Elevated parathyroid hormone levels after successful parathyroidectomy for primary hyperparathyroidism: a clinical review

F18-Choline PET/CT or MIBI SPECT/CT in the Surgical Management of Primary Hyperparathyroidism: A Diagnostic Randomized Clinical Trial

Importance

Whether F18-choline (FCH) positron emission tomographic (PET)/computed tomographic (CT) scan can replace Tc99m-sestaMIBI (MIBI) single-photon emission (SPE)CT/CT as a first-line imaging technique for preoperative localization of parathyroid adenomas (PTA) in patients with primary hyperparathyroidism (PHPT) is unclear.

Objective

To compare first-line FCH PET/CT vs MIBI SPECT/CT for optimal care in patients with PHPT needing parathyroidectomy and to compare the proportions of patients in whom the first-line imaging method resulted in successful minimally invasive parathyroidectomy (MIP) and normalization of calcemia 1 month after surgery.

Design, Setting, and Participants

A French multicenter randomized open diagnostic intervention phase 3 trial was conducted. Patients were enrolled from November 2019 to May 2022 and participated up to 6 months after surgery. The study included adults with PHPT and an indication for surgical treatment. Patients with previous parathyroid surgery or multiple endocrine neoplasia type 1 (MEN1) were ineligible.

Interventions

Patients were assigned in a 1:1 ratio to receive first-line FCH PET/CT (FCH1) or MIBI SPECT/CT (MIBI1). In the event of negative or inconclusive first-line imaging, they received second-line FCH PET/CT (FCH2) after MIBI1 or MIBI SPECT/CT (MIBI2) after FCH1. All patients underwent surgery under general anesthesia within 12 weeks following the last imaging. Clinical and biologic (serum calcemia and parathyroid hormone levels) assessments were performed 1 and 6 months after surgery.

Main Outcomes and Measures

The primary outcome was a true-positive first-line imaging-guided MIP combined with uncorrected serum calcium levels of 2.55 mmol/l or less 1 month after surgery, corresponding to the local upper limit of normality.

Results

Overall, 57 patients received FCH1 (n = 29) or MIBI1 (n = 28). The mean (SD) age of patients was 62.8 (12.5) years with 15 male (26%) and 42 female (74%) patients. Baseline patient characteristics were similar between groups. Normocalcemia at 1 month after positive first-line imaging-guided MIP was observed in 23 of 27 patients (85%) in the FCH1 group and 14 of 25 patients (56%) in the MIBI1 group. Sensitivity was 82% (95% CI, 62%-93%) and 63% (95% CI, 42%-80%) for FCH1 and MIBI1, respectively. Follow-up at 6 months with biochemical measures was available in 43 patients, confirming that all patients with normocalcemia at 1 month after surgery still had it at 6 months. No adverse events related to imaging and 4 adverse events related to surgery were reported.

Conclusions

This randomized clinical trial found that first-line FCH PET/CT is a suitable and safe replacement for MIBI SPECT/CT. FCH PET/CT leads more patients with PHPT to correct imaging-guided MIP and normocalcemia than MIBI SPECT/CT thanks to its superior sensitivity.

Trial Registration

ClinicalTrials.gov Identifier: NCT04040946.

Long-Term Calcium Monitoring Post Parathyroidectomy for Primary Hyperparathyroidism

BACKGROUND

 Cure rates following parathyroidectomy for primary hyperparathyroidism are excellent, with well-documented low short-term recurrence rates of hypercalcaemia. Rates of long-term recurrence have been investigated to a lesser extent, but recent studies have reported higher than anticipated rates. This study sought to evaluate recurrence rates at more than four years post seemingly corrective surgery and depending on the findings, propose whether recommendations of annual calcium monitoring post-parathyroidectomy are appropriate based on the limited data available at the time of formulating guidelines.

METHODS

Fifty-two sequential parathyroidectomies for primary hyperparathyroidism from 2014-2016 from a single unit were retrospectively followed up with serum calcium levels. A hospital computer system was used to collect data on pre-operative, immediate post-operative and most recent follow-up calcium levels. Patients were excluded if there was no minimum of 48 months between the operation date and most recent calcium. Recurrence was defined as hypercalcaemia more than six months after eucalcaemia post-parathyroidectomy.

