Intraoperative Parathyroid Hormone Monitoring Research Articles

Intra-operative Parathyroid Hormone Monitoring in Patients with Parathyroid Cancer

Intra-operative parathyroid hormone (PTH) monitoring (IPM) is 97% accurate in predicting postoperative eucalcemia in sporadic primary hyperparathyroidism (SPHPT). However, its usefulness in parathyroid cancer has not been demonstrated. This study reports IPM accuracy during surgical resections for parathyroid cancer. Eight of 556 consecutive patients with SPHPT underwent parathyroidectomy using IPM and had parathyroid cancer. Operative success was defined as eucalcemia > six months and operative failure/persistent cancer as hypercalcemia within six months of parathyroidectomy. The IPM criterion for operative success was defined as a >50% decrease of peripheral PTH levels from the highest either pre-incision or pre-excision values, 10 minutes after resection. In eight patients, 11 operations were performed. Ten operations (91%) resulted in >50% intra-operative PTH decrease. However, in only seven (70%) of these resections, eucalcemia was achieved for >6 months with five of these seven (71%) procedures being initial en bloc resections. The remaining 3/10 (30%) operations with >50% intra-operative PTH decrease resulted in operative failures. In the last operation, intraoperative parathormone monitoring (IPM) correctly predicted operative failure. IPM sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy in predicting outcome were 100, 40, 70, 100, and 75%, respectively. IPM with the criterion of >50% PTH drop from the highest level is less accurate in predicting operative success in parathyroid cancer when compared to SPHPT. A >50% intra-operative PTH level decrease in patients with parathyroid cancer, particularly in reoperative cases, is less predictive of complete resection. The initial recognition of this disease followed by proper resection remains essential in the treatment of parathyroid cancer.

1112 Consecutive Bilateral Neck Explorations for Primary Hyperparathyroidism

Bilateral neck exploration has been the standard approach for patients with primary hyperparathyroidism. Improved localization studies and the availability of intraoperative parathyroid hormone monitoring have challenged the necessity of four-gland exploration. In this series we report a single surgeon's experience with bilateral neck exploration for primary hyperparathyroidism in an effort to establish benchmark outcomes from which to evaluate minimally invasive protocols. The charts of 1112 consecutive patients who underwent neck exploration for primary hyperparathyroidism by a single surgeon over a 17-year period were reviewed. All patients underwent bilateral neck exploration under either general (n = 264) or local (n = 848) anesthesia. The overall cure rate was 97.4% with a complication rate of 3.4%. Morbidity included recurrent laryngeal nerve injury (0.2%), postoperative bleeding (0.8%), and transient hypocalcemia (1.8%). There was no mortality. Overall mean operating time was 52.5 +/- 30.2 minutes. A single gland was removed in 78.4% of patients, and 22.3% of patients underwent concomitant thyroidectomy. The cure rate was lower for patients undergoing reexploration (89.2% vs. 97.9%, p < 0.05). Choice of anesthetic approach did not affect the cure or complication rate. The overall conversion rate from local to general anesthesia was 1.5%. Patients undergoing general anesthesia were operated on earlier in the series and were less likely to be managed on an ambulatory basis (local 87.5% vs. general 38.4%, p < 0.05). During the last 5 years of the series, more than 90% of patients underwent exploration under local anesthesia. This large modern series of neck explorations for primary hyperparathyroidism confirms the safety, feasibility, and efficacy of the bilateral approach. It further demonstrates that individual surgeons can achieve outcomes equivalent to those with four-gland explorations under local anesthesia.

Short-Term Outcomes of Parathyroidectomy in Patients With or Without 25-Hydroxy Vitamin D Insufficiency

