Parathyroid autotransplantation in forty-four patients with primary hyperparathyroidism: the role of thallium scanning

Forty-four patients with primary hyperparathyroidism were followed for 18 to 126 months after subtotal or total parathyroidectomy and parathyroid autotransplantation. Indications for autotransplantation included the devascularization of parathyroid glands during concomitant thyroid lobectomy or total thyroidectomy and the excision of the only remaining parathyroid tissue in patients with persistent hyperparathyroidism after previous unsuccessful parathyroidectomies. Before implantation, all parathyroid tissue was histologically evaluated by frozen-section light microscopy with hematoxylin and eosin stain. Fifteen patients had histologically normal implants; to date none of these patients have developed recurrent hyperparathyroidism. Twenty-nine patients had either adenomatous or hyperplastic parathyroid tissue used for implants; two of these patients developed graft-dependent recurrent hyperparathyroidism 4 and 7 years later. In both patients the grafts were preoperatively localized by thallium scanning and their resection restored eucalcemia. One hundred thirty-one patients from 11 series in the current literature had a cumulative incidence of 17.5% for presumed graft-dependent recurrence and a 9.2% incidence of graft excision followed by eucalcemia. In comparison, in the present series the incidence of graft-dependent recurrent hyperparathyroidism in patients with either adenomatous or hyperplastic implants stands at 6.9%. In contrast, in 15 patients with normal parathyroid tissue implants, the incidence was zero.     

Calcium-lowering medications in patients with primary hyperparathyroidism: intraoperative findings and postoperative hypocalcemia

BackgroundWe analyzed how calcium-lowering medications (CLMs) influenced surgical findings in patients with primary hyperparathyroidism.MethodsA retrospective review was conducted of 281 patients undergoing surgery for primary hyperparathyroidism. Logistic regression evaluated the relationship between CLM and surgical findings. A mixed-effects model determined the influence of CLMs on these curves.ResultsWe found that CLM (P = .018) and a higher serum calcium level (P = .018) were variables making 4-gland hyperplasia less likely. Analysis of intraoperative parathyroid hormone (IOPTH) plots revealed that CLMs altered the kinetics (P = .043). However, the 2 groups did not differ in the number of measurements necessary for a 50% decrease in IOPTH levels. Multivariate logistic regression also revealed that patients taking more than one CLM had an increased association with postoperative hypocalcemia (P = .018).ConclusionsAlthough CLM contributed to differences in IOPTH curves, their use does not require changing standard IOPTH protocol but should alert the surgeon to the risk of postoperative hypocalcemia.     

Video-assisted parathyroidectomy in the management of patients with primary hyperparathyroidism

INTRODUCTION: In recent years, different minimally invasive techniques of parathyroidectomy have been described. We performed a retrospective study to evaluate the indications and results of video-assisted parathyroidectomy (Vap) in the management of our patients with primary hyperparathyroidism (PHPT). MATERIALS AND METHODS: During the last 5 years (1998-2002), we operated on 528 patients with PHPT. Vap was proposed for patients with sporadic PHPT, without associated goiter and without previous neck surgery, in whom a single adenoma was localized by means of sonography and/or sestamibi scanning. Vap was performed by lateral approach with insufflation for patients with adenoma located deeply in the neck and by gasless midline approach for patients with adenoma located anteriorly. A quick parathyroid (qPTH) assay was used during the surgical procedures. Calcemia, phosphoremia and PTH were systematically evaluated in patients on days 1 and 8, 1 month and 1 year after surgery. All patients underwent pre-operative and postoperative investigations of vocal cord movements. RESULTS: Among 528 patients with PHPT, 228 (43%) were not eligible for Vap: associated nodular goiter (99 cases), previous neck surgery (42 cases), suspicion of multiglandular disease (25 cases), lack of pre-operative localization (48 cases), and miscellaneous causes (14 cases). Vap was performed in 300 patients with sporadic PHPT: 282 lateral access, 17 midline access and 1 thoracoscopy. Median operative time was 50 min (20-130 min). Conversion to conventional parathyroidectomy was required in 42 patients (14%): missed adenomas (11 cases), difficulties of dissection (7 cases), multiglandular disease correctly predicted by qPTH (10 cases); qPTH assay false negative results (3 cases), sestamibi scan false positive results (10 cases) and 1 sonography false positive result. One patient presented definitive recurrent nerve palsy. One patient had a persistent PHPT and one other patient had a recurrent PHPT. CONCLUSION: Vap can be proposed for more than half of patients with PHPT. In our experience Vap and conventional parathyroidectomy are complementary. Immediate results of Vap are similar to those obtained with conventional parathyroidectomy but no conclusions can be drawn in terms of influence of Vap on the outcome of the patients operated for PHPT.     

