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

Clinical Biomarkers in Otolaryngology-Head and Neck Surgery

OBJECTIVE

The purpose of this paper is to review the literature and compile promising and clinically relevant biomarkers in otolaryngology-head & neck surgery not related to autoimmune disorders.

STUDY DESIGN

Narrative review.

METHODS

PubMed and Google Scholar were queried using combined key words such as "biomarkers" and "otolaryngology." Additional queries were made with combined key words such as "biomarkers" and a particular subspecialty such as "rhinology" or "otology" to maximize yield of relevant titles. Subsequently, specific biomarkers identified, such as "beta-2 transferrin," were used as key words. Relevant titles were reviewed and selected for abstract review. Applicable abstracts were then selected for review of the full text.

RESULTS

Biomarkers currently in clinical use within the field of otolaryngology were included in this review. The compiled biomarkers were then detailed individually regarding their molecular characteristics, function, and clinical significance.

CONCLUSIONS

The number of biomarkers in use in otolaryngology is rapidly expanding representing a new diagnostic modality for our field. This review defines the key biomarkers that are currently or likely to be soon translated into clinical use within the field of otolaryngology. The majority of these biomarkers are in the form of proteins such as beta-2 transferrin, thyroglobulin, and P16. Given their growing impact on diagnosis, management and surveillance of otolaryngologic disorders periodic surveys are needed for education and to guide further advances and applications of otolaryngologic biomarkers.

OUP accepted manuscript

Background

Several studies have reported on the use of intraoperative parathyroid hormone (ioPTH) measurements during parathyroidectomy (PTX) for renal hyperparathyroidism (rHPT), but there is no consensus on whether it is helpful and, if so, what protocol should be used. Therefore, the literature was systematically reviewed to assess a correlation between ioPTH and early postoperative parathyroid hormone (PTH) levels in patients undergoing PTX for rHPT, separately for those on dialysis and those with a functioning renal transplant.

Methods

A systematic literature search was performed in electronic databases. Quality assessment was performed using the Quality In Prognosis Studies tool. Mean ioPTH values were calculated at different time points and correlated to the postoperative PTH levels within 1 month. Fixed-effect and random-effects models were performed to assess the mean ioPTH levels at 10 or 20 min after resection (T10 and T20). Stratified analyses were performed for patients on dialysis and those with a functioning renal transplant.

Results

Of the 3087 records screened, 14 studies were included, including some 1177 patients; 1091 were on dialysis and 86 had a functioning kidney transplant. Risk of bias was moderate for most studies. For patients on dialysis, T10 and T20 mean ioPTH levels were 32.1 (95 per cent c.i. 24.3 to 39.9) pmol/l and 15.4 (95 per cent c.i. 7.8 to 22.9) pmol/l) in the random effects meta-analysis. Between individual studies, ioPTH ranged from 4.0–65.1 pmol/l at T10 and 8.6–25.7 pmol/l at T20. T10 and T20 ioPTH were 9.6 and 4.1 times the postoperative PTH—after T20 ioPTH stabilized in those on dialysis. In patients with a functioning renal transplant, ioPTH levels seemed to plateau after 10 min and measured 2.6 times the postoperative PTH.

Conclusion

There is a strong correlation between ioPTH and early postoperative PTH levels, indicating that ioPTH is potentially a useful instrument during PTX in patients with rHPT. For patients on dialysis, at T20 ioPTH levels have stabilized and are approximately four times the postoperative PTH. Therefore, it is recommended to use ioPTH 20 min after resection in patients on dialysis, which might be longer than necessary for those with a kidney transplant.

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.

Incidentally discovered severe hypercalcaemia from a functioning parathyroid cyst: the limitations of intraoperative parathyroid hormone (IOPTH) monitoring

Parathyroid cysts (PCs) are rare pathologies and are typically non-functional (do not secrete parathyroid hormone (PTH)). The aetiology of PCs is highly debated, and management is complex. We present a unique case of a parathyroid adenoma contained within a functional PC and highlight the limitations of intraoperative PTH monitoring during the surgical resection of functional PCs.

The role of intraoperative parathyroid hormone (IOPTH) determination for identification and surgical strategy of sporadic multiglandular disease in primary hyperparathyroidism (pHPT)

Intraoperative PTH monitoring (IOPTH) made minimally invasive parathyroidectomy in patients with primary HPT possible. However, with the increasing accuracy of preoperative localization studies there is a growing discussion if IOPTH is necessary in patients with localized single gland disease (concordant preoperative localization studies). Different interpretation criteria have been developed - each with their particular advantages and disadvantages, but the "perfect" criterion is still missing. Despite several pitfalls, which can be recognized intraoperatively and do not necessarily lead to a more extensive surgery, IOPTH seems to be a useful adjunct in surgery for PHPT. However, according to current guidelines, selected patients may be operated without IOPTH but need to be informed about the possibly increased risk of recurrent disease.

