Intraoperative Parathyroid Hormone Assay Research Articles

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

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

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

Abstract 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 u...

Accuracy of preoperative localization studies and intraoperative parathyroid hormone assay in patients with primary hyperparathyroidism and double adenoma.

The purpose of this retrospective investigation was to evaluate the results of preoperative localization studies and intraoperative parathyroid hormone (IOPTH) assay in patients with primary hyperparathyroidism and double adenomas. Twenty-one of 287 consecutive patients with primary hyperparathyroidism who had double adenomas identified during first-time parathyroid exploration between July 1999 and September 2002 were analyzed. Individual and combined accuracy of preoperative localization studies, and IOPTH assay and their influence on surgical strategy, were compared. Seven percent of these 287 patients had double adenomas. Fifteen of the patients were female and six were male with a mean age of 59 years (range 17 to 76 years). The accuracy of ultrasonography (US) and technetium 99m sestamibi ((99m)TC-sestamibi) was 40% and 30%, respectively, in this select group. Combined accuracy of both tests reached 60% and guided the surgeon to select a bilateral approach. After removal of the first gland, IOPTH failed to decrease by 50% relative to the highest baseline value in 43% of the cases, indicating other hyperfunctioning parathyroid glands. These results prompted the surgeon to explore further after an initially planned focused approach. When the combination of three tests was analyzed, at least one test accurately suggested a double adenoma in 80% of the patients; in 15% of the patients, no test was suggestive of a double adenoma and in 5% the sestamibi scan was false positive. This retrospective investigation documents that neither preoperative localization tests nor IOPTH assay accurately document double adenomas in patients with primary hyperparathyroidism. The combined accuracy of US, sestamibi, and IOPTH assay predicted a double adenoma in 80% of the patients.

Minimally invasive parathyroidectomy.

Efforts to minimize the incision, extent of exploration, length of hospital stay, and cost associated with parathyroidectomy have resulted in the development of a number of new surgical techniques, including minimally invasive, "concise," radio-guided, and endoscopic parathyroid exploration. With minimally invasive parathyroidectomy, a small incision is used in combination with a cervical block and sedation to perform a unilateral neck exploration. In so doing, risks of bilateral neck exploration are avoided, and the procedure can be done on an outpatient basis. This minimally invasive strategy has been shown to maintain the outstanding success of conventional bilateral neck exploration. All of the new surgical techniques necessitate pre-operative localization, which allows for unilateral neck exploration, and are facilitated by use of the intra-operative parathyroid hormone assay, which provides surgeons with feedback in the operating room regarding whether the patient has undergone adequate resection.

Minimally invasive parathyroidectomy: 101 consecutive cases from a single surgeon.

Intraoperative rapid parathyroid hormone (iPTH) assay is changing parathyroid surgery. One surgeon's experience at a tertiary care hospital was followed as minimally invasive parathyroidectomy (MIP) was adopted. In this prospective case study, patients underwent technitium 99m sestamibi scanning, iPTH monitoring, and MIP. A sestamibi-directed incision was made, and iPTH was measured preincision, preexcision of abnormal gland(s), and at 5- and 10-minute intervals. MIP was complete after gland(s) was excised and iPTH fell to less than 50% of preoperative levels. Routine discharge was on the day of surgery with daily calcium and calcitriol to minimize outpatient hypocalcemia. Secondary and tertiary hyperparathyroidism patients were excluded. From December 1999 to June 2002, 101 patients underwent MIP. Patients were 27% men and 73% women, with two reoperations. Preoperation laboratory results averaged serum calcium 11.08 (normal 8.5 to 10.5 mg/dL) and parathyroid hormone (PTH) 169 pg/mL (normal 10 to 55 pg/mL). Average iPTH values at operative intervals were 152, 151, 68, and 50 pg/mL, respectively. Operation demonstrated 12% of patients had four-gland hyperplasia, 3% had double adenomas, 2% had parathyroid carcinomas, and 83% had single adenomas. Discharge on the day of surgery occurred in 83% of single-adenoma patients. Postoperative laboratory results averaged calcium 9.4 mg/dL (p < 0.001 versus preoperation) and PTH 48 pg/mL (p < 0.001). Fifteen patients (16%) had elevated PTH after operation, but without elevated calcium levels. One patient had persistant hyperparathyroidism. MIP with iPTH monitoring is a safe and effective means of treating hyperparathyroidism. This approach allows for limited dissection and early discharge for the majority of patients.