The role of intraoperative parathyroid hormone assay in the surgical management of hyperparathyroidism

Surgical management of primary hyperparathyroidism has undergone several chances in recent years and historically has required bilateral neck exploration with identification of the parathyroid adenoma together with three normal glands. The intraoperative hormone assay allows a more limited procedure by confirming complete removal of hypersecreting tissue. The Authors report surgical treatment of 24 consecutive hyperparathyroidism and conclude that evaluation of intraoperative hormone assay accurately predicts the determination of adequacy of resection and the correct outcome of surgery in patients with parathyroid adenomas.     

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: The outcome of MIP without ioPTH monitoring was comparable to that reported in series that used ioPTH monitoring.     

Clinical characteristics and surgical treatment of sporadic primary hyperparathyroidism with emphasis on chief cell hyperplasia

In 570 patients with sporadic primary hyperparathyroidism, the age, sex, symptoms, and preoperative serum calcium values were related to the histopathologic diagnoses, operative findings, and the extent and outcome of parathyroid surgery. Renal stone formation was especially prevalent in younger patients with slight hypercalcemia and parathyroid chief cell hyperplasia, whereas neuromuscular and psychiatric disturbances were overrepresented among older women with higher serum calcium values. Serum calcium concentration was inversely correlated to the proportional incidence of chief cell hyperplasia and positively correlated to the glandular weight of both adenomas and hyperplasias. Glandular size was markedly irregular in chief cell hyperplasia, with increased gland weights of no more than two glands in 78% of patients. During follow-up, for as long as 27 years, normocalcemia was obtained in 91% of patients with adenomas, with failures mainly depending on difficulties in identifying the parathyroid glands. The rate of normocalcemia was lower (80%) among patients with hyperplasia, but an inability to visualize the glands was not a major cause of failure. In patients with hyperplasia with asymmetric and more markedly enlarged glands, it appeared sufficient to remove only the enlarged glands, whereas the findings advocated a subtotal 3- to 3.5-gland resection in patients with more symmetrically or less enlarged hyperplastic glands.     

原发性甲状旁腺机能亢进患者术中监测甲状旁腺激素的临床意义

目的：探讨原发性甲状旁腺机能亢进症（PHPT）患者术中动态监测甲状旁腺激素（IOPTH）的临床价值。 方法：回顾性分析1998年1月—2012年1月行手术治疗的36例PHPT患者的临床资料,其中2005年以后术中行IOPTH监测患者22例（IOPTH组）,2005年以前术中未行IOPTH监测的患者14例（常规组）,比较两组的术中情况与治疗效果。 结果：与常规组比较,IOPTH组手术时间明显缩短[（72.95±24.34）min vs.（81.86±29.46）min,P=0.000],术后短期（1个月内）甲状旁腺功能恢复患者比例增加（90.9% vs. 57.1%,P=0.018）,永久性甲状旁腺功能减退发生率明显减少（4.5% vs. 28.6%,P=0.042）。IOPTH监测对于判断高功能病灶完全切除与否的敏感度为100%,准确率为95.5%。 结论：PHPT手术中,在术前定位基础上联合IOPTH,有助于判断功能亢进腺体是否全部切除,避免遗漏多发病变腺体及不必要的双侧探查,缩短手术时间,疗效确切。     

Surgical therapy for primary hyperparathyroidism in patients with previous thyroid surgery

