Minimal-access parathyroid surgery using intraoperative parathyroid hormone assay

Improving Intraoperative Parathyroid Hormone Lab Efficiency

BACKGROUND

Intraoperative parathyroid hormone (iPTH) testing is often used to confirm successful removal of hypersecreting parathyroid glands during parathyroidectomy. Unfortunately, the iPTH test can be a time-consuming and highly variable process that occurs while the patient is under anesthesia. We set out to improve iPTH lab efficiency and variability.

METHODS

We performed a retrospective review of 85 patients who underwent parathyroidectomy at our institution from October 2017 to October 2019. Each step of the iPTH lab reporting process was recorded and analyzed. Three simulations were performed of the entire process. We then established interventions to modify inefficiencies in the process and studied 21 patients who underwent parathyroidectomy at our institution from November 2019 to March 2020.

RESULTS

Twenty-five minutes of time inherent to the process were identified. Four critical steps were identified as modifiable steps in the process:1. Operating room (OR) blood draw ---> lab receipt.2. Lab receipt ---> placement on centrifuge.3. Removal from centrifuge ---> placement on PTH machine.4. PTH machine result ---> OR verbal report.We improved iPTH lab efficiency by 19%, decreasing the average lab result from 45 to 36 minutes (P = .001). We improved iPTH lab variability by 62%, decreasing the standard deviation from 21 to 8 minutes (P = .001).

DISCUSSION

Utilizing a team-based approach to identify and expedite critical steps in the iPTH lab process can make a significant improvement in iPTH lab efficiency, improving patient care by decreasing total anesthesia time.

Optimizing Efficacy of Quick Parathyroid Hormone Determination in the Operating Theater

The usefulness of intraoperative parathyroid hormone (PTH) monitoring has been extensively documented in primary hyperparathyroidism (HPT), whereas few data have been published on its use in reoperations or in secondary and tertiary HPT. We report our initial experience with a rapid (12 min response) PTH immunochemiluminometric assay performed in the operating room during surgery in 12 patients with primary HPT, 16 end-stage renal disease patients with secondary HPT and five kidney transplanted subjects with tertiary HPT. Blood samples were taken at baseline, within 10 min after resection and subsequently at various intervals whenever needed. The mean PTH levels before and after parathyroidectomy were 230.5 pg/mL (range 69–842) and 47.3 pg/mL (range 5–184), respectively, in primary HPT, 855.0 pg/mL (416–1655) and 202.2 pg/mL (53–440) in secondary HPT, and 205.6 pg/mL (116–301) and 45.4 pg/mL (18–97) in tertiary HPT. All patients but one had a significant percentage decline from pre-excision values (mean 76.9%, 76.0%, and 76.1% in primary, secondary and tertiary HPT, respectively). While a reduction of more than 50% was observed in 30 out of 33 patients after the first intraoperative sampling, additional measurements were performed in 10 cases. On-site PTH monitoring with this user-friendly and reliable system has proved helpful in targeting PTH tests to give the surgeon a rapid and accurate assessment of the intervention. The development of optimal PTH sequence strategies with decision-focused analytical and clinical limits will improve the efficacy of “point-of-care” PTH assay and resource utilization.

The Dilemma of the Normal Baseline Parathyroid Hormone Level using the Intraoperative PTH Assay

OBJECTIVE: To analyze patients with “normal” baseline quick intraoperative parathyroid hormone (QPTH) levels during parathyroidectomy and to determine the prevalence of this finding, the usefulness of the assay in this situation, and to explain the possible causes for this phenomenon.

STUDY DESIGN AND SETTING: Patients who underwent parathyroidectomy using QPTH in a tertiary hospital.

METHODS: Retrospective analysis of 39 patients treated surgically for primary hyperparathyroidism using QPTH.

RESULTS: Of the patients, 14 (36%) had normal baseline QPTH. 8 patients with localizing sestamibi scans had a single adenoma, and excision resulted in a mean decrease of 85.4% in QPTH. Six patients had nonlocalizing sestamibi scans, 1 patient had an 84% drop in QPTH level after removal of a single adenoma, and 5 patients had hyperplasia requiring ≥3 glands excision. At 11.36 months' mean follow-up, 13 patients (93%) were normocalcemic.

CONCLUSIONS: A “normal” baseline QPTH level was found in 36% of patients. A 50% decrease in QPTH remains predictive of biochemical cures in patients with localizing sestamibi scans. The likely explanation for this variability in “normal” levels between different assays is the variability in detection of the 7-84 PTH fragment, which results in an overestimation of the PTH level. Assays such as the QPTH, which are more sensitive for the biologically active PTH molecule [(1-84) PTH] than other laboratory PTH assays will tend to have lower PTH levels that can be within the normal range. EBM rating: B-3.

Intra-operative parathyroid hormone kinetics and influencing factors with high baseline PTH: a prospective study

BACKGROUND AND OBJECTIVE

Intra-operative parathyroid hormone (IOPTH) kinetics and therefore the efficacy of IOPTH utilization as a predictor of cure are likely to be affected by baseline IOPTH levels, vitamin D deficiency and parathyroid weight.

PATIENTS AND METHODS

Consecutive subjects with primary hyperparathyroidism (PHPT, n = 51) undergoing parathyroidectomy with IOPTH monitoring were studied prospectively during the period October 2009-November 2011. Samples were collected pre-incision, pre-excision and post-excision (5, 10, 15 min). Iterative analysis of IOPTH kinetics and half-life calculation was carried out in subgroups. Nonparametric testing was used for group statistics.

RESULTS

Hypovitaminosis D (25(OH)D3 < 50 nm) was present in 39 (76%), serum PTH > 1000 ng/l in 23 (45%), and giant parathyroid adenoma (weight > 3000 mg) in 23 (45%). The percentage drop at 10 min was significantly higher in large adenomas (weight > 3000 mg). Miami and 5 min criteria showed the highest negative predictive value and maximum accuracy. The average percentage IOPTH drop observed at 5 min post-excision was 79.8%. Kinetic analysis showed a mean half-life of PTH of 2.57 ± 0.27 min (range: 0.07-11.55).

CONCLUSION

IOPTH monitoring is reliable even in patients with extremely high baseline IOPTH value, with a greater percentage drop at 5 and 10 min post-excision. In patients with high baseline IOPTH, a 50% decay in PTH value at 5 min may be indicative of cure, obviating the need for 10 and 15 min samples. IOPTH kinetics are altered by adenoma weight but not affected by vitamin D status or baseline IOPTH levels.

Primary hyperparathyroidism in pregnancy-a rare cause of life-threatening hypercalcemia: case report and literature review

Objective. To report a case of primary hyperparathyroidism in a pregnant patient, report the obstetric and neonatal outcomes, and review the relevant literature. Results. A 29-year-old primigravida was successfully treated for PHP with minimally invasive resection of a parathyroid adenoma in the second trimester of pregnancy. A healthy baby girl was delivered at 37-week gestation with an unremarkable neonatal course. To the best of our knowledge, this is the second case report in the literature utilizing intraoperative PTH during a parathyroidectomy in a pregnant woman. Conclusions. Primary hyperparathyroidism is a rare life-threatening condition that can present during pregnancy. The diagnosis can be difficult to establish during pregnancy, given the nonspecific symptoms related to hypercalcemia. However, a better understanding of the condition, improved diagnostic studies, and well-organized multidisciplinary management decisions can significantly reduce the morbidity and mortality associated with the disease during pregnancy. This case report is presented to highlight the value of early diagnosis and appropriate management of PHP during pregnancy.

Minimally Invasive Parathyroid Surgery, The Norman 20% Rule: Is It Valid?