Analytical Differences in Intraoperative Parathyroid Hormone Assays

BACKGROUND

We compared the rates of intraoperative parathyroid hormone (PTH) decline using the Siemens Immulite^® Turbo PTH and Roche Elecsys^® short turnaround time PTH assays in 95 consecutive surgical patients to investigate analytical and turnaround time (TAT) differences between the tests performed in the operating room (OR) vs the central clinical chemistry laboratory (CCL).

METHODS

Serial blood samples from 95 patients undergoing parathyroidectomy were collected and measured using the 2 immunoassays. Specimens from the first 15 patients were measured simultaneously in the OR and CCL and used for the TAT study. In addition to 2 baseline samples, specimens were collected at 5, 10, and 15 min (for some patients, >15 min) after parathyroidectomy.

RESULTS

In the TAT study, a significant difference was observed (OR median 20 min vs CCL median 27 min; P < 0.05). Of the 95 patient series, slower rates of parathyroid hormone decrease were observed in approximately 20% of the patients when comparing the Roche with the Immulite immunoassay.

CONCLUSIONS

There was a slightly longer TAT in the CCL compared with running the assay directly within the OR (median difference of approximately 7 min). For a majority of the patients, both methods showed equivalent rates of PTH decline; however, for approximately 20% of the patients, there was a slower rate of PTH decline using the Roche assay.

Is intraoperative parathyroid hormone monitoring necessary in symptomatic primary hyperparathyroidism with concordant imaging?

INTRODUCTION

Symptomatic primary hyperparathyroidism (PHPT) is still seen frequently in referral centers all over India. These patients require parathyroidectomy and this study aimed to assess the roll of intraoperative parathyroid hormone (PTH) assay when concordant results of two localization studies were available.

STUDY DESIGN

We analyzed the case records of patients who underwent parathyroidectomy for PHPT from January 2005 to June 2015.

RESULTS

Of 143 patients included in the study, technetium 99m methoxyisobutylisonitrate dual phase scintigraphy showed true positive images in 93.7% and high definition ultrasonography in 84.6% of patients. Concordance in localization studies was observed in 121 (84.6%) patients, successful parathyroidectomy was done in 117 (96.7%) patients with concordant localization studies. Intraoperative PTH monitoring showed 97.84% sensitivity and 75% specificity and predicted failure in 2 patients with concordant imaging. However, re-exploration was not successful in these patients.

CONCLUSION

When concordant result is available between parathyroid scintigraphy and anatomical imaging surgical cure rate is high in trained hands. Re-exploration is unlikely to be successful since these patients require higher imaging.

Intra-operative parathyroid hormone monitoring through central laboratory is accurate in renal secondary hyperparathyroidism

OBJECTIVE

The usefulness, the methods and the criteria of intra-operative monitoring of the parathyroid hormone (ioPTH) during parathyroidectomy (PTX) for renal secondary hyperparathyroidism (rSHPT) in patients on chronic hemodialysis remain still matter of debate. The present study aimed to evaluate the ability of a low cost central-laboratory second generation PTH assay to predict an incomplete resection of parathyroid glands (PTG).

METHODS

The ioPTH decay was determined In 42 consecutive patients undergoing PTX (15 subtotal and 27 total without auto-transplant of PTG) for rSHPT. The ioPTH monitoring included five samples: pre-intubation, post-manipulation of PTG and at 10, 20 and 30min post-PTG excision. The patients with PTH exceeding the normal value (65pg/ml) at the first postoperative week, 6 and 12months were classified as persistent rSHPT.

RESULTS

The concentrations of ioPTH declined significantly over time in patients who received total or subtotal PTX; however, no difference was found between the two types of PTX. Irrespective of the type of PTX and the number of PTG removed, combining the absolute and percentage of ioPTH decay at 30min after PTG excision, we found high sensitivity (100%), specificity (92%), negative predictive value (100%) and accuracy (93%) in predicting the persistence of rSHPT.

CONCLUSIONS

The monitoring of the ioPTH decline by a low cost central-laboratory second generation assay is extremely accurate in predicting the persistence of disease in patients on maintenance hemodialysis undergoing surgery for rSHPT.

Intraoperative parathyroid hormone assay-cutting the Gordian knot

BACKGROUND

Hyperparathyroidism is treated by surgical excision of the hyperfunctioning parathyroid gland. In case of adenoma the single abnormal gland is removed, while in hyperplasias, a subtotal excision, that is, three-and-a-half of the four glands are removed. This therapeutic decision is made intraoperatively through frozen section evaluation and is sometimes problematic, due to a histological overlap between hyperplasia and the adenoma. The intraoperative parathyroid hormone (IOPTH) assay, propogated in recent years, offers an elegant solution, with a high success rate, due to its ability to identify the removal of all hyperfunctioning parathyroid tissue.

AIM

To study the feasibility of using IOPTH in our setting.

MATERIALS AND METHODS

Seven patients undergoing surgery for primary hyperparathyroidism had their IOPTH levels evaluated, along with the routine frozen and paraffin sections.

RESULTS

All seven patients showed more than a 50% intraoperative fall in serum PTH after excision of the abnormal gland. This was indicative of an adenoma and was confirmed by histopathological examination and normalization of serum calcium postoperatively.

