Preoperative Preoperative Parathyroid Hormone Research Articles

Clinical characteristics of primary parathyroid adenoma and its relationship with coexisting papillary thyroid carcinoma: a clinical retrospective study.

Parathyroid adenoma (PA) is a common but relatively poorly understood endocrine tumor. A significant number of PA patients also have papillary thyroid carcinoma (PTC). The clinicopathological characteristics of PA and its relationship with PTC need further study. The clinical data of 99 PA patients were reviewed and the clinicopathologic features of PA were analyzed. PTC occurred in 22 PA patients. The clinicopathologic features of 22 patients with PA + PTC and 77 patients with PA alone were compared. According to age, gender and thyroid surgery methods, 22 PA + PTC patients were matched with 1,123 patients with PTC alone during the same period. The pathological characteristics of the two groups of patients were compared. All data analysis was performed using SPSS23.0, variables were compared by t-test, chi square test or Mann Whitney U-test as appropriate. Ninety-nine PA patients (21 males, 78 females) with a median age of 51 [10-80] years were included. The preoperative parathyroid hormone (PTH) (P=0.007) and preoperative blood calcium (P=0.036) of male patients were higher than those of female patients, and the proportion of asymptomatic patients (P=0.008) and postoperative PTH level (P=0.013) were lower. The preoperative PTH level (P=0.002), preoperative blood calcium level (P=0.004), preoperative alkaline phosphatase (ALP) level (P=0.018) and postoperative PTH levels (P=0.023) in PA + PTC group were lower than those in PA group. The asymptomatic rate was higher in PTC + PA group than that in PA group (P<0.001). There was no statistical difference between PA + PTC group and PTC group in multifocal tumor, capsule invasion, lymph node metastasis (P>0.05). The lymph node metastasis rate in PA + PTC group (9/215) was significantly lower than that in PTC group (37/337) (P=0.005). PA exhibited the following characteristics: occurred in all age groups; more common in women but more severe in men; more located in the lower pole. The coexistence of PTC and PA did not promote the progression of PA, nor did it increase the aggressiveness of PTC. Conversely, their co-existence may lead to early diagnosis of the disease. PA patients (22.2%) also have PTC, so surgeons should pay attention to thyroid disease to prevent the need for reoperation.

Shifting from open to video-assisted parathyroidectomy: effect of the adjustment period on safety, clinical outcomes and cost.

Bilateral neck exploration (BNE) has been the gold standard for the treatment of primary hyperparathyroidism (PHPT). Minimally invasive parathyroidectomy (MIP) has emerged as an alternative procedure for localised solitary adenomas. The most popular MIP techniques are the open MIP (OMIP) and the minimally invasive video-assisted parathyroidectomy (MIVAP). This study aims to assess whether we achieved a smooth transition from OMIP to MIVAP without compromising the results or increasing the cost. A parathyroid adenoma was successfully localised preoperatively in 77/86 patients with PHPT. MIP was contraindicated in 27/86 cases. For MIVAP, a 5mm, 30 degree camera was employed, along with special instruments. Median preoperative parathyroid hormone (PTH) level was 145.9pg/dl (59-2,151) and median calcium (Ca) was 10.8mg/dl (9.3-19). Comparing MIVAP (N=31) with OMIP (N=28), there was no significant difference in the age, sex, location of the adenoma, preoperative PTH and Ca levels as well as in all the other factors compared, apart from the size of adenomas, which were bigger in the OMIP group (1.85cm vs 1.4cm, p=0.032). Moreover, cure rates, operating time, hospital stay and rates of postoperative normocalcaemia were similar between the two groups. Despite the learning curve, MIVAP was not found to be inferior to OMIP for localised adenomas. The final cost was no higher for MIVAP than OMIP with the use of common reusable instruments. This, along with surgeons' experience in parathyroid and endoscopic surgery facilitates a smooth and cost-effective transition from OMIP to MIVAP.