Intraoperative parathyroid hormone assay: an accurate predictor of symptomatic hypocalcemia following thyroidectomy.

Intraoperative parathyroid hormone (IOPTH) assay is useful for predicting symptomatic hypocalcemia following total thyroidectomy. A prospective study of 30 patients undergoing total thyroidectomy with IOPTH levels obtained following skin closure and ionized calcium (Ca2+) levels obtained 6 hours postoperatively and on postoperative day 1. All patients were evaluated for symptoms of hypocalcemia. University teaching hospital. Patients who developed symptomatic hypocalcemia were compared with asymptomatic patients in regard to age, diagnosis, thyroid weight, thyrotropin level, Ca2+ level, parathyroid status, and IOPTH level. The onset of symptomatic hypocalcemia ranged from 8 to 48 hours postoperatively (n = 10). One patient required readmission. Of 10 patients with symptoms, 5 developed tetany. There were no significant differences in age, diagnosis, thyroid weight, thyrotropin level, or the number of parathyroid glands preserved in patients with or without symptomatic hypocalcemia. All patients with an IOPTH level of less than 10 pg/mL (1.1 pmol/L) had symptoms (n = 8). The mean +/- SD IOPTH level (7.6 +/- 12.0 pg/mL [0.8 +/- 1.3 pmol/L]) in patients who developed symptomatic hypocalcemia was significantly lower than the mean IOPTH level (55.7 +/- 31.8 pg/mL [5.9 +/- 3.3 pmol/L]) in patients without symptoms (P =.001). The 6-hour and postoperative day 1 Ca2+ levels were significantly lower in patients with symptomatic hypocalcemia (P =.19 and P =.13, respectively). An IOPTH level of less than 10 pg/mL is 80% sensitive and 100% specific for the development of symptomatic hypocalcemia. The incorporation of the IOPTH assay in the management of thyroid disease is recommended to prevent and prospectively treat symptomatic hypocalcemia, thereby reducing readmissions following thyroidectomy.

Rapid parathyroid hormone analysis during venous localization.

To determine the usefulness of the rapid parathyroid hormone (PTH) assay during venous localization for primary hyperparathyroidism (1 degrees HPTH). Remedial exploration for persistent 1 degrees HPTH poses a significant challenge when noninvasive preoperative localization studies are negative. Based on experience with the intraoperative rapid PTH assay, this technique was extrapolated to the interventional radiology suite and generated near real-time data for the interventional radiologist employing on-site hormone analysis, with a 12-minute turnaround time from blood sampling to assay result. Between November 1997 and July 2002, 446 patients with 1 degrees HPTH were referred for treatment. Of these, 56 (12.5%) represented remedial patients who had each undergone one or more previous cervical explorations. Noninvasive imaging studies were positive for or suggestive of localized disease in 49/56 (87.5%) of these patients, who therefore proceeded directly to surgical exploration. Seven patients with persistent 1 degrees HPTH and negative noninvasive studies underwent selective venous sampling employing a rapid PTH assay in the interventional suite. Venous localization demonstrated an apparent PTH gradient in six of the seven patients. In three, a subtle gradient demonstrated in near real-time prompted additional sampling, which confirmed an unequivocal hormone gradient. In an additional case, the absence of a gradient on initial sampling prompted further sampling, which was positive. All of the patients were explored, and in five of the six patients with a positive PTH gradient, a parathyroid adenoma (mean weight 636 +/- 196 mg) was resected from a location predicted by venous localization. In the sixth patient with a positive gradient, parathyroid tissue was not identified; however, there was a significant fall in the intraoperative PTH values, and immediate postoperative and follow-up laboratory data at 1 month are indicative of a cure. In the one patient with negative localization, abnormal parathyroid tissue could not be located during surgical exploration. The rapid PTH assay is a major adjunct for obtaining informative venous localization in patients with persistent 1 degrees HPTH. This information is extremely helpful to the surgeon in this challenging group of patients and resulted in a 100% cure rate when a venous gradient was demonstrated. The authors now employ this technique routinely in remedial patients with negative noninvasive imaging studies.

Differing histologic findings after bilateral and focused parathyroidectomy.

