Intraoperative Parathyroid Hormone Measurement Research Articles

The Safety and Efficacy of Surgery for Primary Hyperparathyroidism without Intraoperative Parathyroid Hormone Measurement in Japan

Introduction: Primary hyperparathyroidism (PHP) is a curable disease because most patients have only one adenoma and can fully recover after adenoma removal at the location determined by preoperative imaging. However, many Japanese surgeons believe that intraoperative intact PTH measurement (IOPM) is essential to the surgery. Hence, many general surgeons in Japan are unable to perform surgeries for PHP in their local hospitals and must refer the patients to urban high volume centers that have introduced IOPM, even though they are experienced in general surgery and the surgery for PHP is technically simple and related to general surgery. So, we analyzed the relationship of surgical outcomes, with and without IOPM. Method: Between January 2007 and December 2016, 183 consecutive patients with PHP underwent surgery in our institution. We performed the surgery between 2007 and 2012 without IOPM, and starting from 2013 we performed the surgery with IOPM. We compared and evaluated the cure rate and surgical complications between patients who underwent unilateral neck exploration without IOPM with clear preoperative localization of the affected adenoma, and those who underwent any surgery with IOPM. Result: There was no significant difference in cure rate between the two groups and there were no surgical complication in either group. Conclusion: In cases where preoperative imaging is able to clearly localize the affected adenoma and an experienced general or endocrine surgeon performs the surgery, there is no significant difference in overall cure rate and surgical complications with or without IOPM. Though many hospitals in Japan currently do not perform IOPM routinely, our study may encourage many general surgeons to perform the surgery without IOPM.

Validation of selective use of intraoperative PTH monitoring in parathyroidectomy

BackgroundThe objective of this study was to validate our approach of treating primary hyperparathyroidism using sestamibi scan directed parathyroidectomy, without routine use of intraoperative parathyroid hormone measurements (ioPTH).MethodsWe prospectively established a protocol limiting the use of ioPTH to patients with negative or equivocal sestamibi scans, and those who had risk factors for multi-gland disease. We then performed a retrospective review to determine our disease control rate.Results128 patients underwent sestamibi-guided parathyroidectomy without (111/128 = 87%) or with (17/128 = 13%) ioPTH. The overall disease control (eucalcemia) rate was 95%. 3/111 (3%) of patients who had surgery without ioPTH measurements required re-exploration.ConclusionsSelective use of ioPTH is an effective strategy. ioPTH is best reserved for patients who have non-localizing preoperative imaging, are at risk for multi-gland disease, or require revision surgery.

SURGERY OUTCOMES IN PATIENTS WITH SECONDARY HYPERPARATHYROIDISM AND IMPACT OF INTRA-OPERATIVE PTH MEASUREMENT.

The current therapeutical management of secondary hyperparathyroidism (S-HPTH) is difficult to obtain due to the lack of kidney donors. Surgical intervention on the pathologic parathyroid tissue has been suggested as a method to alleviate symptoms in patients with chronic kidney disease (CKD). The aim of our study was to evaluate the outcomes of parathyroid surgery in patients with S-HPTH and the advantages of intraoperative quick PTH (iqPTH) to improve surgical results. In a real-life study, we compared one group of S-HPTH with iqPTH performed after removing all suspected glands and before wound suture (Group 1) and one group in that iqPTH was not assessed (Group 2). When iqPTH dropped less than 50%, additional exploration followed. Eight out of the 34 patients from Group 1, who underwent subtotal parathyroidectomy, showed elevated levels of serum PTH and calcium, which remained elevated during follow-up, thus, suggesting disease persistence. From the 21 patients in Group 2, none showed early postoperative disease persistence. Serum calcium, but not PTH was increased in one patient from the iqPTH group but normalized after one month. Overall, iqPTH allowed detection of a supplementary parathyroid gland in one case, thereby increasing early post-surgery remission to 100% in Group 2 compared to 76.47% in Group 1. Late postoperative remission of hyperparathyroidism with no further increase in the rate of hypoparathyroidism was obtained in Group 2. Assessment of intra-operative PTH levels proved to be a useful tool in augmenting the outcome of S-HPTH surgery. In patients which are eligible for renal transplantation who undergo a subtotal resection, iqPTH can enhance the post-operative quality of life by lowering disease recurrence rates until the kidney transplant procedure.