BACKGROUND: In patients with primary hyperparathyroidism (HPTH) and previous thyroid operations, complications of parathyroidectomy are more frequent than in patients undergoing initial neck surgery. The aim of this study was to investigate the value of preoperative imaging with regard to its influence on the surgical strategy. METHODS: We retrospectively analyzed 17 patients with primary HPTH and previous thyroid surgery. Preoperatively 16 patients underwent sonography and/or scintigraphy. RESULTS: Sonography had an overall accuracy to correctly localize enlarged parathyroid glands of 80%, and scintiscanning had overall accuracy of 78.6%. The accuracy of localization was increased up to 84.6% if both diagnostic procedures were applied. In patients with normal thyroid residues the accuracy of sonography was 85.7%, and it was 100% if scintiscanning was used. CONCLUSIONS: Preoperative localization techniques in patients with primary HPTH and previous thyroid surgery have high accuracy. This allows for an imaging-directed operative strategy, thus preventing unnecessary bilateral neck explorations, which carry a high risk of recurrent laryngeal nerve injury.     

The role of intraoperative parathyroid hormone testing in patients with tertiary hyperparathyroidism after renal transplantation

BACKGROUND: Intraoperative parathyroid hormone (PTH) testing has been shown to accurately define adequacy of parathyroid resection in patients with primary hyperparathyroidism (HPT) and alters the operative management in 10% to 15% of cases. However, the benefit of this technique in patients with tertiary HPT after renal transplantation undergoing parathyroidectomy is unclear. METHODS: Intraoperative PTH was measured in 32 consecutive patients undergoing parathyroidectomy for tertiary HPT after renal transplantation between March 2001 and November 2004 by using the Elecsys assay at baseline and, subsequently, 5, 10, and 15 minutes after curative resection. The outcomes of these patients were evaluated. RESULTS: All patients were cured after surgery. Of the 32 patients, 29 were found to have parathyroid hyperplasia, while 1 had a single adenoma and 2 had double adenomas. The average drop in intraoperative PTH levels after curative resection was 69 +/- 3.5% at 5 min., 77 +/- 2.3% at 10 minutes, and 83 +/- 3.4% at 15 minutes. PTH testing changed the intraoperative management in 5 (16%) patients. One patient with a single adenoma and 2 patients with double adenomas had a >50% drop at 10 minutes. after excision; therefore, the operation was terminated without further resection. Two patients did not have a >50% drop at 10 minutes after 3.5 gland resection. These patients were explored further, and additional supernumerary parathyroid glands were identified and resected. After resection of these additional glands, the PTH fell by >50%, indicating cure. CONCLUSIONS: In patients undergoing parathyroidectomy for tertiary HPT after renal transplantation, a decrease in intraoperative PTH levels >50% at 10 minutes after completion of the operation indicated adequate resection. Furthermore, intraoperative PTH testing altered the operative management in 16% of patients. Therefore, similar to its role in patients with primary HPT, intraoperative PTH testing appears to play an equally important role in the management of patients with tertiary HPT undergoing parathyroidectomy.     

The influence of surgery on the risk of death in patients with primary hyperparathyroidism

The previous finding of an increased risk of premature death in a consecutive series of 896 patients operated on for primary hyperparathyroidism between 1953 and 1982 [1] raised the question of the role that surgery plays in relation to the risk of death. In the present study, undertaken to examine that issue, 3 factors—age, calendar year of surgery, and time passed after surgery—have been found to be significantly related to the risk of death (p<0.001), each factor contributing independently. A correlation was found between a late calendar year of surgery and a low degree of hyperparathyroidism as evaluated by serum calcium and creatinine levels. There was an increased risk of premature death in all age groups. The risk was less among patients operated on in later years. The observed normalization of the increased risk of death with time after surgery also took place sooner in patients operated on in later years. Our finding of improved survival following surgical intervention contrasts favorably with the findings of others in studies of subjects with untreated mild hyperparathyroidism. We have also found that preoperative serum calcium levels affect the risk of death, and that there is an additional factor related to the calendar year of surgery affecting the risk of death. Circumstantial evidence indicates that the duration of hyperparathyroidism contributes to this factor. Our results also show that early surgery decreases the risk of premature death in mild cases of the disease.

