Parathyroid Hormone Assay Research Articles

Intact Parathyroid Hormone (iPTH) Assay: An Early Approach for Bone Health Assessment in Chronic Renal Failure

Intact Parathyroid Hormone (iPTH) Assay: An Early Approach for Bone Health Assessment in Chronic Renal Failure

7337 High Parathyroid Hormone (PTH) Due To Immunoassay Interference

Abstract Disclosure: V.A. Mendpara: None. A.J. McShane: None. L.Z. Khan: None. Background: PTH levels are not always accurate. This case illustrates immunoassay interference in a female with markedly abnormal PTH values. Understanding immunoassay interference in diverse hormonal assessments can prevent diagnostic inaccuracies. Clinical Case: A 63-year-old female with osteopenia underwent serum parathyroid hormone (PTH) testing as part of a thorough bone evaluation. The initial PTH level revealed an abnormal level of 4008 pg/mL (normal range: 15 to 65 pg/mL). The follow-up PTH level with the same assay continued to result in elevated values of >5000 pg/mL. The medication list was negative for biotin use, which is a well-known interfering substance in the PTH assay. Clinical evaluation was negative for hyperparathyroidism symptoms, and thyroid/parathyroid ultrasound was normal, as were serum levels of phosphate, vitamin D, and calcium. No PTH values had been checked for patients in the past after an extensive review of prior records. The initial PTH testing used the Roche Elecsys PTH STAT assay. To investigate a potential immunoassay interference, the following studies were performed: First, the sample was diluted with polyethylene glycol (PEG) to precipitate large molecular weight proteins; second, the sample was treated with a commercial heterophilic blocking reagent (Scantibodies Laboratory); and lastly, the sample was assayed utilizing a different PTH vendor (Siemens Atellica, chemiluminescent immunoassay). The PEG and heterophilic blocking treatments resulted in significantly lower PTH concentrations of 895.6 and 40.7 pg/mL, respectively. We do not anticipate a change in PTH levels in samples supplemented with blocking reagents or PEG without interference. The result from Siemens’ assay was markedly lower at 43.4 pg/mL. Both the Siemens and Roche assays employ mouse antibodies; however, the antibodies are proprietary between the vendors. This results in potentially different anti-mouse antibody epitope targets. Due to a history of advanced ovarian cancer, the patient was taking Oregovomab, a murine monoclonal antibody, as therapy for her advanced disease. It is unclear if this medication resulted in assay interference, but it is possible. Discussion: In summary, the discrepancy in PTH assay results highlights the need to consider immunoassay interference, particularly in patients with a history of cancer on immunotherapy agents. Our case highlights the importance of the clinician’s review of medications when assessing patients. While prior PTH assays were not conducted before the patient started Oregovomab, the potential development of interfering antibodies warrants consideration. Clinicians should be vigilant for atypical results and collaborate closely with laboratory professionals, as detecting interfering substances can result in misdiagnosis. Presentation: 6/2/2024