The 20 per cent rule proposed by Norman established a guideline using radioactivity in the minimally invasive radioguided parathyroidectomy (MIRP) technique to localize and confirm removal of an abnormal parathyroid gland in patients with primary hyperparathyroidism. If radioactivity in the resected gland was at least 20 per cent of excision site/background radioactivity, the 20 per cent rule was satisfied. Patients meeting these criteria underwent unilateral MIRP without intraoperative parathyroid hormone assay or intraoperative frozen section. The study aim was to independently evaluate the 20 per cent rule in MIRP patients with primary hyperparathyroidism. Using the University of Louisville Parathyroid Database from January 1, 1999 to December 31, 2007, 216 MIRP patients with complete radioguided and postoperative management data were identified. The average percentage of ex vivo parathyroid gland radioactivity compared with excision site/background radioactivity was 107 per cent with a range from 14 to 388 per cent. For 99 per cent (196/198) radioactivity recorded from the excised gland was at least 20 per cent of radioactivity recorded from the excision site. Normocalcemia was documented in 98.5 per cent (195/198) at 12 month follow-up. Our data supports the 20 per cent rule in that in 99 per cent of MIRP patients the resected gland radioactivity was at least 20 per cent of excision site radioactivity allowing localization and confirmation of an overactive gland without intraoperative parathyroid hormone monitoring or tissue analysis.

Directed parathyroid exploration: Evolution and evaluation of this approach in a single-institution review of 346 patients

OBJECTIVES/HYPOTHESIS

Critical evaluation of a directed exploration protocol used by a single surgeon in the management of surgical parathyroid disease.

STUDY DESIGN

Retrospective chart review was made of patients surgically managed for hyperparathyroidism at an academic tertiary care center.

METHODS

Three hundred forty-six patients were evaluated for biochemically proven hyperparathyroidism between March 1995 and February 2002. A directed exploration protocol was implemented in appropriately selected patients with primary hyperparathyroidism and in patients with secondary or tertiary hyperparathyroidism requiring repeat operation. The protocol included preoperative technetium-99m sestamibi imaging for hyperfunctional parathyroid localization, targeted neck exploration, rapid intraoperative parathyroid hormone determination, and limited-stay discharge from the ambulatory surgical recovery unit. Data collection was accomplished by entering patient evaluation, management, and outcome information prospectively into collective case report forms. A retrospective analysis of the data was conducted for the purpose of evaluating the effectiveness of the protocol.

RESULTS

Sustained normocalcemia beyond 6 months postoperatively was achieved in 323 of 327 (99%) patients with primary hyperparathyroidism. Eighty-four percent (84%) of patients with secondary or tertiary hyperparathyroidism achieved normocalcemia or had resolution of symptoms as a measure of therapeutic success. The complication rate for the entire series of patients was 2.8%. Ninety-two percent of positive findings on sestamibi scan correctly predicted the location of an adenoma, whereas a negative finding accurately predicted the absence of an enlarged gland in a "usual" location in 81% of patients. Twenty-six patients (9%) had a false-positive finding on the scan, whereby a solitary adenoma was found contralateral to the side indicated by the scan. Overall, the positive predictive value for sestamibi imaging in the series was 91%. Intraoperative parathyroid hormone determination yielded an overall rate of reduction of 80% from preoperative levels during directed exploration. Sustained normocalcemia was achieved in all patients in whom intraoperative parathyroid hormone determination demonstrated a minimum decline of 50% from preoperative levels following resection of hyperfunctional parathyroid tissue (adenoma[s]). The majority (72%) of patients were managed in an outpatient (ambulatory surgery) setting and were discharged to home within 8 to 12 hours after surgery.

CONCLUSION

The directed exploration protocol for surgical management of hyperparathyroidism generated surgical rates of success that were as good as and, in most cases, improved over that of traditional bilateral exploration. This achievement was associated with low morbidity and reduced time and facility utilization, conveying improved cost-effectiveness. This surgical strategy should serve to enhance the capability of the surgeon to safely and efficiently manage the majority of patients with surgical parathyroid disease.

Surgical and calcium outcomes in 427 patients treated prospectively in an image-guided and intraoperative PTH (IOPTH) supplemented protocol for primary hyperparathyroidism: outcomes and opportunities

Unilateral exploration based upon preoperative imaging has become increasingly applied in the management of patients with primary hyperparathyroidism. Unilateral surgical exploration purportedly has high rates of disease control, limited morbidity, and shortened operative time. Unfortunately, significant cohorts of patients with primary hyperparathyroidism are unable to have abnormal glands localized on preoperative imaging evaluation.

AIM

The aim of our study was to evaluate the efficacy of Tc(99m) sestamibi preoperative imaging, intraoperative Tc(99m) sestamibi with gamma probe, and intraoperative parathyroid hormone (IOPTH) assessment in a large cohort of patients with primary hyperparathyroidism.

RESULTS

A total of 427 patients were prospectively evaluated who were deemed surgical candidates for the treatment of primary hyperparathyroidism. Of these patients, 240 (56%) presented with positive Tc(99m) sestamibi imaging. Another 105 (25%) presented with equivocal Tc(99m) sestamibi imaging. Finally, 82 (19%) presented with negative Tc(99m) sestamibi imaging. Intraoperative rapid assessment of parathyroid hormone was performed at the time of surgical exploration in all patients with negative and equivocal preoperative imaging. All 240 patients with positive preoperative imaging underwent unilateral surgical exploration utilizing intraoperative Tc(99m) sestamibi with gamma probe. The most common finding in the positive Tc(99m) sestamibi scan group was single adenoma in 235 (98%). Normocalcemia was achieved in 233 (97%) of these patients, although in 25 (10%) this was normocalcemia with a persistent elevation in parathyroid hormone (PTH). The most common surgical finding in the equivocal Tc(99m) sestamibi scan group was single adenoma in 85 (81%). Additionally 85 (81%) of these equivocal patients were able to undergo unilateral exploration limited by IOPTH assessment. Normocalcemia was achieved in 101/105 (96%) of patients; although, 10 patients were normocalcemic with persistently elevated PTH and 2 patients had normocalcemia with low PTH. All patients with negative Tc(99m) sestamibi scan underwent bilateral cervical exploration plus IOPTH; 52/82 (63%) were found to have a single adenoma which was the most common surgical finding. Normocalcemia was achieved in 77/82 (94%) of the negative Tc(99m) sestamibi cohort; although 5 patients had normocalcemia with persistently elevated PTH and 2 had normocalcemia with low PTH. Only 3 (0.7%) overall recurrent laryngeal nerve injuries were encountered, and only 1 (0.2%) was permanent. Wound complication rates are reported in detail and were low and comparable for all three Tc(99m) sestamibi imaging based cohorts.

CONCLUSIONS

Tc(99m) sestamibi preoperative imaging, intraoperative Tc(99m) sestamibi with gamma probe, IOPTH, and combinations of these strategies allow for excellent opportunities for targeted excision of pathologic parathyroid tissue with the least dissection necessary while achieving excellent long-term calcium control and low rates of complication.

Parathyroidectomy monitored by intra-operative PTH: The relevance of the 20 min end-point

OBJECTIVES

RI-PTH measurements are a prerequisite for minimally invasive parathyroidectomy, providing guidance regarding the removal of hyper-functioning tissue. Different criteria of PTH decrease, concentration and clearance were analyzed in order to predict surgical treatment.

DESIGN AND METHODS

Blood samples at pre-incision, manipulation, 5, 10 and 20 min after resection, were collected from 145 patients presenting unambiguous, pre-surgical "single adenoma" diagnosis.

RESULTS

The meeting of Irvin criterion would have permitted the identification of 28% uncured cases leading to 4% unnecessary neck exploration. On the contrary, we would have identified all of the uncured patients, to the detriment of 7% unnecessarily prolonged procedure by taking into account PTH drop, concentration and clearance shape at 20 min.

CONCLUSIONS

The 20' end-point plays a key role in the correct determination of surgical outcome, strongly improving the possibility of adequate patient treatment. However, since the high success rate of traditional parathyroidectomy, yet not provided by RI-PTH, the utmost improvement to hyper-parathyroidism surgical treatment by RI-PTH could be achieved in pre-operative equivocal glands localization or multiglandular disease selected population to quickly guide and confirm the complete removal of all hyper-secreting tissue.

