Postoperative Parathyroid Hormone Levels in Conjunction with Corrected Calcium Values as a Predictor of Post-Thyroidectomy Hypocalcemia: Review of Outcomes 1 Year after the Implementation of a New Protocol

Comparison of iPTH and calcium levels between total thyroidectomy and lobectomy: a prospective study of 840 thyroid cancers with three years of follow-up

Background

Hypocalcemia is the most frequent complication after thyroidectomy and central neck dissection (CND). Early intact parathyroid hormone (iPTH) determination has been proposed as an early predictor parathyroid gland state. We aim to describe iPTH kinetics after central compartment lymph node dissection (CLND).

Methods

A large prospective observational study was conducted among 840 patients who underwent thyroid cancer surgery between July and December 2016 in China-Japan Union Hospital of Jilin University. Data were obtained from the patient’s iPTH evaluation 15 min after CND and serum calcium records during three years of post-operative follow-up. Age, sex, BMI, preoperative PTH, operative and pathologic details were analyzed. Backward stepwise logistic regression analyses were performed to find potential risk factors for predicting iPTH <15 pg/mL. The odds ratio and 95% confidence interval are estimated using the logistic regression coefficients. The prediction model was assessed using the receiver operating characteristic curve.

Results

The incidence of permanent hypocalcemia was 0.12%, while, 44.52% of patients were central lymph node metastasis. Multivariate analyses found associations among iPTH <15 pg/mL and several risk factors, especially preop PTH and type of surgery. The risk of iPTH <15 pg/mL, after total thyroidectomy plus CND, is almost 17 times that of lobectomy plus CND (OR =17.648, 95% confidence interval: 10.011–31.110). A model was created using multivariate analysis, which involved surgical procedure, and preop PTH could separate thyroid operation with iPTH <15 pg/mL. The biological index showed an area under the ROC curve of 0.697 and 0.613 separately. Using values below the lowest or above the highest cut-off point, the presence or absence of iPTH <15 pg/mL could possibly be predicted before thyroidectomy and CND.

Conclusions

A lobectomy procedure for papillary thyroid carcinoma patients with clinically uninvolved neck lymph nodes (cN0) who have primary tumors (T1 or T2) could accompany prophylactic CND (ipsilateral or bilateral) to provide clearance of disease compared to total thyroidectomy.

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.

Meta-analysis of routine calcium/vitamin D3 supplementation versus serum calcium level-based strategy to prevent postoperative hypocalcaemia after thyroidectomy

BACKGROUND

The aim was to assess the effectiveness of routine administration of calcium +/- vitamin D3 compared with a serum calcium level-based strategy to prevent symptomatic hypocalcaemia after thyroidectomy.

METHODS

RCTs comparing routine supplementation of calcium +/- vitamin D3 with treatment based on serum calcium levels measured after total thyroidectomy, published between 1980 and 2017, were identified in MEDLINE, Embase, LILACS and Google Scholar databases. Risk of bias was evaluated using the Cochrane Collaboration tool. Risk differences were calculated by random-effects meta-analysis. Meta-regression and cumulative meta-analysis were used to explore the best therapeutic approach.

RESULTS

Fifteen studies with 3037 patients were included, and seven treatment comparisons were made. Routine supplementation with calcium + vitamin D3 offered a lower risk of symptomatic (risk difference (RD) -0·25, 95 per cent c.i. -0·32 to -0·18) and biochemical (RD -0·24, -0·31 to -0·17) hypocalcaemia than treatment based on measurement of calcium levels. The number needed to treat was 4 (95 per cent c.i. 3 to 6) for symptomatic hypocalcaemia. No publication bias was found; although heterogeneity was high for some comparisons, sensitivity analysis did not change the main results.

CONCLUSION

Routine postoperative administration of calcium + vitamin D3 is effective in decreasing the rate of symptomatic and biochemical hypocalcaemia.

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.

Early prediction of hypocalcemia following thyroid surgery. A prospective randomized clinical trial

PURPOSE

The aim of this randomized-controlled trial was to validate the results of a previous prospective single-cohort observational study conducted in the same surgical unit regarding the use of concomitant intact parathyroid hormone (iPTH) and serum calcium measurement in predicting hypocalcemia after total thyroidectomy.

METHODS

From January 2014 to January 2015, 150 patients underwent total thyroidectomy in our department and were randomized into two groups. The experimental group was submitted to iPTH assay 6 h after surgery while the control group was submitted to a daily assay of serum calcium and phosphorus. Sensitivity and specificity of different serum measurements have been calculated using the receiver-operator characteristics (ROC) curve.

