Postoperative Hypoparathyroidism: Prognosis, Prevention, and Treatment (Review)

Personalized parathyroid hormone therapy for hypoparathyroidism: Insights from pharmacokinetic-pharmacodynamic modelling

AIMS

A 42-year-old male developed chronic primary hypoparathyroidism after total thyroidectomy. Conventional therapy led to recurrent nephrolithiasis and therefore rhPTH(1-84) (parathyroid hormone [PTH]) treatment was considered. According to the dosing guideline for PTH, calcium plasma levels are adequately controlled with once-daily administration. However, the effect on urinary calcium excretion is only transient and hence does not lower the risk of nephrolithiasis. This raises the question of whether multiple-daily or continuous administration of PTH is more effective in lowering urinary calcium excretion. We aimed to construct a pharmacokinetic-pharmacodynamic (PKPD) model to answer this question.

METHODS

A single patient was treated with intermittent PTH followed by off-label continuous infusion of PTH. PTH was measured in plasma, calcium and phosphate in plasma and urine. A one-compartment PKPD model for PTH was developed with Edsim++. The effect of PTH was described by the relative clearance of calcium and phosphate.

RESULTS

The PKPD model for PTH showed visually a marked effect on phosphate clearance, but less on calcium clearance. During the study, the patient also received medication that influenced calcium homeostasis but to a lesser extent phosphate homeostasis. Therefore, phosphate was chosen as the effect parameter, resulting in an EC50 of 6.3 pmol/L PTH.

CONCLUSIONS

The PKPD model for PTH was completed with the unique data of a single patient who received PTH according to various dosing regimens, including continuous infusion. Continuous administration of PTH is favoured because it permanently increases the phosphate clearance and therefore needs to be further investigated.

Meta-Analysis of Image-Based Versus Probe-Based Parathyroid Near-Infrared Autofluorescence

Proper identification of parathyroid tissue is a critical component in surgery involving the thyroid and parathyroid gland (PG). In recent years, near infrared autofluorescence (NIRAF) has been investigated as a non-invasive strategy to detect PG in parathyroidectomy and in PG preservation in thyroidectomy. There are currently two FDA approved NIRAF modalities, image-based and probe-based. The aim of this meta-analysis is to evaluate the efficacy of these two NIRAF modalities. PubMed, Scopus, and MEDLINE were utilized, with 238 studies analyzed via independent, blinded review. Studies from January 2000 to February 2023, Boolean phrase "parathyroid autofluorescence", written in English, and included results found within the body of the article were the inclusion criteria used. Conference abstracts, reviews, case reports, commentary, discussion and letter, non-English, animal studies, in vitro studies, contrast enhanced fluorescence, and NIRAF with use of indocyanine green, were the exclusion criteria used. Five studies were enrolled based on inclusion and exclusion criteria. The estimated overall accuracy of image-based methods is 0.96 (95% CI of (0.87, 0.99)), while the estimated overall accuracy of probe-based methods is 0.93 (95% CI of (0.92, 0.94)). With p=0.36, there is insufficient evidence to indicate a significant difference in overall accuracy, sensitivity and specificity between image-based methods and probe-based methods. Both imaging and probe-based detection modalities offer effective, noninvasive means for identifying parathyroid glands intraoperatively. Further studies comparing the efficacy of these two modalities are needed to further differentiate their clinical performance.

Thyroidectomy and Its Complications: A Comprehensive Analysis

Background/Objectives: This study aims to assess the rate of complications in patients who underwent thyroid surgery and were monitored post-operatively to explore potential correlations between various parameters that may aid in clinical decision making. Methods: An observational retrospective study was conducted on patients who underwent thyroid surgery and were followed up in our Endocrinology Unit. Patients were selected based on strict criteria. The following data were collected: sex; age; type of thyroid disease; pre-operative symptoms due to thyroid pathology; surgical procedures; post-operative complications; histopathological diagnosis; and post-operative blood levels of TSH, PTH, vitamin D, and calcium. Results: Among 340 patients, 25.29% had benign thyroid disease. Total thyroidectomy was performed in 89.4% of cases. Recurrent laryngeal nerve injury was found in 32 patients. Hypocalcemia occurred in 14 patients within 24 h post-operatively. Histopathological examination identified incidental parathyroid tissue in 5.88% of thyroidectomy specimens. Post-operative hypoparathyroidism was observed in 26 patients, and vitamin D deficiency in 68 patients. Conclusions: The study demonstrated that thyroid surgery is quite a safe procedure; however, complications may occur. A statistically significant correlation was found between the type of surgery and the risk of vocal fold palsy, without correlation with the type of thyroid disease. A thorough pre-operative evaluation by a multidisciplinary team may help reduce the risk of post-operative complications. Despite the extensive knowledge of thyroid surgery, small refinements may further improve surgical outcomes.