Parathyroid Lipoadenoma: A Diagnostic Pitfall during Frozen Section Evaluation of Parathyroid Lesions

Parathyroid lipoadenomas are a rare and benign variant of parathyroid adenomas that are defined morphologically by an abundance of adipocytes. The clinical manifestations and the laboratory findings are indistinguishable from those of the usual forms of parathyroid adenomas. Unlike parathyroid adenomas, parathyroid lipoadenomas can be functional or nonfunctional. We present a case of a functioning parathyroid lipoadenoma, which presented diagnostic difficulty on frozen section examination. The diagnosis was aided by intra-operative parathyroid hormone measurement.

The use of intraoperative parathyroid hormone monitoring in minimally invasive parathyroid surgery.

Introduction Surgery is the first-line management option for patients with primary hyperparathyroidism (pHPT). Minimally invasive parathyroidectomy (MIP) is now preferable but few centres offer this service, mainly because of lack of intraoperative parathyroid hormone (IOPTH) testing. The aim of this study was to identify whether the measurement of IOPTH in patients having minimally invasive parathyroidectomy for pHPT alters their management. Methods A retrospective review was carried out of 78 consecutive patients who underwent parathyroid surgery by a single surgeon with a special interest in parathyroid surgery. The clinical impact of IOPTH monitoring was recorded postoperatively in a timely manner. Serum adjusted calcium levels were checked preoperatively (on admission) and one month postoperatively; normalisation was considered a cure. Results In the setting of curative MIP, IOPTH measurement did not influence the management in any of the patients but it could have led to bilateral parathyroid exploration (BPE) in three instances. Similarly, in cases that required lengthening of the MIP incision, IOPTH results did not influence patient management although it could have led to BPE in one case. Conclusion MIP offers an effective cure for patients with hyperparathyroidism. The addition of IOPTH testing adds increased expense, operating time and risk to patients otherwise suitable for MIP.

Outcomes of minimally invasive parathyroidectomy in pediatric patients with primary hyperparathyroidism owing to parathyroid adenoma: A single institution experience

BackgroundGuidelines for treatment of primary hyperparathyroidism (PHPT) in young patients recommend surgery. Outcomes of minimally invasive parathyroidectomy (MIP) are well established in adults, but not in pediatric patients. ObjectiveThe objective of the study is to determine effectiveness of preoperative imaging and MIP aided by intraoperative PTH (ioPTH) measurement in children with primary hyperparathyroidism (PHPT). Methods and designThis is a retrospective chart review of diagnostic and follow-up data up to 12months post-MIP of patients with PHPT who underwent parathyroidectomy at the Children's Hospital of Philadelphia between January 1, 2009 and March 31, 2015. ResultsData were available for 16 of 17 patients age 8–17years (11 females, 6 males): 2 had ectopic intrathymic adenomas while 14 had eutopic adenomas. Fifteen patients had ioPTH, including 14 who underwent MIP, defined as a 2cm central neck incision. All patients with data at 6months postparathyroidectomy (13/16) showed normal PTH and calcium. Ultrasound and sestamibi scans had a combined sensitivity of 87.5%. ConclusionsMIP is an appropriate alternative to standard neck exploration in pediatric patients with PHPT with a single parathyroid adenoma. ioPTH is especially useful to confirm cure and limit surgical exploration when imaging studies are negative. Sestamibi scans and ultrasound are complementary studies.

A Comparative Analysis of the Initial East European Center Experience with a Western High-volume Center for Open Minimally Invasive Parathyroidectomy (OMIP) as Treatment of Primary Hyperparathyroidism