CONCLUSION

The intraoperative parathyroid hormone is a sensitive and specific guide to a complete removal of the abnormal parathyroid tissue. It can be incorporated without difficulty as an intraoperative guide and is superior to frozen section diagnosis in parathyroid surgery.

Feasibility of rapid parathormone assay for enabling minimally invasive parathyroid excision

There is no doubt that the success of minimally invasive parathyroidectomy (MIP) has changed the whole treatment of patients with primary hyperparathyroidism, especially the approach towards traditional bilateral neck exploration. A single adenoma is the most common cause of primary hyperparathyroidism and its removal results in cure. Hence, it is worth the effort to localise and excise the single adenoma using modern technologies such as high-quality sestamibi scans and to confirm complete excision using rapid intra operative parathormone (IOPTH) assays. The objective of the study was to evaluate the feasibility of rapid IOPTH assay in successfully facilitating minimally invasive parathyroid excision. This research involved the retrospective study of seven patients, who underwent MIP at Sagar Hospital in Bengaluru, India, for parathyroid adenoma. All patients with evidence of unifocal disease on sestamibi scanning and cervical ultrasonography, underwent MIP via 2-3 cm lateral incision. Blood samples for measurement of IOPTH were taken at the time of induction of anaesthesia and 10 min after the adenoma excision. Reduction of parathormone (PTH) levels of more than 50 % in the postexcision sample was taken as evidence for complete extirpation of parathyroid adenoma. A solitary adenoma was identified in all the seven patients. After MIP, IOPTH levels fell in six of the seven patients. Following the surgery, all the cases were followed up for a period of 1 month. During this time, except for one patient, six patients remained asymptomatic and blood tests revealed normal serum calcium levels. A histopathological examination confirmed the diagnosis of parathyroid adenoma in six of the seven patients. After accurate preoperative localisation of the adenoma in patients with primary hyperparathyroidism, MIP with IOPTH measurement offers a safe and successful outcome.

Intraoperative parathyroid hormone concentration to confirm removal of hypersecretory parathyroid tissue and time to postoperative normocalcaemia in nine dogs with primary hyperparathyroidism

OBJECTIVE

To determine (1) whether the intraoperative parathyroid hormone concentration ([PTH]) during parathyroidectomy (PTX) can be used to indicate cure in dogs with primary hyperparathyroidism and (2) the time taken for postoperative serum calcium concentration to normalise.

DESIGN

Retrospective study (2005-10) from a private referral hospital in Sydney, New South Wales, Australia.

PROCEDURE

Nine client-owned dogs underwent surgical PTX for naturally occurring primary hyperparathyroidism. [PTH] was measured from serum samples taken immediately post-induction (pre-PTX]) and at least 20 min after adenoma removal (post-PTX) for all dogs, and during parathyroid gland manipulation (intra-PTX) for six dogs. The concentration of ionised calcium (iCa) was measured at various time points postoperatively until it normalised, then stabilised or decreased below reference ranges. Statistical analysis compared the mean pre-, intra- and post-PTX [PTH] and the average rate of decline of iCa concentration postoperatively.

RESULTS

All dogs demonstrated a significant decrease from mean pre-PTX [PTH] (168.51 pg/mL) to mean post-PTX [PTH] (29.20 pg/mL). There was a significant increase in mean intra-PTX [PTH] (279.78 pg/mL). The average rate of decline of iCa concentration postoperatively to within the reference range (1.12-1.40 mmol/L) occurred after 24 h.

CONCLUSION

Intraoperative measurements of [PTH] can be used clinically to determine cure of primary hyperparathyroidism. Parathyroid hormone increases significantly during parathyroid gland manipulation. Plasma iCa concentration returns to within the reference range on average 24 h after successful PTX. Not all dogs require vitamin D or calcium supplementation pre- or postoperatively.

Rapid intraoperative parathyroid hormone assay in the surgical management of hyperparathyroidism

CONTEXT

Historically, successful surgical management of primary hyperparathyroidism has required bilateral exploration of the neck. By confirming complete removal of hypersecreting tissue, an intraoperative parathyroid hormone (IO-PTH) assay allows use of a more limited procedure.

OBJECTIVE

Our objective was to evaluate the utility of IO-PTH assay used in 32 parathyroid explorations versus conventional bilateral exploration used before the advent of IO-PTH assays.

METHODS

Minimally invasive parathyroidectomy (MIP) was used. Plasma samples were obtained at several intervals and were analyzed for IO-PTH by use of a rapid immunochemiluminescent assay (ICMA). Outcomes were assessed by univariate inferential testing, yielding one-tailed t-test results.

RESULTS

The study group had a mean plasma IO-PTH level decrease of 87% at ten minutes after excision. All 32 patients who underwent MIP using IO-PTH monitoring had successful surgery. At last postoperative follow-up examination, all 32 patients were normocalcemic. There were statistically significant decreases in duration of surgery, length of hospital stay, and surgery cost.

