Parathyroid Hormone Monitoring during Total Parathyroidectomy for Renal Hyperparathyroidism: Pilot Study of the Impact of Renal Function and Assay Specificity

The American Association of Endocrine Surgeons Guidelines for the Definitive Surgical Management of Secondary and Tertiary Renal Hyperparathyroidism

OBJECTIVE

To develop evidence-based recommendations for safe, effective, and appropriate treatment of secondary (SHPT) and tertiary (THPT) renal hyperparathyroidism.

BACKGROUND

Hyperparathyroidism is common among patients with chronic kidney disease, end-stage kidney disease, and kidney transplant. The surgical management of SHPT and THPT is nuanced and requires a multidisciplinary approach. There are currently no clinical practice guidelines that address the surgical treatment of SHPT and THPT.

METHODS

Medical literature was reviewed from January 1, 1985 to present January 1, 2021 by a panel of 10 experts in SHPT and THPT. Recommendations using the best available evidence was constructed. The American College of Physicians grading system was used to determine levels of evidence. Recommendations were discussed to consensus. The American Association of Endocrine Surgeons membership reviewed and commented on preliminary drafts of the content.

RESULTS

These clinical guidelines present the epidemiology and pathophysiology of SHPT and THPT and provide recommendations for work-up and management of SHPT and THPT for all involved clinicians. It outlines the preoperative, intraoperative, and postoperative management of SHPT and THPT, as well as related definitions, operative techniques, morbidity, and outcomes. Specific topics include Pathogenesis and Epidemiology, Initial Evaluation, Imaging, Preoperative and Perioperative Care, Surgical Planning and Parathyroidectomy, Adjuncts and Approaches, Outcomes, and Reoperation.

CONCLUSIONS

Evidence-based guidelines were created to assist clinicians in the optimal management of secondary and tertiary renal hyperparathyroidism.

Delayed sampling of intraoperative parathormone may be unnecessary during parathyroidectomy in kidney-transplanted and dialysis patients

INTRODUCTION

Some authors advise in favor of delayed sampling of intraoperative parathormone testing (ioPTH) during parathyroidectomy in dialysis and kidney-transplanted patients. The aim of the present study was to evaluate the intensity and the role of delayed sampling in the interpretation of ioPTH during parathyroidectomy in dialysis patients (2HPT) and successful kidney-transplanted patients (3HPT) compared to those in single parathyroid adenoma patients (1HPT).

METHODS

This was a retrospective study of ioPTH profiles in patients with 1HPT, 2HPT, and 3HPT operated on in a single institution. Samples were taken at baseline ioPTH (sampling at the beginning of the operation), ioPTH-10 min (10 minutes after excision of the parathyroid glands), and ioPTH-15 min (15 minutes after excision of the parathyroid glands). The values were compared to baseline.

RESULTS

Median percentage values of ioPTH compared to baseline (100%) were as follows: 1HPT, ioPTH-10 min = 20% and ioPTH-15 min = 16%; 2HPT, ioPTH-10 min = 14% and ioPTH-15 min = 12%; 3HPT, ioPTH-10 min = 18% and ioPTH-15 min = 15%.

DISCUSSION

The reduction was equally effective at 10 minutes in all groups. In successful cases, ioPTH decreases satisfactorily 10 minutes after parathyroid glands excision in dialysis and transplanted patients, despite significant differences in kidney function. The postponed sampling of ioPTH appears to be unnecessary.

Comparison between Second- and Third-Generation PTH Assays during Minimally Invasive Parathyroidectomy (MIP)

METHODS

112 patients (of which 72.3% females) underwent MIP by the same surgeon. Age, sex, body mass index (BMI), pre- and postoperative serum calcium, creatinine, 25(OH)D levels, PTH at baseline (PTH T0), and PTH at 10 minutes after adenoma resection (PTH T10) were recorded. Both PTH 2G and PTH 3G assays were assessed using the Diasorin assays.

RESULTS

The mean age was 56.1 ± 14.7 years. Mean value of BMI, preoperative calcium, 25(OH)D, and CKD-EPI-eGFR were, respectively, 26.8 ± 4.8 kg/m², 110.9 ± 7.9 mg/L, 19.3 ± 9.2 ng/mL, and 88.6 ± 25.6 mL/min/1.73 m². PTH 2G and PTH 3G assays were well correlated at PTH T0 and PTH T10 (respectively, correlation coefficient 0.74 and 0.72 for intraclass correlation type 3). The median PTH fall was, respectively, of 79.9% and 82.5% for PTH 2G and PTH 3G. Multivariate analysis using the combined PTH 2G and PTH 3G as a dependent variable with 2 repeated measurements (at PTH 0 and PTH 10) showed a significant effect of preoperative calcium on IOPTH fall (p=0.001, effect size 0.13), while no significant effects were observed for sex, age, BMI, and 25(OH)D.