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Resumen El hallazgo, previamente informado, de muerte precoz en una serie consecutiva de 896 pacientes operados por hiperparatiroidismo primario entre 1953 y 1982 [1], planteó el interrogante sobre el papael de la cirugía en relación con el riesgo de muerte. En el presente estudio, emprendido con el propósito de examinar este fenómeno, se encontraron 3 factores significativamente relacionados con el riesgo de muerte (p<0.001) cada uno con una contribución independiente: edad, año calendario de la cirugía, y tiempo transcurrido después de la cirugía. Se encontró correlación entre un ano calendario tardio de la cirugía y un bajo grado de hiperparatiroidismo, según evaluación por los niveles séricos de calcio de creatinina. Se presentó un riesgo aumentado de muerte precoz en todos los grupos de edad. El riesgo fue menor en los pacientes operados en los últimos años. La normalización del riesgo aumontado de muerte con el lapso postoperatorio también se observó en los pacientes operados en los últimos años. Nuestros hallazgos de mejor supervivencia después de la intervención quirúrgica contrastan favorablemente con los hallazgos en otros estudios sobre pacientes con hiperparatiroidismo leve no tratado. También encontramos que los niveles preoperatorios de calcio sérico afectan el riesgo de enfermedad, y que existe un factor adicional relacionado con el año calendario de la cirugía; evidencia circunstancial indica que la duración del hiperparatiroidismo contribuye a este factor. Nuestros resultados muestran que la cirugía temprana disminuye el riesgo de muerte precoz también en los casos de hiperparatiroidismo leve.

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Résumé Il a été démontré dans une étude antérieure portant sur 896 patients vus de façon consécutive et opérés pour hyperparathyroïdie primitive entre 1953 et 1982 [1] que le risque postopératoire de mort précoce était augmenté. Ceci pose la question de savoir quel rôle joue la chirurgie dans ce risque. Le but de cette étude a été d'examiner ce rôle. On a mis en évidence 3 facteurs indépendants, correlés de façon significative avec le risque de mort (p<0.001): âge, année de l'acte chirurgical, et intervalle écoulé depuis l'acte chirurgical. L'année tardive de l'acte chirurgical et le degré d'hyperparathyroïdie, évalué par la calcémie et la créatininémie, étaient correlés entre eux. Le risque de mort précoce était augmenté chez tous les patients, quel que soit leur âge. Ce risque était toutefois moindre chez les patients opérés pendant ces dernières années. Le risque de mort en rapport avec la durée de l'intervalle écoulé depuis l'acte chirurgical s'est normalisé d'autant plus vite que le malade a été opéré plus tard dans la période d'étude. La survie postchirurgicale dans cette étude, contraste avec les résultats des sujets ayant une hyperpathyroïdie modérée non traitée. Nous avons trouvé également que la calcémie préopératoire était correlée avec le risque de mort et que l'année de l'acte chirurgical était sans doute en rapport avec la durée même de l'hyperparathyroïdie. Nos résultats démontrent que la chirurgie pratiquée au début dans l'hyperparathyroïdie modérée diminue le risque de mort précoce.

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Supported by grants from the Göteborg Medical Society, the Faculty of Medicine, University of Göteborg, the King Gustav V Jubilee Clinic Research Foundation, Sahlgrenska sjukhuset's Foundation (Gunhild Karlsson's donation), and the Swedish Medical Research Council (6534).     

Glucose, fat, and protein kinetics in patients with primary and secondary hyperparathyroidism