Predictors of adenoma size and location in primary hyperparathyroidism

PurposeIn primary hyperparathyroidism (PHPT), intraoperative localization of the parathyroid adenoma can be challenging, especially in cases of negative preoperative imaging. Since a focused unilateral parathyroidectomy has benefits compared to a conventional bilateral neck exploration, the question arises whether adenoma size prediction can facilitate a targeted approach. We investigated whether single parathyroid adenoma size can be estimated using preoperative parathyroid hormone (PTH), calcium, and phosphate in patients with PHPT. Preoperative imaging accuracy was evaluated.MethodsThe data of 156 patients who underwent curative parathyroidectomy for single adenoma PHPT were analyzed retrospectively. Information obtained included laboratory data, imaging results, intraoperative data, and final pathology. Imaging accuracy was analyzed descriptively. The association between preoperative biochemical markers and adenoma dimensions was investigated using Spearman’s correlation coefficient and multivariable regression modeling.ResultsCervical ultrasound correctly predicted adenoma laterality in 95.5%, sestamibi scintigraphy in 80.6%, both had lower true-positive rates for quadrant prediction. Patients with negative imaging results showed higher thyroid volumes than those with positive results. Adenoma volume was positively correlated with preoperative PTH (p < 0.001) and calcium (p < 0.001) and negatively correlated with preoperative phosphate (p = 0.001). Using these preoperative biochemical markers and patient age and BMI, adenoma volume can be significantly predicted using the multivariable regression algorithm.ConclusionCervical ultrasound is superior to scintigraphy for predicting adenoma location and should be the first-choice imaging method, but both methods may be limited by increased thyroid volume. Large adenomas are more likely with higher PTH, higher calcium, and lower phosphate levels. In cases of undetermined adenoma location, an estimation of adenoma volume via our algorithm could corroborate sonographic volume measurements of the suspected adenoma.

Relationship between parathyroid oxyphil cell proportion and clinical characteristics of patients with chronic kidney disease.

Parathyroid glands consist of chief cells and oxyphil cells. The parathyroid oxyphil cell proportion increased dramatically in patients with chronic kidney disease (CKD). The importance of the oxyphil cell in the treatment of secondary hyperparathyroidism (SHPT) has been enhanced in recent years. The aim of this study was to explore the possible relationship between parathyroid oxyphil cell proportion and clinical features of patients with CKD. From December 2010 to December 2018, 78 consecutive patients with CKD 5 who underwent parathyroidectomy (PTX) were reviewed. None of the patients had used Cinacalcet. Patients were divided into two groups according to their parathyroid oxyphil cell proportion. The mean parathyroid oxyphil cell proportion of all the patients was obtained. Group 1 consisted of 37 patients, the parathyroid oxyphil cell proportion of whom was more than or equal to mean proportion. Group 2 consisted of 41 patients, the parathyroid oxyphil cell proportion of whom was less than mean proportion. The demographic and biochemical data of the two groups were compared. Preoperative parathyroid hormone (PTH) and total weight of removed parathyroid glands in the patients of group 1were less than those in group 2. There was no difference between the two groups in terms of preoperative calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), age and dialysis years. The parathyroid oxyphil cell proportion was associated with preoperative PTH and total weight of removed parathyroid glands in the patients with CKD. Patients with more parathyroid oxyphil proportion had lower preoperative PTH level and smaller total weight of the removed parathyroid glands.

Influence of Pre-renal Transplant Secondary Hyperparathyroidism on Later Evolution After Transplantation

Persistence of secondary hyperparathyroidism (SHPT) is common after renal transplantation. Good diagnosis and treatment are important to avoid complications. The objective of our work was to perform a retrospective analysis of the evolution of SHPT after renal transplantation.We selected patients who had received a kidney transplant at our hospital between 2000 and 2014. The biochemical variables of chronic kidney disease–metabolic bone disorders (CKD-MBD) were collected at pretransplantation and at 3, 6, 12, and 24 months post-transplantation. Treatments related to SHPT were also analyzed.Five hundred forty-three renal transplants were included. The average preoperative parathyroid hormone (PTH) was 241.14 pg/mL, 115.7 pg/mL at 3 months, and at 12 and 24 months postoperatively, PTH levels stabilized to 112 pg/mL. Treatment related to SHPT was present in 27.3% of patients during the preoperative period, 40.4% at 3 months postoperatively, 24.2% at 12 months postoperatively, and 23.2% at 24 months postoperatively. There was a significant association between requiring some type of treatment preoperatively and the rest of the postoperative periods (P < .005).The sample was later divided into 3 groups based on preoperative PTH (1: <150 pg/mL, n = 223 [41.1%]; 2: 150–300 pg/mL, n = 173 [31.9%]; 3: >300 pg/mL, n = 147 [27.1%]) and their evolutions were compared. Higher levels of postoperative PTH in group pre-PTH 3 were observed. Group 3 also presented with greater need for treatment in the postoperative periods, with significant association (P < .05). A regression analysis was performed and found that postoperative PTH were dependent on preoperative PTH adjusted by glomerular filtration.In conclusion, parameters related to CKD-MBD (mainly PTH) after kidney transplant, dependent on preoperative levels and glomerular filtration. Patients with a greater grade of SHPT presented with higher levels of postoperative PTH despite receiving more intensive treatment.