CONCLUSIONS

IO-PTH levels predicted the postoperative outcome for all patients studied, can provide valuable information to surgeons, and can decrease the duration of surgery and hospital stay.

A fast intraoperative PTH point-of-care assay on the Philips handheld magnotech system

Background

Intraoperative parathyroid hormone (ioPTH) is used during minimally invasive parathyroidectomy (MIP) to predict the success of surgery and should be accurate with a short turnaround time.

Material and method

We developed an ioPTH point-of-care (POC) assay on Philips handheld magnotech system. Magnotech technology is based on magnetically controlled movement of superparamagnetic nanoparticles in stationary sample fluid. During first phase, intact-PTH is captured by magnetic particles coated with anti-N-terminal-PTH antibodies. Subsequently, magnetic particles are collected by magnetic forces at sensor surface coated with anti-C-terminal-PTH antibodies. Unbound/nonspecifically bound particles are pulled away from detection surface, using a second magnetic force. Amount of specifically bound particles is measured using a surface-sensitive optical imaging technique.

Results

ioPTH test could be performed with a turnaround time of less than 10 min and could detect low intact-PTH concentrations (picomolar). Integrated cartridge contains a blood separation filter and dry reagents for the assay.

Conclusion

The next magnotech ioPTH assay will be the only POC test able to give accurate results in less than 10 min, using 25 μL of whole blood. Thanks to the ease-of-use, magnotech ioPTH could be performed in the operating theater by any member of surgical staff.

Minimally invasive parathyroidectomy: benefits and requirements of localization, diagnosis, and intraoperative PTH monitoring. long-term results

BACKGROUND

Surgery is the only curative treatment for primary hyperparathyroidism. Initial parathyroidectomy procedures fail due to ectopic gland location and unappreciated multigland disease.

METHODS

An evidence-based literature review was performed,which surveyed all human studies in PubMed, searching for parathyroidectomy in humans between 1990 and 2009. Between 10 and 30% of patients have multigland disease caused by double adenomas or hyperplasia. Use of preoperative imaging studies and intraoperative PTH monitoring helps parathyroid surgeons overcome these obstacles.

RESULTS

Sestamibi nuclear scan and neck ultrasound identify 70-80% of abnormal glands in patients with single adenomas. The sensitivity of ultrasound or sestamibi to identify all abnormal glands in patients with multigland disease is extremely low. Intraoperative PTH monitoring should be utilized in all patients who undergo neck exploration for primary hyperparathyroidism to reduce failures due to multigland disease. Blood samples should be drawn from peripheral veins only and a postresection level 10-15 min after gland removal should have a >50%decrease from baseline preoperative levels, and also must go to the normal range for the PTH assay being used.

CONCLUSIONS

Contemporary prospective studies (level of evidence III/IV) show that by combining preoperative imaging and IOPTH it is possible to maximize performance of successful outpatient minimally invasive parathyroidectomy.

[Intraoperative parathyroid hormone determination for primary hyperparathyroidism]

Intraoperative parathyroid hormone measurement (IOPTH) has proved to be an important promoter for focused and minimally invasive parathyroidectomy procedures in primary hyperparathyroidism. IOPTH enables multiglandular disease to be excluded with a high degree of certainty at the time of operation. The choice of the cut-off value for IOPTH as the criterion for success is of utmost importance with respect to the prognosis for operative success (biochemical healing). Advantages and disadvantages of the variety of existing IOPTH success criteria are confusing and their assessment is contradictory. Particularly with respect to cost-benefit aspects the standard application of IOPTH as "biochemical frozen section" even in conventional open parathyroidectomy remains a matter of controversy. This article gives an up-date on current knowledge and provides practical guidelines for clinical use of IOPTH.

Validity and limits of intraoperative parathyroid hormone monitoring during minimally invasive parathyroidectomy: a 10-year experience

BACKGROUND

The availability of intraoperative intact parathyroid hormone monitoring allows the success of minimally invasive parathyroidectomy to be ensured during the operation. However, false-negative results leading to unnecessary explorations and difficulties in interpreting the data raise concern about the effectiveness of the method.

METHODS

Patients with primary hyperparathyroidism (pHPT) and one unequivocally enlarged parathyroid gland on preoperative ultrasound or (99m)Tc-SestaMIBI scintigraphy underwent minimally invasive video-assisted parathyroidectomy according to the technique initially described by Miccoli. Intraoperatively, rapid electrochemiluminescence immunoassay was used to measure intact parathyroid hormone (iPTH) levels before the operation, after complete mobilization of the adenoma (preexcision value), and 5, 10, and 15 min after the excision. The operation was considered successful when more than a 50% decrease in preexcision iPTH levels and subsequent attainment of the normal range within 15 min were observed.

RESULTS

Between November 1999 and November 2009, 235 (43%) of 546 patients with pHPT were eligible for a minimally invasive approach. Intraoperative iPTH monitoring showed 221 true-positive, 1 false-positive, 6 false-negative, and 7 true-negative results. This calculated to a sensitivity of 97% and a specificity of 88%.