Initial Experience With Ultra-High-Definition 3D Exoscope in Thyroid and Parathyroid Surgery

BACKGROUND

Operation with a 3D exoscope has recently been introduced in clinical practice. The exoscope consists of two cameras placed in front of the operative field. Images are shown on a large 3D screen with high resolution. The system can be used to enhance precise dissection and provides new possibilities for improved ergonomics, fluorescence, and other optical-guided modalities.

METHODS

Initial experience with the ultra-high-definition (4K) 3D exoscope in thyroid and parathyroid operations. The exoscope (OrbEyeTM) was mounted on a holding system (Olympus).

RESULTS

We used the exoscope in parathyroidectomy (N = 6) and thyroidectomy (N = 6). Immediate advantages and disadvantages were discussed and recorded. The learning curve for use of the exoscope may be shorter for surgeons with training in endoscopic or robotic procedures. There may be improved ergonomics compared with normal open-neck operations. Further, the optical guided operations can be used with fluorescence and have potential for different on-lay techniques in the future. The 4 K 3D image quality is state-of-art and is highly appreciated during fine surgical dissection and eliminates the need for loupes.

CONCLUSION

In several ways, using the ORBEYE™ in thyroid and parathyroid surgery provides the surgical team with a new and enhanced experience. This includes improved possibility for teaching, surgical ergonomics, and a 4K 3D camera with a powerful magnification system. However, it is not clear if utilization of these features would improve surgical outcomes. Furthermore, the ORBEYE™ lacks incorporation of parathyroid autofluorescence, and the current costs for the system do not facilitate general access to exoscope assisted operations.

Risk Factors for Transient and Permanent Hypoparathyroidism Following Thyroidectomy: A Comprehensive Review

Hypoparathyroidism is a common complication following thyroidectomy, resulting in significant disturbances in calcium homeostasis due to low parathyroid hormone (PTH) levels. This comprehensive review examines the risk factors associated with transient and permanent hypoparathyroidism post-thyroidectomy, emphasizing surgical, patient-related, and perioperative factors. Transient hypoparathyroidism, characterized by temporary hypocalcemia resolving within weeks to months, is often managed with short-term calcium and vitamin D supplementation. In contrast, permanent hypoparathyroidism persists beyond six months post-surgery, necessitating lifelong supplementation and potentially PTH replacement therapy. The review delves into the anatomy and physiology of the parathyroid glands, mechanisms leading to hypoparathyroidism, and incidence rates. Surgical factors such as the extent of thyroidectomy, surgeon expertise, and intraoperative parathyroid gland preservation are critical in determining the risk of hypoparathyroidism. Patient factors, including age, sex, pre-existing conditions, and perioperative management, influence outcomes. Diagnostic and monitoring strategies, along with management protocols for both transient and permanent hypoparathyroidism, are discussed. Prevention strategies, emerging research, future surgical techniques, and intraoperative monitoring directions are highlighted to improve clinical outcomes. This review aims to enhance understanding, inform surgical practices, and optimize postoperative care to minimize the incidence and impact of hypoparathyroidism in thyroidectomy patients.

Iatrogenic Hypoparathyroidism Development After Thyroidectomy: A Retrospective Cohort Study

BACKGROUND

Iatrogenic hypoparathyroidism is a common cause of postthyroidectomy hypocalcaemia. It has varying incidence rates after neck surgery in Saudi Arabia, ranging from 0.07% to 65.30%. Hypoparathyroidism can manifest with a spectrum of symptoms, ranging from mild to severe and life-threatening. This study aimed to assess the rate and predictors of iatrogenic hypoparathyroidism after thyroid surgery and its natural course.

METHODS

This retrospective cohort study used a data collection form to extract patient information from the electronic healthcare system (Best-Care) for patients treated from 2017 to 2022. Patients' demographics, surgical specifics and biochemical profiles were recorded for subsequent analysis.

RESULTS

Among the 343 patients who underwent thyroidectomy, 130 (37.9%) developed hypoparathyroidism, primarily within the first day after surgery. Calcium or vitamin D supplementation before surgery did not significantly influence hypoparathyroidism development. Notably, extensive combined lymph node dissection was significantly associated with postoperative hypoparathyroidism development (p = 0.0004). More patients who underwent central and lateral lymph node dissection (n = 19, 79.17%) developed hypoparathyroidism than patients who underwent central (n = 18, 40.91%) or lateral (n = 8, 38.10%) dissection alone. Permanent hypoparathyroidism was observed in 40 patients (11.66%).