We performed a series of isotopic studies in 16 normal volunteers, four patients with secondary hyperparathyroidism (SHPT), and in nine patients with primary hyperparathyroidism (PHPT). Using the primed constant infusion of stable and radioisotopes, we have determined glucose, glycerol, free fatty acids, and urea kinetics, as well as glucose oxidation. Measurements were performed both in the basal state and during glucose infusion (4 mg/kg body weight/min). Compared with normal volunteers, PHPT patients are intolerant of glucose because of a limited suppression of endogenous glucose turnover during glucose infusion (34% versus 96% suppression). In addition, the plasma cortisol level increased in the PHPT patients during glucose infusion. Glucose oxidation and fat kinetics in both PHPT patients and volunteers were similar, but the rate of net protein loss was significantly greater in the PHPT patients than in the volunteers (2.1 +/- 0.5 versus 1.4 +/- 0.2 gm/kg/day). Rates of VO2 in the PHPT patients and volunteers were similar, but the value in the SHPT patients was higher (120 +/- 9 versus 142 +/- 20 mumol/kg/min for PHPT and SHPT patients, respectively). The SHPT patients had significantly increased rates of glucose turnover, glucose clearance, and glycerol turnover, compared with the other two groups, as well as an increased reliance on glucose for energy. We conclude from these studies that (1) SHPT patients are catabolic and have increased rates of glucose and fat turnover; (2) PHPT patients have limited suppression of endogenous glucose turnover after glucose infusion compared with volunteers and higher rates of net protein loss; (3) fat metabolism and glucose utilization are unimpaired in PHPT patients; and (4) these alterations in metabolism and hormonal response to glucose infusion suggest that some of the symptoms seen in these patients may have a metabolic-hormonal basis.     

The utility of sestamibi scanning in the operative management of patients with primary hyperparathyroidism

BACKGROUND: The role of imaging studies before parathyroidectomy has been extensively debated and recent advances in unilateral parathyroidectomy intensify this controversy. The purpose of this study was to review the parathyroidectomy experience of a single surgeon, looking at the role of sestamibi scans and a standard postoperative care regimen. STUDY DESIGN: Retrospective review of office and hospital charts was completed on 90 patients with primary hyperparathyroidism who underwent parathyroidectomy from 1991 to 1998. Patient workup and outcomes were noted, as were results of preoperative imaging. True-positive scans visualized an abnormality ipsilateral to the adenoma found at operation. Statistics were performed using nonparametric testing and Student's t-test. RESULTS: There were 21 male and 69 female patients, with an average age of 54 years (range 29 to 81). There were zero mortalities, three morbidities (3.3%), and three patients who had persistent hypercalcemia, yielding a 96.7% success rate. Sixty-seven patients underwent preoperative sestamibi scanning, with a sensitivity of 74% and positive predictive value of 89%. Operative time in imaged patients averaged 103 +/- 49.9 minutes versus 121.5 +/- 85.9 minutes for patients without sestamibi scans. Operating time differences were not statistically significant and a preoperative sestamibi scan did not affect the success of parathyroidectomy. Discharge on postoperative day 1 was accomplished in 80% of patients and 13% were discharged the next day. There was no morbidity from hypocalcemia. CONCLUSIONS: A preoperative sestamibi scan does not improve efficacy or decrease operating time for primary hyperparathyroidism when bilateral neck exploration is performed. A postoperative care protocol including oral calcium and vitamin D supplementation allows the majority of patients to be discharged on postoperative day 1 with excellent results.     

Effect of parathyroidectomy on T cell functions in patients with primary hyperparathyroidism

The notion that parathyroid hormone (PTH) can serve as an immunomodulator was examined. T cell function tests were performed in 3 patients with primary hyperparathyroidism before and 1 month after parathyroidectomy (PTX). Three normal volunteers, age and sex matched, were used as controls. One patient with lipoma of the neck was also examined before and after surgical removal of the lesion. In the primary hyperparathyroidism patients the total T cells were lower, the suppressors were higher and the helper to suppressor ratio was significantly lower than in control subjects. The lectin-stimulated lymphocyte transformation was significantly inhibited. All these abnormalities were restored to normal after PTX. Depressed lymphocyte activity was found also in the patient with lipoma. However, no change occurred after surgery. These results support the assumption that excess blood levels of PTH may have an immunosuppressive effect.     