12410 Intra-operative Parathyroid Hormone Monitoring: Comparative Evaluation Of Sampling Sites And Assay Methods

Abstract Disclosure: R. Kwayess: None. S. Ajjour: None. M. Rahme: None. M. Assaad: None. J. Abbas: None. S. Jabbour-Khoury: None. R. Daher: None. E. Cavalier: None. O. Kreidieh: None. M. Chakhtoura: None. G. El-Hajj Fuleihan: None. Background: Primary hyperparathyroidism is a common endocrine disorder increasingly managed by minimally invasive parathyroidectomy (MIP) with intra-operative parathyroid hormone (IOPTH) monitoring using 2nd generation parathyroid hormone (PTH) assay. Objective: Compare the use of central sampling versus peripheral sampling, and of 3rd as opposed to 2nd generation PTH assays’ performance. Methods: We collected preoperative baseline characteristics and laboratory values for consenting participants undergoing parathyroidectomy at our center. We then measured IOPTH levels from peripheral and central venous sites using 2nd and 3rd generation assays at various intraoperative time points. We calculated the maximal intraoperative PTH drop from highest baseline (pre-incision or pre-excision) at peripheral site and pre-excision at central site for participants who were normocalcemic at ≥ 6 months post-operatively. We used paired t-test to compare the mean % drop in IOPTH by 2nd vs 3rd generation assays, and peripheral vs central sampling. Results: Out of 88 participants enrolled, 63 had follow-up data at 6 months or beyond and normal serum calcium level (9.41 ± 0.43 mg/dL). Mean age was 56.16 ± 11.5 years, 77.8% females and 47.6% had osteoporosis or osteopenia. Pre-operative mean values were: serum calcium 10.94 ± 0.73 mg/dL, ionized calcium 5.6 ± 0.68 mg/dL, PTH 131.93 ± 120.1 pg/mL and creatinine 0.77 ± 0.19 mg/dL. The majority of patients underwent excision of one abnormal gland (79.4%). On average, 57.3% of patients had the highest PTH drop at 10 mins, 32.7% beyond 10 minutes, and 9.7% at 5 minutes, regardless of assay type and site. Median PTH decrements were 81% and 83.8% for 2nd generation assay, and 86.5% and 89% for 3rd generation assays, at peripheral and central sites, respectively. There was no significant difference in the PTH drop comparing central to peripheral sites using either assay. However, 3rd generation assays displayed a higher drop compared to 2nd generation assay, for both central and peripheral sites (p-value <0.001). Discussion/Conclusion: Our study shows no difference in % drop between peripheral and central sampling, using either 2nd or 3rd generation assays. Central PTH sampling is commonly used by surgeons because of ease of access, while applying the Miami criterion. However, the drop in median 3rd generation PTH level was higher compared to the 2nd generation assay, regardless of the sampling site. Our findings suggest the necessity of defining larger PTH drop cut-off values for 3rd generation PTH assay than the commonly used Miami criterion.

A-038 Interlaboratory Comparison of Parathyroid Hormone Analytical Results Across Clinical Assays from 8 Manufacturers - Steps Towards Standardization

Abstract Background Parathyroid hormone (PTH) is an 84 amino acid peptide produced by the parathyroid gland and is a key biomarker used for the diagnosis and treatment of Chronic Kidney Disease-Mineral and Bone Disorder, as well as hypo- and hyperparathyroidism. PTH clinical assays were previously reported to exhibit significant inter-assay measurement variability, which limits the utility of PTH as a diagnostic biomarker and can result in the misclassification of patients. Thus, there is a need for PTH clinical assay standardization to improve clinical assay measurement agreement. The Centers for Disease Control and Prevention’s Clinical Standardization Program (CDC-CSP) will launch a PTH standardization program, which is in support of and coordinated with the IFCC Committee on Bone Metabolism. In preparation, the CDC-CSP conducted an Inter-Laboratory Comparison Study to evaluate the current status of PTH inter-assay variability and to investigate potential sources of variability. Methods Eight PTH assay manufacturer’s laboratories measured PTH in 42 deidentified, fresh-frozen single donor serum samples in duplicate over 2 independent runs. Sample PTH concentrations ranged from 1.3 - 324 pg/mL, based on initial screening values. Five manufacturers submitted data for 2 different assays, resulting in PTH measurements from 13 assays total. Data were submitted to the CDC CSP for analysis. Results Assay precision was <5% for 10/13 measurement procedures (MP) assessed and 3 MPs exhibited precisions between 5 - 18%. Assay-specific PTH measurements demonstrated good linear correlation compared to the all-assay mean concentration. Interestingly, inter-assay variability increased with increasing PTH concentrations, with individual sample standard deviations increasing from 2.9 - 123, with a mean SD of 24.1 and individual sample CVs increasing from 18.9 - 44.5%, with a mean CV of 24.2%. Conclusions This study provides new insights into PTH inter-assay variability and assay performance for assays commonly used in the clinical setting. The findings of this PTH Interlaboratory Comparison Study establish a baseline for PTH inter-assay variability and will guide future PTH standardization efforts.