25-OH Vitamin D (VitD) plays a role in serum calcium (Ca) and parathyroid hormone (PTH) homeostasis. VitD insufficiency in patients with primary hyperparathyroidism (HPT) may be associated with greater disease severity and a higher incidence of multi-gland disease and postoperative normocalcemic PTH elevation. One hundred ten patients with HPT undergoing parathyroidectomy had preoperative VitD levels as follows: levels were insufficient (< or =20 ng/mL) in 55 patients (group 1) and sufficient (>20 ng/mL) in 55 patients (group 2). All patients had preoperative localizing sestamibi scans and/or ultrasounds and postoperative serum Ca and PTH levels. A focused approach was performed when possible, and intraoperative PTH monitoring (IPM) was used in all patients. Patients with VitD insufficiency had significantly higher preoperative Ca (11.3 +/- 1.2 versus 10.8 +/- 0.9 mg/dL, P = 0.012) and PTH levels (204 +/- 138 versus 156 +/- 179 pg/mL; P = 0.006) as well as higher bone specific alkaline phosphatase (P = 0.006). Localization studies were similar. IPM levels were significantly higher in group 1 at all time intervals. Both groups were similar in operative time, conversions to bilateral explorations, number of glands removed, and number of frozen sections. The glands in group 1 were larger (1757 versus 524 g; P = 0.005). Postoperative Ca levels, PTH levels, rates of eucalcemia, and rates of eucalcemic PTH elevation were all similar. Patients with HPT and VitD insufficiency may have significantly more severe disease based on preoperative serum Ca and PTH levels, bone markers, and gland size. IPM levels in these patients are higher but can be used to predict postoperative eucalcemia, an outcome which appears be independent of VitD status.

Parathyroidectomy: Overview of the Anatomic Basis and Surgical Strategies for Parathyroid Operations

It is imperative for the surgeon who performs parathyroidectomy to have a thorough understanding of the anatomy and embryology of the parathyroid glands in order to optimize the cure rate for patients with hyperparathyroidism (HPT). Furthermore, all clinicians caring for patients with hyperparathyroidism should be aware of the advancements in preoperative parathyroid localization, intraoperative PTH monitoring and surgical strategies for treatment of hyperparathyroidism. In this chapter, the anatomy and embryology of the parathyroid glands will be reviewed. The available surgical options for treatment of patients with hyperparathyroidism will be addressed, including “focused” parathyroidectomy, bilateral neck exploration, radioguided parathyroidectomy, and endoscopic and video-assisted parathyroidectomy. The unique challenge associated with reoperative parathyroidectomy for persistent or recurrent hyperparathyroidism will be outlined. Finally, insight into how to locate a qualified surgeon will be provided and recommendations will be made on what constitutes an appropriate choice of operation for specific patients with primary hyperparathyroidism.

To autotransplant simultaneously or not—can intraoperative parathyroid hormone monitoring reliably predict early postoperative parathyroid hormone levels after total parathyroidectomy for hyperplasia?

Intraoperative parathyroid hormone (IOPTH) monitoring is well-established in operation for primary hyperparathyroidism (HPT). In diseases where total parathyroidectomy (tPx) is a treatment option its reliability to predict postoperative residual parathyroid hormone (PTH) remains in question. Thirty-eight consecutive patients with tPx due to secondary autonomous renal (26 patients), familial (8 patients), or lithium-induced (4 patients) HPT were analyzed retrospectively for the relationship between IOPTH and postoperative PTH. Three concepts were tested to predict a postoperative PTH below the normal range: a mandatory intraoperative decline of PTH less than 50% and 90% of the baseline value as well as an intraoperative decline below a threshold of 100 pg/ml 10 minutes after tPx. There was no significant correlation between IOPTH decline and postoperative PTH (R = .265; P = .108). In patients with a 4-gland resection (n = 34) the positive predictive value was 62.5% and the sensitivity was 90.9% for the '50% concept.' The corresponding values were 68.8% and 50.0% for the '90% concept,' and 81.8% and 81.8% for the '100 pg/ml concept.' The decision for simultaneous autotransplantation after tPx can not be based on IOPTH monitoring, because the reliability in prediction of early postoperative PTH status is insufficient.