To compare results of treatment of primary hyperparathyroidism (PHPT) in two teaching hospitals (eastern and western Europe) and to establish conclusions regarding quality of surgery for PHPT in Romania. We reviewed two prospectively collected databases of patients submitted to open minimally invasive parathyroidectomy (OMIP) for symptomatic PHPT in two centers from Romania and the United Kingdom (UK). We included patients with biochemically proven PHPT and positive pre-operative localization studies. We excluded patients with negative localization studies, suspected multiglandular disease, concomitant thyroid disorders and chronic renal failure. 60 patients were included, 27 in group A (Romanian cohort) and 33 in group B (UK cohort). We noted significant differences between groups in pre-operative serum calcium and phosphorus levels (p<0.5). There were no differences between groups regarding the presence of symptoms; in group A we had significantly more patients with renal calculi history (p=0.02), digestive symptoms (p=0.006) and osteitis fibrosa cystica (p=0.01). Two patients from the UK group had lithium associated hyperparathyroidism and 2 patients had genetic disease. Intraoperative parathyroid hormone measurement (ioPTH) was available only for group B and frozen sections were selectively used in both groups. Both the adenoma size and weights were significantly higher in group A. The median operative time was significantly longer in Romanian group (p=0.001); in this group we noted the single conversion to traditional cervicotomy (3.7%) from all studied patients. In group A we noted two patients (7.4%) with failed parathyroidectomy and persistent PHPT; the cure rate was 92.5% for Romanian group and 97% for the UK group. OMIP can be performed safe with a high cure rate in "small" volume endocrine centres with results comparable to western experienced endocrine centres. Romanian patients presented with more severe PHPT with more frequent end-organ damage, due probably to late diagnosis.

Intraoperative measurement of parathyroid hormone: A Copernican revolution in the surgical treatment of hyperparathyroidism

Intraoperative parathyroid hormone (PTH) monitoring in the setting of the operating room represents a valuable example of the rationale use of the laboratory diagnostic in a patient-oriented approach. Rapid intraoperative PTH (ioPTH) assay is a valid tool for an accurate evaluation of the success of parathyroid surgery. The reliability of the user-friendly portable systems as well as the collaboration between operators and surgical staff allow the one-site monitoring of the ioPTH decrements on the course of the surgical management of hyperparathyroidism.The rapid answer provided by an effective decrement of PTH during parathyroidectomy contributes dramatically to the efficacy of parathyroid surgery and the reduction of the number of re-operations. Therefore the dose of ioPTH is a valid and reliable support for the success of the intervention of parathyroidectomy at controlled costs.

Contemporary surgical treatment of primary hyperparathyroidism without intraoperative parathyroid hormone measurement.

Primary hyperparathyroidism (pHPT) is usually the result of a single adenoma that can often be accurately located preoperatively and excised by a focused operation. Intraoperative parathyroid hormone (IOPTH) measurement is used occasionally to detect additional abnormal glands. However, it remains controversial as to whether IOPTH monitoring is necessary. This study presents the results of a large series of focused parathyroidectomy without IOPTH measurement. Data from 2003 to 2014 were collected on 180 consecutive patients who underwent surgical treatment for pHPT by a single surgeon. Preoperative ultrasonography and sestamibi imaging was performed routinely, with computed tomography (CT) and/or selective venous sampling in selected cases. The preferred procedure for single gland disease was a focused lateral approach guided by on-table surgeon performed ultrasonography. Frozen section was used selectively and surgical cure was defined as normocalcaemia at the six-month follow-up appointment. Focused surgery was undertaken in 146 patients (81%) and 97% of these cases had concordant results with two imaging modalities. In all cases, an abnormal gland was discovered at the predetermined site. Of the 146 patients, 132 underwent a focused lateral approach (11 of which were converted to a collar incision), 10 required a collar incision and 4 underwent a mini-sternotomy. At 6 months following surgery, 142 patients were normocalcaemic (97% primary cure rate). Three of the four treatment failures had subsequent surgery and are now biochemically cured. There were no complications or cases of persistent hypocalcaemia. This study provides further evidence that in the presence of concordant preoperative imaging, IOPTH measurement can be safely omitted when performing focused parathyroidectomy for most cases of pHPT.

6. Outcomes following parathyroidectomy in primary hyperparathyroidism with and without intraoperative PTH measurements: A propensity score matched cohort study

6. Outcomes following parathyroidectomy in primary hyperparathyroidism with and without intraoperative PTH measurements: A propensity score matched cohort study

The Weight of the Resected Gland Predicts Rate of Success After Image-Guided Focused Parathyroidectomy.