[Modifications in intact parathyroid hormone, total serum calcium, and ionized calcium levels in the surgery of primary hyperparathyroidism for single adenoma]

INTRODUCTION

We evaluated total serum calcium (TSC) and ionized calcium (IC) and their correlation with intraoperative intact parathyroid hormone (iPTH) in the surgery of primary hyperparathyroidism in patients with a single adenoma.

MATERIAL AND METHOD

We performed a prospective, blind trial with determination of iPHT, TSC and IC in a cohort of surgical patients (n = 279; 244 were valid for the study) who underwent surgery in the Department of Surgery, Hospital de Cruces, between October 1999 and April 2006. Total calcium, ionic calcium and iPTH were measured in the outpatient department, on admission and intraoperatively (at anesthesia induction and every 5 minutes after surgical excision).

RESULTS

Levels of calcium and iPTH were corrected in 234 (95.9%) patients. iPTH decreased from abnormal preoperative values of 294.43 +/- 286.38 pg/ml to 97.89 +/- 121.01 mg/dl (minute 5), 58.58 +/- 58.37 pg/ml (minute 10), 44.62 +/- 54.77 pg/ml (minute 15), and 38.42 +/- 51.72 pg/ml (minute 20). TSC decreased from preoperative values of 10.93 +/- 1.04 mg/dl to 10.2 +/- 0.97 mg/dl (minute 5), 10.17 +/- 1.00 mg/dl (minute 10), 10.12 +/- 0.98 mg/ml (minute 15), and 10.09 +/- 1.03 mg/ml (minute 20). The results for ionized calcium were as follows: 4.90 +/- 0.63 mg/dl at induction, 4.84 +/- 0.61 mg/dl (minute 5), 4.84 +/- 0.66 mg/dl (minute 10), 4.82 +/- 0.63 mg/dl (minute 15), and 4.82 +/- 0.63 mg/dl (minute 20). Frozen samples were conclusive for parathyroid tissue (19.56 +/- 15.3 after excision).

CONCLUSIONS

Intraoperative total calcium levels may help to predict adequate elimination of parathyroid tissue in primary hyperparathyroidism when intraoperative iPTH is not available. Ionized calcium levels did not show the same decrease.

Adénome parathyroïdien : stratégie chirurgicale

OBJECTIVES

The purpose of this study is to reach a better understanding in the handling of parathyroid adenomas, and to emphasize the importance of pre-operatory explorations in order to establish the best surgical approach and its cost.

MATERIAL AND METHODS

We are using a retrospective study of 51 patients that underwent surgery in our department between the years 1997 and 2002, for the treatment of primary hyperparathyroidism. Every patient received to a pre-operatory exploration in order to localize the parathyroid tumors, including cervical echography in 51 of the cases, and a sestamibi scintigraphy in 49 of the cases. Two surgical procedures were performed: unilateral approach, and bi-lateral approach.

RESULTS

The implementation of a systematic pre-surgical checkup allowed for unilateral surgery in 76% of the patients (39 out of 51), from which 31% (12 out of 39) under local anesthesia.

CONCLUSIONS

The accuracy of the pre-operatory explorations in order to localize the parathyroidian tumors in regard to HPTP, allows for precise surgery via unilateral approach under local anesthesia. The benefits are significant with shorter procedure time, shorter patient hospitalization, and lower risks for complications. The pre-operatory explorations also decrease the total cost of the procedure and are a critical tool for the surgeon.

Parathyroidectomy in the third trimester of pregnancy

The objective of this study was to estimate the incidence of complications when primary hyperparathyroidism (PHPT) is treated by parathyroidectomy in the third trimester of pregnancy. After searching the literature published through/including January 2005, we identified and analyzed 16 cases of PHPT treated surgically after 27 weeks of gestation. Parathyroid adenomas were detected in 81.2% of cases, hyperplasia in 6.3%, and carcinoma in 12.5%. Only one case failed surgical therapy. The postoperative incidence of clinically significant complications from the surgery was as low as 5.9% in fetuses and 0% in mothers. The incidence of clinically significant complications resulting from delayed diagnosis or postponed surgery ranged from 17.6% to 23.5% in fetuses and 18.8% to 25.0% in mothers. Postoperative hypocalcemia was detected in 62.5% of mothers and 17.6% of their newborns. All cases were easily treated with calcium replacement. Preeclampsia was diagnosed in 25% of cases. No clinically significant complications have been reported between 1993 and January 2005. This review suggests that parathyroidectomy performed in the third trimester of pregnancy is effective and has less risk than previously reported. Postponing surgery may be hazardous. Postoperative hypocalcemia is common but easily treated. Hyperparathyroidism should be considered a risk factor for preeclampsia.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to summarize the maternal and fetal complications of a delayed diagnosis and/or postponed surgery, recall that surgery of a parathyroid tumor can be safely performed in the third trimester, and describe pregnancy complications of hyperparathyroidism.

Sequential changes in plasma intact and whole parathyroid hormone levels during parathyroidectomy for secondary hyperparathyroidism

Most commercial assays for intact parathyroid hormone (iPTH) cross-react with non-PTH1-84 fragments (likely to be PTH7-84). We aimed to evaluate a whole PTH assay that measured only PTH1-84 by comparing it with an assay measuring iPTH levels during parathyroidectomy in secondary hyperparathyroidism (HPT). Twenty-eight patients with secondary HPT who underwent total parathyroidectomy with autotransplantation served as subjects. Blood samples for postoperative assay were drawn after anesthesia; immediately prior to excision of the last parathyroid gland; and at 5, 10, and 15 minutes after excision. The PTH7-84 level was calculated by subtracting the whole PTH value from the iPTH value. Plasma whole PTH decreased more rapidly than iPTH after parathyroidectomy (p < 0.0001). PTH levels that decreased by 50% or more from levels prior to excision to 10 minutes after excision were used to predict successful parathyroidectomy; decreases in whole PTH substantiated curative surgery for all patients without introducing false-positive and false-negative results. iPTH levels decreased by at least 50% in only 16 patients at 10 minutes after excision without false-positive results. Out of 11 cases in which iPTH decreased less than 50%, two were true-negatives and nine were false-negatives. Decreases in whole PTH levels more accurately reflect surgical outcome than do decreases in iPTH levels during parathyroidectomy in secondary HPT patients. Even though the quick iPTH assay is used infrequently during surgery for secondary HPT, our results suggest that a quick whole PTH assay may be more useful than the iPTH assay currently used in parathyroidectomy procedures for secondary HPT.

A systematic review of the diagnosis and treatment of primary hyperparathyroidism from 1995 to 2003

OBJECTIVE

To systematically review the current preoperative diagnostic modalities, surgical treatments, and glandular pathologies associated with primary hyperparathyroidism.

STUDY DESIGN

A systematic literature review.

RESULTS

Of the 20,225 cases of primary hyperparathyroidism reported, solitary adenomas (SA), multiple gland hyperplasia disease (MGHD), double adenomas (DA), and parathyroid carcinomas (CAR) occurred in 88.90%, 5.74%, 4.14%, and 0.74% of cases respectively. Tc 99m -sestamibi and ultrasound were 88.44% and 78.55% sensitive, respectively, for SA, 44.46% and 34.86% for MGHD, and 29.95% and 16.20% for DA, respectively. Postoperative normocalcemia was achieved in 96.66%, 95.25%, and 97.69% of patients offered minimally invasive radio-guided parathyroidectomy (MIRP), unilateral, and bilateral neck exploration (BNE). Intraoperative PTH assays (IOPTH) were helpful in approximately 60% of bilateral neck exploration conversion (BNEC) surgeries.

CONCLUSION

The overall prevalence of multiple gland disease (MGD and DA) was lower than often suggested by conventional wisdom. Furthermore, preoperative imaging was less accurate than it is often perceived for accurately imaging MGD. MIRP and UNE were more successful in achieving normocalcemia than is typically quoted. IOPTH was a helpful but not "fool-proof" adjunct in parathyroid exploration surgery.