A-110 Analytical Performance Evaluation of Vitros® Immunodiagnostic Products Intact PTH II Assay

Abstract Background Intact parathyroid hormone (iPTH) is indicated to aid in the diagnosis of hyperparathyroidism, hypoparathyroidism, differential diagnosis of hypocalcemia or hypercalcemia and for intraoperative measurement of iPTH levels. Studies were conducted to evaluate the analytical performance of the Vitros Immunodiagnostic Products Intact PTH II (Vitros iPTH II) assay by determining limit of detection (LoD), limit of quantitation (LoQ), and precision. A method comparison of the Vitros iPTH II assay against the Roche Elecsys PTH assay was also conducted. Methods The LoD and LoQ were determined consistent with CLSI EP17. Precision was evaluated consistent with CLSI EP05 using six patient pools for 20 days. Repeatability was determined using two replicates per run. Within-lab precision was determined using a single reagent lot and a single calibration. A quantitative comparison between the Vitros iPTH II assay on a Vitros 3600 system and the Roche Elecsys PTH assay on a Roche Cobas 8000 system was conducted in accordance with CLSI guideline EP09 using 206 endogenous patient samples. Samples were selected to cover the full measuring interval and were tested over a total of six non-consecutive days. Results The LoD for the Vitros iPTH II assay was determined to be 1.7 pg/mL. The claimed LoQ was determined using a precision profile approach with a %CV limit of 20% and set at 1.7 pg/mL. For mean parathyroid hormone (PTH) concentrations ranging from 15.9 to 4656 pg/mL, repeatability (within-run) percent coefficient of variation (%CV) ranged from 0.8% to 1.4% and within-lab %CV ranged from 1.5% to 3.0%. The method comparison of the Vitros iPTH II assay versus the Roche Elecsys PTH assay yielded a correlation coefficient of 0.991 and a Passing-Bablok regression slope of 1.01 and intercept of 0.3. Conclusions The Vitros iPTH II assay demonstrated acceptable analytical performance in these studies, with high correlation and close agreement to the Roche Elecsys PTH assay.

Verification of analytical performance of intact parathyroid hormone assay on the Abbott Alinity ci®: Experience of the central laboratory of Mohammed VI University Hospital of Oujda

The primary goal of our study was to verify the analytical performance of intact parathyroid hormone measurements conducted on the Abbott CI analyzer using the immuno-chemiluminescence method. This verification took place in the biochemistry laboratory at Mohammed VI University Hospital in Oujda. Our methodology was aligned with the recommendations outlined in the French accreditation committee (COFRAC) technical guide (GTA) 04, emphasizing the assessment of reproducibility and repeatability. Overall, the results of this evaluation were satisfactory and met the standards set by both the supplier and the French Society of Clinical Biology. This study illustrates that the biochemistry laboratory at Mohammed VI University Hospital of Oujda is equipped to provide accurate and precise results, which are crucial for effective clinical diagnosis and decision-making.

Intraoperative parathyroid hormone assay benefits surgery for primary hyperparathyroidism when preoperative localisation is negative or not performed.

Parathyroid localisation is now routine before first-time surgery for patients with primary hyperparathyroidism (PHPT). The aim of this study was to investigate the contribution of intraoperative parathyroid hormone (PTH) (ioPTH) in patients in whom localisation was either not undertaken or negative for a tumour. This was a retrospective study of patients undergoing first-time parathyroidectomy for PHPT in a regional endocrine centre. Data were collected prospectively (Microsoft Excel) and the all-Wales electronic patient record portal was used to retrieve missing data. Statistical analysis appropriate for nonparametric data was undertaken, with statistical significance reached when p<0.05. Between 1 July 2002 and 31 December 2022, 1,490 patients underwent a first-time parathyroidectomy for PHPT. Of this cohort, 1,133 patients had at least one positive imaging modality; the study group consisted of 343 patients that had negative imaging, and 13 that had no preoperative localisation. Patients with MEN-1 (n=26), an incorrect diagnosis (n=4), or less than six months follow-up (n=6) were excluded. Of the remaining 321, 106 patients underwent surgery without ioPTH (Group A), 215 cases with ioPTH (Group B). In Group B there were more women (170 female/45 male; 79% vs 67 female/37 male; 63% p=0.002, chi-squared), lower calcium (median [range] 2.77 [2.63-3.24] mmol/l; vs 2.85 [2.60-4.52] p=0.001) and lower PTH (12.0pmol/l [3.4-39.5] vs 14.4 [3.9-97.0] p=0.001) and smaller weights of resected tissue (320mg [50-9,000] vs 454 [46-8,280] p=0.02) (Student's t-test). The rate of multiple gland disease was similar (Group A 29%; Group B 27%). The rate of normocalcaemia at 6 months was significantly higher when ioPTH was used (Group B 202/215; 94% vs Group A 90/106; 85%) (p=0.014, chi-square test). The sensitivity and specificity of ioPTH was 98.5% [confidence interval (CI) 96.2-99.6] and 91.2% [80.7-97.0] (positive predictive value 99.9%, CI 93.6-100.0). Despite milder hyperparathyroidism and smaller tumour weight, the outcome in patients in whom ioPTH was used was superior, with failure rates 2.5-fold higher in the cohort where ioPTH was not utilised. The results of this study demonstrate that ioPTH is a valuable adjunct for the surgeon in cases where localisation has failed or not been undertaken.