Diminished Dose Minimally Invasive Radioguided Parathyroidectomy: A Case for Radioguidance

Minimally invasive radioguided parathyroidectomy (MIRP) has been established as an alternative to bilateral neck exploration (BNE) for primary hyperparathyroidism. We investigate whether a diminished dose of technetium-99m sestamibi gives similar results to the standard dose. One hundred one patients were offered MIRP or diminished-dose MIRP (ddMIRP). Patients received intravenous Tc-99m sestamibi at a dose of either 25 mCi 1.5 hours or 5 mCi 1 hour preoperatively. The procedure was terminated when the 20 per cent rule was satisfied. All tissue was confirmed to be parathyroid tissue by frozen section analysis. In addition, intraoperative parathyroid hormone levels were measured in a majority of patients. Patients who failed IOM underwent BNE. Frozen section analysis and intraoperative parathyroid hormone monitoring were also performed in the BNEs. Postoperatively, serum calcium levels were measured at 1 week and 6 months. Fifteen per cent of patients were male and 85 per cent were female. The median age was 63 years (range, 25-89 years). The first 58 patients had the standard dose of 25 mCi, whereas 43 patients had ddMIRP. Six patients (10%) failed intraoperative mapping in the MIRP group and were found to have single-gland disease. Five patients (12%) failed intraoperative mapping in the ddMIRP group. However, two patients were identified to have multigland disease making the true failure rate of intraoperative mapping 7 per cent (three patients). Median operative times for MIRP, ddMIRP, and BNE were 40 minutes, 46 minutes, and 105 minutes, respectively. The 20 per cent rule was satisfied in 96 per cent of patients undergoing MIRP and 98 per cent of patients undergoing ddMIRP. Frozen section analysis and intraoperative parathyroid hormone monitoring did not result in a change in management. Median follow up was 193 days and serum calcium levels at 6 months were normal. Diminished-dose MIRP is a feasible alternative to standard-dose MIRP without compromising surgical outcomes.

Central Venous Sampling for Intraoperative Parathyroid Hormone Monitoring: Are Peripheral Guidelines Applicable?

Intraoperative parathyroid hormone (PTH) monitoring has become an integral adjunct to minimally invasive parathyroidectomy. Guidelines for predicting therapeutic excision of all hyperactive parathyroid tissue have been routinely based on peripheral blood samples drawn at various time intervals. Whether these same guidelines can be used to predict success based on central blood draws has not been established. The authors wanted to evaluate whether peripheral criteria were applicable when PTH levels were drawn from a central location. Simultaneous peripheral venous (PV) and central venous (CV) PTH samples were drawn from 64 patients undergoing cervical exploration for primary hyperparathyroidism. Median preexcision PTH was significantly higher centrally at 165 pg/mL (interquartile range [IQR], 101-391 pg/mL) versus peripherally 102 pg/mL (interquartile range, 73-156 pg/mL, P < 0.0001). Postexcision PTH was slightly greater in CV (38 pg/mL; IQR, 24-62) than in PV (29 pg/mL; IQR, 22-51; P < 0.0001). The decrease in intraoperative PTH was compared after excision of an initial gland. Fifty-four of the 64 patients had all hyperfunctioning parathyroid tissue removed after initial gland resection. Pre- to postexcision ratios for CV and PV were compared using receiver operating characteristic curve methods, and summarized by area under the curve (AUC). PV (AUC = 0.85) appears to be a slightly more sensitive discriminator than CV (AUC = 0.83), although the difference is not statistically significant (P = 0.5). Despite higher absolute values for CV, both peripheral and central sample sites accurately predict outcomes based on established guidelines for intraoperative PTH monitoring.

Radioguided Parathyroidectomy for Recurrent Parathyroid Cancer

We report a case of radioguided parathyroidectomy in a patient with parathyroid carcinoma. A 61-year-old woman presented to our center with persistent hypercalcemia (17.2 mg/dL) and hyperparathyroidism (PTH=324 pg/mL) following her second neck resection for recurrent parathyroid carcinoma at an outside facility. Her elevated serum calcium had not responded to treatment with intravenous bisphosphonates, furosemide, or calcitonin. Calcimemetic therapy (Cinacalcet) was effective but had to be discontinued due to GI intolerance. She requested a second opinion at our center after being referred for palliative radiation therapy for presumed inoperable disease. On presentation, she remained symptomatic with bone and joint pain, diffuse abdominal pain and fatigue. Repeat technetium-99m sestamibi (Tc-99m sestamibi) scintigraphy showed a faint area of uptake near the right clavicular head, adjacent to the site of her previous resections. With the intraoperative guidance of a hand-held gamma probe, a 2 cm recurrent parathyroid carcinoma was located and successfully excised. Intraoperative PTH levels confirmed surgical cure of this previously undetected foci of disease. The use of radioguidance and intraoperative PTH monitoring were the keys to a successful resection, and our patient remains disease free with 17 months of follow-up.