SIGNIFICANCE

These results support a greater role for the treatment of primary hyperparathyroidism using less invasive approaches. EMB rating: B-3.

Focused Cervical Exploration for Primary Hyperparathyroidism without Intraoperative Parathyroid Hormone Monitoring or Use of the Gamma Probe

Selected patients with primary hyperparathyroidism (pHPT) who have a positive preoperative sestamibi scan can be managed safely and successfully with a focused cervical exploration without either adjuvant intraoperative parathyroid hormone (PTH) monitoring or use of a gamma probe. This article reports a retrospective analysis of a consecutive series of patients surgically treated at a tertiary referral center. From August 1998 to August 2002, 100 patients (68 women, 32 men; mean age 63 years [range: 29-89 years]) underwent a focused cervical approach without intraoperative PTH monitoring or use of the gamma probe after perioperative sestamibi injection. The study group comprised 9% of all patients (n = 1063) undergoing cervical exploration for pHPT during the study period. Ninety patients underwent an initial exploration, and 10 others underwent repeat cervical exploration following prior parathyroid (n = 7) or thyroid (n = 3) operation. Sestamibi scanning correlated with one enlarged parathyroid gland in all patients. Other enlarged glands were, however, not demonstrated in three patients (true positive = 97%; false negative = 3%). The single enlarged glands excised in all patients had a mean weight of 795 mg (range: 90-3640) and were histologically compatible with an adenoma. Postoperatively, 97% of patients were eucalcemic. Three patients remained hypercalcemic (3%). Of the three patients with persistent hypercalcemia, one underwent successful re-exploration with excision of a 500 mg second adenoma, whereas the other two patients (with confirmed familial HPT) remained hypercalcemic. Mean hospitalization was 0.5 days (range: 0-3 days). There was no operative mortality. No patients had permanent hypocalcemia. Postoperative morbidity occurred in three patients: two self-limiting cervical hematomas and one permanent vocal cord paralysis. Selected patients with pHPT due to single-gland disease and an unequivocally positive preoperative sestamibi scan can safely and successfully be managed with a focused unilateral cervical exploration without either intraoperative PTH monitoring or use of the gamma probe. Further experience with this surgical approach seems warranted to determine the overall cure rate, operative morbidity, and the sensitivity and specificity of preoperative localization studies.

The cost-effectiveness of sestamibi scanning compared to bilateral neck exploration for the treatment of primary hyperparathyroidism

This article presents a cost-effectiveness analysis to determine whether preoperative imaging with Tc99m-sestamibi for detection and treatment of solitary adenomas associated with primary hyperparathyroidism is cost-effective compared with routine bilateral neck exploration.

Endoscopic parathyroidectomy

This article describes the techniques of endoscopic and endoscopic assisted parathyroidectomy, with a special emphasis on the accumulated experience as well as the advantages and drawbacks of these novel techniques.

Unilateral and bilateral surgery for parathyroid disease

The principles of successful parathyroid surgery, regardless of the approach, demand a clear understanding of the philosophy behind the surgical exploration. A systematic approach, founded in science and refined by experience, is necessary to achieve long-term, reproducible surgical success. This article discusses the underlying logic and the advantages and disadvantages of the two basic approaches to parathyroid pathology: unilateral and bilateral cervical exploration. The authors do not to advocate a particular technique;instead, they provide a conceptual framework to surgical parathyroid disease upon which more advanced discussion can be built.

Recent trends becoming standard of care yielding smaller, more successful operations at a lower cost

Surgeons are now performing much smaller, more directed parathyroid operations in less time, and reported cure rates are the highest they have ever been. The ability to operate physiologically,and not just anatomically, has allowed a more directed and confident approach. This approach has subsequently led to minimal use of anesthesia and to immediate postoperative discharge,changes that have been embraced enthusiastically by referring endocrinologists. This article discusses the intraoperative monitoring used by the author and the pitfalls that can await the inexperienced surgeon.

Measurement of parathyroid hormone and application of parathyroid hormone in intraoperative monitoring

There has been a clear progression in assays for the analysis of PTH and its clinical applications. This includes the innovative use of PTH as a point-of-care assay as an intraoperative measure of the success of parathyroid surgery. The rapid PTH assay has served as a model for the development of other rapid hormone assays, such as for adrenocorticotropic hormone,although the clinical usefulness of these other applications is less well established. Knowledge of the circulating forms of PTH continues to progress. Information about the biologic and immunologic activities of these forms will aid in the interpretation and clinical use of current assays and in the development of new assays with improved specificities. The clinical laboratory will continue to play a vital role in providing testing and support for this important mediator of mineral metabolism.

Management of primary hyperthyroidism: toward minimal access surgery

Fifteen years ago, bilateral exploration of the neck was dogma in parathyroid surgery. Now, less invasive procedures can be used to target lesions identified by new tests such as dual-phase Sestamibi scanning or intraoperative documentation of parathyroid hormone (PTH) level changes after removal of a parathyroid gland. A hand-held gamma probe can be used for intraoperative detection of high-uptake lesions, and video-assisted endoscopic surgery has been used successfully. With these new techniques, surgical exploration can be confined to one side of the neck through smaller incisions associated with better cosmetic results. The operating time is reduced, and in some cases the procedure can be done under local anesthesia. The objective of this article is to describe recent changes in the management of parathyroid adenoma requiring surgery.

Intraoperative monitoring of kinetic total serum calcium levels in primary hyperparathyroidism surgery

BACKGROUND

In the setting of minimal approach Sestamibi-guided parathyroid surgery for primary hyperparathyroidism we evaluated if total serum calcium level monitoring is as valuable as intraoperative parathyroid hormone (iPTH) monitoring.

STUDY DESIGN

Prospective open single-blinded efficacy trial of two intraoperative diagnostic monitoring methods (iPTH and total serum calcium level) on a cohort of surgical patients. All patients (n = 35) were undergoing parathyroid surgery at the Department of General Surgery at B Cruces' Hospital, Vizcaya, Spain, between October 1999 and March 2001. Kinetics of serum levels of Ca and iPTH during surgery and time of prediction of cure for each method (measured in the clinic, admission, and intraoperatively, such as induction of anesthesia, and every 5 minutes after removal of adenoma) were analyzed.

RESULTS

Hypercalcemia and iPTH levels became corrected in 34 patients. Average serum calcium levels dropped from pathologic 11.07 +/- 0.41 mg/dL (mean +/- standard deviation) to normal values 9.7 +/- 0.82 mg/dL during the first intraoperative determination (minute 5), but mean iPTH decreased from pathologic (192 +/- 98 pg/mL) to normal values (39.93 +/- 25.12 pg/mL) during the third intraoperative determination (minute 15). Serum calcium level at 5 minutes after removal decreased by 100% in 34 patients, but iPTH only showed a similar drop during the third determination at 15 minutes. Frozen sections were conclusive for parathyroid tissue (20.56 +/- 10.3 minutes after removal).

CONCLUSIONS

Intraoperative measurement of total calcium level might be an easier and less expensive method than iPTH measurement in the prediction of cure during surgery for primary hyperparathyroidism resulting from adenoma.

Rapid intraoperative immunoassay of parathyroid hormone and other hormones: a new paradigm for point-of-care testing

BACKGROUND

The first description of the use of a rapid assay for the measurement of intact parathyroid hormone (PTH) in patients undergoing parathyroidectomy for hyperparathyroidism was reported in 1988. Subsequent improvements in the analytical performance of the rapid intraoperative PTH assay allowed the establishment of its clinical utility in the surgical management of hyperparathyroidism. These modifications also allowed the assay to be performed in or near the operating suite.

METHODS

We searched MEDLINE, using the following key words: intraoperative, rapid, quick, parathyroid hormone, hormone, and immunoassay. Relevant articles that focused on the analytical aspects and clinical utility of rapid intraoperative hormone immunoassays were selected for this review.