CONCLUSION

PTH 2G and PTH 3G assays resulted in a similar drop in IOPTH values. Elevated preoperative calcium levels are the only independent predictor of IOPTH decline. Further studies are needed to determine other factors that can influence PTH kinetics.

Management of Post-transplant Hyperparathyroidism and Bone Disease

Significant advances in immunosuppressive therapies have been made in renal transplantation, leading to increased allograft and patient survival. Despite improvement in overall patient survival, patients continue to require management of persistent post-transplant hyperparathyroidism. Medications that treat persistent hyperparathyroidism include vitamin D, vitamin D analogues, and calcimimetics. Medication side effects such as hypocalcemia or hypercalcemia, and adynamic bone disease, may lead to a decrease in the drugs. When medical management fails to control persistent post-transplant hyperparathyroidism, treatment is a parathyroidectomy. Surgical techniques are not uniform between centers and surgeons. Undergoing the surgery may include a subtotal technique or a technique including total parathyroid gland resection with partial heterotopic gland reimplantation. In addition, there are possible post-surgical complications. The ideal treatment for persistent post-transplant hyperparathyroidism is the treatment and prevention of the condition while patients are being managed for their late-stage chronic kidney disease and end-stage renal disease.

How radical is total parathyroidectomy in patients with renal hyperparathyroidism?

Purpose

Total parathyroidectomy (tPTX) in patients with renal hyperparathyroidism (RHPT) aims at the complete removal of all hyperfunctioning parathyroid tissue. Whenever parathyroidectomy is termed “total,” undetectable postoperative parathyroid hormone (PTH) levels within the first postoperative week are expected. The aim of this study was to evaluate if tPTX is technically possible using a radical surgical procedure.

Methods

In 109 consecutive patients with RHPT (on hemodialysis: n = 50; after kidney grafting n = 59), removal of all visible parathyroid tissue, bilateral thymectomy, bilateral central neck dissection (level VI), and immediate autotransplantation (AT) was performed. Intact PTH (iPTH) levels were measured in the first postoperative week. PTX was classified “total” when iPTH dropped below 10 pg/ml, “subtotal” between 10 and 65 pg/ml, and “insufficient” where levels stayed above 65 pg/ml.

Results

According to the postoperative PTH value, tPTX was achieved in 80 of 109 (73.4%) patients (hemodialysis n = 27, normal kidney function: n = 43, restricted: n = 10). PTX was “subtotal” in 25 patients (22.9%), 19 on hemodialysis, 2 had normal, and 4 had restricted kidney graft function. PTX turned out to be insufficient in four patients (3.7%); all of them were on hemodialysis. Insufficient PTX was not observed in kidney-grafted patients. Postoperative temporary laryngeal nerve morbidity was 1.8% (no permanent paresis).

Conclusions

Although applying a very radical concept in patients with RHPT, PTX was “total” in only 73.4%. Persistence of disease was avoided in 91.7%, and low morbidity was documented. In conclusion, it seems difficult to remove all parathyroid tissue from the neck which has to be considered when choosing the surgical procedure.

Niche point-of-care endocrine testing - Reviews of intraoperative parathyroid hormone and cortisol monitoring

Point-of-care (POC) testing, which provides quick test results in near-patient settings with easy-to-use devices, has grown continually in recent decades. Among near-patient and on-site tests, rapid intraoperative and intra-procedural assays are used to quickly deliver critical information and thereby improve patient outcomes. Rapid intraoperative parathyroid hormone (ioPTH) monitoring measures postoperative reduction of parathyroid hormone (PTH) to predict surgical outcome in patients with primary hyperparathyroidism, and therefore contributes to the change of parathyroidectomy to a minimally invasive procedure. In this review, recent progress in applying ioPTH monitoring to patients with secondary and tertiary hyperparathyroidism and other testing areas is discussed. In-suite cortisol monitoring facilitates the use of adrenal vein sampling (AVS) for the differential diagnosis of primary aldosteronism and adrenocorticotropic hormone (ACTH)-independent Cushing syndrome. In clinical and psychological research settings, POC testing is also useful for rapidly assessing cortisol in plasma and saliva samples as a biomarker of stress. Careful resource utilization and coordination among stakeholders help to determine the best approach for implementing cost-effective POC testing. Technical advances in integrating appropriate biosensors with microfluidics-based devices hold promise for future real-time POC cortisol monitoring.