RESULTS

Of the 52 cases analysed, two were lost to long-term follow-up, two patients died during the follow-up period while 10 did not meet the inclusion criteria of at least 48 months follow-up. This resulted in a cohort of 38 patients (mean age 66.4 years, 78.9% female). The median follow-up of 73.17 months (range 48.77-95.47 months) demonstrated a hypercalcaemia recurrence of 5.26% (2/38 patients). These cases were due to misdiagnosed parathyroid hyperplasia as opposed to suspected adenoma. Therefore, the long-term cure rate was 94.74% (36/38 patients).

CONCLUSION

These findings support the high cure rates and low recurrence rates of the numerous short-term studies already performed despite a longer follow-up period. This is in contrast to recent series which have documented a higher recurrence in the long-term. This study would, therefore, suggests recommendations of annual calcium monitoring are excessive and that less frequent calcium monitoring is necessary in the first few years post-operation. However, the 5.26% recurrence rate in this study is not insignificant and follow-up is still paramount. Therefore, following the initial post-operative assessment, the authors propose a follow-up at the five-year mark and an annual continuation from this point forward due to the evidenced delayed recurrence of hypercalcaemia.

Normocalcemic hyperparathyroidism after successful parathyroidectomy for single parathyroid adenoma: Prevalence, etiological factors, predictive markers, treatment and evolution

BACKGROUND AND OBJECTIVE

Postparathyroidectomy normocalcemic hyperparathyroidism (PPNCHPPT) is a frequent situation for which we have no information in our country. The objective is to know our prevalence of PPNCHPPT, the associated etiological factors, the predictive markers, the treatment administered and the evolution.

PATIENTS AND METHOD

Retrospective observational cross-sectional study on 42 patients. Twelve patients with PPNCHPPT and 30 without PPNCHPPT are compared.

RESULTS

HPPTNCPP prevalence: 28.6%. Etiological factors: vitamin D deficiency: 75%; bone remineralization: 16.7%; renal failure: 16.7%; hypercalciruria: 8.3%. No change in the set point of calcium-mediated parathormone (PTH) secretion was observed, but an increase in the preoperative PTH/albumin-corrected calcium (ACC) ratio was observed. Predictive markers: PTH/ACC ratio (AUC 0.947; sensitivity 100%, specificity 78.9%) and PTH (AUC 0.914; sensitivity 100%, specificity 73.7%) one week postparathyroidectomy.

EVOLUTION

follow-up 30 ± 16.3 months: 50% normalized PTH and 8.3% had recurrence of hyperparathyroidism. Patients with PPNCHPPT less frequently received preoperative treatment with bisphosphonates and postoperative treatment with calcium salts.

CONCLUSIONS

This is the first study in our country that demonstrates a mean prevalence of PPNCHPPT, mainly related to a vitamin D deficiency and a probable resistance to the action of PTH, which can be predicted by the PTH/ACC ratio and PTH a week post-intervention and often evolves normalizing the PTH. We disagree with the etiological effect of hypercalciuria and the change in the PTH/calcemia regulation set point, and we acknowledge the scant treatment administered with calcium salts in the postoperative period.

The Eucalcemic Patient With Elevated Parathyroid Hormone Levels

Primary hyperparathyroidism (PHPT) is classically characterized by hypercalcemia with elevated or inappropriately normal parathyroid hormone (PTH) levels. Elevated PTH levels in the presence of normal calcium levels are not infrequently found during the evaluation of metabolic bone disorders or kidney stone disease. This can be caused by secondary hyperparathyroidism (SHPT) or normocalcemic primary hyperparathyroidism (NPHPT). NPHPT is due to autonomous parathyroid function whereas SHPT is caused by a physiologic stimulation to PTH secretion. Many medical conditions and medications can contribute to SHPT, and differentiation between SHPT and NPHPT may be difficult. Cases are presented to illustrate examples. In this paper, we review the distinction between SHPT and NPHPT as well as end organ effects of NPHPT and outcomes of surgery in NPHPT. We suggest that the diagnosis of NPHPT be made only after careful exclusion of causes of SHPT and consideration of medications that can increase PTH secretion. Further, we advise a conservative approach to surgery in NPHPT.

Risk factors for surgical failure in patients undergoing surgery for primary hyperparathyroidism

INTRODUCTION

Primary hyperparathyroidism is the third most common endocrine disease. The aim of our study was to determine long-term outcomes and risk factors for persistence in patients undergoing parathyroidectomy for primary hyperparathyroidism.