CONTENT

On the basis of the positive impact that the rapid intraoperative PTH test has had on both patient outcomes and cost savings, other rapid intraoperative hormone immunoassays for the diagnosis and/or treatment of other endocrine-hormone-secreting tumors have been developed. These hormones share certain characteristics that make them suitable for use as rapid intraoperative tests, i.e., short analyte half-life and/or large analyte concentration gradient, rapid analysis time, and positive clinical utility. Initial studies with cortisol, gastrin, insulin, adrenocorticotropic hormone, and testosterone have shown promising results in preoperative localization studies and/or for assessing the effectiveness of tumor resection during surgery.

CONCLUSION

The emergence of these rapid intraoperative immunoassays indicates that this test format is likely to provide future opportunities to improve patient care by advances in clinical laboratory testing.

Comparison of parathyroid hormone levels from the intact and whole parathyroid hormone assays after parathyroidectomy for primary and secondary hyperparathyroidism

BACKGROUND

Most commercial intact parathyroid hormone (intact PTH) assays cross-react with non-(1-84) PTH (likely 7-84 PTH). Using a whole-molecule PTH (whole PTH) assay that specifically measured only 1-84 PTH, we compared the kinetics of whole PTH and intact PTH after parathyroidectomy in patients with primary hyperparathyroidism (HPT) and secondary HPT.

METHODS

This study comprised 74 patients with primary HPT caused by a single adenoma and 18 patients with secondary HPT who underwent parathyroidectomy. Blood samples were drawn after anesthesia, just before excision of a single adenoma in primary HPT, and just before excision of the last parathyroid gland in secondary HPT, and at 5, 10, and 15 minutes after excision. The 7-84 PTH level was calculated by subtracting the whole PTH value from the intact PTH value.

RESULTS

There was a difference between the percentage of 7-84 PTH/intact PTH in plasma samples from patients with primary HPT and secondary HPT (28%+/-12% vs 35%+/-9%; P<.05). Plasma whole PTH decreased more rapidly than intact PTH after parathyroidectomy in patients in both the primary HPT (P<.0001) and secondary HPT groups (P<.0001). Decline of intact PTH was slower in patients with secondary HPT than in patients with primary HPT; however, there was no significant difference in the decline of whole PTH between the 2 groups.

CONCLUSIONS

The quick intact PTH assay is not used frequently during surgery in patients with secondary HPT; however, our results suggest that a quick whole PTH assay may be a more useful adjunct to parathyroidectomy in both secondary HPT and primary HPT.

Intraoperative testing for parathyroid hormone: a comprehensive review of the use of the assay and the relevant literature

OBJECTIVE

The rapid intraoperative parathyroid hormone assay is transforming the parathyroidectomy procedure. We present a review of the literature on the use of the assay as an adjunct to surgery. To our knowledge, this is the first review of the literature to encompass and compare all known primary studies of this assay in parathyroidectomy patients.

DATA SOURCES

Articles were collected by searching MEDLINE databases using relevant terminology. The references of these articles were reviewed for additional studies. Supplementary articles pertinent to the parathyroidectomy procedure, preoperative parathyroid localization studies, and intraoperative parathyroid hormone assay development also were examined.

STUDY SELECTION AND DATA EXTRACTION

One hundred sixty-five references were analyzed and categorized separately into groups.

DATA SYNTHESIS

The primary studies of intraoperative data on patients undergoing parathyroidectomy were compared when possible. Studies were analyzed by type of assay used, where performed, turnaround time, and efficiency of use. Reviews of the types of parathyroid surgery and preoperative localization were included for educational purposes.Conclusions.-The intraoperative parathyroid hormone assay is a useful adjunct to preoperative imaging and parathyroid surgery because of its unique ability to detect an occult residuum of hyperfunctioning parathyroid tissue. Use of this assay will obviate the need for frozen section in most routine cases. The test facilitates minimally invasive parathyroidectomy for single parathyroid adenomas, which, in turn, improves cost-effectiveness and cosmetic outcome. Its use in patients with known preoperative multiglandular disease is promising but requires further study.

Parathyroid surgical failures with misleading falls of intraoperative parathyroid hormone levels

According to earlier reports, a decrease below 50% of baseline of intraoperative PTH levels measured 5 min after resection of the parathyroid adenoma predicts a cure of hyperparathyroidism. To reveal previously unrecognized pitfalls of intraoperative PTH measurements, we reviewed surgical failures in our series of parathyroidectomies combined with intraoperative PTH sampling. PTH measurements were performed in 251 patients with primary hyperparathyroidism (PHPT) between November 1999 and December 2002. PHPT due to parathyroid hyperplasia were found in 8 cases, double parathyroid adenomas in 6 cases, parathyroid carcinoma in 1 case and single parathyroid adenomas in 236 cases, all confirmed by histological examination. Of the 236 cases of single adenomas, initial surgery failed to cure PHPT in 4 patients. In 3 patients a false-positive decrease of intraoperative PTH (from 269 to 40 pg/ml, from 211 to 27 pg/ml, and from 140 to 59 pg/ml) was observed, whereas in the fourth patient a true-negative decrease of intraoperative PTH (from 758 to 401 pg/ml) was mistakenly interpreted as indication for a cure of PHPT. In each of the 4 patients in whom initial surgery failed the intervention included thyroid surgery and reoperative parathyroid surgery resulted in a permanent cure of PHPT. These observations support the possibility that thyroid surgery may compromise the blood supply of parathyroid adenomas resulting in a misleading drop of intraoperative PTH levels. Therefore, a careful evaluation of intraoperative PTH levels and, perhaps, other intraoperative aids such as histological evaluation of frozen sections are recommended when parathyroid surgery is combined with simultaneous thyroid intervention.

Intraoperative parathyroid hormone testing: what have we learned?

OBJECTIVES/HYPOTHESIS

The development of rapid, sensitive assays for measuring the intact parathyroid hormone (iPTH) molecule has the potential to allow the surgeon to determine the success of parathyroid surgery intraoperatively. The purpose of the study was to review our results in the context of currently held beliefs regarding the ability of the intraoperative iPTH to predict resolution of hyperparathyroidism.

STUDY DESIGN

Retrospective review.

METHODS

The study series is a retrospective review of 107 consecutive parathyroidectomies performed by a single surgeon. Patients with primary, secondary, and tertiary hyperparathyroidism were included.

RESULTS

The intraoperative assay allowed an overall success rate of 93.4% across all patient categories. The success rate in patients with primary hyperparathyroidism was 95.7%. Measuring the iPTH level at 10 versus 15 minutes after the removal of tissue did not significantly affect the predictive value of the test. A decrease of 50% in the iPTH level after the resection of hyperfunctioning tissue was prognostic of successful treatment of the hyperparathyroid state. By contrast, a postexcision iPTH level that was within the normal range was not always predictive of cure.

CONCLUSIONS

The intraoperative iPTH assay is particularly useful in the treatment of primary hyperparathyroidism. The assay eliminates the need for intraoperative frozen-section analysis in most cases and allows the surgeon to perform limited resections with confidence. This is especially true in complicated parathyroid surgeries, such as revision surgeries or those requiring concomitant thyroid surgery. The assay is also useful in secondary hyperparathyroidism, although it appears that the inability to identify small nonfunctional or hypofunctional supernumerary parathyroid glands means that long-term normocalcemia may not be assured.

[Value of the intraoperative determination of parathyroid hormone (PTH) in hyperparathyroidism surgery]

INTRODUCTION

The success in the surgical management of hyperparathyroidism has conventionally required a bilateral neck exploration. The intraoperative monitoring of intact parathyroid hormone (PTHi), allows a less extensive procedure by confirming the complete removal of hypersecreting tissue.

METHODS

Plasma samples were obtained from 32 consecutive patients before and 10 minutes after removal of abnormal parathyroid tissue. PTH was measured with a modifie immunochemiluminometric assay with a short incubation time and the results made available in 15 minutes.