Minimally invasive parathyroid surgery with intraoperative parathyroid hormone testing has been reported to be as successful as a bilateral operation. This study aimed to determine whether the histologic findings and outcomes differ in patients with primary sporadic hyperparathyroidism treated by a focal or a bilateral parathyroid exploration with intraoperative parathyroid hormone testing. To make the two groups comparable all patients had a solitary parathyroid adenoma identified preoperatively. Eighty unselected patients with primary hyperparathyroidism and a single abnormal parathyroid gland identified preoperatively by sestamibi scanning or ultrasonography were included in this study. All patients had intraoperative parathyroid hormone testing. Forty-five patients had standard bilateral neck explorations and 35 patients had focal neck explorations. In the bilateral neck exploration group a single adenoma was found in 38 patients (84%), a double adenoma in 3 patients (7%), hyperplasia in 3 patients (7%), and carcinoma in 1 patient (2%). In contrast, a single adenoma was identified in all patients in the focal neck exploration group. Sestamibi scanning and intraoperative parathyroid hormone assay were accurate in 87% and 84%, respectively, in the bilateral neck exploration group and in 96.9% and 94.3%, respectively, in the focal neck exploration group. All patients were normocalcemic (mean followup 17 months). Patients with primary hyperparathyroidism having a bilateral exploration had about a 15% higher rate of multiple parathyroid tumors than did patient having a focal approach. Despite this observation all patients were normocalcemic postoperatively. This suggests that either some histologically abnormal parathyroid glands do not function or there will be recurrences in patients treated by a focused approach. Longterm followup will be necessary to determine whether patients treated by focal neck exploration will develop recurrent primary hyperparathyroidism.

Preoperative Sestamibi Localization Combined with Intraoperative Parathyroid Hormone Assay Predicts Successful Focused Unilateral Neck Exploration during Surgery for Primary Hyperparathyroidism

A retrospective review of 54 cases of primary hyperparathyroidism operated upon by five general surgeons at Santa Barbara Cottage Hospital between March 1998 and March 2001 was performed to determine whether positive preoperative sestamibi localization (PSL) of a solitary adenoma combined with intraoperative parathyroid hormone assay (IOPHA) could predict successful focused unilateral neck exploration. A solitary adenoma was found in each of 50 patients (93%). PSL for solitary adenomas had an accuracy of 87 per cent, positive predictive value (PPV) of 96 per cent, sensitivity of 90 per cent, and specificity of 50 per cent. Forty-five patients (83%) achieved a 50 per cent reduction in IOPHA at 10 minutes after excision of a solitary adenoma for an accuracy of 85 per cent, PPV of 97 per cent, sensitivity of 88 per cent, and specificity of 50 per cent. All patients remain eucalcemic. The combination of PSL and IOPHA resulted in a PPV of 97.5 per cent and a sensitivity of 100 per cent. From these data we conclude that a focused unilateral neck exploration could have been performed successfully in 78 per cent of the cases.

Long-term results of less than total parathyroidectomy for hyperparathyroidism in multiple endocrine neoplasia type 1

Background. Our aim was to assess long-term results after less than total parathyroidectomy for hyperparathyroidism in multiple endocrine neoplasia type 1. Methods. Of 1888 patients undergoing operation at our institution for primary hyperparathyroidism between 1972 and 2001, 83 (4.4%) had multiple endocrine neoplasia type 1. Outcome data were available for 79; 66 underwent subtotal parathyroidectomy, 55 (83%) of these with bilateral thymectomy. In 13 patients, only grossly enlarged glands were resected (mean 1.1 per patient) as the syndrome of multiple endocrine neoplasia type 1 was not yet evident or the initial exploration was performed elsewhere. Results. Follow-up has been 48 ± 51 months (mean + SD). Intraoperative serum PTH assay decay in 20 patients was suggestive of cure in 18 patients, none of whom required reoperation. Nine patients (11%) required reoperation (3 required reoperation twice) after a mean interval of 77 ± 53 months. Subtotal parathyroidectomy resulted in a lesser reoperation rate than resection of grossly enlarged glands (7% vs 30%, P =.02). At the time of review, 63 patients (80%) were normocalcemic, 10 (13%) hypocalcemic (2 after unsuccessful delayed autograft), and 7% hypercalcemic (none after reoperation). By Kaplan-Meier analysis, the rate of surgical cure (patients who are nonhypercalcemic) is 60% and 51% at 10 and 15 years, respectively. Conclusion. Subtotal parathyroidectomy reduces the need for reoperation. Selective reoperation leads to long-lasting biochemic cure. (Surgery 2002;132:1119-25.)