CONCLUSIONS

Despite the availability of high-resolution ultrasound and (99m)Tc-SestaMIBI scintigraphy, the presence of multiple glandular disease cannot be ruled out completely. Although the authors observed six false-negative results, they believe that intraoperative iPTH monitoring represents a valuable asset for minimally invasive parathyroidectomy because it identifies sporadic hyperplasia.

Intraoperative adjuncts in surgery for primary hyperparathyroidism

PURPOSE

This paper is a review of the evidence base to produce recommendations for the use of intraoperative parathyroid hormone (PTH), radioguided parathyroidectomy (RGP), methylene blue (MB), frozen section, and intraoperative neuromonitoring during surgery for primary hyperparathyroidism (PHPT).

MATERIALS AND METHODS

A Medline keyword search of English-language articles led to the production of a draft document, subsequently revised by committee, containing levels of evidence and the grading of recommendations as proposed by the Agency for Healthcare Research and Quality.

RESULTS

Literature review provides the basis for clear recommendations on the use of intraoperative PTH at surgery for PHPT. There is little evidence to support the use of RGP, MB, routine frozen section, and intraoperative neuromonitoring.

Evaluation of Halle, Miami, Rome, and Vienna intraoperative iPTH assay criteria in guiding minimally invasive parathyroidectomy

BACKGROUND AND AIMS

Intraoperative parathyroid hormone assay (IOPTH) has been used during minimally invasive parathyroidectomy (MIP) to predict operative success. However, the applied criteria are not equivalent in detection of multiglandular disease (MGD) and predicting cure. The purpose of this study was to evaluate the most commonly applied criteria of IOPTH in patients undergoing MIP in a tertiary referral center.

MATERIALS AND METHODS

A retrospective review of 260 patients with sporadic primary hyperparathyroidism and concordant results of sestamibi scanning and ultrasound of the neck undergoing MIP (135 video-assisted and 125 open) between Dec 2002 and May 2008, with a 6-month postoperative follow-up of intact parathyroid hormone and serum calcium levels, was performed. The main outcome measures included evaluation of predictive values of Halle, Miami, Rome, and Vienna IOPTH interpretation criteria.

RESULTS

The following overall accuracy, sensitivity, specificity, positive predictive value, and negative predictive values were found, respectively: 65%, 62.9%, 100%, 100%, and 14.2% for Halle criterion; 97.3%, 97.6%, 93.3%, 99.6%, and 70% for Miami criterion; 83.8%, 82,9%, 100%, 100%, and 26.3% for Rome criterion; and 92.3%, 92.2%, 93.3%, 99.6%, and 60.9% for Vienna criterion.

CONCLUSIONS

Miami criterion followed by Vienna criterion was found to be the best balanced among other criteria, with the highest accuracy in intraoperative prediction of cure. However, Rome criterion followed by Halle criterion was found to be the most useful in intraoperative detection of MGD. Nevertheless, their application in patients qualified for MIP with concordant results of sestamibi scanning and ultrasound of the neck would result in a significantly higher number of negative conversions to bilateral neck explorations and only a marginal improvement in the success rate of primary operations.

When initial postexcision PTH level does not fall appropriately during parathyroidectomy: what to do next?

BACKGROUND

Inadequate fall in the intraoperative parathyroid hormone (PTH) level after removing enlarged parathyroid gland(s) typically signifies additional hyperfunctioning gland(s), prompting further neck dissection, but it may also be a false negative result. We analyzed intraoperative management of patients with an inadequate fall on PTH after excision of enlarged parathyroid gland(s).

METHODS

Analysis involved a prospective database of 189 patients undergoing 193 procedures for primary hyperparathyroidism. The PTH level was determined before neck incision and 10-15 min after excision of enlarged parathyroid gland(s). A PTH decrease > 50% and into normal range was used as the criterion of successful parathyroidectomy.

RESULTS

In 48 of 193 operations, initial postexcision PTH level did not fall appropriately. That inadequate fall in PTH level was a false negative result in 16 patients (33%) and cure was achieved without additional neck exploration in all but one patient, who had additional (negative) neck exploration after excision of a parathyroid adenoma. In all patients with false negative postexcision PTH assay, operative findings concurred with preoperative imaging tests.

CONCLUSIONS

Inadequate fall in intraoperative PTH may be false negative, particularly after removal of an adenoma found in the location determined by preoperative imaging. Repeat PTH may confirm the initial assay as false negative, obviating the need for additional neck dissection. Importantly, if repeat PTH does not fall appropriately, additional neck exploration needs to be performed.

Predictors of intra-operative parathyroid hormone decline in subjects operated for primary hyperparathyroidism by minimally invasive parathyroidectomy

BACKGROUND

The predictors of intra-operative PTH (IOPTH) decline during minimally invasive parathyroidectomy (MIP) for primary hyperparathyroidism have been but poorly studied.

MATERIALS AND METHODS

This retrospective study included 108 patients who underwent MIP for a single adenoma. Serum calcium and phosphorus were measured before surgery and 1 day post-operatively. IOPTH was measured before (intra-operative preincision or PTHt0) and 10 min after removal of the adenoma (PTHt10). The Modification of Diet in Renal Disease (MDRD) equation was used to estimate the glomerular filtration rate. The weight of the adenoma was assessed in all the subjects.