RESULTS

PTHi decreased by at least 60% in 30 of 32 cases. A single adenoma was removed in 26 cases, and multiple hyperplastic glands in 4 cases. The two cases in which PTHi fell < 60% were diagnosed as hyperplasia. PTHi decreased > 60% after the removal of the remnant hyperplastic glands.

CONCLUSIONS

The rapid PTHi assay had excellent analytical performance and predicted the success of parathyroid surgery.

[Diagnostic value of parathyroid localization techniques in surgery for primary hyperparathyroidism]

OBJECTIVES

To determine the accuracy of imaging techniques for localization of nodular lesions of parathyroid glands.

MATERIAL AND METHODS

Seventy one patients were prospectively enrolled and underwent surgical examination for primary hyperparathyroidism. Ultrasonography (US), 201Tl/99mTc parathyroid subtraction scintigraphy and 99mTc MIBI scintigraphy were evaluated.

RESULTS

The sensitivity and specificity for combined 201Tl/99mTc parathyroid subtraction scintigraphy and US for parathyroid adenomas were 72.27% and 89.22% respectively. The combination of 99mTc MIBI scintigraphy and US resulted in improved specificity (93.67%) and positive predictive value (80.39%). The accuracy of the localizing studies was lower for patients with hyperplasia.

CONCLUSIONS

The combination of scintigraphy and US is the best approach for localization of nodules. In most cases, the two techniques are complementary.

Surgical considerations and controversies in thyroid and parathyroid surgery

The techniques of thyroid surgery have been fully elucidated in several surgical texts and atlases. This article discuss surgical pearls of thyroid and parathyroid surgery. We discuss preoperative, intraoperative, and postoperative considerations and controversies for both procedures.

Minimally invasive parathyroidectomy: the role of radio-guided surgery

OBJECTIVES

Objectives were to review our current experience with radio-guided parathyroid surgery and to compare various techniques of minimally invasive parathyroidectomy.

STUDY DESIGN

1) To review our recent experience of radio-guided gamma probe localization during surgery for primary hyperparathyroidism and 2) to compare the intraoperative findings with the preoperative sestamibi scan.

METHODS

Analysis was made of the 10 most recent surgical procedures for primary hyperparathyroidism at a single institution to compare the operative localization with preoperative sestamibi scan and to determine the radioactivity in the tissue removed during surgery, such as parathyroid adenoma, normal parathyroid gland, thyroid tissue, or lymph nodes.

RESULTS

The sestamibi scan was able to localize the enlarged parathyroid gland in eight patients. Although gamma probe was helpful in localizing the parathyroid gland, the identification of an enlarged parathyroid gland was directly based on the preoperative findings of sestamibi scan. In the remaining two patients, the intraoperative gamma probe was not helpful.

CONCLUSIONS

The major advantage of gamma probe in the series was to evaluate the radioactivity in the tissue that was removed and to determine whether it was an enlarged parathyroid gland, lymph node, thyroid tissue, or fatty tissue. The radio-guided surgery did not add substantially to the surgical procedure in patients in whom the sestamibi scan had localized the enlarged parathyroid gland preoperatively.

[Descriptive analysis and surgical outcome of primary hyperparathyroidism]

Primary hyperparathyroidism (PHPT) was a rare but serious disease with massive biochemical, renal and skeletal signs at the time of diagnosis. In the last decades it has become a more common disorder often diagnosed by chance. The disease usually shows minimal symptoms. These clinical changes are due to advances in biochemical screening procedures, which have led to a remarkable increase in the incidence of PHPT. The aim of this study is to describe the clinical profiles, biochemical data, operative findings and postoperative results. Seventy one consecutive patients were prospectively enrolled and underwent surgical examination. Most of them showed symptoms: 6 patients were asymptomatic and 11 had a normocalcemic hyperparathyroidism. After surgery 5 patients showed persistent primary hyperparathyroidism. Parathyroid hormone concentration returned to normal levels in 95.77% of the patients studied. Parathyroidectomy is a safe and effective approach to the treatment of primary hyperparathyroidism.

Kinetic Analyses of Parathyroid Hormone Clearance as Measured by Three Rapid Immunoassays during Parathyroidectomy

Background: Rapid intraoperative parathyroid hormone (PTH) measurements are an important prerequisite for minimally invasive parathyroidectomy, serving as a feasible marker for “cure” because of the short half-life of PTH. Because automated analysis may facilitate monitoring, two automated PTH assays were compared with an established manual method.

Methods: We collected 109 plasma samples during minimally invasive surgery on 20 patients with primary hyperparathyroidism and single-gland disease. PTH was analyzed manually with a test from Nichols and by two automated assays from Diagnostic Product Corporation (DPC) and Roche, respectively. PTH half-life and residual concentrations were calculated by two kinetic models.

Results: Despite good overall correlations between methods [DPC = 1.07(Nichols) − 12 ng/L; r = 0.95, Sy|x = 26 ng/L and Roche = 1.16(Nichols) − 2.82 ng/L; r = 0.98; Sy|x = 16 ng/L], marked interindividual differences were observed. The iterative kinetic model failed with a nonuniform PTH decrease, but the interpolative model produced valid results. The mean (SD) half-life of 3.7 ± 1.4 min with DPC differed significantly (P &lt;0.05) from the 4.3 ± 1.6 min with Roche (Nichols, 4.0 ± 1.6 min). DPC produced significantly lower mean residual PTH (15 ng/L) vs Roche (27 ng/L); Nichols results were between them (20 ng/L). However, these differences were clinically irrelevant.

Conclusions: Automated methods are as suitable as the manual test. The preoperative baseline PTH is necessary but is insufficient for kinetic calculations.

Intraoperative parathyroid hormone testing: survey of testing program characteristics

OBJECTIVE

To examine the number and testing characteristics of laboratories that offer intraoperative testing of intact parathyroid hormone (PTH).

DESIGN

Laboratories (n = 355) that participated in 2001 in PTH proficiency testing with the College of American Pathologists Special Ligand Survey were surveyed about intraoperative PTH testing.

RESULTS

Of the 320 laboratories that responded to the survey, 92 performed intraoperative PTH testing. Testing practices were divided nearly equally among laboratories that performed intraoperative PTH testing for all parathyroidectomies (40%), most but not all cases (31%), and less than half of cases (30%). Testing frequency usually was low, with about two thirds of laboratories reporting 5 or fewer cases per month. A surprising finding was that, although intraoperative PTH testing originally became widely practiced as a point-of-care test, 71% of laboratories performed testing in a central laboratory, 6% in satellite laboratories, and only 23% in operating suites. A survey of methods showed that 33% used the manual QuiCk-Intraoperative test, 47% used the automated Immulite Turbo intact PTH assay, and 20% used other methods.

CONCLUSIONS

Intraoperative testing of intact PTH, although relatively new, has come into widespread practice during parathyroid surgery. Service delivery has evolved from a point-of-care model toward a central laboratory model, with this test serving as an illustrative example of factors that affect the balance between point-of-care and laboratory testing.

[Value of a structured report for the interpretation of parathyroid scintigraphy in primary essential hyperthyroidism]

The aim of the study was to evaluate whether a four-stage report scheme increases the diagnostic accuracy of dual phase Tc-99 m sestamibi scintigraphy (MIBI-scintigraphy) in patients with primary hyperparathyroidism (pHPT). We analysed the scans of 35 patients with primary hyperparathyroidism referred for Tc-99 m sestamibi scintigraphy and compared them with the sonographic and surgical findings. All scans were interpreted following a four-stage report scheme: Group A--typical scintigraphic findings of a single gland disease, group B--scan consistent with single gland disease, group C--multiple gland disease, group D--non diagnostic scan. Twenty-three scans were ranked in group A. In all these patients, scintigraphy diagnosed both the side and the localization of the adenoma correctly. Sonography made the correct diagnosis in 21/23 individuals and showed false-positive results in 2/23 cases. Group B included 10 scans. In 7/10 individuals, both the side and the localization of the adenoma were diagnosed correctly, whereas in 2/10 patients only the side was diagnosed. The scan of a single patient with hyperplasia of all 4 parathyroid glands was falsely interpreted as "consistent with a left caudal single gland disease". Sonography made the correct diagnosis in 8/10 cases, two individuals were diagnosed as false positive and false negative, respectively. No scan was interpreted as multiple gland disease (group C) and two scans were non diagnostic (group D). Both patients of the last group were correctly diagnosed by sonography. These findings suggest that in case of typical scintigraphic findings of single gland disease, scintigraphy but not sonography should be the primary localization technique for minimally invasive parathyroidectomy.