Disparity between Preoperative and Pre-Excisional Intraoperative Parathyroid Hormone in Parathyroid Surgery.

Introduction Intraoperative parathyroid hormone (ioPTH) testing is a widely accepted standard for assessing the parathyroid gland function. A decline of preoperative parathyroid hormone (PTH) levels by more than 50% is one accepted measure of parathyroid surgery adequacy. However, there may be a variation between preoperative PTH levels obtained at a clinic visit and pre-excisional ioPTH. Objective Our study explores the differences between preoperative PTH and pre-excisional ioPTH levels, and the potential impact this difference has on determining the adequacy of parathyroid surgery. Methods A retrospective study that consisted of 33 patients that had undergone parathyroid resection between September 2009 and March 2016 at a tertiary academic center was performed. Each subject's preoperative PTH levels were obtained from clinic visits and pre-excisional ioPTH levels were recorded along with the time interval between the measurements. Results There was a significant difference between the mean preoperative PTH and the pre-excisional ioPTH levels of 147 pg/mL (95% confidence interval [CI] 11.43 to 284.47; p = 0.0396). The exclusion of four outliers revealed a further significant difference with a mean of 35.09 pg/mL (95% CI 20.27 to 49.92; p < 0.0001). The average time interval between blood draws was 48 days + 32 days. A weak correlation between the change in PTH values and the time interval between preoperative and pre-excision blood draws was noted (r2 = 0.15). Conclusion Our study reveals a significant difference between the preoperative PTH levels obtained at clinic visits and the pre-excisional intraoperative PTH levels. We recommend routine pre-excisional intraoperative PTH levels, despite evidence of elevated preoperative PTH levels, in order to more accurately assess the adequacy of surgical resection.

Correlations between parathyroid hormone level, adenoma size, and serum calcium level in patients with primary hyperparathyroidism

Aim: The main goal of this study is to determine the association of preoperative parathyroid hormone (PTH) levels with parathyroid gland adenoma sizes and serum calcium levels in patients with primary hyperparathyroidism caused by single-gland adenoma. Methods: We included all patients with single parathyroid gland adenoma who were admitted to and underwent parathyroidectomy at Security Forces Hospital in Riyadh during a period of 10 years from January 1, 2000 to October 30, 2011. PTH level and serum corrected calcium were recorded 1 day before surgery. Adenoma size was recorded from pathology reports for all patients. Results: In 35 cases of parathyroid adenoma including 12 males (34.3%) and 23 females (65.7%) with an average age of 48.94 years (±13.52), the average PTH level 1 day preoperatively was 769.94 pg/mL (±793.27), the average largest dimension (LD) of parathyroid adenoma was 2.18 cm (±1.38), and the average calcium level 1 day preoperatively was 2.71 mmol/L (±0.3). The mean PTH level in males was 1098.5 pg/mL compared to 598.5 pg/mL in females (P = 0.068), mean LD of parathyroid adenoma in males was 2.34 cm versus 2.09 cm in females (P = 0.72), and mean calcium level in males was 2.70 mmol/L compared to 2.72 mmol/L in females (P = 0.46). A positive correlation was found between PTH level and adenoma size, with a correlation coefficient of 0.29 (P = 0.095). The correlation between PTH level and calcium level was negative, with a correlation coefficient of −0.033 (P = 0.85). Negative correlation was also found between adenoma size and calcium level, with a correlation coefficient of −0.033 (P = 0.85). Conclusion: Based on the findings of this study, preoperative PTH level or serum calcium level cannot be used to predict adenoma size. Further prospective studies with larger sample sizes are recommended.