Limited versus radical parathyroidectomy in familial isolated primary hyperparathyroidism

Background. Familial isolated primary hyperparathyroidism (FIHPT) is characterized by earlier onset, higher incidence of multiglandular disease, and higher recurrence rate when compared with sporadic primary hyperparathyroidism. Excision of 3.5 or 4 glands with autotransplantation has been recommended; however, these approaches lead to permanent hypoparathyroidism in 13% to 41% of patients. It is reported that many patients with FIHPT return to normocalcemia after single-gland excision. The use of preoperative localization and intraoperative parathyroid hormone assay permits limited resection of only hypersecreting glands. We report the outcome of this operative approach. Methods. Fifteen consecutive patients with FIHPT underwent limited parathyroidectomy with resection guided by intact parathyroid hormone secretion in 2 university centers. Patients were followed up postoperatively for serum calcium and intact parathyroid hormone levels. Results. With an operative success of 93%, 14 patients had only single-gland excision and 80% had unilateral neck exploration. All initial patients had their hypercalcemia corrected. In 4 reoperations, permanent hypoparathyroidism occurred in 2 patients. One recurrence was observed in 40 (8-122) months of follow-up. Conclusion. Limited parathyroidectomy allows successful single-gland excision in many patients with FIHPT, thus decreasing the risk of hypoparathyroidism. In these patients, a low incidence of hypoparathyroidism may be preferable to the possibility of late recurrence. (Surgery 2002;132:1050-5.)

Utility of rapid intraoperative parathyroid hormone assay to predict severe postoperative hypocalcemia after reoperation for hyperparathyroidism

Background. Patients undergoing reoperative parathyroidectomy may develop severe transient or permanent hypoparathyroidism. This study's purpose was to determine the utility of intraoperative parathyroid hormone (IO-PTH) values in predicting the development of severe hypocalcemia for patients undergoing reoperation for primary hyperparathyroidism. Methods. Between March 1999 and October 2001, 68 patients with persistent or recurrent hyperparathyroidism underwent reoperation using IO-PTH measurements. The maximum percent decrease and lowest actual PTH value obtained at surgery were compared to determine any correlation with the development of postoperative hypocalcemia requiring supplementation. Results. Of 68 patients, 25 required calcium and calcitriol postoperatively and 43 did not. There was a significant difference between the 2 groups with respect to lowest IO-PTH value (18.4 ± 2.6 vs 28.0 ± 3.9 pg/mL; P =.02), percent decrease in IO-PTH (89% ± 1% vs 80% ± 3%; P =.03), and lowest postoperative ionized calcium (1.06 ± 0.01 vs 1.19 ± 0.01 mmol/L; P <.001). A percent decrease in IO-PTH of 84% or greater was found to be predictive of patients experiencing hypocalcemia requiring supplementation with a positive predictive value of 46% and a negative predictive value of 82%. Conclusions. Although a maximum percent decrease in IO-PTH of 84% or greater was associated with an increased incidence of postoperative hypocalcemia requiring supplementation in the 68-patient cohort, on further analysis the association was significant only for patients with multiglandular disease and not those with single adenomas. This value may be useful for identifying patients who will need closer postoperative monitoring or prophylactic supplementation. (Surgery 2002;132:1028-34.)

Applicability of intraoperative parathyroid hormone assay during thyroidectomy.

To evaluate the applicability of intraoperative parathyroid hormone (quick PTH) assay to monitor parathyroid function and to identify clinically significant hypocalcemia compared with postoperative serum calcium monitoring. Close monitoring of serum calcium levels is a standard of care to identify post-thyroidectomy hypocalcemia due to parathyroid insufficiency. Quick PTH assay was performed before and after thyroidectomy for 100 patients at risk of postoperative hypocalcemia and 20 control patients who underwent unilateral lobectomy. Postoperative serum calcium levels were closely monitored. Control patients had a normal but 38.9 +/- 5.9% (mean +/- SEM) decline in quick PTH after thyroidectomy. Eleven of 100 at-risk patients (11%) developed postoperative hypocalcemia. Hypocalcemic patients had significantly lower quick PTH values after thyroidectomy compared with that of normocalcemic patients. Serum calcium was significantly lower in hypocalcemic patients the morning after operation but not early after the operation (within 6 hours). A normal or less than 75% decline in quick PTH after thyroidectomy can accurately identify normocalcemic patients during surgery as compared to more than 24 hours by serum calcium monitoring. The quick PTH assay can monitor parathyroid function during thyroidectomy and identify patients at risk of clinically significant hypocalcemia much earlier than serum calcium monitoring. It may facilitate early discharge and the use of parathyroid autotransplantation during thyroidectomy.