Eduardo Slatopolsky: A Pioneer in the Field of Mineral and Bone Disorders in Kidney Disease.

Eduardo Alberto Slatopolsky (1934-2024), Washington University Joseph Friedman Professor Emeritus of Medicine, a prominent physician-scientist, was born in Buenos Aires, Argentina. The impact of his research in the area of mineral and bone disorders in kidney disease has been profound for over 50 years starting in the 1960s. He was a global authority on secondary hyperparathyroidism. He was instrumental in illustrating the role of hyperphosphatemia in chronic kidney disease (CKD) and in developing the first reliable parathyroid hormone (PTH) assay. His research led to the utilization of calcium salts as phosphate binders replacing the toxic aluminum salts. Moreover, he illustrated the role of vascular calcifications in CKD patients, paving the way for non-calcium phosphate binders. He proposed the use of calcitriol and later vitamin D analogs in the management of secondary hyperparathyroidism, which is the current standard of care. He demonstrated the decreased expression of the calcium-sensing receptor in parathyroid tissue in CKD patients. Dr. Slatopolsky's global legacy will last for generations.

Evaluation of Focused Mini-Incision Parathyroidectomy in Primary Hyperparathyroidism

Abstract Background In the era of effective preoperative localization and availability of intraoperative parathyroid hormone (IOPTH) assay, the trend now in parathyroidectomy is shifting from bilateral neck exploration (BNE) into minimal invasive parathyroidectomy (MIP). The concept of MIP is based on the fact that 85% of cases have single adenoma. This study highlights the outcomes of focused mini- incision parathyroidectomy (FMIP) for the treatment of selected cases of primary hyperparathyroidism. Aim of study: To evaluate and assess the outcome and advantages of focused mini-incision parathyroidectomy in parathyroid adenoma of primary hyperparathyroidism. Patients and Methods This cohort study was conducted at endocrine surgery unit, Ain Shams University Hospital, and Sohag Cancer Institute including 22 patients with benign solitary parathyroid adenoma; 17 retrospective cases &amp; 5 prospective cases. These included patients had been operated with focused mini-incision parathyroidectomy within the time period from January 2018 to December 2020 as retrospective cases and from January 2021 to December 2021 as prospective cases. Results In this study, age ranged from 30 to 70 years with mean age 50.23 ± 10.71 years. The preoperative serum calcium level ranged from 10.8 to 14.2 mg/dl (mean 12.28 ± 1.16 mg/dl). The preoperative parathyroid hormone level was elevated ranging from 256 to 2090 pg/mL (mean 970.68 ± 563.97 pg/mL). In this study, the operative time ranged from 55 to 75 minutes with mean 64.36 ± 6.33 minutes, percentage of IOPTH decrease level ranged from 75-95 % with mean percentage 85.72 ± 6.28 %. There were no cases with intraoperative bleeding or recurrent laryngeal nerve (RLN) injury. Hospital stay ranged from 6-16 days with mean 10.77 ± 3.10 days. There is no wound infection in all cases. All cases reached a success rate up to 100% (decrease the IOPTH level ≥ 75 %, and resolution of preoperative hypercalcemic manifestations). Conclusion Depending to the high successful rate, very low intraoperative morbidity and better postoperative recovery and cosmoses of FMIP technique, it should be the first choice for pHPT cases with solitary parathyroid adenoma, provided by the concordance localization study of U/S and MIBI scan preoperative.