Risk Factors for Elevated Preoperative Alkaline Phosphatase in Patients with Refractory Secondary Hyperparathyroidism

Elevated preoperative levels of alkaline phosphatase (ALP) in patients with refractory secondary hyperparathyroidism are correlated with postoperative hypocalcemia and mortality. The aim of this study was to identify the predictors of preoperative ALP in patients with secondary hyperparathyroidism. From April 2012 to December 2015, 220 patients with refractory secondary hyperparathyroidism undergoing total parathyroidectomy without autotransplantation were reviewed. A total of 164 patients presented with elevated preoperative ALP. Univariate analysis showed that patients with elevated ALP were significantly younger. The elevated ALP group had significantly higher levels of preoperative parathyroid hormone (PTH), lower preoperative serum calcium, higher preoperative phosphorus, lower postoperative hypocalcemia, and a longer hospital stay. Logistic regression analysis showed that elevated preoperative PTH was a significant independent risk factor for elevated preoperative ALP (P = 0.000), and its value of 1624 pg/mL was the optimal cutoff point. Factors predictive of elevated preoperative ALP in patients with secondary hyperparathyroidism include preoperative PTH. Earlier surgery, aggressive calcium supplementation, and more careful or aggressive postoperative care for high-risk patients are needed.

Minimally elevated preoperative parathyroid hormone level influences the management of primary hyperparathyroidism.

To determine the effect of preoperative parathyroid hormone (PTH) level on the extent of surgery and the accuracy of parathyroid imaging in primary hyperparathyroidism. Retrospective cohort. Final diagnosis of single-gland adenoma and its location versus multigland disease was established in this retrospective cohort study. Positive predictive value, negative predictive value, and accuracy of imaging were analyzed in relation to preoperative PTH levels. Eighty-seven percent of the 218 patients enrolled in the study underwent unilateral targeted operation and had a 97.9% (95% confidence interval: 95.8%-100%) success rate. However, in patients with PTH <65 pg/mL, 28.6% had bilateral exploration compared to 10.3% in those with PTH ≥65 pg/mL (P = .042). In patients with PTH <65 pg/mL, 7/21 (33.3%) had inaccurate sestamibi findings compared to 24/174 (13.8%) in patients with PTH ≥65 pg/mL (P = .047). Accuracy of sestamibi drops significantly, by threefold, in patients with mild primary hyperparathyroidism and PTH <65 pg/mL. Patients with PTH < 65 pg/mL have a 2.5-fold higher rate of bilateral operation to identify the hypersecreting gland(s) compared to patients with PTH ≥65 pg/mL. 4. Laryngoscope, 128:1016-1021, 2018.

Risk stratification for outpatient parathyroidectomy and predictors of postoperative complications

IntroductionThe mainstay of treatment for primary hyperparathyroidism is surgery. Hypocalcemia after parathyroidectomy is common and poses a significant challenge, leading to increased patient morbidity and health care costs. While several groups have found predictor factors for hypocalcemia, none have created a risk stratification model. Here, we recognize important factors and optimal cut-off values that can allow risk stratification of patients. MethodsA single-institution retrospective chart review of 339 patients that underwent parathyroidectomy from 2009 to 2012 was conducted. Pre-operative, intra-operative, and post-operative data were collected. A non-routine outcome was defined as post-operative admission, outpatient hypocalcemia-related complication, or inpatient hypocalcemia-related complication. The preoperative or intraoperative factors of patients that experienced a non-routine outcome were compared to those that did not. Optimal cut-off values were determined for preoperative and intraoperative factors and a risk stratification method was created. ResultsA total of 39 patients experienced a non-routine outcome including 24 postoperative admissions, 2 inpatient hypocalcemia-related complications, and 17 outpatient hypocalcemia-related complications. Patients with a non-routine outcome displayed a trend toward preoperative hypercalcemia (calcium >11.0mg/dL) than not (p=0.0543). The median preoperative parathyroid hormone (PTH) level was significantly higher among patients with a non-routine outcome (p=0.0037). Furthermore, the median percent decrease in PTH at 20min intraoperatively among patients with a non-routine outcome was significantly higher compared to those that did not (p=0.0421). The optimal cut-off value for preoperative PTH was 129pg/mL and for median percent decrease in intraoperative PTH at 20min was 90.7% for predicting a non-routine outcome. A risk stratification model was created based on these data. ConclusionOur analysis reveals that patients with larger intraoperative decrease in PTH levels (greater than 90.7% drop at 20min), higher preoperative hypercalcemia (greater than 11mg/dL), and higher preoperative PTH levels (greater than 129pg/mL) are more likely to experience a non-routine outcome during outpatient parathyroidectomy. Patients can be risk stratified based on this criteria.