RESULTS

The prevalence of hypocalcemia was 14.25% in both groups. The assay of iPTH 6 h after surgery combined with the serum calcium assay 24 h after surgery yielded the highest diagnostic accuracy in predicting hypocalcemia using ROC curves, with 100% sensitivity and 100% specificity.

CONCLUSIONS

According to our previous study, the combined measurement of iPTH 6 h after surgery and of serum calcium 24 h after surgery are highly predictive of early postoperative hypocalcemia. These results are important in selecting the patients eligible for early discharge and those who need calcium and vitamin D supplementation.

Early intact PTH (iPTH) is an early predictor of postoperative hypocalcemia for a safer and earlier hospital discharge: an analysis on 260 total thyroidectomies

BACKGROUND

Hypocalcemia is the most frequent complication after thyroidectomy. Serum calcium levels are reliable only 48-72 hours postoperatively. Early intact PTH (iPTH) has been proposed as early predictor of postoperative hypocalcemia. Our aim is to assess the ability of iPTH in predicting postoperative hypocalcemia.

METHODS

Two hundred and sixty patients underwent thyroidectomy with postoperative iPTH evaluation. The iPTH samplings were early performed after thyroidectomy. The calcium levels were dosed postoperatively. Age, sex, clinical diagnosis, obesity, comorbidities, previous neck surgery, preoperative therapy, type of surgery, dissectors used, lymphadenectomy, post-operative complications, reoperation and histological diagnosis were considered. The primary end-point was the postoperative hospital stay. The secondary end-points were serum calcium and iPTH. Three iPTH cut-offs were tested to assess which was the best value (10.0, 15.0, and 20.0 pg/mL).

RESULTS

The iPTH cut-off value of 10.0 pg/mL was the most accurate and specific for hypocalcemia. Comparing the iPTH value with the different values of calcium respectively 24 and 48 hours after surgery, a statistically stronger association with the serum calcium levels 48 hours postoperatively has been shown. iPTH ≥10 pg/mL 3-6 hours after surgery was strongly correlated to early discharge.

CONCLUSIONS

The correlation of iPTH with hypocalcemia is significant since a few hours after surgery and the value of iPTH ≥10 pg/mL is able to select those patients for a safe and early discharge. The use of the iPTH might avoid unnecessary extensions of hospitalization.

Comparison of Intraoperative versus Postoperative Parathyroid Hormone Levels to Predict Hypocalcemia Earlier after Total Thyroidectomy

OBJECTIVE

To determine differences in the mean parathyroid hormone (PTH) levels for normocalcemic and hypocalcemic total thyroidectomy patients who were tested for PTH during the intraoperative or early postoperative period.

DATA SOURCES

MEDLINE, the Cochrane Database, and other databases from 1960 to 2014 in the English language and specific to humans for relevant articles.

REVIEW METHODS

Studies were included if PTH was obtained within 24 hours of thyroidectomy. Studies were excluded (1) if only a hemithyroidectomy was performed, (2) if means of studied PTH values were not reported in the article, or (3) if the time of the PTH draw fell outside of defined "intraoperative" or "early postoperative" windows. PTH values were divided into 3 groups: preoperative (control group), intraoperative (ie, discharge decisions were based on PTH values drawn in the operating room), and early postoperative (ie, PTH values at 1 to 4 hours after surgery were used as a guide).

RESULTS

The reported means of perioperative PTH levels and percentage of patients who developed hypocalcemia were collected from 14 studies. PTH evaluated at both the intraoperative and early postoperative periods was significantly lower in patients who became hypocalcemic versus patients who remained normocalcemic. There was no significant difference when PTH was measured intraoperatively or early postoperatively.

CONCLUSION

Intraoperative PTH has no significant disadvantage versus early postoperative PTH when used as a clinical guide for discharge after thyroidectomy.

Intact parathyroid hormone measurement at 24 hours after thyroid surgery as predictor of parathyroid function at long term

BACKGROUND

There is no consensus about the usefulness of postoperative intact parathyroid hormone (iPTH) determination to predict permanent hypoparathyroidism (pHPP). We evaluated the value of calcium (Ca2+) and iPTH concentration at 24 hours after total thyroidectomy (TT) for predicting pHPP.

METHODS

Ca2+ and iPTH levels from 70 consecutive patients who underwent TT were measured at 24 hours and 6 months after TT.

RESULTS

Five patients (7.1%) developed pHPP. An iPTH concentration ≤5.8 pg/mL at 24 hours after TT identified patients at risk for pHPP (sensitivity, 100%; specificity, 81.5%), but it was not accurate enough to predict its development (positive predictive value, 30%). Conversely, an iPTH level >5.8 pg/mL predicted normal parathyroid function at 6 months (negative predictive value, 100%). Compared with iPTH, a postoperative Ca2+ level ≤1.95 mmol/L was 60% sensitive and 78.5% specific to predict pHPP.