RESULTS

The sex ratio female/male was 5.37 with a mean age of 57.3 yr. The mean pre- and postoperative values were for calcium 2.80 and 2.19 mmol/l, respectively (p<0.0001) and for phosphorus 0.90 and 1.16 mmol/l, respectively (p<0.0001). The PTH dropped from a mean value of 184.8 to 50.8 pg/ml 10 min after adenoma resection with a mean drop of 69.7%. Thirteen patients (12%) did not achieve a PTH fall of more than 50%. In a bivariate analysis, age, an MDRD<60 ml/min and weight of adenoma were inversely associated with IOPTH fall (p=0.009, p=0.004, and p<0.001, respectively) while gender, body mass index, hypertension, diabetes, pre-operative phosphorus and calcium had no significant effects. In the multivariate analysis, age, weight of adenoma, and MDRD were still independent negative predictors of the IOPTH fall (p=0.01, p=0.018, and p<0.001, respectively).

CONCLUSION

Our results suggest that during MIP the presence of a parathyroid adenoma with a high weight, in an elderly subject or in a subject with altered renal function, will result in a lesser degree of IOPTH fall.

Contemporary parathyroidectomy: exploiting technology

BACKGROUND

Conventional parathyroidectomy, as practiced only 10 years ago, has given way to considerable change, largely as a result of the evolution of technology. Several of these important technologies include radio-guided surgery, ultrasound imaging, high-resolution endoscopy, and rapid intraoperative parathyroid hormone (IOPTH) monitoring. Modern parathyroid surgeons should maintain familiarity with the appropriate role of these approaches.

STUDY DESIGN

Evidence-based analysis of state-of-the-art approaches to the diagnosis and management of primary hyperparathyroidism.

METHODS AND MATERIALS

Four distinct technologies are analyzed in detail, with particular attention to their impact on the practice of parathyroid surgery. These include radio-guided surgery, ultrasound imaging, high-resolution endoscopy, and IOPTH.

RESULTS

Each of the technologies examined has substantial value in the current practice of parathyroidectomy. Judicious implementation of these technologies will vary from practice to practice. Radio-guided surgery may obviate the need for IOPTH monitoring, therefore resulting in the fastest procedural times. Ultrasound imaging is useful as an adjunct to sestamibi scanning to localize adenomatous parathyroid glands. Endoscopic techniques facilitate visualization through small openings and may help surgeons achieve minimal access incisions. Finally, the use of IOPTH is a useful adjunct to directed explorations, and it imparts confidence that all hyperfunctioning parathyroid tissue has been removed.

CONCLUSIONS

The practice of parathyroid surgery has undergone tremendous change in the past decade, and this change has largely been a technology-driven phenomenon. Acquisition of familiarity and skill with these new technologies will be necessary for the endocrine head and neck surgeon wishing to stay abreast of modern surgical techniques and provide quality care.

Rapid Cortisol Assay during Adrenal Vein Sampling in Patients with Primary Aldosteronism

Background: Adrenal vein sampling is considered the gold standard test to identify primary aldosteronism, the most frequent form of secondary hypertension. Technical difficulties with this procedure may be overcome by monitoring cortisol concentrations in the different sampling sites during catheterization.

Methods: We applied a rapid automated cortisol assay performed on a benchtop immunoassay analyzer near the operating suite during the catheterization procedures in 5 hypertensive patients. A mean of 7.8 samples (range, 5–13) were collected from the vena cava as well as from right and left adrenal veins.

Results: Cortisol concentrations measured by the rapid assay and by our routine method were comparable. Two of 5 patients were found to be affected by an aldosterone-producing adenoma and 3 of 5 by a bilateral adrenal hyperplasia. Cortisol determination during the adrenal vein sampling procedure allowed a successful cannulation in all patients, including a patient in whom it was necessary to cannulate 9 different candidate right adrenal veins before finding the correct one.

Conclusions: Intraoperative cortisol assays appeared safe, reproducible, simple to perform, rapid, and cost-effective. The approach represents a service-oriented model for the laboratory and can provide valuable and timely information for improving the success rate of adrenal vein catheterization.

A "defined baseline" in PTH monitoring increases surgical success in patients with multiple gland disease

BACKGROUND

Parathyroid hormone (PTH) monitoring with a quick intact PTH (QIPTH) assay is used in minimally invasive exploration for primary hyperparathyroidism (PHPT) in order not to miss multiple gland disease (MGD). Controversy exists on which criterion is most reliable to predict cure.

METHODS

QIPTH values of 310 consecutive patients (single gland disease [SGD]: n = 289; MGD: n = 21) with sporadic PHPT were analyzed using 3 different criteria: "Vienna Criterion": >/=50% decay from a defined "baseline" level (right after induction of anesthesia before skin incision) 10 min after excision. "Miami Criterion": >/=50% decay from highest (preincision or preexcision) value 10 min after excision; "Halle Criterion": decay of the PTH- level to less than or equal to 35 pg/mL within 15 min after excision.