METHODS

Retrospective study including patients undergoing parathyroidectomy between 2009-2019. Cure was defined as reestablishment of normal calcium homeostasis lasting a minimum of 6 months. Persistence was defined by ongoing hypercalcemia more than 6 months after surgery. Recurrent PHTP was defined by recurrence of hypercalcemia after a normocalcemic interval at more than 6 months after surgery. A more detailed analysis was performed on patients with normocalcemia and persistently elevated PTH levels after surgery. Variables independently related to persistence were analyzed by multivariate analysis.

RESULTS

We included 212 patients. Mean age was 59 years and 83% were women. Cure was observed in 204 patients (96.2%), persistence in 8 (3.8%) and recurrence in 3 (1.4%). Four patients (1.9%) presented normocalcemia and persistently elevated PTH after surgery. All presented parathyroid pathology (2 adenomas and 2 hyperplasia). In follow-up we observed that adenoma subgroup presented one patient with CKD and one with vitamin D deficiency while in the hyperplasia subgroup two patients presented CKD. Persistence was independently associated with hyperplasia (Odds ratio = 12.6, IC95% = 1.28-124, p = 0.030) and normal parathyroid tissue (Odds ratio = 188, IC95% = 9.33-379, p = 0.001) on histopathological report.

CONCLUSION

Primary hyperparathyroidism is a safe procedure in terms of morbidity and long-term outcomes. Hyperplasia and normal parathyroid tissue on histopathological report are risk factors for persistence. An interdisciplinary diagnostic and therapeutic approach is required to prevent persistence.

Evolution of intra-operative parathyroid hormone and its application in parathyroid surgery

The history and evolution of parathyroid hormone is a true testament to inter-disciplinary collaboration among anatomists, biochemists and surgeons. The parathyroid glands were the last endocrine glands to be discovered in the mid-1800s. Over the next century, progress in the evaluation of primary hyperparathyroidism, the identification of parathyroid hormone (PTH) and its application for use in the field of parathyroid surgery have led to a significant improvement in surgical cure rates, accompanied by a shift toward minimally invasive surgical options. This chapter provides a historical lens through which we can view these relatively recent advancements, as well as the current role of parathyroid hormone, both with regards to pre-operative localization and intra-operative detection of abnormal glands. Furthermore, we discuss the importance of parathyroid hormone in the management of complex multiglandular disease and reoperative cases, as well as the significance of persistently elevated PTH levels post-parathyroidectomy.

Analysis of the cause and management of persistent laboratory abnormalities occurring after the surgical treatment of primary hyperparathyroidism

Purpose

The surgical success rate for primary hyperparathyroidism (PHPT) is currently 95%–98%. However, 3%–24% of patients show persistently elevated (Pe) parathyroid hormone (PTH) levels after parathyroidectomy (PTX). This single-center retrospective study aimed to compare the outcomes of patients with normal PTH and PePTH levels after successful PTX and to identify the factors associated with PePTH.

Methods

The normal group, defined as patients with normal serum calcium and PTH levels immediately after PTX, was compared with the PePTH group (patients with normal or low serum calcium and increased serum PTH levels up to 6 months postoperatively) to determine the causes of disease in the PePTH group.

Results

There were no significant differences in age, sex, or preoperative estimated glomerular filtration rate between the normal PTH group (333 of 364, 91.5%) and the PePTH group (31 of 364, 8.5%). However, there were significant differences in preoperative 25-hydroxyvitamin D (17.9 and 11.8 ng/mL, respectively; P = 0.003) and PTH levels (125.5 and 212.4 pg/mL, respectively; P < 0.001) between the 2 groups. Among the 31 cases of the PePTH group, 18 were attributed to vitamin D deficiency.

Conclusion

Preoperative vitamin D deficiency is a predictive factor for PePTH. Therefore, preoperative administration of vitamin D supplements may reduce the probability of postoperative disease persistence. Patients with temporary laboratory abnormalities within 6 months after successful PTX should be monitored, and appropriate vitamin D and calcium supplementation may reduce the effort and cost of various examinations or reoperations.