Clinical and operative management of persistent hyperparathyroidism after renal transplantation: A single‐center experience

Persistent (tertiary) hyperparathyroidism (TH) after renal transplantation may cause considerable morbidity and necessitate parathyroidectomy. This study investigated the characteristics of this patient subgroup. The medical data and pathology specimens of 20 kidney transplant recipients who underwent parathyroidectomy for TH in 2001 to 2004 were reviewed. Treatment consisted of subtotal resection of 3.5 glands in 13 patients, resection of 3 to 3.5 glands under intraoperative parathyroid hormone monitoring (iPTH) in 5 patients, and selective resection in 2 patients with markedly asymmetric gland enlargement. Eighteen patients had hyperplasia-diffuse in 10, nodular in 4, or both in 2; 2 patients had 1 large nodule in every gland. Six patients had postoperative complications. Follow-up of 2 years revealed recurrent hypercalcemia in 1 patient and a high level of PTH (>60 pg/mL) in 12. Subtotal resection for TH may be insufficient. The use of iPTH monitoring is recommended. Renal transplant recipients have distinctive characteristics and require special perioperative attention.

Rapid Intraoperative Parathyroid Hormone Assay in the Surgical Management of Hyperparathyroidism

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. 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. 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. 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. 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.

Use of Pre-Operative Tc99m-Sestamibi Scintigraphy and Intraoperative Parathyroid Hormone Monitoring to Eliminate Neck Exploration in Mediastinal Parathyroid Adenocarcinoma

A 66-year-old white woman was found to have an elevated serum calcium and parathyroid hormone (PTH) on routine health evaluation. Physical examination was unremarkable as was ultrasonography of the neck. A sestamibi parathyroid scan revealed abnormal uptake in the anterior mediastinum. Computed tomography of the chest demonstrated an anterior mediastinal mass compatible with a parathyroid adenoma but no neck masses. The patient underwent mediastinoscopy that was converted to a median sternotomy to fully access the mass. The mass was completely resected with surrounding thymus gland. Frozen section confirmed that excised tissue was parathyroid gland in origin. An intraoperative PTH obtained 20 minutes after specimen removal showed a decrease of more than 50% from preoperative levels. The strategy for initial surgery for hyperparathyroidism when a sestamibi scan is "positive" in the mediastinum (only) is a point of some controversy. Traditional recommendations have been to "clear the neck" of abnormal parathyroid tissue before undertaking a more morbid sternotomy. Mediastinoscopy was attempted to remove the mediastinal lesion and to avoid a sternotomy. Preoperative Tc99m sestamibi scintigraphy, frozen section histology, and intraoperative PTH monitoring permitted the authors to conclude that neck exploration was unnecessary.

Parathyroidectomy outcomes according to operative approach

Background Parathyroidectomy for primary sporadic hyperparathyroidism (psHPT) has evolved with advances in preoperative gland localization and intraoperative parathyroid hormone (ioPTH) monitoring to minimally invasive approaches (MIPS). Methods Two hundred twenty patients underwent parathyroidectomy for psHPT. Forty-nine patients underwent bilateral neck exploration (BNE) (group 1), 60 patients underwent BNE with ioPTH monitoring (group 2), and 111 patients underwent MIPS with ioPTH monitoring (group 3). Results At 3 months postoperatively, mean serum calcium and intact parathyroid hormone (PTH) levels were similar between groups, and eucalcemia rates were 100%, 100%, and 99%. The ultimate rates of persistent disease and recurrence were also similar. Operative time was shorter in group 3 compared to group 2 ( P < .001) but not group 1. Frozen sections and patient charges were significantly lower in group 3 compared to groups 1 and 2 ( P < .005). Conclusion Parathyroidectomy for psHPT is highly successful with these techniques. When a MIPS approach can be done, it is potentially quicker and associated with lower patient charges.

