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

Early hospital discharge through prediction of post-thyroidectomy hypoparathyroidism

INTRODUCTION

Hypoparathyroidism is the most common postsurgical complication of total thyroidectomy. Furthermore, it is the main cause of prolonged hospitalisation after this procedure.

OBJECTIVE

To predict the probability of post-thyroidectomy hypocalcaemia according to the levels of intact parathyroid hormone (iPTH), as well as to determine the needs for treatment with exogenous calcium according to the levels of serum calcium (Ca).

MATERIALS AND METHODS

Retrospective study was carried out on patients who underwent total thyroidectomy between January 2017 and January 2020 at Los Arcos del Mar Menor University Hospital (HULAMM). iPTH and Ca levels ​​were measured at 4, 24 and 48 h after the surgery. Follow-up was 6 months.

RESULTS

Ninety-four patients were operated on. Temporary and permanent postoperative hypoparathyroidism percentages were, respectively, 51.06% and 6.38%. iPTH level 24 h after the procedure was the most reliable predictor of post-thyroidectomy temporary hypoparathyroidism (Area Under the ROC Curve (AUC) = 0.933, p < .001). iPTH levels ​​≥29 pg/mL predicted normal parathyroid metabolism.

CONCLUSIONS

The combined values of iPTH and Ca levels 24 h after thyroidectomy seems to be a reliable, safe and efficient method to control the post-thyroidectomy hypoparathyroidism. Our protocol could reduce the hospital stay of patients at low risk of hypocalcaemia, allowing them to be discharged from the hospital on the first postoperative morning and identifying patients at high risk of hypocalcaemia early.

Lower Rates of Hypocalcemia Following Near-Infrared Autofluorescence Use in Thyroidectomy: A Meta-Analysis of RCTs

BACKGROUND

Iatrogenic injury of the parathyroid glands is the most frequent complication after total thyroidectomy.

OBJECTIVE

To determine the effectiveness of near-infrared autofluorescence (NIRAF) in reducing postoperative hypocalcemia following total thyroidectomy.

METHODS

PubMed, Scopus, and Google Scholar databases were searched. Randomised trials reporting at least one hypocalcemia outcome following total thyroidectomy using NIRAF were included.

RESULTS

The qualitative data synthesis comprised 1363 patients from nine randomised studies, NIRAF arm = 636 cases and non-NIRAF arm = 637 cases. There was a statistically significant difference in the overall rate of hypocalcemia log(OR) = -0.7 [(-1.01, -0.40), M-H, REM, CI = 95%] and temporary hypocalcemia log(OR) = -0.8 [(-1.01, -0.59), M-H, REM, CI = 95%] favouring the NIRAF. The difference in the rate of permanent hypocalcemia log(OR) = -1.09 [(-2.34, 0.17), M-H, REM, CI = 95%] between the two arms was lower in the NIRAF arm but was not statistically significant.

CONCLUSIONS

NIRAF during total thyroidectomy helps in reducing postoperative hypocalcemia. Level of evidence-1.

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.

Carbon Nanoparticles for Thyroidectomy and Central Lymph Node Dissection for Thyroid Cancer

PURPOSE

To evaluate whether the application of carbon nanoparticles (CNs) in total or near-total thyroidectomy combined with central lymph node dissection (CLND) for thyroid cancer (TC) is beneficial to lymph node dissection, parathyroid, and recurrent laryngeal nerve (RLN) protection.

METHODS

Relevant literatures were systematically searched on PubMed, EMBASE, and Cochrane Library Databases until March 31, 2021. All analyses were performed using Revman Manager 5.3 software. The main results were the number of central lymph nodes, the number of central metastatic lymph nodes, accidental parathyroidectomy, postoperative hypoparathyroidism, postoperative hypocalcemia, and postoperative transient RLN paralysis.

RESULTS

This meta-analysis identified 4 randomized controlled trials and 8 non-randomized controlled trials comprising 1870 patients. Compared with the control, the use of CNs was helpful to dissect more central lymph nodes (weighted mean difference [WMD]: 3.55, 95% confidence interval [CI]: 2.12-4.98, P < .00001) and central metastatic lymph nodes (WMD: 1.69, 95% CI:1.31-2.08, P < .00001), lower rate of accidental parathyroidectomy (odds ratio [OR]: .33, 95% CI: .23-.47, P < .00001), lower rate of both postoperative transient hypoparathyroidism (OR: .40, 95% CI: .31-.51, P < .00001), and transient hypocalcemia (OR: .37, 95% CI: .27-.51, P < .00001). However, there were no statistical difference between the groups for postoperative permanent hypoparathyroidism (OR: .29, 95% CI: .06-1.28, P = .10), postoperative permanent hypocalcemia (OR: .94, 95% CI: .10-9.16, P = .96), and postoperative transient RLN paralysis (OR: .66, 95% CI: .40-1.12, P = .12).