RESULTS

The "Vienna" and "Halle Criteria" correctly detected MGD in 19 (91%) and the "Miami Criterion" in 12 (57%) of 21 patients. Incorrect prediction of incomplete excision occurred in 22 patients (8%) with SGD, using the "Vienna Criterion" ("Miami Criterion": 2%, "Halle Criterion": 29%). All of these were recognized intraoperatively from unintended intraoperative manipulation (n = 18), technical failure (n = 2), or borderline increased PTH values (n = 2), and they did not lead to bilateral exploration. Analyzing patients with SGD and MGD, accuracy and specificity were 92% and 89% for the "Vienna Criterion," 93% and 54% applying the "Miami Criterion," and 72% and 89% using the "Halle Criterion."

CONCLUSION

Strict definition of a PTH "baseline level" ("Vienna Criterion") improves intraoperative diagnosis of MGD, thus reducing reoperations and increasing long-term cure.

Are frozen sections useful and cost-effective in the era of intraoperative qPTH assays?

BACKGROUND

Since intraoperative quick parathormone (IOqPTH) assays are available, the role of frozen sections (FS) during parathyroid exploration has become questionable. This study compares the results of FS and IOqPTH in primary hyperparathyroidism (pHPT).

METHODS

FS and IOqPTH assays were performed in 102 patients who underwent bilateral neck explorations or targeted parathyroidectomy for pHPT. The operation was considered complete when both an IOqPTH drop >50% and a FS diagnosis of parathyroid adenoma were obtained.

RESULTS

Cure was achieved in all patients. Potential pitfalls for successful operation were encountered in 14 patients with multiglandular diseases and in 4 patients who had nonparathyroid tissue removed. FS correctly predicted the definitive histologic diagnosis with an accuracy of 81%. FS failures potentially misguided the operative therapy in 19% (14 insufficient explorations and 5 unnecessarily prolonged explorations), while IOqPTH identified all potential pitfalls and correctly guided the operative strategy, suggesting further exploration, in 100% of cases (P < .0001). After bilateral neck exploration, FS and IOqPTH correctly guided operative strategy in 86% and 100% of cases, respectively (P < .05), but both techniques were never indispensable, because potential pitfalls were already evident by macroscopic intraoperative appearance. The turnaround time and costs for IOqPTH were lower (P < .001).

CONCLUSIONS

The role of FS should be reconsidered, since it can misguide the operative strategy. IOqPTH is indispensable for a focused approach and, although unnecessary in bilateral neck exploration, is more useful and cost-effective than FS.

Parathyroid hormone response to tracheal intubation in hyperparathyroid patients and normal subjects

The stress of direct laryngoscopy and passing an endotracheal tube through the vocal cords elicits haemodynamic, metabolic and hormonal changes such as raising blood catecholamine levels. Catecholamines are known stimulants of PTH secretion. The effect of tracheal intubation on plasma parathyroid hormone levels has not yet been investigated. We monitored changes in plasma parathyroid hormone levels before and after tracheal intubation in 72 hyperparathyroid patients undergoing elective parathyroidectomy for primary and secondary hyperparathyroidism. These findings were compared to data collected from 20 subjects who underwent elective surgery (thyroidectomy or laparoscopic cholecystectomy) under general anesthesia. In the control group, tracheal intubation significantly increased plasma parathyroid hormone levels from 59 +/- 31 pg/ml to 91 +/- 40 pg/ml (mean +/- SD) (p<0.0003). In primary hyperparathyroid patients, the identical procedure increased plasma parathyroid hormone levels from 206 +/- 104 pg/ml to 217 +/- 113 pg/ml (p = 0.12) and from 898 +/- 495 pg/ml to 1162 +/- 613 pg/ml (p = 0.07) in secondary hyperparathyroidism patients. We concluded that tracheal intubation raises plasma parathyroid hormone levels. The mechanism underlying this response requires further investigation.

Primary hyperparathyroidism, cognition, and health-related quality of life

OBJECTIVE

To provide a rigorous and critical review of studies in which formal neuropsychological (NP) testing and measurement of health-related quality of life (HRQL) were conducted pre- and post-parathyroidectomy for primary hyperparathyroidism (PHPT). These data contribute to the discussion on the utility of surgical intervention for nonclassic PHPT.

SUMMARY BACKGROUND DATA

PHPT is a complex endocrinopathy involving calcium metabolism and a potent hormone made by the parathyroid glands. Approximately 1.5% of Americans age 65 years and older, representing more than 3.9 million people, have PHPT, and the prevalence in postmenopausal women is estimated at 3.4%. Current National Institutes of Health guidelines for curative, surgical intervention of PHPT exclude 80% of patients with hyperparathyroid disease who have subjective neurobehavioral and physical symptoms that affect the quality of their lives.

METHODS

An electronic search was conducted of prospective studies in which cognitive functioning was measured with formal NP tests and HRQL was measured with valid and reliable instruments before and following parathyroidectomy for PHPT.