Rare genetic disorders that impair parathyroid hormone synthesis, secretion, or bioactivity provide insights into the diagnostic utility of different parathyroid hormone assays.

Parathyroid hormone (PTH) is the major peptide hormone regulator of blood calcium homeostasis. Abnormal PTH levels can be observed in patients with various congenital and acquired disorders, including chronic kidney disease (CKD). This review will focus on rare human diseases caused by PTH mutations that have provided insights into the regulation of PTH synthesis and secretion as well as the diagnostic utility of different PTH assays. Over the past years, numerous diseases affecting calcium and phosphate homeostasis have been defined at the molecular level that are responsible for reduced or increased serum PTH levels. The underlying genetic mutations impair parathyroid gland development, involve the PTH gene itself, or alter function of the calcium-sensing receptor (CaSR) or its downstream signaling partners that contribute to regulation of PTH synthesis or secretion. Mutations in the pre sequence of the mature PTH peptide can, for instance, impair hormone synthesis or intracellular processing, while amino acid substitutions affecting the secreted PTH(1-84) impair PTH receptor (PTH1R) activation, or cause defective cleavage of the pro-sequence and thus secretion of a pro- PTH with much reduced biological activity. Mutations affecting the secreted hormone can alter detection by different PTH assays, thus requiring detailed knowledge of the utilized diagnostic test. Rare diseases affecting PTH synthesis and secretion have offered helpful insights into parathyroid biology and the diagnostic utility of commonly used PTH assays, which may have implications for the interpretation of PTH measurements in more common disorders such as CKD.

Wild Alaskan salmon supplementation increases 25-OHD levels in sled dogs

Vitamin D deficiency affects canines and humans alike. Athletes are a particularly high-risk group. Further research regarding optimal intake and supplementation is needed to establish the parameters of vitamin D status in both humans and canines and to create a physiologically-relevant definition for vitamin D sufficiency. The objectives of this study were to (1) compare 25-OHD (25-hydroxy vitamin D) levels in sled dogs before and after receiving a diet supplemented with wild Alaskan salmon and (2) correlate biomarkers associated with vitamin D metabolism to 25-OHD levels in sled dogs. Plasma samples from 14 working sled dogs between 10 months and 7 years of age were collected before and after a 4-week supplementation with »0.45 kg of salmon/day. Samples were analyzed using enzyme-linked immunosorbent assays (ELISA) for parathyroid hormone and vitamin D binding protein (DBP); 25-OHD levels were measured via radioimmunoassay. 25-OHD and DBP in sled dogs significantly increased after a 4-week supplementation with salmon (P=0.0011 and 0.0367, respectively). Additional variations in 25-OHD were observed when separated by sex (P=0.0404) and age (P&lt;0.0001). 57% of the dogs were deficient prior to the salmon supplementation and 14% at the completion of the study. Wild Alaskan salmon is one of the few food sources that provide appreciable amounts of vitamin D. A 4-week salmon supplementation in sled dogs was sufficient to improve 25-OHD concentrations in most sled dogs in this study. Confounding factors such as age and sex affect circulating 25-OHD levels.

Comparison of two parathyroid hormone (pth) assay methods in the monitoring of black african hemodialysis patients in the ivory coast (Maglumi® vs Vidas Biomerieux® Kits)

Parathyroid hormone (PTH) testing is recommended once or twice a year to prevent bone complications resulting from chronic kidney disease. However, its interpretation is subject to many factors, including the generation of the PTH test used. For this reason, it is recommended that each laboratory establish its own PTH Upper Limit of Normality (ULN). In order to guarantee optimal management of hemodialysis patients in the public sector in Côte d'Ivoire (West Africa), it proved important to compare the diagnosis of hyperparathyroidism made using two platforms used in the laboratory in charge of monitoring these patients: PTH VIDAS® (3rd Generation) and PTH MAGLUMI® (2nd Generation). This was a cross-sectional study of 65 haemodialysis patients in Abidjan. PTH determinations were performed simultaneously on VIDAS® and MAGLUMI® platforms. The results obtained were interpreted on the basis of PTH threshold values pre-established in the laboratory. 86.15% of patients had concordant diagnoses on both platforms, compared with 13.85% with discordant diagnoses. Statistical analysis of these results showed a non-statistically significant difference.: The limitation posed by differences in PTH concentration given by different platforms can be circumvented by using PTH ULN stablished for each platform for a given population. Conclusion: The diagnoses made by the two platforms are thus superimposable using their respective PTH ULN.