180: Outcomes of parathyroidectomy in patients with or without 25 hydroxy vitamin D insufficiency

Background: 25-OH Vitamin D (VitD) plays a role in serum calcium (Ca) and parathyroid hormone (PTH) homeostasis. We hypothesized that VitD insufficiency in patients with primary hyperparathayroidism (HPT) may be associated with greater disease severity and higher incidence of multiglandular disease and postoperative normocalcemic PTH elevation. Methods: 110 patients treated surgically for HPT had preoperative VitD levels. Fifty-five patients in Group 1 had levels ≤20 ng/ml (insufficient), and 55 patients in Group 2 had VitD levels >20 ng/ml (sufficient). All patients had pre and postoperative serum Ca & PTH levels and preoperative localization using sestamibi and/or ultrasound. A focused approach was performed when possible, and intraoperative PTH monitoring (IPM) was utilized in all patients. Analysis was performed using two sample t-test, Wilcoxon rank sum, chi square, and Fisher exact test with p< 0.05 indicating significance. Results: VitD insufficient patients had significantly higher preoperative serum Ca (11.3 ± 1.2 vs. 10.8 ± 0.9 mg/dl, p=0.012) and PTH levels (204 ± 138 vs. 156 ± 179 pg/ml; p=0.006) as well as more advanced bone disease (p<0.001). Results from localization studies were similar between groups. Intraoperative PTH levels were significantly higher in Group 1 at baseline (p=0.02), 5 minutes (p=0.01), and 10 minutes post gland excision (p=0.009). Both groups were similar in operative time, conversions to bilateral explorations, number of glands removed, number of gland biopsies, and frozen sections. The glands in Group 1 were larger (1757 ± 3968 vs. 524 ± 244 gm; p=0.005). The incidence of cure (98% vs. 100%), and normocalcemic PTH elevation were similar. Postoperative serum Ca (9.4 ± 0.9 vs. 9.4 ± 0.5 mg/dl) and PTH (69 ± 65 vs. 51 ± 35 pg/ml; p=0.382) were similar. Postoperative VitD levels were not affected by parathyroidectomy. Conclusion: Patients with HPT and VitD insufficiency have significantly more severe disease based on preoperative serum Ca and PTH levels, bone markers, and parathyroid gland size. Intraoperative PTH levels in VitD insufficient patients are typically higher but IPM can still be used to accurately predict cure. Parathyroidectomy cure rates are similar regardless of preoperative VitD status. Patients with HPT and VitD insufficiency may benefit from oral VitD supplementation after parathyroidectomy.

Minimally invasive parathyroidectomy using the lateral focused mini-incision technique without intraoperative parathyroid hormone monitoring

Minimally invasive parathyroidectomy (MIP) involves scan-directed removal of a single adenoma through a 2.0-cm mini-incision without intraoperative monitoring. The aim of this study was to analyse the outcomes of MIP using such a simplified technique. The study group comprised 500 consecutive patients undergoing MIP via a lateral mini-incision from August 2000 to September 2005. Levels of parathyroid hormone (PTH) were measured after operation solely to aid informed discharge. Some 97.4 per cent of patients were initially cured by MIP. Eight patients remained hypercalcaemic and a further five were normocalcaemic on the day after surgery but became hypercalcaemic again within 3 months of the procedure. Eleven of these patients were cured with subsequent re-exploration. Analysis of postoperative PTH data indicated that, at best, the use of intraoperative PTH measurement during surgery would have increased the cure rate by only a further 1 per cent. Three (0.6 per cent) of 500 patients had permanent recurrent laryngeal nerve palsy after MIP. MIP performed by the lateral focused mini-incision technique, without the use of intraoperative PTH monitoring, is a safe and effective procedure that results in outcomes equal to those of bilateral neck exploration.