A recent study of focused minimally invasive parathyroidectomy (FPTX) in sporadic primary hyperparathyroidism (pHPT) using intraoperative parathyroid hormone (ioPTH) measurements shows that inadequate ioPTH drop and multiglandular disease are more commonly found when a first gland<200 mg is resected. Our aim was to study if a resected gland that weighed <200 mg was associated with an increased persistence rate after FPTX. This is a cohort study of FPTX for pHPT performed in the period 1998-2013. FPTX was performed in patients with pHPT where Sestamibi and Ultrasound imaging localized single-gland disease, only one gland was excised and the weight recorded. IoPTH was not used routinely. Two groups were composed according to the weight of the resected gland: Group A<200 mg and Group B≥200 mg. Persistent or recurrent disease was defined if it occurred within, or after 6 months. The primary outcome measure was the rate of persisting pHPT. A total of 3,511 parathyroidectomies were performed, and a total 1,745 FPTX (1,347 female) met inclusion criteria. There were 245 and 1,500 patients in groups A and B, respectively. The rate of persistent pHPT was higher in Group A, 6.1 versus 2.0% (p<0.001). Findings at re-operative surgery showed that the ipsilateral gland was diseased in 47% (7/15) of persistent cases in group A. The risk of persistent disease after MIP was higher if the resected gland weighed ≤200 mg, and this corroborates the findings of a recent study. A heightened awareness of the possibility of multigland disease should be raised, and ioPTH monitoring, identification of the ipsilateral gland or bilateral exploration may be advisable in such cases.

Tratamiento quirúrgico del hiperparatiroidismo asociado a insuficiencia renal crónica: Experience in 71 patients

Surgery is an effective method for the management of renal hyperparathyroidism.To report the clinical presentation and results of surgical treatment of renal hyperparathyroidism.Retrospective analysis of 58 patients aged 46 ± 11 years with secondary hyperparathyroidism (HPT2) and 13 patients aged 53 ± 11 years with tertiary hyperparathyroidism (HPT3), operated at a clinical hospital.In 55 cases (77.4%) the indications for surgery were complications of excess parathyroid hormone (PTH) and in 16 patients (22.6%) a failure of medical treatment. Total parathyroidectomy with intraoperative measurement of PTH (PTHop) plus a forearm parathyroid autograft was performed in 54 (93.1%) patients with HPT2 and in all patients with HPT3. PTHop decreased ≥ 75% in 51 patients (88%) with HPT2 and in 9 patients (69.2%) with HPT3, respectively. Cure of the disease was achieved in 52 (89.7%) and 11 (84.6%) patients with HPT2 and 3, respectively. Median follow-up was 41 months. Five (9.6%) patients with HPT2 and two patients (18.2%) with HPT3 had a recurrence of the disease.In patients with renal hyperparathyroidism, the primary indication for surgery was the presence of complications of PTH excess. A drop in PTHop ≥ 75% from baseline predicts healing in 98% and 100% of cases with secondary or tertiary HPT respectively. Surgery was a safe and effective treatment in both groups.

What's in a name?: Providing clarity in the definition of minimally invasive parathyroidectomy.

In recent years minimally invasive parathyroidectomy has become the procedure of choice for many surgeons, but the meaning of the term is unclear. This is confusing for both the medical community and patients. We hypothesize that because the definition of minimally invasive parathyriodectomy in the literature is so variable this term has little meaning. We performed a Pubmed search using the terms: parathyroidectomy, minimally invasive, localized, focused, unilateral, radio-guided, video-assisted, and endoscopic. Data were collected for: author, journal title, year published, and all described aspects of parathyroidectomy. We analyzed 443 (44%) articles after applying the exclusion criteria. Eighteen words were used in 75 different combinations to describe minimally invasive parathyroidectomy. We established four categories that encompassed all 75 definitions: 1. operative approach (incision size, describing as open; endoscopic; robotic; or video-assisted), 2. number of glands explored, 3. operative adjuncts, and 4. anesthesia type. Operative approach was the most commonly described attribute and was mentioned in 47% (n = 207) of the articles (mean incision size was found to be 2.2 cm), followed by number of glands explored, operative adjuncts, and anesthesia type. The finding that there are 75 different definitions for minimally invasive parathyroidectomy confirms that this term is too generic to be useful. We propose a new taxonomic format to describe minimally invasive parathyroidectomy based on the four descriptive categories identified: (operative approach), (# of glands explored), parathyroidectomy using (operative adjuncts) under (anesthesia type). For example, "2 cm, single gland parathyroidectomy using intraoperative parathyroid hormone measurement, under general anesthesia".