RESULTS

: In studies conducted pre- and post-parathyroidectomy for PHPT, 6 small studies of cognitive functioning report inconsistent findings; however, 7 well-designed studies of HRQL report improvement across multiple domains following surgery.

CONCLUSIONS

Surgical treatment of PHPT is a viable option for patients with laboratory diagnosed, "nonclassic" PHPT. Formal NP testing and evaluation of HRQL are useful tools that may assist physicians in choosing whom to refer for parathyroidectomy. Further longitudinal study of NP functioning and HRQL in patients with laboratory diagnosed PHPT is warranted.

Best practice no 183. Examination of parathyroid gland specimens

The pathological examination of parathyroid glands is an essential component of the evaluation of hyperparathyroidism. Traditionally, this has involved intraoperative frozen sections during bilateral surgical exploration of the neck, to confirm removal of parathyroid tissue. With recent developments in imaging, some diseased glands can be localised preoperatively, enabling removal by minimally invasive, targetted surgery, with or without additional non-histological intraoperative procedures to confirm the removal of all hyperfunctioning parathyroid tissue. This article reviews these developments and describes the ideal approach to reporting parathyroid specimens.

Surgical management strategies in patients with primary hyperparathyroidism: which technique in which patients?

OBJECTIVE

This study was planned to investigate the efficacy of either 99mTc-sestamibi scan or ultrasonography in predicting the operative treatment in patients with primary hyperparathyroidism (PHPT).

SUBJECTS AND METHOD

Thirty patients (25 female, 5 male; mean age: 53 years) being operated for symptomatic primary PHPT were included in this study. Ultrasonography was used in 29 patients while 99mTc-sestamibi scintigraphy was done in 28 patients to localize the hyperfunctioning gland(s). Standard bilateral neck exploration was done in 6 patients. Although unilateral intervention had been planned for 24 patients, bilateral intervention was performed in 9 of them.

RESULTS

Sensitivity of 99mTc-sestamibi was 81%, while that of ultrasonography was 42%. 99mTc-sestamibi localization method led to misleading results in 10/28 (35.7%) patients. False-positive localization and accompanying thyroid pathologies played an important role in determining transition from unilateral to bilateral intervention.

CONCLUSION

Our findings indicate that bilateral intervention remains a successful management option without prior localization in patients with PHPT especially in an endemic goiter region.

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.

Predictive value of intact parathyroid hormone measurement during surgery for renal hyperparathyroidism

BACKGROUND AND AIMS

In contrast to that in patients with primary hyperparathyroidism, the value of intraoperative intact parathyroid hormone (iPTH) measurement is still unclear in patients with renal hyperparathyroidism and was, therefore, evaluated in a large cohort of patients.

PATIENTS

Intraoperative iPTH measurement was performed in 153 patients with renal hyperparathyroidism (129 with terminal renal failure and 24 with functioning kidney graft). Subtotal and total parathyroidectomy were performed in 123 and 13 patients, respectively, during initial surgery. In patients with recurrent disease (17), the respective hyperfunctioning tissue was removed. Intraoperative blood samples were obtained by puncture of the internal jugular vein before preparation of the parathyroids (PTH0) and 15 min after parathyroidectomy (PTH15). iPTH was measured with the Elecsys 2010 system. Postoperative iPTH levels (PTH(post)) were determined at postoperative days 1 to 3 and at week 2. Patients were arbitrarily divided in four groups according to the postoperative iPTH values: 0-25 pg/ml (group 1), 26-65 pg/ml (group 2), 66-150 pg/ml (group 3) and more than 150 pg/ml (group 4).

RESULTS

The mean PTH0 value was 869+/-57 pg/ml, which decreased to 167+/-15 pg/ml at PTH15. The mean relative PTH15 value was 21.6+/-1.7%. Postoperatively, iPTH decreased to 42+/-9 pg/ml. The postoperative iPTH value of the 129 patients with terminal renal failure was 25 pg/ml or less in 99 patients, 26-65 pg/ml in 11 patients, 66-150 pg/ml in eight patients and higher than 150 pg/ml in 11 patients. Two successive criteria of iPTH decrease were used: first, a PTH15 of < or =150 pg/ml or, second, a relative PTH15 of < or =30% less was used. Fifteen patients did not fulfil both criteria. In 13 of them (86.7%) iPTH(post) was higher than 65 pg (true failure to decline). Of 114 patients who fulfilled the criteria, 108 (94.7%) had normal postoperative iPTH values (true decline). Absolute PTH15 values of less than 150 pg/ml predicted normal postoperative iPTH levels in 77 of 78 patients.

CONCLUSION

A PTH15 value of 150 pg/ml or less predicts operative success in patients with renal failure in 98.7% of cases, independently of the relative decay. In contrast, if the relative PTH15 is higher than 30%, high postoperative PTH values are predicted with a probability of 86.7%. Although there remain some borderline cases, intraoperative iPTH measurement is accurate and also can be useful in patients with renal hyperparathyroidism.