Biochemical Testing Relevant to Bone

Laboratory biochemical testing is critical to the clinical understanding of bone disorders. Patients with skeletal diseases have underlying themes in their pathophysiology that would be impossible to detect without biochemical assessment of serum and urine minerals, vitamin D, parathyroid hormone, parathyroid hormone-related peptide, and bone turnover markers. Bone disorders are caused by abnormalities in signaling pathways that affect bone formation and resorption. Therapies for common bone diseases were developed in direct response to underlying biochemical abnormalities.

Diagnostic Accuracy Study of Intraoperative and Perioperative Serum Intact PTH Level for Successful Parathyroidectomy in 501 Secondary Hyperparathyroidism Patients

Parathyroidectomy (PTX) is an effective treatment for severe secondary hyperparathyroidism (SHPT); however, persistent SHPT may occur because of supernumerary and ectopic parathyroids. Here a diagnostic accuracy study of intraoperative and perioperative serum intact parathyroid hormone (iPTH) was performed to predict successful surgery in 501 patients, who received total PTX + autotransplantation without thymectomy. Serum iPTH values before incision (io-iPTH0), 10 and 20 min after removing the last parathyroid (io-iPTH10, io-iPTH20), and the first and fourth day after PTX (D1-iPTH, D4-iPTH) were recoded. Patients whose serum iPTH was >50 pg/mL at the first postoperative week were followed up within six months. Successful PTX was defined if iPTH was <300 pg/mL, on the contrary, persistent SHPT was regarded. There were 86.4% patients underwent successful PTX, 9.8% remained as persistent SHPT and 3.8% were undetermined. Intraoperative serum iPTH demonstrated no significant differences in two subgroups with or without chronic hepatitis. Receiver operating characteristic (ROC) curves showed that >88.9% of io-iPTH20% could predict successful PTX (area under the curve [AUC] 0.909, sensitivity 78.6%, specificity 88.5%), thereby avoiding unnecessary exploration to reduce operative complications. D4-iPTH >147.4 pg/mL could predict persistent SHPT (AUC 0.998, sensitivity 100%, specificity 99.5%), so that medical intervention or reoperation start timely.

Point-of-care diagnostics for niche applications

Point-of-care or point-of-use diagnostics are analytical devices that provide clinically relevant information without the need for a core clinical laboratory. In this review we define point-of-care diagnostics as portable versions of assays performed in a traditional clinical chemistry laboratory. This review discusses five areas relevant to human and animal health where increased attention could produce significant impact: veterinary medicine, space travel, sports medicine, emergency medicine, and operating room efficiency. For each of these areas, clinical need, available commercial products, and ongoing research into new devices are highlighted.

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.

Surgical management of secondary hyperparathyroidism in chronic kidney disease--a consensus report of the European Society of Endocrine Surgeons

BACKGROUND

Despite advances in the medical management of secondary hyperparathyroidism due to chronic renal failure and dialysis (renal hyperparathyroidism), parathyroid surgery remains an important treatment option in the spectrum of the disease. Patients with severe and complicated renal hyperparathyroidism (HPT), refractory or intolerant to medical therapy and patients with specific requirements in prospect of or excluded from renal transplantation may require parathyroidectomy for renal hyperparathyroidism.

METHODS

Present standard and actual controversial issues regarding surgical treatment of patients with hyperparathyroidism due to chronic renal failure were identified, and pertinent literature was searched and reviewed. Whenever applicable, evaluation of the level of evidence concerning diagnosis and management of renal hyperparathyroidism according to standard criteria and recommendation grading were employed. Results were discussed at the 6th Workshop of the European Society of Endocrine Surgeons entitled Hyperparathyroidism due to multiple gland disease: An evidence-based perspective.

RESULTS

Presently, literature reveals scant data, especially, no prospective randomized studies to provide sufficient levels of evidence to substantiate recommendations for surgery in renal hyperparathyroidism. Appropriate surgical management of renal hyperparathyroidism involves standard bilateral exploration with bilateral cervical thymectomy and a spectrum of four standardized types of parathyroid resection that reveal comparable outcome results with regard to levels of evidence and recommendation. Specific patient requirements may favour one over the other procedure according to individualized demands.