Preoperative parathyroid hormone level as a predictive factor for post-thyroidectomy hypoparathyroidism

Purpose: Whether the level of the preoperative parathyroid hormone (PTH) is a risk factor of postoperative hypoparathyroidism remains unclear. The aim of this study was to evaluate the predictive value of preoperative PTH for the hypoparathyroidism following total thyroidectomy. Methods: Five hundred two patients performed total thyroidectomy from January 2009 to July 2010 in Seoul National University Hospital were enrolled. Demographics, operative variables, and the development of hypoparathyroidism were collected and evaluated. Results: A total of 502 patients were enrolled during the study period. Patients had a mean age of 48.1±12.1 years (range, 16 to 95 years) and showed a female predominance (n=420, 83.7%). Preoperative PTH of 44.5 pg/㎖ was recommended as cut-off value. Transient hypoparathyroidism developed 2.4 times (95% confidence interval [CI], 1.1 to 5.1) more frequently in low PTH group (P=0.021). Percentage decline of the preoperative PTH also showed significant association with transient hypoparathyroidism. When the value of 73.9% decline was used, the chance of transient hypoparathyroidism was 3.3 times (95% CI, 2.0 to 5.5) higher in high percentage decline group (P<0.001). Correlation between postoperative PTH level and development of transient hypoparathyroidism was not found (P=0.171). In regard to the permanent hypoparathyroidism, there were no significant differences in all factors. Conclusion: Preoperative PTH level and percentage decline can be used as a predictive factor for postoperative hypoparathyroidism. In patients with low PTH level (<44.5 pg/㎖), caution should be given to prevent injury of the parathyroid glands. Keywords: Hypoparathyroidism, Predictive value of tests, Complication, Total thyroidectomy, Parathyroid hormone

Creation of a “Wisconsin Index” Nomogram to Predict the Likelihood of Additional Hyperfunctioning Parathyroid Glands During Parathyroidectomy

The aim of our study was to create a preoperative "index" that could predict the likelihood of additional hyperfunctioning parathyroid glands and let the surgeon determine whether to wait for the intraoperative parathyroid hormone (ioPTH) or to explore further. During parathyroidectomy for primary hyperparathyroidism (PHPT), discovering a minimally "enlarged" parathyroid gland creates a dilemma for the surgeon regarding the need for further exploration. Although ioPTH testing can potentially solve this problem after a 20- to 30-minute period, several surgeons recognize that further operative exploration may be more effective. We analyzed a prospective database of 1235 consecutive patients who underwent parathyroidectomy for PHPT at our institution between March 2001 and August 2010. The Wisconsin Index (WIN) was defined as the multiplication of preoperative serum calcium by preoperative parathyroid hormone (PTH). Patients were divided into 3 WIN categories: low (<800), medium (801-1600), and high (>1600). The utility of the WIN was then validated on a subsequent cohort of 216 patients. The median age of the patients was 61 years (range, 10-91), and 77% of the patients were female. The mean preoperative calcium and PTH levels were 11.0 ± 0 mg/dL and 127 ± 3 pg/mL, respectively. The mean WIN for the entire cohort was 1461 ± 38 and highly correlated with gland weight (P < 0.000001). A single adenoma was identified in 1000 patients (81%), double adenoma in 100 patients (8%), and hyperplasia in 135 patients (11%). The mean gland weights for the 3 WIN catagories were low = 370 ± 33 mg, medium = 532 ± 39 mg, and high = 985 ± 28 mg, respectively (P < 0.000001). A WIN nomogram, consisting of the combination of WIN and parathyroid gland weight, accurately predicted the likelihood of additional hyperfunctioning parathyroid glands. For example, for a WIN of less than 800 and a gland weight of 500 mg, there is a 9% chance for additional hyperfunctioning parathyroid glands based on the WIN nomogram. In contrast, for the same gland weight, if the WIN is 801 to 1600, these chances increase to 28%, and if the WIN is more than 1600, the chance of multigland disease is 61%. Comparison between the predicted chances for another gland with the actual chance in the validation cohort identified an R(2) value of 0.96. The WIN nomogram predicts the likelihood of additional hyperfunctioning parathyroid glands during parathyroidectomy. This simple intraoperative tool may be used to guide the decision of whether to wait for ioPTH results or to proceed with further neck exploration.