Role of cyclase activating parathyroid hormone (1-84 PTH) measurements during parathyroid surgery: potential improvement of intraoperative PTH assay

SUMMARY BACKGROUND DATA

Quick intraoperative parathyroid hormone assays are widely used as a guide to the adequacy of resection during parathyroid surgery. However, some authors have reported a 15% error rate of these assays because of the presence of false-positive and false-negative results. Recently the authors have found that most commercial intact PTH (iPTH) assays cross-react with non-(1-84) PTH (likely 7-84 PTH) and that the proportional levels of non-(1-84) PTH in patients were variable in a much wider range, accounting mostly for 20% to 60% of the immunoreactivity in samples obtained from hyperparathyroid patients. A cyclase activating PTH (CAP) measured by a novel immunoradiometric assay was shown to measure specifically 1-84 PTH. Using a CAP assay, the authors studied the rate of decline of CAP after parathyroidectomy and compared it with iPTH as measured by the Nichols intact PTH immunoradiometric assay.

METHODS

This study comprised 29 patients with primary hyperparathyroidism (pHPT) caused by a single adenoma and 7 patients with secondary hyperparathyroidism (secondary HPT) who underwent parathyroidectomy. Blood samples were drawn after anesthesia, before excision of one enlarged parathyroid gland in pHPT and of the last gland in secondary HPT, and at 5, 10, and 15 minutes after excision. The 7-84 PTH level was calculated by subtracting the CAP value from the iPTH value.

RESULTS

The percentage of 7-84 PTH in iPTH in plasma samples was 27.5 +/- 14.4% in pHPT and 39.6 +/- 15.1% in secondary HPT. In pHPT patients the plasma CAP and iPTH value decreased to 23.4 +/- 10.8 and 32.0 +/- 11.3% of the preexcision level at 5 minutes, 10.6 +/- 7.7 and 21.1 +/- 8.8% at 10 minutes, and 8.5 +/- 4.9 and 16.1 +/- 6.8% at 15 minutes after removal of the enlarged gland, respectively. At 5 minutes, CAP levels of all 29 pHPT patients had decreased to less than 40% of the preparathyroidectomy level; however, 7 (24%) patients still had an iPTH level of more than 40%. In secondary HPT patients, CAP and iPTH values had dropped to 43.3 +/- 20.2 and 66.1 +/- 19.7% at 5 minutes, 28.6 +/- 16.6 and 53.6 +/- 18.1% at 10 minutes, and 14.2 +/- 9.0 and 41.0 +/- 12.9% at 15 minutes after removal of the last enlarged gland, respectively. At 10 minutes, CAP levels of all seven secondary HPT patients had decreased to less than 50% of the preexcision level; however, three (43%) patients still had an iPTH level of more than 50%. In pHPT and secondary HPT, the 7-84 PTH level had dropped to 57.4 +/- 85.9 and 62.1 +/- 84.9%, respectively, of the preexcision value 15 minutes after removal of the enlarged gland or glands.

CONCLUSIONS

The percentage of 7-84 PTH in iPTH in plasma samples varies substantially between patients with HPT. In both pHPT and secondary HPT, the plasma CAP value decreased more rapidly than iPTH after parathyroidectomy, depending on the amount of 7-84 PTH in circulation. These results suggest that the CAP assay may be a more useful adjunct to parathyroidectomy than the currently used iPTH assay.

Primary hyperparathyroidism in pregnancy: evidence-based management

Primary hyperparathyroidism during pregnancy poses significant risks to the mother and the fetus. Fortunately, prompt diagnosis and effective management can improve outcomes for both. There is controversy regarding appropriate management of these patients, especially late in gestation. The objective of this article, therefore, is to review the literature and to propose an evidence-based approach to managing these patients. The prevalence of primary hyperparathyroidism in the general population is 0.15%. This condition is more common in women and 25% of cases appear in women during the childbearing years. The true incidence during pregnancy, however, is not known. Because up to 80% of gravid patients with primary hyperparathyroidism are asymptomatic, diagnosing this condition is more difficult. Complications associated with primary hyperparathyroidism in pregnancy have been reported to occur in up to 67% of mothers and 80% of fetuses. In addition to many constitutional symptoms, maternal complications include nephrolithiasis, bone disease, pancreatitis, hyperemesis, muscle weakness, mental status changes, and hypercalcemic crisis. Reported fetal complications include intrauterine growth retardation, low birth weight, preterm delivery, intrauterine fetal demise, postpartum neonatal tetany, and permanent hypoparathyroidism. A four-fold decrease in perinatal complications may be achieved with appropriate therapy. Conservative intervention may be appropriate under certain circumstances, but excision of a parathyroid adenoma remains the only definitive treatment. Debate continues regarding the safety of surgery in the third trimester. However, several cases of successful surgery have been reported.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to describe the typical presentation of a patient with hyperparathyroidism, summarize the work up and management of a patient with hyperparathyroidism, and list the treatment options for a pregnant patient with hyperparathyroidism.

Evaluation of the Performance and Clinical Impact of a Rapid Intraoperative Parathyroid Hormone Assay in Conjunction with Preoperative Imaging and Concise Parathyroidectomy

Background: 99mTc-sestamibi scans and rapid, intraoperative intact parathyroid hormone (PTH) assays allow preoperative identification of diseased glands and intraoperative confirmation of diseased gland removal, respectively. Use of these two new technologies may facilitate simpler, more concise surgery, shorter hospital stays, and decreased costs for frozen-section analysis. One major drawback to this new strategy has been the high cost of rapid point-of-care PTH assays.

Methods: We performed rapid PTH assays with the DPC Turbo PTH assay on the DPC IMMULITE automated analyzer. The number of intraoperative frozen sections, type of anesthesia, surgical approach, length of hospital stay, and pre- and postoperative calcium values were compared between a group of 49 patients undergoing parathyroidectomy where the intraoperative PTH assay was used in conjunction with preoperative imaging, and a historical control group of 55 patients before the use of these two technologies in our institution.

Results: Comparison of the Turbo PTH assay to the standard IMMULITE PTH assay gave the following: y = 1.08x − 4.36 (r = 0.97; n = 48). For the 49 patients, the median turnaround time for each intraoperative PTH determination was 19 min (range, 14–40 min). The median decrease in PTH values from baseline was 88% (range, 33–99%). Thirty-seven patients required two PTH determinations, 7 required three, 4 had four, and 1 required five determinations. The average laboratory cost for the rapid intraoperative PTH assays was &lt;$100 per patient (range, $55 to $113). Compared with the control group, the experimental group had significantly fewer frozen sections (1.4 vs 2.5; P &lt;0.0001), shorter hospital stays (17 discharged on the day of surgery vs none discharged on the day of surgery; P &lt;0.0001), greater use of local anesthesia (33% vs 0%; P &lt;0.001), and more unilateral, rather than bilateral neck explorations (65% vs 0%; P &lt;0.001).

Conclusions: The combination of intraoperative Turbo PTH assay and preoperative 99mTc-sestamibi scans can lead to significant decreases in laboratory and surgical pathology costs, hospital stays, and exposure to general anesthesia by facilitating concise parathyroidectomy surgery.