CONCLUSIONS

Surgery for patients with renal hyperparathyroidism in the era of calcimimetics continues to play an important role in selected patients and achieves efficient control of hyperparathyroidism. The overall success rate and long-term control of renal hyperparathyroidism and optimal handling of postoperative metabolic effects also depend on the timely indication, individually suitable type of parathyroid resection and specialized endocrine surgery.

A Retrospective Study of the Impact of Intraoperative Intact Parathyroid Hormone Monitoring During Total Parathyroidectomy for Secondary Hyperparathyroidism: STARD Study

The study aimed to evaluate the diagnostic accuracy of intraoperative intact parathyroid hormone (IO-iPTH) in patients with secondary hyperparathyroidism (HPT). The cut-off for IO-iPTH monitoring remains unknown. This was a single-center retrospective review of 226 consecutive patients (107 males and 119 females) who underwent parathyroidectomy for secondary HPT between May 2010 and March 2014. The predetermined cut-off for IO-iPTH was a 70% IO-iPTH drop from baseline 10 minutes after total parathyroidectomy and thymectomy. We used <60 pg/mL iPTH value on postoperative day 1 (POD1) as an indicator of successful removal of parathyroid glands and reviewed the frequency of reoperation other than in autografted sites during the observation period. This study was based on the Standards for the Reporting of Diagnostic accuracy compliant. The reoperation rate in patients with >60 pg/mL iPTH value (POD1) was significantly higher than that in patients with <60 pg/mL iPTH value (POD1), (13.0% versus 0.5% P = 0.003). Sensitivity, specificity, and accuracy of >70% IO-iPTH drop were 97.5%, 52.2%, and 92.9%, respectively, this criterion was demonstrated to be beneficial in 26 patients. In 5 patients, <70% IO-iPTH drop was observed and further exploration enabled sufficient removal of parathyroid glands. In 21 patients, although fewer than 4 parathyroid glands were removed after enough explorations, >70% IO-iPTH drop enabled termination of operations and iPTH value (POD1) was <60 pg/mL.An iPTH value of <60 pg/mL (POD1) was a good predictor for successful parathyroidectomy. A 70% IO-iPTH drop from the baseline was appropriate to determine sufficient parathyroid gland removal during parathyroidectomy for patients with secondary HPT. [Corrected]

Outcomes of Total Parathyroidectomy with Autotransplantation versus Subtotal Parathyroidectomy with Routine Addition of Thymectomy to both Groups: Single Center Experience of Secondary Hyperparathyroidism

BACKGROUND

Secondary hyperparathyroidism is a common acquired disorder seen in chronic renal failure. It may result in potentially serious complications including metabolic bone diseases, severe atherosclerosis and undesirable cardiovascular events. Parathyroidectomy is required in about 20% of patients after 3-10 years of dialysis and in up to 40% after 20 years.

AIMS

The aim of the current study was to evaluate the short-term and long-term outcomes of patients with secondary hyperparathyroidism who had undergone total parathyroidectomy with autotransplantation and thymectomy or subtotal parathyroidectomy with thymectomy by the same surgical team during the study period.

STUDY DESIGN

Retrospective comparative study.

METHODS

Clinical data of 50 patients who underwent parathyroid surgery for secondary hyperparathyroidism between 2003 and 2011 were reviewed retrospectively. Patients were divided into two subgroups of total parathyroidectomy with autotransplantation or subtotal parathyroidectomy. Thymectomy was routinely performed for both groups. Short term outcome parameters included intact parathyroid hormone, ionized calcium and alkaline phosphatase levels. Bone pain, bone fractures, persistent or recurrent disease were included in long term outcome parameters.

RESULTS

The mean duration of dialysis was eight years. The mean ionized calcium levels dropped significantly in the total parathyroidectomy with autotransplantation group (p=0.016). No serious postoperative complications were observed. Postoperative intravenous calcium supplementation was required in four patients in the total parathyroidectomy with autotransplantation group (total PTX+AT) and in three patients in the subtotal parathyroidectomy group (subtotal PTX). Postoperatively, all patients received oral calcium carbonate and calcitriol. The length of average hospital stay was 5 (3-10) days. Including nine patients who underwent successful renal transplantation pre-operative bone symptoms, hypercalcemia, hyperphosphatemia, and an increased alkaline phosphatase levels were improved or resolved in all patients. After a mean follow-up of 65 months, three patients (6%) had persistent and one (2%) had recurrent disease.