Changing biochemical presentation of primary hyperparathyroidism

Patients with primary hyperparathyroidism, pHPT, present with milder symptoms than previously. Some, but not all studies, suggest that this change in clinical pattern also implies lower preoperative parathyroid hormone (PTH) and/or calcium levels and smaller adenomas. This is important since reports indicate that smaller adenomas are more difficult to detect on preoperative imaging, possibly increasing the risk of surgical failure. There were 640 patients with histologically confirmed single-gland pHPT identified in a prospectively collected database. Median values of preoperative calcium, PTH, as well as adenoma weight were compared in three different time periods: 1990-1995, 1996-2000, and 2000-2007. Correlation between the preoperative levels of calcium and PTH and adenoma weight was calculated. Preoperative ionized calcium decreased significantly over time (p < 0.001). There was a positive correlation between preoperative PTH and adenoma weight (r = 0.32, p < 0.001). The magnitude of this correlation decreased over time. In women, adenoma weight decreased significantly over time (p = 0.03). Median (25th-75th percentile) adenoma weight in women was 750 (400-1,380) mg, 650 (350-1,205) mg, and 520 (305-1,065) mg in the first, second, and third period, respectively. From 1990 to 2007, there was a significant trend to operate pHPT patients with lower preoperative serum ionized calcium levels. In women, the adenoma weight decreased. This trend could potentially lead to decreased sensitivity in preoperative localization procedures.

Sestamibi (99mTc) scan as a single localization modality in primary hyperparathyroidism and factors impacting its accuracy

BackgroundThe proper localization of a hypersecreting parathyroid gland is of vital importance for successful unilateral neck exploration (UNE) and parathyroidectomy.Aim:In this study we aim to evaluate the (99mTc) sestamibi parathyroid scan as a single localizing modality, and we also assess its relation to the weight of the gland and to the preoperative parathyroid hormone (PTH) levels.Patients and Methods:We reviewed 170 patients from our hospital (Notre-Dame hospital) from 2005 to 2008, with a mean age of 56.6 years and a female to male ratio of 3.3:1. With primary hyperparathyroidism, all of them had (99mTc) sestamibi parathyroid scan for the localization of the parathyroid adenoma. Preoperative and postoperative PTH levels were recorded. The histopathology reports confirmed the diagnosis and weight of the diseased gland, which were recorded every time. The results were analyzed and correlated with the sestamibi results, to evaluate its accuracy.Results:Seventy-eight patients (41%) of the 170 had an exact match (EM) sestamibi results, 81 (51.6%) had a partial match, and only 11 patients were reported as mismatch. Analyzing the mean weight of the gland in each group between matching (EM, PM) versus mismatch resulted in a mean difference of 0.823 g (1.05 and 0.247 g, respectively) P = 0.045. Hyperplasia to adenoma ratio was more in the partial matching group (18.5%) versus the exact matching group (7.6%). Finally the mean PTH level was higher in the EM group (28.8 pmol/L) compared to the mismatch group (10.1 pmol/L) P = 0.02. Overall sensitivity and specificity for the (99 mTc) sestamibi in our data was 98.1 and 97%, respectively.Conclusion:(99mTc) sestamibi is a highly accurate test that can be employed as a single localizing modality for identifying a hypersecreting parathyroid, a UNE, or a parathyroidectomy. The weight of the gland plays an important role in the accuracy of the test, as also the preoperative PTH levels.

Advantages of a Targeted Approach in Minimally Invasive Radioguided Parathyroidectomy Surgery for Primary Hyperparathyroidism

In a large series of patients, we associated the need for preoperative parathyroid hormone (PTH) and calcium levels as a vital component in our approach to the radioguided minimally invasive parathyroidectomy (MIRP) procedure. Our objective was to determine whether these preoperative levels indeed complemented the procedure. Our study also included a postoperative assessment of excised gland volume and length of operation. This was a prospective cohort study. : One hundred seventy-three patients with primary hyperparathyroidism enrolled in our radioguided MIRP protocol. Patients were divided into groups based on the results of sestamibi scans. Comparisons were made between these results and the assessed preoperative PTH and calcium levels and the postoperative excised gland volume and length of operation. PTH and calcium levels did not statistically relate with the likelihood of having a "positive," "equivocal," or "negative" sestamibi scan, but the volume of excised gland was significantly different among the three groups (P < .01). There was no significant difference between positive and equivocal scans (P = .40). Operative time was significantly different between positive and equivocal scans (P < .01), positive and negative scans (P < .01), and equivocal and negative scans (P < .01). Routine preoperative PTH and calcium levels are necessary for the biologic diagnosis of hyperparathyroidism, but they do not appear to relate to the outcome of a sestamibi scan and therefore do not complement the radioguided MIRP procedure. Because the size of the affected gland, however, did correlate with a positive sestamibi scan, we conclude that as the volume of the gland increases, so does the likelihood of a successfully chosen minimally invasive surgical approach.