Chirurgie parathyroïdienne dirigée : une série de 100 patients consécutifs

Introduction: The treatment of primary hyperparathyroidism has long required a bilateral neck exploration to localize all parathyroid glands. New techniques in pre-operative imaging (technetium-99m-sestamibi scanning, high resolution ultrasonography) have allowed an accurate localization of pathological glands. Moreover, the intraoperative intact parathyroid hormone assay (iPTH) now permits to confirm the resection of all hyper-secreting glands. Material and methods: Two hundred and twenty patients underwent parathyroid operations during the last 3 years, by different minimally invasive techniques. Pre- and intra-operative data, as well as the follow-up were recorded prospectively. The results of the last 100 unilateral approaches, performed for primary hyperparathyroidism, were analyzed. Results: There were 78 women and 22 men, with a mean age of 57 ± 15 years (25 to 92 years). Mean operative time was 44 ± 25 min. Ninety-three solitary adenomas, three double adenomas, three carcinomas and one hyperplasia were resected. Two patients required a bilateral exploration. There was one intra-operative complication (pneumothorax) during the resection of a mediastinal gland. Three post-operative complications occurred, with 2 hematomas and one transient recurrent laryngeal nerve paralysis. Median hospital stay was 2 ± 7,5 hours (1–72 hours). All patients were cured following the operation, as predicted by the intra-operative iPTH assays. Conclusion: These results suggest that unilateral, targeted, neck explorations offer a cure rate similar to those obtained by bilateral neck explorations. Moreover, this operation can be performed under local anesthesia, with a short hospital stay and recovery time. The morbidity rate is low but should be addressed by large-scale comparative studies.

Section 1. Parathyroid: Intraoperative quick parathyroid hormone assay in the surgical management of hyperparathyroidism

Intraoperative quick parathyroid hormone (QPTH) assay is claimed to prevent failure during parathyroidectomy for hyperparathyroidism. The causes of operative failure have included multiglandular disease, ectopic parathyroid glands, supernumerary parathyroid glands, errors in frozen section evaluations, and missed diagnosis. A QPTH assay has been recognized as a useful method of determining whether hyperfunctioning tissues have been completely excised. However, an intraoperative QPTH assay may fail to detect the presence of double parathyroid adenomas. Use of this assay in conjunction with preoperative and intraoperative localization studies has led to the advocacy of more directed cervical procedures, such as limited, video-assisted, and endoscopic parathyroidectomy.

Section 1. Parathyroid: Total endoscopic parathyroidectomy

During the last five years, minimally invasive procedures have been adopted for the surgical treatment of hyperparathyroidism, because preoperative localization studies such as high-resolution ultrasonography and sestamibi scintigraphy, guidance by intraoperative scans, and the use of quick, intraoperative parathyroid hormone assay have improved. Endoscopic parathyroidectomy was performed by Gagner in 1996, and surgical procedures using endoscopy have been devised. The endoscopic procedures range from the “pure” endoscopic approach characterized by constant gas insufflation to video-assisted gasless techniques. We adopted the “pure” endoscopic approach, because a small incision can be made far from the neck and the cosmetic result is excellent. We report our technique with no scars in the neck region for endoscopic unilateral neck exploration with primary hyperparathyroidism and for endoscopic bilateral neck exploration with renal hyperparathyroidism.

Worldwide trends in the surgical treatment of primary hyperparathyroidism in the era of minimally invasive parathyroidectomy.

Minimally invasive surgery for primary hyperparathyroidism has become an accepted part of endocrine surgical practice worldwide. Survey of members of the International Association of Endocrine Surgeons. Clinical practice of endocrine surgeons worldwide. Numbers of parathyroid procedures performed, types of minimally invasive procedures undertaken, and techniques used to ensure completeness of removal of hyperfunctioning parathyroid tissue as reported by the survey respondents. Of 160 surveys completed, 95 (59%) indicate that the surgeons currently perform minimally invasive parathyroidectomy and use this technique on average for 44% of patients with primary hyperparathyroidism. The most common approach is the focused technique with a small incision, either central or lateral (92% [87 respondents]), followed by a video-assisted technique (22% [21 respondents]), and a true endoscopic technique with gas insufflation (12% [11 respondents]). Techniques used to ensure completeness of resection include the quick intraoperative intact parathyroid hormone assay (68% [65 respondents]), a same-day intact parathyroid hormone assay (17% [16 respondents]), and the nuclear probe (14% [13 respondents]). The number of parathyroidectomies performed worldwide increased from 1727 in 1980 to 6977 in 2000 with the average number per surgeon increasing from 23 in 1980 to 45 in 2000. Geographically, 20 (59%) of 34 surveys from the Americas report the use of minimally invasive parathyroidectomy, 23 (56%) of 41 from the Australasian region, and 34 (49%) of 69 from Europe or the Middle East. The number of parathyroidectomies performed for primary hyperparathyroidism has increased worldwide over the past 20 years. More than half of the surgeons responding to the survey perform minimally invasive parathyroidectomy, with the most using the focused small-incision technique.