CONCLUSION

Total parathroidectomy with autotransplantation is a beneficial and safe surgical procedure for patients on chronic dialysis with otherwise uncontrollable secondary hyperparathroidism and even in patients who have undergone renal transplantation after parathyroidectomy. Careful cervical exploration and routine thymectomy should be considered as a routine part of the surgical approach regardless of the preferred technique.

Factors that influence parathyroid hormone half-life: determining if new intraoperative criteria are needed

IMPORTANCE

Minimally invasive parathyroidectomy using intraoperative parathyroid hormone monitoring remains the standard approach to the majority of patients with primary hyperparathyroidism. This study demonstrates that individual patient characteristics do not affect existing criteria for intraoperative parathyroid hormone monitoring.

OBJECTIVE

To identify patient characteristics, such as age, sex, race, body mass index (BMI), and renal function, that may affect existing criteria for intraoperative parathyroid hormone (IOPTH) levels during minimally invasive parathyroidectomy.

DESIGN

Retrospective review of a prospectively collected parathyroid database populated from August 2005 to April 2011.

SETTING

Academic medical center.

PARTICIPANTS

Three hundred six patients with sporadic primary hyperparathyroidism who underwent initial parathyroidectomy between August 2005 and April 2011.

INTERVENTIONS

All patients underwent minimally invasive parathyroidectomy with complete IOPTH information.

MAIN OUTCOME AND MEASURES

Individual IOPTH kinetic profiles were fitted with an exponential decay curve and individual IOPTH half-lives were determined. Univariate and multivariate analyses were performed to determine the association between patient demographics or laboratory data and IOPTH half-life.

RESULTS

Mean age of the cohort was 60 years, 78.4% were female, 90.2% were white, and median BMI was 28.3. Overall, median IOPTH half-life was 3 minutes, 9 seconds. On univariate analysis, there was no association between IOPTH half-life and patient age, renal function, or preoperative serum calcium or parathyroid hormone levels. Age, BMI, and an age × BMI interaction were included in the final multivariate median regression analysis; race, sex, and glomerular filtration rate were not predictors of IOPTH half-life. The IOPTH half-life increased with increasing BMI, an effect that diminished with increasing age and was negligible after age 55 years (P = .001).

CONCLUSIONS AND RELEVANCE

Body mass index, especially in younger patients, may have a role in the IOPTH half-life of patients undergoing parathyroidectomy. However, the differences in half-life are relatively small and the clinical implications are likely not significant. Current IOPTH criteria can continue to be applied to all patients undergoing parathyroidectomy for sporadic primary hyperparathyroidism.

Current trends in surgery for renal hyperparathyroidism (RHPT)--an international survey

PURPOSE

The indications and results of preoperative localization, surgical strategy, indication for thymectomy, the application of intraoperative parathyroid hormone (PTH) monitoring, cryopreservation, and replantation of cryopreserved parathyroid tissue are not well documented in renal hyperparathyroidism (RHPT). The current trends in surgery for RHPT are to be evaluated in an international online survey.

METHODS

Thirty-three questions regarding preoperative localization, surgical management of RHPT, intraoperative PTH monitoring, immediate/delayed autotransplantation (AT), and parathyroid cryopreservation were sent to members of various societies of endocrine surgeons.

RESULTS

The data from 86 responses were analyzed, 61.6 % reported more than 50 parathyroid surgeries per year, and 62.7 % operated on less than 16 patients with RHPT per year. Subtotal or total parathyroidectomy (with/without AT) was the standard procedure in 98.8 % of the cases. Immediate AT was performed in 40.7 % (72.7 % in the forearm). In most patients, the onset of graft function was documented later than 1 week after AT. Cryopreservation was routinely performed in 27.4 %. In 10.7 %, replantation was performed in more than five patients (hypo- or aparathyroidism: n = 41; fresh graft failure: n = 13; reoperations: n = 9). Intraoperative PTH monitoring (in RHPT) was routinely used in 46.2 %. Its influence on surgical strategy was confirmed in 40 %.

CONCLUSIONS

The survey reflects the divergent strategies applied for AT, cryopreservation, and PTH monitoring in RHPT.