CONCLUSIONS

An iPTH concentration >5.8 pg/mL on the first postoperative day rules out pHPP with much better diagnostic accuracy than Ca2+. Postoperative iPTH could be helpful in identifying patients at risk for developing pHPP.

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.

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.

PACU PTH Facilitates Safe Outpatient Total Thyroidectomy

Objective. To determine if a serum parathyroid hormone (PTH)–based discharge algorithm can be used to safely facilitate outpatient total thyroidectomy.

Study Design. Case series with chart review of consecutive total and completion thyroidectomies performed by the senior author from March 2008 to November 2009.

Setting. An academic tertiary care center.

Subjects and Methods. At the authors’ institution, patients undergoing total or completion thyroidectomy are subject to a same-day discharge algorithm that incorporates postanesthesia care unit rapid PTH as the major discharge criterion. Patients with PTH >30 pg/mL are eligible for same-day discharge without supplementation, patients with PTH between 20 and 30 pg/mL are eligible for discharge but receive calcium supplementation, and patients with PTH <20 pg/mL are observed overnight (23 hours) with calcium and vitamin D supplementation.

Results. One hundred eighty patients (mean age, 48.9 years; 83.3% female) underwent total (77.2%) or completion (22.7%) thyroidectomy with or without node dissection. Forty-two percent were performed with minimally invasive video-assisted (MIVA) technique. Seventy-six percent (137/180) of patients had a PTH >20 pg/mL, meeting the PTH discharge criterion. Sixty-nine percent (95/137) of eligible patients were discharged on the same day (53.1% of total). Ten percent of discharge-eligible patients were admitted due to drain placement. Of the 95 patients undergoing outpatient surgery, none were admitted, seen, or called for symptoms of hypocalcemia in the postoperative period. All 180 patients were eucalcemic at postoperative day (POD) 7 and POD 30 office visits. No patients were hypoparathyroid at POD 30. No significant difference in postoperative hypoparathyroidism existed between completion versus total thyroidectomy (11.1% vs 22.2%, P = .28) or MIVA versus standard technique ( P = .37).

Conclusion. A PTH-based discharge algorithm can safely facilitate outpatient total or completion thyroidectomy, with minimal risk of clinically significant outpatient hypocalcemia.

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 Role of Rapid Pacu Parathyroid Hormone in Reducing Post-Thyroidectomy Hypocalcemia

OBJECTIVES: Post-thyroidectomy parathyroid hormone (PTH) levels have been used to predict hypocalcemia. The goal of this study was to determine whether selective supplementation for post anesthesia care unit (PACU) PTH < 15 mg/dL reduced hypocalcemia compared to observation or routine supplementation.

STUDY DESIGN: Controlled cohort study of thyroidectomy patients, with chart review.

SETTING: Chart review of total or completion thyroidectomy patients in an academic setting.

SUBJECTS AND METHODS: The control group consisted of 124 subjects. The selective supplementation group consisted of 169 subjects with routine PACU PTH testing. The routine supplementation group consisted of 155 subjects with immediate postoperative calcium and vitamin D supplementation. The control group received supplementation for hypocalcemia (calcium < 8.0 mg/dL). The selective PTH group received calcium and vitamin D supplementation for PACU PTH < 15 mg/dL or hypocalcemia. The routine supplementation group received oral calcium and calcitriol supplementation immediately after surgery. Four separate postoperative day 1 (POD1) outcome measures were evaluated: 1) mean serum calcium; 2) rate of hypocalcemia < 8 mg/dL; 3) rate of significant hypocalcemia < 7.5 mg/dL; and 4) rate of hypercalcemia > 10 mg/dL.

RESULTS: Mean serum calcium was lower and the rate of hypocalcemia was higher in the control group than the selective PACU PTH group on POD1 (8.2 vs 8.6 mg/dL, P < 0.0001, and 35% vs 14%, P < 0.0001, respectively). Mean serum calcium was higher (8.9 vs 8.6 mg/dL, P < 0.0001) and the rate of hypocalcemia lower in the routine supplementation group than in the selective group. However, the rate of hypercalcemia was higher in the routine supplementation group than in the selective group (4.5% vs 0%, P = 0.006).

CONCLUSION: Routine PTH testing and supplementation for patients with hypoparathyroidism reduced the proportion of patients experiencing hypocalcemia. However, supplementation for intraoperative PTH < 15 mg/dL had a higher rate of hypocalcemia than routine supplementation, but with a lower rate of hypercalcemia.

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.

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.