High parathyroid hormone levels after parathyroidectomy for parathyroid adenoma are not related to the cellularity of the remaining glands

BACKGROUND

Patients with primary hyperparathyroidism (PHPT) treated surgically occasionally have normalized calcium, but persistently high parathyroid hormone (PTH). We hypothesized that a possible explanation for this phenomenon is an underlying hyperplasia rather than adenoma.

METHODS

Retrospective cohort of patients who underwent parathyroidectomy for PHPT with biopsy of a normal-appearing parathyroid gland were included. Cellularity level of each biopsy and of the adenoma's rim was determined.

RESULTS

Forty-seven patients were included. Of them, 19 (40%) had postoperative normocalcemia but elevated PTH. There was no correlation between cellularity either in the rim or of the normal-appearing parathyroid gland and postoperative PTH. The postoperative high PTH group had higher preoperative PTH (P = 0.001) and larger adenomas (P = 0.025).

CONCLUSIONS

High PTH levels after successful parathyroidectomy in patients with primary hyperparathyroidism do not appear to result from underlying hyperplasia. A possible alternative explanation is that these patients have a higher preoperative burden of disease.

Risk factors for surgical failure in patients undergoing surgery for primary hyperparathyroidism

INTRODUCTION

Primary hyperparathyroidism is the third most common endocrine disease. The aim of our study was to determine long-term outcomes and risk factors for persistence in patients undergoing parathyroidectomy for primary hyperparathyroidism.

METHODS

Retrospective study including patients undergoing parathyroidectomy between 2009- 2019. Cure was defined as reestablishment of normal calcium homeostasis lasting a minimum of 6 months. Persistence was defined by ongoing hypercalcemia more than 6 months after surgery. Recurrent PHTP was defined by recurrence of hypercalcemia after a normocalcemic interval at more than 6 months after surgery. A more detailed analysis was performed on patients with normocalcemia and persistently elevated PTH levels after surgery. Variables independently related to persistence were analyzed by multivariate analysis.

RESULTS

We included 212 patients. Mean age was 59 years and 83% were women. Cure was observed in 204 patients (96.2%), persistence in 8 (3.8%) and recurrence in 3 (1.4%). Four patients (1.9%) presented normocalcemia and persistently elevated PTH after surgery. All presented parathyroid pathology (2 adenomas and 2 hyperplasia). In follow-up we observed that adenoma subgroup presented one patient with CKD and one with vitamin D deficiency while in the hyperplasia subgroup two patients presented CKD. Persistence was independently associated with hyperplasia (Odds ratio=12.6, IC95%=1.28-124, p=0.030) and normal parathyroid tissue (Odds ratio=188, IC95%=9.33-379, p=0.001) on histopathological report. CONCLUSIóN: Primary hyperparathyroidism is a safe procedure in terms of morbidity and long-term outcomes. Hyperplasia and normal parathyroid tissue on histopathological report are risk factors for persistence. An interdisciplinary diagnostic and therapeutic approach is required to prevent persistence.

[Normocalcemic with elevated post-operative parathormone in primary hyperpara-thyroidism: 9 case reports and literature review]

OBJECTIVE

To summarize and analyze the clinical characteristics of primary hyperpara-thyroidism (PHPT) with normocalcemic parathormone elevation (NPE) after surgical treatment, so as to improve the therapeutic ability and standardized post-operative follow-up of PHPT patients.

METHODS

Nine patients who were diagnosed with PHPT in the Department of Endocrinology of China-Japan Friendship Hospital from August 2017 to November 2019 were selected as the subjects. They all developed NPE within 6 months after surgical treatment. The clinical features and outcomes were collected and analyzed retrospectively, in addition, the related literature was reviewed.

RESULTS

Clinical features: among the 9 patients, 6 were middle-aged and elderly females and 3 were male. The main clinical manifestations were bone pain, kidney stones, nausea and fatigue except for one case of asymptomatic PHPT. Pre-operative examination showed high serum calcium [(3.33±0.48) mmol/L], low serum phosphorus [0.76 (0.74, 0.78) mmol/L], high 24-hour urinary calcium [8.1(7.8, 12.0) mmol/24 h], obviously elevated intact PTH [(546.1±257.7) ng/L], vitamin D deficiency [25-hydroxyvitamin D₃ (21.0±5.7) nmol/L]. Serum levels of bone alkaline phosphatase [7 patients 41.3(38.6, 68.4) μg/L, 2 patients >90 μg/L] and N-terminal midcourse osteocalcin (>71.4 μg/L) were significantly elevated. The estimated glomerular filtration rate decreased in 2 patients. Imaging examination: 7 patients had osteoporosis. Renal calculi were found in 3 patients by renal ultrasound. Imaging examination of parathyroid glands found definite lesions in all the patients, including 2 cases of multiple lesions and 7 cases of single lesions.