Unicentre Results in Surgery of Primary Hyperparathyroidism with Postoperative Long-Term Follow-Up and Value of Intraoperative Quick Parathormone Test

The increasing use of focussed parathyroidectomy is attributed to introduction of intraoperative parathyroid hormone measurement (ioPTH) and novel preoperative imaging techniques. This study assesses the early postoperative and long-term outcomes of surgery and the value of standardised ioPTH in patients undergoing surgery for primary hyperparathyroidism (pHPT). From 01/01/1996 to 09/30/2011, all consecutive patients undergoing surgery for pHPT were documented. Data of this observational study were retrospectively evaluated. Patients were subdivided into 2 groups: A.) use of Quick Intraoperative Intact PTH Assay (n = 142; "ioPTH group") vs. B.) control group ("CG", n = 44). For clinical long-term follow-up, also pre- and postoperative signs, symptoms and findings of the initial 43 patients obtained during the first 4 years of the study were semiquantitatively compared. 186 consecutive operations for pHPT were performed - in particular, 73 sole parathyroidectomies; 113 combined thyroid and parathyroid resections. Mean operation time was 87 (SD ± 48) min for parathyroidectomy and 120 (SD ± 49) min for combined resections. A persisting hypercalcaemia was found in 16 patients (8.6%) while postoperative elevation of serum calcium and parathormone occurred in 7 patients (3.8%). Postoperative hypocalcaemia was present in 35 patients (18.8%). Differences between both groups regarding hypocalcaemia (p = 1.0), hypercalcaemia (p = 0.67), hyperparathyrinaemia (p = 0.12) and rate of reintervention (p = 0.055) were not significant. Thirty nine of the initial 43 patients reported one or more signs of pHPT (90.7%). Most frequent symptoms were nephrolithiasis (41.9%), back pain (51.2%), discomfort in the upper abdomen (41.9%), fatigue (41.9%) and general weakness (61.1%). Follow-up investigations (mean, 4.7 [range, 3.2-6.5] years) revealed that 65 % of patients reported improvement of general condition, 27% had no change and 8% reported deterioration. IoPTH is now standard in parathyroid surgery. Value of ioPTH correlates directly with selected centre-specific intraoperative criteria. The stricter the criteria the more reliable is the exclusion of multiglandular disease. Surgery for pHPT was performed with a very low complication rate. Through the long-term follow-up, nearly two thirds of patients benefited from the operation.

314. Minimally invasive parathyroidectomy in patients with primary hyperparathyroidism: Intra-operative PTH measurements and frozen section analysis are not beneficial in case of positive pre-operative imaging

Background: Primary goal of our study was to evaluate whether intra-operative PTH measurement and frozen section analysis affect intra-operative decision making when pre-operative localising studies are positive.

The use of intraoperative PTH-measurement in the prediction of post-operative hypocalcemia for thyroid surgery: a meta-analysis

INTRODUCTION: Hypocalcemia is a common occurrence in the early postoperative period following thyroid surgery. The intraoperative parathyroid hormone (IOPTH) assay has been proposed by many groups as a tool for early risk assessment, though a definitive evaluation of its’ predictive value for post thyroidectomy hypocalcemia has not been made. We investigate the prognostic value of IOPTH assay for post thyroid surgery hypocalcemia via meta-analysis of current literature.

Radioguided Parthyroidectomy is Successful in 98.7% of Selected Patients

To examine an individualized approach to patients with primary hyperparathyroidism (PHPT) in an effort to identify factors that would differentiate patients who can be treated with radioguided parathyroidectomy (RP) from those that require more extensive parathyroid exploration (PE) using intraoperative parathyroid hormone (IOPTH) measurement and to compare rates of recurrent and persistent hypercalcemia. A total of 100 patients were retrospectively studied. Patients with positive single photon emission computed tomography (SPECT) scans underwent surgeon-performed sonography (SPS) followed by RP. Patients with negative or equivocal SPECT scans underwent PE utilizing SPS as a guide and IOPTH. The success rate, recurrence and persistence rates, and rate of bilateral exploration were compared. Seventy-five percent of patients with PHPT had a positive SPECT scan and underwent RP, whereas 25% of patients had a negative SPECT scan and underwent PE with IOPTH utilizing SPS as a guide. Persistent hypercalcemia was noted in 1 patient (1.3%) and recurrent hypercalcemia in 2 patients (2.6%) in the RP group, whereas no persistent hypercalcemia was noted in the group undergoing PE utilizing SPS and IOPTH. Overall, 89% of patients were cured with unilateral surgery. Patients with positive SPECT scans may undergo RP with an expected cure rate of 98.7%. Patients with negative SPECT scans should undergo SPS followed by PE using IOPTH and can expect a cure rate near 100%. Properly selected patients may undergo RP, with low rates of persistent (1.3%) and recurrent (2.6%) hypercalcemia.