CONCLUSIONS

The application of CNs in total or near-total thyroidectomy combined with CLND for TC can better dissect the central lymph nodes and protect parathyroid glands (PGs) and their function.

Intraoperative frozen section performance for thyroid cancer diagnosis

Objective

A primary medical relevance of thyroid nodules consists of excluding thyroid cancer, present in approximately 5% of all thyroid nodules. Fine-needle aspiration biopsy (FNAB) has a paramount role in distinguishing benign from malignant thyroid nodules due to its availability and diagnostic performance. Nevertheless, intraoperative frozen section (iFS) is still advocated as a valuable tool for surgery planning, especially for indeterminate nodules.

Methods

To compare the FNAB and iFS performances in thyroid cancer diagnosis among nodules in Bethesda Categories (BC) I to VI. The performance of FNAB and iFS tests were calculated using final histopathology results as the gold standard.

Results

In total, 316 patients were included in the analysis. Both FNAB and iFS data were available for 272 patients (86.1%). The overall malignancy rate was 30.4%% (n = 96). The FNAB sensitivity, specificity, and accuracy for benign (BC II) and malignant (BC V and VI) were 89.5%, 97.1%, and 94.1%, respectively. For all nodules evaluated, the iFS sensitivity, specificity, and accuracy were 80.9%, 100%, and 94.9%, respectively. For indeterminate nodules and follicular lesions (BC III and IV), the iFS sensitivity, specificity, and accuracy were 25%, 100%, and 88.7%, respectively. For BC I nodules, iFS had 95.2% of accuracy.

Conclusion

Our results do not support routine iFS for indeterminate nodules or follicular neoplasms (BC III and IV) due to its low sensitivity. In these categories, iFS is not sufficiently accurate to guide the intraoperative management of thyroidectomies. iFS for BC I nodules could be an option and should be specifically investigated.

Predictive value of postoperative day 1 parathyroid hormone levels for early and late hypocalcaemia after thyroidectomy

PURPOSE

Early parathyroid hormone (PTH) levels after total thyroidectomy can predict patients at low risk of hypocalcaemia who can be discharged early without calcium supplementation. For centres without facility to perform early PTH levels, PTH levels sent on the first postoperative day (POD1) may be an alternative. However, there is less data regarding optimal cut-off PTH levels for POD1 discharge.

METHODS

Retrospective review of prospective database of thyroid operations between September 2009 and February 2020 at tertiary referral centre. Main outcome measure was symptomatic hypocalcaemia.

RESULTS

Five hundred seventy patients undergoing total (521) or completion thyroidectomy with POD1 PTH levels available were included. Among patients with POD1 PTH levels ≥ 20 pg/ml and POD1 calcium ≥ 2.0 mmol/l, the incidence of symptomatic hypocalcaemia was 1% (3/300), and need for intravenous calcium 0.3% (1/300). For POD1 PTH levels 15-19 pg/ml and POD1 calcium ≥ 2.0 mmol/l, the incidence of symptomatic hypocalcaemia and need for intravenous calcium was 5.4% (3/55). For PTH levels 10-14 pg/ml and calcium ≥ 2.0 mmol/l, the incidence of symptomatic hypocalcaemia and need for intravenous calcium was 11.7% (7/60). The risk of permanent hypoparathyroidism was < 1% for POD1 PTH levels ≥ 15 pg/ml; 5.4% for levels 10-14 pg/ml; and 19.8% for levels < 10 pg/ml.

CONCLUSIONS

POD1 PTH levels ≥ 15 pg/ml along with calcium ≥ 2.0 mmol/l are associated with low risk of symptomatic hypocalcaemia, and represent a safe criterion for discharge of most patients without calcium supplementation. For certain patient groups, a higher threshold of 20 pg/ml could be considered.

Use of the parathyroid hormone assay at H6 post thyroidectomy: an early predictor of hypocalcemia

PURPOSE

Hypocalcemia linked to a diminished circulating intact parathormone (iPTH) is the most common complication after total thyroidectomy. The objective of this study was to evaluate iPTH as a predictor of post-thyroidectomy hypocalcemia.

METHODS

Hundred-and-eight patients who underwent total thyroidectomy were included. Blood samples (iPTH, calcium and albumin) were performed at different times: preoperatively (H₀), after removal of the gland (H_drop), 6 h (H₆) and one day (D₁) after the surgery. Hypocalcemia was defined by total calcium corrected by serum albumin ≤ 2.10 mmol/l. The area under the ROC curve (AUC) was used to determine the best cut-off value and predictability of iPTH for hypocalcemia in terms of absolute value (ng/L), decrease in the slope (ng/L) and decline (%) between two times.