The surgical management of renal hyperparathyroidism

Secondary and tertiary hyperparathyroidism (HPT) develop in patients with renal failure due to a variety of mechanisms including increased phosphorus and fibroblast growth factor 23 (FGF23), and decreased calcium and 1,25-dihydroxy vitamin D levels. Patients present with various bone disorders, cardiovascular disease, and typical laboratory abnormalities. Medical treatment consists of controlling hyperphosphatemia, vitamin D/analog and calcium administration, and calcimimetic agents. Improved medical therapies have led to a decrease in the use of parathyroidectomy (PTX). The surgical indications include parathyroid hormone (PTH) levels >800 pg/ml associated with hypercalcemia and/or hyperphosphatemia despite medical therapy. Other indications include calciphylaxis, fractures, bone pain or pruritis. Transplant recipients often show decreased PTH, calcium and phosphorus levels, but some will have persistent HPT. Evidence suggests that PTX may cause deterioration in renal graft function in the short-term calling into the question the indications for PTX in these patients. Pre-operative imaging is only occasionally helpful except in re-operative PTX. Operative approaches include subtotal PTX, total PTX with or without autotransplantation, and possible thymectomy. Each approach has its proponents, advantages and disadvantages which are discussed. Intraoperative PTH monitoring has a high positive predictive value of cure but a poor negative predictive value and therefore is of limited utility. Hypocalcemia is the most common complication requiring aggressive calcium administration. Benefits of surgery may include improved survival, bone mineral density and alleviation of symptoms.

Intraoperative adjuncts for parathyroid surgery

In recent years, parathyroid surgery has evolved from traditional bilateral neck exploration to minimal invasive parathyroidectomy. This trend became possible due to preoperative localization imaging that guides the surgeon in the search for a parathyroid adenoma. Intraoperative adjuncts are complementary to preoperative localization and assist in localizing parathyroid glands, confirming parathyroid tissue and establishing a cure. Institutions and surgeons utilize different intraoperative adjuncts in different protocols with varying results. The purpose of this article is to review the available intraoperative adjuncts to parathyroid surgery and critically evaluate their utility, accuracy and their added value to the surgeon.

Usefulness of intraoperative parathyroid hormone measurements in patients with renal hyperparathyroidism

BACKGROUND

In renal hyperparathyroidism, it remains unclear whether intraoperative parathyroid hormone (PTH) measurements can predict postoperative outcome and guide the extent of surgical exploration.

METHODS

In 42 parathyroidectomies for renal hyperparathyroidism, we analyzed the predictive value of the Miami Criterion of 50% intraoperative PTH decrease. We used receiver operating characteristic (ROC) curves to find the criterion with the best diagnostic performance. We also investigated whether the whole PTH assay improved accuracy.

RESULTS

Twenty-six operations (62%) resulted in normal postoperative PTH. With the Miami Criterion, cure was predicted with a sensitivity of 95% and specificity of only 8%. Specificity could be improved to 50% using a 70% PTH decrease as cut-off level. The whole PTH assay did not improve accuracy.

CONCLUSION

Prediction of cure after parathyroidectomy for renal hyperparathyroidism might be improved with a criterion of 70% PTH decrease 10 minutes after excision of all parathyroid glands. Prospective analysis needs to validate this new criterion.

Secondary and tertiary hyperparathyroidism: the utility of ioPTH monitoring

BACKGROUND

The aim of the present study was to examine the utility of intraoperative parathyroid hormone (ioPTH) monitoring in patients with secondary (2) and tertiary (3) hyperparathyroidism (HPT).

MATERIALS AND METHODS

We identified 105 patients with 2HPT (n = 33) and 3HPT (n = 72) who underwent ioPTH monitoring during parathyroidectomy. Data are reported as mean +/- SEM.

RESULTS

The 2HPT patients underwent 17 subtotal, 10 total, and 6 re-exploratory parathyroidectomies, whereas the 3HPT patients underwent 54 subtotal, 15 limited, and 3 re-exploratory parathyroidectomies. The percent decrease from the baseline ioPTH level at 5, 10, and 15 min after parathyroid resection, respectively, were 72% +/- 3%, 76% +/- 3%, and 76% +/- 3% in patients with 2HPT, and 52% +/- 6%, 60% +/- 4%, and 69% +/- 4% in patients with 3HPT. IoPTH levels failed to drop >50% from baseline in 5 patients (2HPT: n = 2, 3HPT: n = 3) who were normocalcemic at last follow-up. IoPTH did not alter the surgical approach in any 2HPT patients, but did alter management in 25% of 3HPT patients (15 limited resections and 3 supernumerary glands). Normocalcemia was achieved in 97% of 2HPT patients and 99% of 3HPT patients; 2 patients developed recurrent disease.