Proposed age-based reference interval for the serum parathyroid hormone assay on the Abbott Alinity i

Proposed age-based reference interval for the serum parathyroid hormone assay on the Abbott Alinity i

Age-specific Reference Intervals of Abbott Intact PTH-Potential Impacts on Clinical Care.

PTH assays are not standardized; therefore, method-specific PTH reference intervals are required for interpretation of results. PTH increases with age in adults but age-related reference intervals for the Abbott intact PTH (iPTH) assay are not available. Deidentified serum PTH results from September 2015 to November 2022 were retrieved from the laboratory information system of a laboratory serving a cosmopolitan population in central-west England for individuals aged 18 years and older if the estimated glomerular filtration rate was ≥60 mL/min, serum 25-hydroxyvitamin D was >50 nmol/L, and serum albumin-adjusted calcium and serum phosphate were within reference intervals. Age-specific reference intervals for Abbott iPTH were derived by an indirect method using the refineR algorithm. PTH increased with age and correlated with age when controlled for 25-hydroxyvitamin D, estimated glomerular filtration rate, and adjusted calcium (r = 0.093, P < .001). The iPTH age-specific reference intervals for 4 age partitions of 18 to 45 years, 46 to 60 years, 61 to 80 years, and 81 to 95 years were 1.6 to 8.6 pmol/L, 1.8 to 9.5 pmol/L, 2.0 to 11.3 pmol/L, and 2.3 to 12.3 pmol/L, respectively. PTH was higher in women compared with men (P < .001). Sex-specific age-related reference intervals could not be derived because of the limited sample size. Age-specific Abbott iPTH reference intervals were derived. Application of age-specific reference intervals will impact the diagnosis and management of normocalcemic hyperparathyroidism, based on current definitions, and secondary hyperparathyroidism. Additional studies are required to clarify the effect of sex and ethnicity on PTH.

An individual approach to intraoperative parathyroid hormone measurement during total thyroidectomy

PurposeHypocalcemia is a common complication of thyroidectomy. Measurement of the intraoperative serum parathyroid hormone (PTH) levels became an established technique but it requires further improvements. We aimed to assess intraoperative PTH level testing results against the hypothesis that the PTH assay may be performed almost immediately after thyroid gland removal. MethodsA retrospective cohort study. During total thyroidectomy surgery, the patients had PTH levels measured at the cutting time and again immediately after the thyroid gland is removed. Post-operatively, serial total blood calcium levels were obtained twice daily and recorded. ResultsAmong 63 enrolled patients, 39 had multinodular goiter, 15 thyroid carcinoma, and nine had Graves' disease. The mean age was 59.8 ± 15.3 years, 43 females. The mean PTH level before surgery was 45.8 ± 22.0 pg/mL. Post-operatively, 11/63 patients developed hypocalcemia with serum calcium levels <8 mg/dL. Four patients with ≥50 % decrease in PTH concentration were normocalcemic a day after surgery and were discharged early. Four patients with ≥70 % PTH decrease were treated accordingly during prolonged hospitalization and did not suffer from permanent hypocalcemia. The cut-off value of 70 % decrease after the gland removal was able to predict postoperative hypocalcemia with a sensitivity of 100 %, specificity 82.9 %, PPV 60.0 % and NPV 100 %. ConclusionMeasurements of intraoperative PTH may not be performed at fixed time intervals but after 1–2 min after removal of the thyroid gland. Defining those not at risk would allow the majority of patients to be waived from post-operative blood calcium testing and safely discharged early after surgery.