CONCLUSION

This study revealed a high incidence of iatrogenic hypoparathyroidism and high rates of permanent hypoparathyroidism. Further research is warranted to better comprehend the risk factors and optimise management strategies for iatrogenic hypoparathyroidism. Overall, our findings emphasise the need for vigilant monitoring and effective management of patients undergoing thyroidectomy and the significance of postoperative replacement therapies.

Parathyroid preservation in total endoscopic thyroid surgeries via the mammary areolas approach: Real-world data from a single center

BACKGROUND

Preserving parathyroid glands in situ is crucial to avoid surgical hypoparathyroidism, but it is also one of the greatest challenges during thyroid surgery. Magnified endoscopic imaging has been proposed as a way to improve parathyroid preservation.

METHODS

2,603 consecutive patients who underwent thyroid surgery at the First People's Hospital of Zunyi from January 2018 to July 2022 were screened. 1,355 patients were eligible, including 965 endoscopic and 390 open cases. Parathyroid hormone (PTH) loss levels and severe parathyroid injury rates were compared between endoscopic and open cases. Meanwhile, factors that contribute to parathyroid injuries were assessed, including surgical extent, tumor size, carbon nanoparticle guidance, and surgical proficiency.

RESULTS

PTH loss levels were similar between endoscopic and open cases (P = 0.440). The incidence of severe parathyroid injuries was also comparable (7.8% for endoscopic vs. 6.9% for open, P = 0.592). The endoscopic group had higher rates of autologous parathyroid transplantation (39.5% vs. 24.4%, P = 0.000), while accidental parathyroidectomy rates were similar (11.4% vs. 10.8%, P = 0.739). Among patients who received the same extent of thyroid surgeries, no significant difference was found in PTH loss levels and severe parathyroid injury rates, except for a higher risk of severe parathyroid injuries in endoscopic bilateral thyroidectomy (18.52% vs. 11.52%, P = 0.033).

CONCLUSIONS

Despite the magnified endoscopic imaging facilitating the identification of parathyroid tissues, endoscopic approaches are not superior to open ones for the in-situ preservation of parathyroid glands. For a bilateral thyroidectomy, open approaches are safer for parathyroid preservation.

Neuroendocrine Parathyroid Tumors: Quality of Life in Patients with Primary Hyperparathyroidism

Tumors of the parathyroid glands, when associated with PTH (parathyroid hormone) excess, display a large area of complications; in addition to the classical clinical picture of primary hyperparathyroidism (PHP), a complex panel of other symptoms/signs can be identified, including memory and cognitive impairment, chronic asthenia/fatigue, reduced muscle functionality, depressive mood, non-specific bone pain, and loss of sleep quality. The perception of quality of life (QoL) can be supplementarily enhanced by their progressive onset, which makes many patients not be fully aware of them. Their improvement was reported very early after parathyroidectomy (PTx), yet the level of statistical evidence does not qualify these non-classical elements as standalone indications for PTx. Our objective is introducing an up-to-date on QoL scores with regards to the patients diagnosed with PHP, particularly taking into consideration PHP management from baseline to post-operatory outcome, including in cases with multiple endocrine neoplasia. This is a narrative review of literature. We revised full-length papers published in English through PubMed research conducted between January 2018 and May 2023 by using the key words "quality of life" and "primary hyperparathyroidism". We particularly looked at data on self-reported QoL (through questionnaires). We excluded from the search the studies focused on non-PTH related hypercalcemia, secondary, and/or renal/tertiary hyperparathyroidism, and vitamin D supplementation. Overall, we identified 76 papers and selected for the final analysis 16 original studies on QoL and PHP (a total of 1327 subjects diagnosed with syndromic and non-syndromic PHP). The studies with the largest number of individuals were of 92, 104, 110, 134, 159, as well as 191. A few cohorts (n = 5) were of small size (between 20 and 40 patients in each of them). Concerning the study design, except for 2 papers, all the mentioned studies provided longitudinal information, particularly the timeframe from baseline (before PTx) and after surgery. The post-operatory follow-up was of 3-6 months, but mostly between 1 and 3 years (maximum a decade of surveillance). The age of the patients varies between medians of 56, 62, 64, and 68 years. Most frequent questionnaires were SF-36, PHPQoL, and PAS. Despite not being unanimously similar, an overall reduced score of QoL in patients with PHP versus controls was registered, as well as general improvement following PTx. Variations of QoL results might have a multifactorial background from different comorbidities, studied populations, technical aspects of collecting the data, etc. QoL scores in PHP represents a complex heterogeneous picture, from their correlation with clinical features and lab assays (e.g., the level of serum calcium), the associated comorbidities (such as multiple endocrine neoplasia syndromes), up to the assessment of the QoL improvement after parathyroidectomy (PTx). While current studies do not unanimously agree on each QoL domain, the assessment of QoL might represent a supplementary argument to consider when deciding for PTx, especially in asymptomatic cases and in patients who do not fit into well-known categories of surgery candidates, according to current guidelines, thus assessing QoL in PHP is part of a current research gap. QoL evaluation in PHP remains an open issue, towards which awareness should be cultivated by both endocrinologists and surgeons. The introduction of a routine evaluation of the QoL scores in patients, as well as the selection of the most appropriate questionnaire(s), represents an open chapter thus awareness in mandatory.