TREATMENT AND OUTCOME

two patients underwent parathyroidectomy, while other patients were treated with microwave thermal ablation. PTH increased 1 month after therapy [(255.0±101.4) ng/L], and no recurrent lesions were found by parathyroid ultrasound. After combined treatment with cal-cium and vitamin D for six months, PTH decreased significantly and the level of serum calcium remained normal at anytime during the follow-up period.

CONCLUSION

The occurrence of postoperative NPE may be related to the higher pre-operative PTH, vitamin D deficiency and lower creatinine clearance. However, NPE may not predict recurrent hyperthyroidism or incomplete parathyroidectomy. Adequate calcium and vitamin D supplementation after surgery seems to be beneficial for patients with NPE. Post-operative follow-up of PHPT patients should be standardized to prevent and treat post-operative NPE.

How should we define cure after parathyroidectomy for normocalcemic primary hyperparathyroidism? A retrospective cohort study

Cure after surgery for normocalcemic primary hyperparathyroidism (NHPT) is defined as parathyroid hormone (PTH) normalization. However, an increase of PTH is frequently observed in cured patients with hypercalcemic primary hyperparathyroidism (HHPT). Therefore, this criterion must be redefined. A single-center retrospective study was performed including all patients who underwent surgery for Primary Hyperparathyroidism from 2013 to 2019. Cure rates of different types of hyperparathyroidism were analyzed. PTH reduction was studied as a possible criterion to define cure in patients with NHPT. One-hundred and eighty-six patients were included: 173 with HHPT and 13 with NHPT. After a mean follow-up of 33.4 months, 174 (93.6%) patients were considered cured. Cure was more frequent in the group of patients with HHPT (97.1% vs. 46.2%, p < 0.001). In the multivariate analysis, surgical failure was associated with NHPT and multiglandular disease. Forty-nine (30.1%) cured patients with HHPT had an increased PTH during the follow-up. When decline of PTH levels was studied in patients with HHPT to define cure, the area under curve was 0.92. A cut-off value of 40% in PTH reduction achieved a sensitivity and specificity of 83.4% and 80.0%. If cure was defined as a 40% reduction of PTH, cure rate in the group of patients with NHPT would increase to 69.2%. Patients with NHPT had a lower cure rate than patients with HHPT. A significant number of cured patients with HHPT had an increased PTH during follow-up. A 40% reduction in PTH levels is proposed as an alternative definition for cure in patients with NHPT.

Ectopic Parathyroid Adenoma in an 11-Year-Old Girl: Case Report and Literature Review

Objective

Primary hyperparathyroidism secondary to an ectopic parathyroid adenoma is rare among children and adolescents.

Methods

We describe the case of an 11-year-old girl with incidentally diagnosed primary hyperparathyroidism secondary to an intrathymic parathyroid adenoma and performed a review of the related literature.

Results

^99mTechnetium sestamibi single-photon emission computerized tomography/computed tomography and 4-dimensional computed tomography confirmed the ectopic location of the adenoma. The patient underwent thoracoscopic thymectomy and remained normocalcemic with elevated parathyroid hormone showing a downward trend. Parathyroid hormone normalized 18 months after successful parathyroidectomy.

Conclusion

We review the case of a rare mediastinal parathyroid adenoma in a pediatric patient and summarize the epidemiologic profile, diagnosis, and management of similar pediatric cases.

Early biochemical response to parathyroidectomy for primary hyperparathyroidism and its predictive value for recurrent hypercalcemia and recurrent primary hyperparathyroidism

BACKGROUND

The traditional definition of cure after parathyroidectomy (PTX) for primary hyperparathyroidism is normocalcemia. Our hypothesis was that early postoperative levels of serum calcium and parathyroid hormone after PTX would have predictive value for later recurrence.