Pitfalls of intraoperative quick parathyroid hormone monitoring and gamma probe localization in surgery for primary hyperparathyroidism

HYPOTHESIS: Intraoperative quick parathyroid hormone (qPTH) monitoring and gamma probe (GP) localization greatly aid the surgeon. DESIGN: Prospective case series of patients undergoing parathyroidectomy (PTX) with preoperative localization studies, operative data (including intraoperative qPTH values and GP localization), and outcomes. Follow-up was complete (mean, 4.2 months). SETTING: University teaching hospital. PATIENTS: We studied 57 consecutive patients with primary hyperparathyroidism from December 1, 1999, through November 30, 2000. Of these, 51 underwent first-time PTX, and 6, reoperative PTX (rePTX). MAIN OUTCOME MEASURES: Cure rate and morbidity after PTX or rePTX; sensitivity and accuracy of preoperative localization studies; prediction of cure from results of qPTH monitoring (comparing Nichols [>50% fall from the highest baseline level and lower than the lowest baseline] or normal-limit [>50% fall from first baseline level and lower than upper limit of the reference range] criteria); and value of GP localization. RESULTS: Patients were cured in 50 (98%) of 51 PTX and 6 (100%) of 6 rePTX for single adenomas (n = 49), double adenomas (n = 4), and multigland hyperplasia (n = 3). Nichols criteria for qPTH monitoring correctly categorized 45 (92%) of 49 cured single adenomas 10 minutes after excision. Only 35 (71%) of these adenomas were correctly categorized as cured by means of the normal-limit criteria. In double adenomas, both sets of criteria in the 10-minute samples indicated unresected glands in only 2 of 4 cases. Preoperative sestamibi parathyroid scans correctly localized 38 (76%) of 50 single adenomas. The GP was used in 54 of 57 cases. All adenomas measured greater than 20% of background ex vivo, but 6 thyroid nodules also measured greater than 20% ex vivo. In double adenomas, the GP helped locate the second adenoma in only 1 of 4 cases. The GP was graded as crucial in 2 cases with dense scar (both rePTX), helpful in 12 (22%) of 54 cases (particularly in retroesophageal glands), confirmatory in 32 (59%), and not helpful in 8 (15%). The GP helped localize 3 (43%) of 7 glands not seen on sestamibi parathyroid scans. CONCLUSIONS: Intraoperative qPTH monitoring confirmed cure in most cases. For single adenomas, use of the Nichols criteria for qPTH assessment allowed more accurate and faster confirmation than the normal-limit criteria. The GP was less useful but was crucial in 2 rePTX cases; it was not specific for parathyroid tissue. Both techniques have potential pitfalls that could result in surgical failure.     

Does rapid intraoperative parathyroid hormone analysis predict cure in patients undergoing surgery for primary hyperparathyroidism? A prospective study.

BACKGROUND AND AIMS: Preoperative 99mTc-sestamibi scintigraphy is used by many surgeons to identify the anatomical location of pathological parathyroid glands in patients undergoing surgical treatment for hyperparathyroidism. However, false negative results do occur. It has been suggested that intraoperative parathyroid hormone (PTH) analysis may enhance the possibility of performing successful focused, unilateral neck surgery in these patients. This study aimed to evaluate whether an adequate fall in intraoperative parathyroid hormone values predicts the removal of all hyperfunctioning parathyroid tissue and postoperative normocalcemia. MATERIAL AND METHODS: One hundred consecutive patients undergoing surgery for hyperparathyroidism had preoperative 99mTc-sestamibi scintigraphy and intraoperative parathyroid hormone (PTH) analysis. A fall in intraoperative PTH value by more than 50% of baseline value ended the procedure. This prospective study presents the clinical and biochemical results. RESULTS: The overall sensitivity of the 99mTc-sestamib scintigraphy was 88% and for single adenomas 95%. The scintigraphy failed to detect the correct pathology in all cases with multiglandular disease (7 patients). A fall in intraoperative PTH value by more than 50% of baseline value was achieved in all patients. The combination of intraoperative PTH analysis and 99mTc-sestamibi scintigraphy enabled us to limit the operation to a focused, unilateral operation in 87 of the 100 patients. All patients were normocalcemic postoperatively. CONCLUSIONS: A fall in intraoperative PTH value more than 50 % of baseline value seems to predict postoperative normocalcemia and the removal of all hyperfunctioning parathyroid tissue. Bilateral neck exploration is avoided in the majority of patients.