RESULTS

The study included 101 patients. Among them, 39 had hypocalcemia (38.6%). At H₆, an iPTH absolute value less than 14.35 ng/L (Se = 0.706; Sp = 0.917) and a decline from the preoperative time of more than 59.5% (Se = 0.850; Sp = 0.820) were predictive of hypocalcemia. Other absolute values, decrease in the sloop and decline between preoperative and postoperative values were less relevant.

CONCLUSION

The iPTH 6 h after total thyroidectomy is predictive of hypocalcemia. It might be used to identify patients not at risk of hypocalcemia and earlier discharge could be considered.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Late Recovery of Parathyroid Function After Total Thyroidectomy: A Case-Control Study

The clinical characteristics of patients with postoperative hypoparathyroidism who recover parathyroid function more than 12 months after surgery have not been studied. We aimed to evaluate whether the intensity of replacement therapy with calcium and calcitriol is related to the late recovery of parathyroid function. We compared the demographic, surgical, pathological, and analytical features of two groups of patients: cases, i. e., late recovery patients (those who recover parathyroid function>1 year after thyroidectomy, n=40), and controls, i. e., patients with permanent hypoparathyroidism (n=260). Replacement therapy with calcium and calcitriol was evaluated at discharge of surgery, 3-6 months, 12 months, and last visit. No significant differences were found in clinical, surgical, pathological, or analytical characteristics between cases and controls. The proportion of cases who required treatment with calcium plus calcitriol at 12 months was significantly lower than that found in controls (p<0.001). Furthermore, daily calcium and calcitriol doses in controls were significantly higher than those in cases at 3-6 months (p=0.014 and p=0.004, respectively) and at 12 months (p<0.001 and p=0.043, respectively). In several models of logistic regression analysis therapy with calcium and calcitriol at 12 months was negatively related to late recovery of parathyroid function. Although delayed recuperation of parathyroid function after total thyroidectomy is uncommon (13%), follow-up beyond 12 months is necessary in patients with postoperative hypoparathyroidism, especially in those whose needs of treatment with Ca and calcitriol are reducing over time.

What are the real rates of temporary hypoparathyroidism following thyroidectomy? It is a matter of definition: a systematic review

INTRODUCTION

Post-operative hypoparathyroidism is the most encountered complication of thyroid surgery and is classified as temporary or permanent. However, its incidence varies greatly in the literature ranging from 0.5% to 65%. This can be mainly attributed to the different definition of hypoparathyroidism used in each study and especially to the different time cutoff applied to distinguish temporary from permanent hypoparathyroidism.

METHODS

We conducted a systematic literature search in PubMed, Scopus, Cochrane and GoogleScholar databases, as well as grey literature. Ultimately, 45 articles with 23,164 patients in total were included in this review. These articles used either the cutoff of six or twelve post-operative months to distinguish temporary from permanent hypoparathyroidism.

RESULTS

The overall incidence of permanent hypoparathyroidism diagnosed at 6 months post-operatively was 4.11% and 4.08% at 12 months post-operatively. There was no statistically significant difference between the two groups (p = 0.92).

CONCLUSIONS

We suggest that adhering to the current guidelines that recommend diagnosing temporary hypoparathyroidism when recovery is made within 6 months after surgery is important when conducting future research in order to narrow the gap that exists currently in the literature, as well as when deciding to put patients on long-term calcium supplements.

[Postoperative hypocalcemia - the most common complication of endocrine head and neck surgery: acute management]

BACKGROUND

In Germany, 8000 patients are affected by postoperative hypoparathyroidism per year following surgery of the thyroid gland, parathyroidal glands and the larynx. Patients do not only suffer from paresthesia in the acute phase of this complication, but are also adversely affected by the fear of loss of control following episodes of tetany even years after the first episode.

OBJECTIVES

Discussion of a diagnostic pathway and presentation of a management pathway for postoperative hypocalcemia.

METHODS

Narrative review, analysis and discussion of current literature and expert recommendations.

RESULTS

Early determination of calcium and parathyroid hormone allows timely diagnosis and treatment of postoperative hypoparathyroidism. Active vitamin D is pivotal for the resorption of calcium. Only the combined treatment with active vitamin D and calcium can mitigate or prevent the postoperative drop of calcium levels.

CONCLUSIONS

A standard operating procedure (SOP) for postoperative hypoparathyroidism should be implemented in every surgical department. An SOP for diagnosis and treatment of postoperative hypoparathyroidism is proposed for institutional individualization and implementation.

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.

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

OBJECTIVE

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

DESIGN

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

MEASUREMENTS

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

RESULTS

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

CONCLUSION

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