Minimally invasive parathyroidectomy without intraoperative parathyroid hormone monitoring in patients with primary hyperparathyroidism

Minimally invasive parathyroidectomy (MIP) is the preferred operation for patients with primary hyperparathyroidism (HPT) and positive preoperative imaging. This non-randomized case series assessed the long-term results of MIP performed without the use of intraoperative parathyroid hormone (ioPTH) monitoring. The study involved prospective collection of demographic, biochemical and operative details on a consecutive, unselected cohort of 298 patients who underwent surgery for non-familial primary HPT during a 5-year interval. The mean preoperative serum calcium level was 3.00 mmol/l with a mean parathyroid hormone concentration of 25.8 pmol/l. (99m)Tc-labelled sestamibi scanning and neck ultrasonography were performed in 262 patients. Sestamibi scan showed unilateral uptake in 182 patients and a single parathyroid adenoma was confirmed on ultrasonography in 161 patients. MIP was performed in 150 patients. The mean duration of operation was 25 (range 8-65) min. Four patients needed conversion to conventional neck exploration. There was one postoperative haematoma and three cases of temporary recurrent laryngeal nerve neuropraxia. All but four patients were normocalcaemic after MIP. All the parathyroid tumours removed were adenomas, with a mean weight of 1.3 (range 0.1-17.4) g. No patient developed recurrent HPT after a median follow-up of 16 (range 3-48) months. The outcome of MIP without ioPTH monitoring was comparable to that reported in series that used ioPTH monitoring.

PTH spikes during parathyroid exploration—a possible pitfall during PTH monitoring?

Parathyroid hormone (PTH) spikes caused by unintentional manipulation of the hypersecreting glands may lead to interpretation problems in intraoperative PTH monitoring. Their frequency and surgical consequences were evaluated. Intraoperative PTH values of 401 patients with primary hyperparathyroidism and single gland disease were analysed. Patients were divided into four groups: extensive increase (>150 pg/ml), moderate PTH increase (<150 pg/ml), no increase (+/-50 pg/ml) and decrease before excision as referred to the baseline level before skin incision. PTH was measured before and up to 25 min after removal of the enlarged gland. Twenty-two (5.5%) patients had an extensive and 36 (9%) a moderate intraoperative PTH increase. The PTH decline was prolonged to 15 min in 7 (31.8%) and to 25 min in 12 (54.5%) patients after extensive manipulation and in 9 patients (25%) each after moderate manipulation, respectively. No increase occurred in 162 (40.4%) and a decrease in 181 (45.1%) patients. The surgical approach (bilateral exploration vs open, minimally invasive parathyroidectomy) did not show a difference in the rate of PTH spikes. PTH spikes often cause a prolonged PTH decline but, when recognized, do not lead to a change in the surgical strategy.

Interpretation of intraoperative parathyroid hormone monitoring in patients with baseline parathyroid hormone levels of

Common guidelines for intraoperative parathyroid hormone (IOPTH) interpretation are based on clearly elevated baseline parathyroid hormone (PTH) values. We hypothesize that patients with low-baseline levels (<100 pg/mL) have a higher incidence of multigland disease (MGD) and display differences in PTH kinetics compared with patients with high-baseline levels. We retrospectively reviewed the cases of 1151 patients with primary hyperparathyroidism who underwent parathyroidectomy with IOPTH monitoring. Of these, 141 patients had low-baseline values. Multiple comparisons were made between the low-baseline and high-baseline groups. Twenty-six percent of the low-baseline patients had MGD versus 15% of the high-baseline patients (P = .002). The PTH kinetics differed between groups after gland excision at both 5 and 10 minutes. Adherence solely to the "50% rule" during minimally invasive parathyroidectomy potentially would have missed 25% of patients with MGD in the low-baseline group versus 10% in the high-baseline group; 5.7% of the low-baseline patients had persistent or recurrent hypercalcemia versus 2.9% of the high-baseline patients. MGD is significantly more prevalent among low-baseline patients, and PTH kinetics are somewhat different between groups. The current guidelines that are used for IOPTH monitoring may not be ideal for use in this low-baseline group and will likely need to be revised after further study of this group of patients.