Section 1. Parathyroid: Endoscopic neck surgery: current status for thyroid and parathyroid diseases

During the last 3 years, 59 patients underwent endoscopic neck surgery. We started the video-assisted neck surgery with the gasless skin-lifting method for benign thyroid and parathyroid diseases to avoid complications of carbon dioxide (CO 2) insufflation. Hemithyroidectomy was performed for benign thyroid tumors and subtotal thyroidectomy was selected for Graves’ disease. Parathyroid adenomas were extirpated for primary hyperparathyroidism with precise preoperative localization by imaging modalities. In order to obtain a better visual field and to improve the cosmetic results, we have adopted the complete endoscopic method via breast approach with low CO 2 insufflation pressure since August 2001. An intraoperative parathormone assay was introduced recently to confirm the complete removal of parathyroid adenomas. Both gasless and insufflation methods are feasible for endoscopic neck surgery with excellent cosmetic results.

New point-of-care intraoperative parathyroid hormone assay for intraoperative guidance in parathyroidectomy.

The use of the intraoperative parathyroid hormone assay (QPTH) to guide a limited parathyroidectomy in patients with sporadic primary hyperparathyroidism (SPHPT) is well established. The advantage of having this assay performed in the operating room is immediate feedback for (1) confirming the complete excision of all hyperfunctioning parathyroid(s); (2) differential jugular venous sampling for localization; and (3) diagnosing suspected tissue without histopathology. For these reasons, the reliability of the hormone measurement and a short assay turnaround time are essential for surgical guidance. We report our experience using a new "point-of-care" assay for intact parathyroid hormone (iPTH). A new two-site chemiluminescent immunometric assay was used. The antibodies are inside a microtiter well, where the iPTH is measured by a strip luminometer after incubation for 5 minutes. Sixteen frozen samples were measured simultaneously using the traditional iPTH assay and this new assay for comparison. Fifty-one patients with SPHPT underwent parathyroidectomy guided by this new assay. The criteria used to predict postoperative normocalcemia was a drop in the hormone level of < or = 50% from the highest preincision or preexcision levels at 10 minutes after excision of all hypersecreting gland(s). The correlation between the traditional and new assays was 0.98. The assay predicted the postoperative calcium levels in all patients except one (false negative-delayed drop). The assay turnaround time was 8 minutes. This new point-of-care assay is reliable for predicting postoperative calcium levels when used with the described criteria. It has advantages over the traditional assay in that it is faster and easier to perform.

A quick intraoperative parathyroid hormone assay in the surgical management of patients with primary hyperparathyroidism: a study of 206 consecutive cases.

The traditional surgical approach for patients with primary hyperparathyroidism (PHPT) consists of the identification of at least four glands and in the removal of all hyperfunctioning parathyroid tissue. To evaluate whether intraoperative parathyroid hormone (PTH) monitoring will allow a more limited surgical procedure by confirming complete removal of all hyperfunctioning tissue. Plasma samples were obtained from 206 consecutive patients with sporadic PHPT before skin incision, during manipulation of a suspected adenoma, and 5 min (T-5) and 10 min after removal of abnormal parathyroid tissue. PTH was measured by a quick immunochemiluminescent assay (QPTH). The operative success was defined by a decrease of PTH greater than 50% of the highest pre-excision value. A >50% decrease of PTH occurred in 203 patients and was evident at T-5 in the majority of cases. All but three had normal serum calcium the day after surgery and afterwards. PTH concentration did not show a >50% decrease in the remaining three cases after completion of surgery. One patients had negative neck exploration and remained hypercalcemic; the other two had normal serum calcium at follow-up. Thus, the intraoperative QPTH correctly predicted the outcome of surgery in 201 patients (97.5%) (200 true positive and 1 true negative), and provided three false positive and two false negative results. The intraoperative QPTH measurement represents a useful tool to assist the surgeon during parathyroidectomy. It indicates whether all hyperfunctioning parathyroid tissue has been removed, limiting the procedure to a unilateral neck exploration in most cases.