CONCLUSIONS

Intraoperative PTH levels fell by >50% in nearly 95% of patients with 2HPT and 3HPT, and the PTH level reliably predicted postoperative cure. Although the use of ioPTH did not alter surgical management in any patient with 2HPT, this rapid PTH assay affected the surgical care of a quarter of the patients with 3HPT, and it may prove to be a useful adjunct in this group of patients.

Variability of parathyroid hormone and other markers of bone mineral metabolism in patients receiving hemodialysis

BACKGROUND AND OBJECTIVES

Clinical management of mineral bone disorder in patients with kidney failure is guided by biochemical targets, in particular parathyroid hormone (PTH) concentration. The biologic variation of PTH and other bone mineral markers was measured in hemodialysis patients to better define their role in management.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Intact PTH, biointact (whole-molecule) PTH, calcium, albumin-adjusted calcium, phosphate, and alkaline phosphatase (ALP) were measured in nonfasting samples obtained twice a week (both short-dialysis interval) over a 6-week period in 22 stable hemodialysis patients. Concurrently, samples were obtained from 12 healthy volunteers. Intraindividual coefficients of variance (CVI) were calculated and used to derive the reference change value (RCV) required to be 95% certain that a change has occurred.

RESULTS

CVI of all markers was significantly (P<0.05) greater in patients than in healthy volunteers. For phosphate, ALP, and PTH this implies that an increased number of samples is required to estimate an individual's homeostatic set point. CVI of intact PTH was 25.6% in hemodialysis patients and 19.2% in healthy volunteers. A greater RCV should be used for patients (72%) compared with healthy volunteers (54%). Ideally 26 specimens should be measured to estimate a patient's intact PTH homeostatic set point (within +/-10%) with 95% probability. The CVI of biointact PTH was at least as high as that for intact PTH.

CONCLUSIONS

The uncertainty of PTH estimation in an individual significantly undermines its value as a tool in the management of chronic kidney disease-mineral bone disorder using current management approaches.

Secondary and tertiary hyperparathyroidism, state of the art surgical management

This article reviews the current surgical management of patients with secondary and tertiary hyperparathyroidism. The focus is on innovative surgical strategies that have improved the care of these patients over the past 10 to 15 years. Modalities such as intraoperative parathyroid hormone monitoring and radioguided probe utilization are discussed.

Radioguided parathyroidectomy for hyperparathyroidism in the reoperative neck

BACKGROUND

The purpose of this study was to determine if radioguided parathyroidectomy (RGP) is effective for hyperparathyroidism (HPT) in the reoperative neck.

METHODS

We retrospectively reviewed all patients with HPT and a history of neck surgery who underwent RGP over a 7-year period. Data are reported as mean +/- SEM.

RESULTS

We identified 110 patients with primary (n = 94), secondary (n = 7), or tertiary (n = 9) HPT who underwent 138 previous neck operations. The average hospital stay was 0.6 +/- 0.1 days. The in and ex vivo counts obtained with the gamma probe were 310 +/- 26 and 130 +/- 13, respectively. The ex vivo percentage of background was 69% +/- 9%, and virtually all resected parathyroids had ex vivo counts > or =20%. After RGP, 96% of patients were cured, and 5% experienced complications (all transient). Cure rates after RGP decreased as the number of previous neck operations increased (P = .002). Additionally, reoperative neck patients with single adenomas were more likely to experience cure than patients with hyperplasia (P = .02).

CONCLUSION

These results illustrate that RGP is valuable in treatment of the reoperative neck. In addition, RGP allows similar lengths of stay, efficacy, and complication rates as those reported for patients undergoing initial parathyroidectomy.

Value of Sestamibi Scans in Tertiary Hyperparathyroidism

OBJECTIVES

To determine the value of preoperative Tc-sestamibi scans and the incidence of ectopic glands in tertiary hyperparathyroidism.

DESIGN

Prospective, non-randomized analysis of a consecutive cohort of surgical patients from the Medical College of Georgia Thyroid/Parathyroid Center.