Raman spectroscopy of parathyroid tissue pathology

Primary hyperparathyroidism (HPT) in 80% of patients is due to a solitary parathyroid adenoma, while in 20% multigland pathology exists, usually hyperplasia [Scott-Coombes, Surgery, 21(12):309-312, 2003]. Despite recent advances in minimally invasive parathyroidectomy, better preoperative localisation techniques and intraoperative parathyroid hormone (PTH) monitoring, a 4% failure rate [Grant CS, Thompson G, Farley D, Arch Surg, 140:47-479, 2005] persists making accurate differentiation between adenomas and hyperplasia of prime importance. We investigated the ability of Raman spectroscopy to accurately differentiate between parathyroid adenomas and hyperplasia. Raman spectra were measured at defined points on the parathyroid tissue sections using a bench-top microscopy system. Multivariate analysis of the spectra was carried out to construct a diagnostic algorithm correlating spectral results with the histopathological diagnosis. A total of 698 spectra were analysed. Principal-component (PCA)-fed linear discriminant analysis (LDA) used to construct a diagnostic algorithm. Detection sensitivity for parathyroid adenomas was 95% and hyperplasia was 93%. These preliminary results indicate that Raman spectroscopy is potentially an excellent tool to differentiate between parathyroid adenomas and hyperplasia.

Accuracy of intra-operative PTH measurement during subtotal parathyroidectomy for tertiary hyperparathyroidism after renal transplantation

Intra-operative parathyroid hormone (IOPTH) results are not known in the setting of tertiary hyperparathyroidism (HPT) after renal transplantation. A retrospective analysis of 35 tertiary HPT patients who all underwent subtotal parathyroidectomy and IOPTH monitoring was conducted. The mean follow-up time was 2.2+/-1.4 years. Thirty-four patients were cured; one patient (2.8%) had a persistent disease and was cured after reoperation. Median parathyroid hormone (PTH) (median percent decrease from highest) at baseline and at 5, 10, 20, and 30 min were 244, 78 (69%), 63 (75%), 53 (79%), and 49 pg/ml (83%), respectively. Four patients who were cured had a decrease of <50% at 5 min and two of them had a decrease of <50% at 10 min. The patient with persistent disease had a decrease of >50% at 10 min. The sensitivity of the test was 94% at 10 min using the Miami criteria. This study shows that IOPTH in tertiary hyperparathyroidism has a high sensitivity. However, because of the low risk of persistent hyperparathyroidism when a subtotal parathyroidectomy is performed, its potential impact on the overall success rate is very small. We therefore do not recommend the routine use of IOPTH in tertiary hyperparathyroidism.

Unilateral Cervical Surgical Exploration Aided by Intraoperative Parathyroid Hormone Monitoring in Patients With Primary Hyperparathyroidism and Equivocal Sestamibi Scan Results

Equivocal parathyroid technetium Tc 99m sestamibi scan results are likely to demonstrate the correct location for parathyroid adenomas. Patients with primary hyperparathyroidism prospectively consented to participate in an institutional review board-approved study. The parathyroid technetium Tc 99m sestamibi scan results were classified as positive, negative, or equivocal. A tertiary private hospital in which university faculty practice. Technetium Tc 99m sestamibi imaging was performed for 464 patients with primary hyperparathyroidism. Eighty-four of these patients had scan results considered equivocal for unilateral adenomas. The algorithm for this group of patients specified that they should receive an injection with technetium Tc 99m sestamibi prior to parathyroidectomy and that an intraoperative parathyroid hormone (iPTH) level decrease of more than 50% be used to define intraoperative success. Seventy-two patients had postoperative calcium levels measured at least 2 weeks after their surgical procedure and defined the study group. The mean follow-up was more than 6 months. Parathyroidectomy. Correlation of equivocal scan interpretation with operative findings and biochemical cure of hyperparathyroidism. Of the 72 patients, 39 underwent unilateral surgical explorations and 33 underwent bilateral surgical explorations; 67 (93%) of the patients were initially cured and 68 (94%) were ultimately cured. In the unilateral group, 38 (97%) of the patients were cured. The 1 failure was associated with a false-positive iPTH level decrease. In the bilateral group, 29 (88%) of the patients were initially cured and 30 (91%) were ultimately cured. Two failures were associated with a false-positive iPTH level decrease and 2 with failure to find the adenoma. Of the 33 patients in the bilateral group, surgical exploration of the opposite side was purely by surgeon choice in 11 cases. Of the other 22 patients, in addition to the 3 failures, 7 had 4-gland hyperplasia, 4 had double adenomas, and 6 had false-negative iPTH level results with iPTH level decreases of less than 50%. Overall, between 48 (67%) and 54 (75%) of the 72 patients would have been cured with unilateral surgical exploration alone.