Autologous parathyroid gland left brachioradialis transplantation: A single-center study and long-term follow-up

Parathyroid gland transplantation into the sternocleidomastoid muscle is effective, but it is not possible to confirm transplant survival with this method. In this study, we evaluated parathyroid autotransplantation into the brachioradialis muscle and its survival rate.

OBJECTIVES

To evaluate autologous parathyroid gland left forearm brachioradial muscle transplantation and its survival rate.

SUMMARY BACKGROUND DATA

The most commonly used transplantation site is the sternocleidomastoid muscle, but transplant survival cannot be confirmed using this method. Autologous parathyroid gland left forearm brachioradial muscle transplantation solves this problem, and we evaluate the transplant survival using this method.

METHODS

We followed-up patients who underwent thyroidectomy and autologous parathyroid left forearm brachioradial muscle transplantation in our center from September 2013 to January 2018. The last follow-up date was January 2021; all enrolled patients underwent at least 3 years of follow-up. We calculated the transplant survival rate at several time points.

RESULTS

We evaluated 238 transplanted cases, for which the long-term survival rate was 85.7% (204/238), and the short-term survival rate was 86.1% (205/238). Sixty-five cases had two parathyroid glands transplanted into the left forearm brachioradialis muscle. The long-term survival rate was 92.3% (60/65), and the short-term survival rate was 95.4% (62/65).

CONCLUSIONS

Autologous parathyroid gland left brachioradialis transplantation is a reliable, measurable method with good survival rate, and we recommend this method for consideration for transplanting parathyroid glands in thyroidectomy.

Establishing a predictive model of hypoparathyroidism after total thyroidectomy and central lymph node dissection for postoperative calcium supplementation selectively

Background

The core goal of this article is to find some meaningful risk factors that can affect the postoperative hypoparathyroidism of thyroid cancer, create an effective prediction model on this basis, and use it to selectively implement routine prophylactic calcium supplementation for patients after thyroid carcinoma surgery.

Methods

The clinicopathological characteristics of patients with papillary thyroid carcinoma (PTC) who underwent conventional bilateral total thyroidectomy (TT) + bilateral central lymph node dissection from January 2020 to August 2021 in the Affiliated Hospital of Nantong University were retrospectively analyzed. Firstly, this study analyzed the relationship between postoperative hypocalcemia and hypoparathyroidism. Then, we included many potential risk factors such as gender, age, body mass index (BMI), lateral lymph node dissection (LLND) and so on and also performed univariate and multivariate analysis of the independent risk factors for postoperative hypoparathyroidism in patients, and established a predictive scoring model.

Results

Among the 401 patients with PTC, 50.1% developed postoperative hypoparathyroidism. There was significant difference in serum calcium concentration between normal parathyroid group and hypoparathyroidism group after thyroid carcinoma surgery. BMI <24 kg/m², lateral lymph node dissection, multifocality, and extrathyroidal extension (ETE) were all identified as independent risk factors for postoperative hypoparathyroidism. Based on these independent risk factors, a nine-point risk scoring model was created to firstly assess the postoperative parathyroid function status of patients and then to determine whether routine prophylactic calcium supplementation is needed. Importantly, the area under the curve (AUC) of the risk scoring model is equal to 0.979.

Conclusions

At present, prophylactic calcium supplementation after thyroid carcinoma surgery is a controversial postoperative treatment. It should be selectively implemented for high-risk patients with hypoparathyroidism after surgery. Routine prophylactic calcium supplementation is recommended for PTC patients with a score greater than or equal to 5, although there are no clinical symptoms of postoperative hypocalcemia caused by hypoparathyroidism. However, prophylactic calcium supplementation is not recommended for patients with PTC with a score of less than 5; if the patient develops hypocalcemia at the later stage, therapeutic calcium supplementation can then be implemented.