes after removal of the thyroid predicts the likelihood of postoperative hypocalcemia.

Same-day discharge after total thyroidectomy: The value of 6-hour serum parathyroid hormone and calcium levels

BACKGROUND

The purpose of this study was to determine whether patients who undergo total thyroidectomy will have postoperative hypocalcemia develop when they reach the critical 6-hour serum levels defined as parathyroid hormone (PTH) > or =28 ng/L and simultaneous corrected calcium > or =2.14 mmol/L.

METHODS

This was a prospective study involving 70 consecutive total thyroidectomy patients. There were 51 women and 19 men involved in the study. The mean age was 49.3 years (range, 21-76 years). Patients who had completion thyroidectomy or neck dissections were excluded. Patients undergoing parathyroidectomy at the time of thyroidectomy were also excluded. PTH and corrected calcium levels were measured postoperatively at 6, 12, and 20 hours.

RESULTS

Hypocalcemia developed in 24% (17 of 70) of the patients. Of the 53 patients who remained normocalcemic, 68% (36 of 53) reached the 6-hour critical level. None of the hypocalcemic patients (0 of 17) attained the 6-hour critical level (chi-square test p < .0001). This translates into a specificity of 100% (95% confidence interval [CI], 80.5% to 100%) and a positive predictive value of 100% (95% CI, 90.1% to 100%).

CONCLUSIONS

The simultaneous evaluation of PTH and corrected calcium levels 6 hours after thyroidectomy allows for an accurate prediction of the trend of serum calcium. This study enables us to confidently consider same-day discharge for most of our thyroidectomy patients.