MATERIALS AND METHODS

A consecutive series of patients with tertiary hyperparathyroidism undergoing parathyroidectomy was analyzed. Demographic data, preoperative Tc-sestamibi scintigraphy results, location of diseased glands, pre- and postoperative calcium, and parathyroid hormone levels were collected.

RESULTS

Twenty-one patients underwent parathyroidectomy for tertiary hyperparathyroidism between March 2004 and September 2006. Of these 21 patients, 3 were re-operative cases for persistent hypercalcemia and each was found to have a single diseased gland. Of the 18 patients undergoing first time surgery, 15 had four-gland hyperplasia, 2 patients had single adenomas, and 1 patient had a double adenoma. Nine of the 21 patients (43%) had ectopic glands (2 of these patients had 2 ectopic glands each). The overall sensitivity of the preoperative Tc-sestamibi scintigraphy was 76% and was not significantly different when comparing patients with ectopic glands (78%) and those without (75%).

CONCLUSIONS

Tc sestamibi scintigraphy has high positive predictive value and sensitivity in patients with tertiary hyperparathyroidism. Sestamibi scanning is particularly valuable in this patient population since the incidence of ectopic glands may be higher than previously recognized.

C-terminal provasopressin (copeptin) as a novel and prognostic marker in acute myocardial infarction: Leicester Acute Myocardial Infarction Peptide (LAMP) study

BACKGROUND

The role of the vasopressin system after acute myocardial infarction is unclear. Copeptin, the C-terminal part of the vasopressin prohormone, is secreted stoichiometrically with vasopressin. We compared the prognostic value of copeptin and an established marker, N-terminal pro-B-type natriuretic peptide (NTproBNP), after acute myocardial infarction.

METHODS AND RESULTS

In this prospective single-hospital study, we recruited 980 consecutive post-acute myocardial infarction patients (718 men, median [range] age 66 [24 to 95] years), with follow-up over 342 (range 0 to 764) days. Plasma copeptin was highest on admission (n=132, P<0.001, day 1 versus days 2 to 5) and reached a plateau at days 3 to 5. In the 980 patients, copeptin (measured at days 3 to 5) was elevated in patients who died (n=101) or were readmitted with heart failure (n=49) compared with survivors (median [range] 18.5 [0.6 to 441.0] versus 6.5 [0.3 to 267.0] pmol/L, P<0.0005). With logistic regression analysis, copeptin (odds ratio, 4.14, P<0.0005) and NTproBNP (odds ratio, 2.26, P<0.003) were significant independent predictors of death or heart failure at 60 days. The area under the receiver operating characteristic curves for copeptin (0.75) and NTproBNP (0.76) were similar. The logistic model with both markers yielded a larger area under the curve (0.84) than for NTproBNP (P<0.013) or copeptin (P<0.003) alone, respectively. Cox modeling predicted death or heart failure with both biomarkers (log copeptin [hazard ratio, 2.33], log NTproBNP [hazard ratio, 2.70]). In patients stratified by NTproBNP (above the median of approximately 900 pmol/L), copeptin above the median (approximately 7 pmol/L) was associated with poorer outcome (P<0.0005). Findings were similar for death and heart failure as individual end points.

CONCLUSIONS

The vasopressin system is activated after acute myocardial infarction. Copeptin may predict adverse outcome, especially in those with an elevated NTproBNP (more than approximately 900 pmol/L).

Update on parathyroid hormone: new tests and new challenges for external quality assessment

It is now 43 years since Berson and Yalow published the first radio-immunoassay (RIA) for parathyroid hormone (PTH) [S.A. Berson, R.S. Yalow, G.D. Aurbach, J.T. Potts, Immunoassay of bovine and human parathyroid hormone. Proc Natl Acad Sci U S A 49 (1963) 613-617] [1]. Since then, there have been marked advances in our understanding of this peptide hormone, its mechanism of action and biological regulation [J.T. Potts, Parathyroid hormone: past and present. J. Endocrinol. 187 (2005) 311-325] [2]. PTH has become a routine assay in tertiary care hospitals and is an essential element in the management of chronic kidney disease, parathyroid disorders and the investigation of abnormalities in calcium homeostasis. Despite continuing technological advances in PTH measurement, analyte heterogeneity remains a problem, while improved turnaround time and better precision are constantly escalating clinical demands. This mini-review begins with a brief update of current knowledge on PTH, followed by a summary of a recent Ontario-wide External Quality Assurance (EQA) survey, and concludes with comments on utilization trends, current and future.