METHODS

We performed a retrospective study of 1,146 patients with primary hyperparathyroidism who underwent PTX and had long-term biochemical follow-up. The first postoperative serum level of calcium and parathyroid hormone values were used to categorize patients into the following four early biochemical response groups: (1) complete response (normal calcium and normal parathyroid hormone), (2) partial response with hyperparathormonemia (normal calcium and increased parathyroid hormone), (3) partial response with hypercalcemia (increased calcium and normal parathyroid hormone), and (4) non-response (increases in both calcium and parathyroid hormone). Incidences of recurrent hypercalcemia and recurrent primary hyperparathyroidism >6 months after operation were then analyzed.

RESULTS

The overall rate of any elevated serum levels of calcium and any increase in serum levels of parathyroid hormone during >6-month follow-up was 9.8% (112 of 1146), with 6.6% (57 of 861) for group 1, 27% (35 of 129) for group 2, and 16% (20 of 127) for group 3 (P < .02). Partial biochemical responses with either increased serum calcium or increased parathyroid hormone levels were the strongest predictors of any episode of increased serum levels of calcium after 6 months and was associated with 2.7× to 4.3× the risk of recurrent primary hyperparathyroidism, respectively.

CONCLUSION

This study demonstrates the importance of measuring parathyroid hormone in the early postoperative period to better predict later recurrent primary hyperparathyroidism.

Normocalcemic Hyperparathyroidism: A Heterogeneous Disorder Often Misdiagnosed?

Normocalcemic primary hyperparathyroidism (NHPT) was first described over 10 years ago, but uncertainties still remain about its definition, prevalence, and rates of complications. As a result, consensus management guidelines for this condition have not yet been published. Several hypotheses have been proposed for the pathophysiology of NHPT, but it may be a heterogeneous disorder with multiple causes, rather than a single etiology that explains this biochemical phenotype. A common clinical concern is whether NHPT should be treated surgically when complications are already present at first recognition of the disorder, rather than following patients clinically over time. The literature on NHPT is based mostly on larger studies of population‐based cohorts and smaller studies from referral centers. Lack of rigorous diagnostic criteria and selection bias inherent in populations seen at tertiary referral centers may explain the heterogeneity of reported rates of bone and renal complications in relation to consistently mild laboratory alterations. Unresolved questions remain about the significance of NHPT when it is diagnosed biochemically without evident bone or kidney complications. Moreover, its natural history remains to be elucidated because a proportion of what is classified as NHPT may revert to normal spontaneously, thus revealing previously unrecognized secondary hyperparathyroidism. These issues indicate that caution should be used in recommending surgery for NHPT. This review will focus on recent issues regarding the pathophysiology, evaluation, and management of NHPT. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Persistently Elevated PTH After Parathyroidectomy at One Year: Experience in a Tertiary Referral Center

CONTEXT/OBJECTIVE

Increased PTH after successful parathyroid surgery represents a clinical conundrum. We aimed to determine the prevalence of persistently elevated PTH (PePTH) postsurgery, along with predisposing factors.

DESIGN

and Setting: Patients ≥ age 18 with parathyroidectomy performed at University of North Carolina Hospitals for primary hyperparathyroidism (PHPT) over a 12-year period were identified from the Carolina Data Warehouse. Clinical and demographic characteristics were collected, transformed, and analyzed.

RESULTS

Five hundred seventy patients met initial criteria for PHPT, and of those 407 had postoperative values. One hundred forty-four had laboratory results within 3 to 18 months post operatively. There was no clinical difference between those with and without long-term laboratory follow-up. Presurgery, patients had average calcium of 11 mg/dL and PTH 125.4 pg/mL. Ninety-seven percent of patients had normalized calcium after surgery, but 30% had PePTH, which can be predicted at 3 months. Patients with PePTH (persistent elevation of PTH) after surgery did not differ from those with normalized PTH in terms of sex, age, body mass index, or excised gland weight; presurgery 25-vitamin D was slightly lower, but not abnormal (26 ± 15 vs 36 ± 11). The presurgical PTH was significantly higher (P < 0.001) in those with PePTH (156.5 pg/mL compared with presurgical level of 102.5 in those whose PTH normalized).

CONCLUSIONS

Nearly one-third of PHPT patients have elevated PTH levels postsurgery in a tertiary hospital setting. At presentation, patients with PePTH tend to have higher PTH relative to calcium levels. Whether PePTH after surgical treatment of PHPT has pathological consequences is unknown.