Unveiling a new era with liquid chromatography coupled with mass spectrometry to enhance parathyroid hormone measurement in patients with chronic kidney disease

Precise determination of circulating parathyroid hormone (PTH) concentration is crucial to diagnose and manage various disease conditions, including the chronic kidney diseases-mineral and bone disorder. However, the lack of standardization in PTH assays is challenging for clinicians, potentially leading to medical errors because the different assays do not provide equivalent results and use different reference ranges. Here, we aimed to evaluate the impact of recalibrating PTH immunoassays by means of a recently developed LC-MS/MS method as the reference. Utilizing a large panel of pooled plasma samples with PTH concentrations determined by the LC-MS/MS method calibrated with the World Health Organization (WHO) 95/646 International Standard, five PTH immunoassays were recalibrated. The robustness of this standardization was evaluated over time using different sets of samples. The recalibration successfully reduced inter-assay variability with harmonization of PTH measurements across different assays. By recalibrating the assays based on the WHO 95/646 International Standard, we demonstrated the feasibility for standardizing PTH measurement results and adopting common reference ranges for PTH assays, facilitating a more consistent interpretation of PTH values. The recalibration process aligns PTH results obtained from various immunoassays with the LC-MS/MS method, providing more consistent and reliable measurements. Thus, establishing true standardization across all PTH assays is crucial to ensure consistent interpretation and clinical decision-making.

A-129 Analytical Performance Evaluation of Vitamin D, Intact Parathyroid Hormone, and Inorganic Phosphorus on the Atellica CI 1900 Analyzer

Abstract Background The Atellica® CI 1900 Analyzer is an automated, mid-throughput, integrated chemistry and immunoassay analyzer utilizing both Atellica CH and Atellica IM assays. This study was designed to evaluate the analytical performance of the Atellica IM Vitamin D (VitD) and Intact Parathyroid Hormone (PTH) and Atellica CH Inorganic Phosphorus (IP) assays* on the Atellica CI 1900 Analyzer*. Methods The Atellica CI 1900 VitD, PTH, and IP assays use the same reagents and calibrators as the Atellica IM VitD and PTH and CH IP assays. Precision and method comparison (MC) were used as performance indicators for the Atellica CI 1900 Analyzer. Precision studies were performed according to CLSI EP05-A3 using native and contrived human serum (VitD and IP) or plasma (PTH) samples. One aliquot of each sample pool was tested in duplicate in two runs per day &amp;gt;2 h apart on each analyzer for &amp;gt;20 days. MC studies were performed according to CLSI EP09-A3. Native and contrived human samples were analyzed using the Atellica IM VitD and PTH assays on both the Atellica IM and Atellica CI 1900 Analyzers. For IP, native and contrived human samples were analyzed using the Atellica CH IP assay on both the Atellica CH and Atellica CI 1900 Analyzers. Results Representative precision and MC results for each assay across indicated sample ranges are listed in the table. For the three assays tested, repeatability and within-lab %CVs were &amp;lt;4.5% and &amp;lt;10%, respectively. Slopes determined by the Deming linear regression model were approximately equal to 1. Conclusion Evaluation of the Atellica IM VitD and PTH and Atellica CH IP assays using the Atellica CI 1900 Analyzer demonstrated good precision and equivalent performance compared to the same assays on their respective Atellica IM and Atellica CH Analyzers. *The products/features mentioned are not commercially available in all countries. Their future availability cannot be guaranteed.

A-042 Comparison of the Second-Generation Parathyroid Hormone Assays: ELSA-PTH and Alinity i Intact PTH