Intraoperative Gamma Probe Localization of Parathyroid Adenomas

OBJECTIVES/HYPOTHESIS

In an effort to reduce operative time, improve diagnostic accuracy, and decrease perioperative morbidity, we combined preoperative technetium Tc 99m-sestamibi localization with the use of the gamma probe intraoperatively. This report examines our experience with the gamma probe for rapid intraoperative localization of parathyroid adenomas.

STUDY DESIGN

A retrospective chart review was performed to identify all patients who underwent parathyroid exploration with the aid of the gamma probe at Lenox Hill Hospital (New York, NY).

METHODS

Charts were reviewed for operative details, radiological findings, and pathological diagnoses.

RESULTS

Between November 1, 1998, and June 30, 2000, 35 parathyroid explorations were performed with the aid of the gamma probe. The preoperative localization study was accurate in 34 of 35 cases. The gamma probe successfully identified the parathyroid adenoma in 33 of 35 cases. There were two false-positive cases in which the gamma probe mistakenly identified a thyroid adenoma rather than a parathyroid adenoma. In 11 of 35 cases, the gamma probe was judged essential for rapid localization of the parathyroid adenoma. These cases included patients with multiple or ectopic adenomas and patients who had previous parathyroid surgery. Average operative time to remove parathyroid disease was 80 minutes (range, 45-140 min), which included 20 to 40 minutes waiting for frozen-section results. All patients became normocalcemic, and there were no major complications in this series.

CONCLUSION

The gamma probe is a useful tool that complements a well-performed localization study. It is most useful in patients who have multiple or ectopic adenomas or have had prior parathyroid surgery.

Intraoperative Parathyroid Hormone Analysis: A Study of 200 Consecutive Cases

Background: Immunoassays for parathyroid hormone (PTH), with short incubation times and results available in &lt;15 min, have allowed intraoperative monitoring of the success of parathyroid surgery. The purpose of this study was to evaluate the analytical performance of a rapid PTH assay and its clinical performance in a series of 200 patients.

Methods: PTH was measured with a modified immunochemiluminometric assay with a 7-min incubation time (QuiCk-IntraOperative™ Intact PTH assay). The rapid assay was compared with results in a central laboratory (immunoradiometric assay) in 44 EDTA-plasma specimens. The rapid assay was used intraoperatively in 200 consecutive cases with specimens analyzed before and 5–10 min after resection of the hypersecreting parathyroid gland(s).

Results: Intraassay imprecision was 12% at 28 ng/L and 11% at 278 ng/L. Regression analysis of results of the rapid PTH assay and the IRMA PTH assay in 44 parathyroidectomy patients yielded y = 1.26x − 12 ng/L, Sy|x = 26.3 ng/L, r = 0.984, and in 40 of 44 patients with values &lt;200 ng/L, y = 1.02x + 1.9, Sy|x = 13.9, r = 0.947. In the 195 cases using intraoperative PTH testing with complete results and defined clinical outcomes, the overall accuracy of the assay in predicting surgical success was 88% using the criterion of a 50% decrease at 5–10 min and 97% including the subset of patients with delayed decreases of PTH.

Conclusions: The rapid PTH assay had excellent analytical performance and excellent agreement with the PTH immunoradiometric assay and predicted the success of parathyroid surgery in this large series of consecutive patients.

Minimally invasive parathyroid surgery

More surgeons are performing unilateral exploration for primary hyperparathyroidism (HPT) than ever before. This article reviews the factors that have led to the trend toward less invasive surgery. Discussion includes the history of unilateral exploration for HPT, the advent of magnetic resonance sestamibi imaging, and the development of intraoperative assays for parathyroid hormone. Results of minimally invasive techniques, including radio-guided parathyroidectomy, endoscopic parathyroidectomy, and outpatient parathyroidectomy, also are presented.

Usefulness of quick intraoperative measurements of intact parathyroid hormone in the surgical management of hyperparathyroidism

We investigated the use of quick measurement of intraoperative intact parathyroid hormone (I-PTH) to predict the outcome of parathyroidectomy. We examined intraoperative monitoring of I-PTH in 34 consecutive primary hyperparathyroidism (pHPT) patients operated on between April and December 1999. The average patient age was 56 +/- 13 years, and all but one were women. Four had a history of thyroidectomy. Blood samples were drawn before excision of enlarged parathyroid gland(s) and at 2, 5, 10, and 15 minutes afterward. Plasma I-PTH was measured by a two-site immunochemiluminometric assay. Twenty-three patients were shown to have single gland disease, and ten had multiglandular disease. All patients, except one, underwent successful parathyroidectomies. The plasma I-PTH value 15 minutes after removal of enlarged gland(s) had dropped to 26 +/- 10% of pre-excision I-PTH value. In one patient with a previous history of thyroidectomy for thyroid papillary cancer, no gland enlargement was found in the area where the lesion had been suggested by both ultrasonography and 99mTc sestamibi scanning. In this case, intraoperative measurements of I-PTH in the bilateral internal jugular veins identified an ectopic parathyroid tumor, which was successfully removed. We conclude that quick measurement of intraoperative I-PTH is a valuable tool for decision-making, especially for reoperative parathyroid surgery, for patients with previous history of thyroidectomy, and for patients in whom unilateral neck exploration or a single-gland approach is scheduled based upon preoperative localization.

Initial experience with intraoperative PTH determinations in the surgical management of 130 consecutive cases of primary hyperparathyroidism

BACKGROUND

Successful surgical management of primary hyperparathyroidism (1 degree HPT) historically has required bilateral neck exploration. The intraoperative parathyroid hormone (IO-PTH) assay allows a more limited procedure by confirming complete removal of hypersecreting tissue.

METHODS

Plasma samples were obtained from 130 consecutive patients both before (preincision and preexcision baselines) and at approximately 5 and 10 minutes (and additional times) after removal of abnormal parathyroid tissue. Samples were assayed for IO-PTH by a rapid, two-site immunochemiluminescent assay (ICMA) with a 7-minute incubation at 45 degrees C.

RESULTS

Plasma IO-PTH decreased by at least 50% in 126 of 130 cases; however, three of these cases were false positives. The four cases in which IO-PTH fell < 50% were classified as two true negatives and two false negatives. A single adenoma was removed in 125 cases, and two or three hyperplastic glands were removed in five cases.

CONCLUSIONS

IO-PTH predicted the postoperative outcome in 125 of 130 cases (96.2%), including two of five cases in which multiple hyperplastic glands were removed, and 1 degree HPT was successfully treated in 97.7% (127/130) of the cases. The IO-PTH procedure can provide valuable confirmation to the endocrine surgeon; however, other sources of information must also be used to ensure that all hyperplastic glands are identified.

Kinetic analysis of the rapid intraoperative parathyroid hormone assay in patients during operation for hyperparathyroidism

BACKGROUND

Rapid intraoperative parathyroid hormone (RI-PTH) assay is used to guide adequacy of resection during operation for hyperparathyroidism. We compared the RI-PTH assay (15 minutes) with a standard PTH assay, determined whether the PTH half-life varied between patients, and constructed a kinetic analysis of the RI-PTH data.

METHODS

Forty-five patients with hyperparathyroidism had blood sampled at baseline and at times after parathyroid resection. Intact PTH was determined using RI-PTH and a standard assay. Values were fitted to an exponential decay curve using the baseline and the follow-up time points. PTH half-life and the new postexcision baseline value were calculated from the decay curve.

RESULTS

The RI-PTH assay and the standard PTH assay correlated well. Average PTH half-life was 1.68 +/- 0.94 minutes (0.42 to 3.81 minutes). A kinetic analysis yielded a formula for the generation of a PTH decay curve. Using a 50% reduction in RI-PTH at 5 minutes as the criterion for adequate resection, 2 patients were incorrectly classified as not being cured. These patients were correctly classified using the kinetic analysis.

CONCLUSIONS

PTH half-life can vary substantially. A kinetic analysis may be more accurate in assessing adequacy of resection. This method allows the surgeon to interpret RI-PTH data independent of the timing of samples.