Is intraoperative parathyroid hormone measurement useful in predicting the successful surgical treatment of primary hyperparathyroidism

Is intraoperative parathyroid hormone measurement useful in predicting the successful surgical treatment of primary hyperparathyroidism

Intraoperative parathyroid hormone assay during focused parathyroidectomy: the importance of 20 minutes measurement

BackgroundParathyroid hormone (PTH) monitoring during the surgical procedure can confirm the removal of all hyperfunctioning parathyroid tissue, as the half-life of PTH is approximately 5 min. The commonly applied Irvin criterion is reported to correctly predict post-operative calcium levels in 96-98% of patients. However, the PTH baseline reference concentration is markedly influenced by surgical manipulations during preparation of the affected glands, interindividual variability of the PTH half-life and modifications in the physiological state of the patient during surgery. The aim of this study was to evaluate the possible impact of the measurement of intraoperative PTH 20 minutes after surgery.MethodsBetween 2003 and 2012, 188 patients underwent a focused parathyroidectomy associated to rapid intraoperative PTH assay monitoring. Blood samples were collected: 1) at pre-incision time, 2) at 10 min after gland excision and 3) at 20 min after excision, if a sufficient reduction of PTH value was not observed. On the bases of the Irvin criterion, an intra-operative PTH drop>50% from the highest either pre-incision or pre-excision level after parathyroid excision was considered a surgical success.ResultsA >50% decrease of PTH after gland excision compared to the highest pre-excision value occurred in 156/188 patients (83%) within 10 min and in further 12/188 after 20 minutes (6.4%). In the remaining 20 patients (10.6%) values of PTH remained substantially unchanged or decreased less than 50% and for this reason bilateral neck exploration was performed. An additional pathologic parathyroid was removed in 9 cases, a third in one. In the other 10 cases further neck exploration by a standard cervical approach was negative and in four of these persistent postoperative hypercalcemia was demonstrated. The overall operative success was 97.3%. Intraoperative PTH monitoring was accurate in predicting operative success or failure in 96.3% of patients.ConclusionsThe 20 minutes PTH measurement appears very useful, avoiding unnecessary bilateral exploration and the related risk of complications with only a slight increase of the duration of surgery and of the costs. PTH values decreasing appeared to be influenced by surgical manipulations during minimally invasive parathyroidectomy.

Intraoperative PTH cutoff definition to predict successful parathyroidectomy in secondary and tertiary hyperparathyroidism

In order to improve success rates in surgery of renal hyperparathyroidism, we evaluated intraoperative PTH (IOPTH) measurement utility. Method86 patients underwent total parathyroidectomy with intramuscular presternal autotransplantation from 04/2000 to 10/2009 and were followed for 26.5 months on average (prospective cohort). Patients were divided in secondary (SHPT) and tertiary hyperparathyroidism (THPT). SHPT group was composed by patients under dialysis treatment, THPT group included renal grafted ones. IOPTH (Elecsys-PTH-Immunoassay/Roche) was measured at anesthesia induction (IOPTH-0’) and 20 minutes (IOPTH-20’) after parathyroidectomy. Results80.2% (69/86) presented with 80% decrease or more in the IOPTH-20’ and all were cured. In 11/86 patients (12.7%), a lower IOPTH-20’ drop (70-79%) was observed, and 2 of them (18.1%) failed to cure. 6/86 (6.9%) patients presented IO-PTH-20’ decrease of less than 70%: two were cured, in three a supernumerary/ectopic parathyroid was found and removed, and in one of these six patients, surgery was finished after 4-gland excision and the patient failure to cure. ConclusionIOPTH-20’ decrease of 80% or more compared to IOPTH-0’ predicts cure in all renal patients throughout follow-up. A decay of less than 70% points to missed or hyperfunctioning supernumerary gland and is predictive of surgical failure in 66.6%. A marginal IOPTH drop of 70-79% leaves the decision whether or not surgery should be continued up to the experienced surgeon.