Abstract Background Measurement of parathyroid hormone (PTH) level is essential in diagnosing and treating hyper- and hypoparathyroidism. Because of the various presenting forms of PTH (biologically active full-length PTH and also PTH fragments) in the blood and the lack of standardization, there can be a difference in results between the assays even when the same assay generation is used. We compared the two second-generation PTH assays, ELSA-PTH and Alinity i Intact PTH, and evaluated the analytical performance of Alinity i Intact PTH, newly adopted in the laboratory. Methods For method comparison, 56 remnant samples of routinely ordered sera for the PTH test were collected. ESLA-PTH assay tested on Gamma-10 contains the anti-[39-84, amino acids] PTH antibody coated on the tube, which captures PTH in the sample and is measured by the radioactivity through the bound I125-labelled anti-[1-34] PTH antibody. Alinity i Intact PTH assay performed on Alinity i system uses the anti-[39-84] PTH antibody coated on a paramagnetic microparticle and is analyzed by the emitted light through the captured acridinium-labeled anti-[1-34] PTH antibody. The correlation between the two tests was evaluated. Additionally, precision, linearity, and reference range verification were analyzed to investigate the performance of the Alinity i Intact PTH assay. Results Of the 56 samples, 35 (62.5%) were requested by the Nephrology department for evaluating chronic kidney disease, 16 (28.6%) by the General surgery department during and after parathyroid and thyroid surgery, and 5 (8.9%) by other departments. 52.3% of the patients were female, and the median age was 61.5 years (interquartile range: 45.3–71). The median values of ELSA-PTH and Alinity i Intact PTH were 69.0 pg/mL and 101.9 pg/mL, respectively, and the PTH values of Alinity i Intact PTH were significantly higher (P &amp;lt; 0.0001) by the Wilcoxon test. The Pearson correlation coefficient (r) was 0.959, and the average difference between the two tests was 78.57 pg/mL. In Alinity i Intact PTH, the coefficient of variation obtained at each low (10.5 pg/mL), medium (66.6 pg/mL), high (254.6 pg/mL) levels were 1.9%, 2.4%, and 1.8% for repeatability, and 2.03%, 2.71%, and 2.65% for within-laboratory precision, respectively. Linearity was observed within the analytical measuring range of 3–3000 pg/mL. The reference range (15–68.3 pg/mL) recommended by the manufacturer was validated with 20 normal sera. Conclusion The PTH values of Alinity i Intact PTH were significantly higher than those of the ELSA-PTH, and both assays showed a strong correlation. Additionally, the Alinity i Intact PTH assay demonstrated acceptable analytical performance.

Tissue Parathyroid Hormone Washout: A Reliable Method for the Localization and Exclusion of Parathyroid Adenomas.

Background and objective Accurate identification of parathyroid adenoma (PA) is essential for minimally invasive treatment of primary hyperparathyroidism (PHPT). The aim of this study is to evaluate the results of parathyroid hormone (PTH) assay in aspirates of suspicious neck lesions and to clarify its reliability in determining whether the lesion is of parathyroid origin. Methods A total of 134 lesions (104 imaging-suspected PA and 30 concomitant thyroid nodules as a control group) of 101 patients were retrospectively analyzed. Patients with positive, negative, or never scintigraphy were included in our study. Ultrasound (US) was performed again and US-guided tissue fine needle aspiration with PTH washout (PTH-WO) was performed from suspicious lesions. A PTH-WO level higher than the patient's serum PTH levels is proposed for a positive test, and a PTH-WO level lower than the upper limit of the laboratory PTH level is proposed for a negative test. A definitive diagnosis was made postoperatively histopathologically. Results PTH-WO levels (median (IQR)) were significantly higher in the positive group (n = 93, 5000 (1600) ng/L) compared to the negative group (n = 11, 17 (13.1) ng/L) and thyroid nodule aspirate group (n = 30, 14 (4.3) ng/L) (p < 0.001). Among 93 PTH-WO-positive lesions, 42 lesions (45.1%) were not identified by parathyroid scintigraphy (PS), 20 (21.5%) lesions were suspiciously PS, and 33 lesions (35.4%) were negative or suspicious byfirst US findings. Of the 93 patients localized with PTH-WO, two were cystic PAsablated by aspiration. The final pathology result of 91 operated patients proved PA. The sensitivity, specificity, negative predictive value, and positive predictive value of the PTH-WO were observed as 1.00, 0.82, 0.09, and 0.91, respectively. Conclusion Comprehensive repeated US and PTH-WO from the lesion increase the accurate localization of PAs. PTH-WO is a highly reliable method for differentiating parathyroid lesions from other cervical lesions.

A commentary on 'The role of rapid intraoperative parathyroid hormone (ioPTH) assay in determining outcome of parathyroidectomy in primary hyperparathyroidism: A systematic review and meta-analysis'.

A commentary on 'The role of rapid intraoperative parathyroid hormone (ioPTH) assay in determining outcome of parathyroidectomy in primary hyperparathyroidism: A systematic review and meta-analysis'.