Lab Med Online.  2023 Oct;13(4):332-340. 10.47429/lmo.2023.13.4.332.

Comparison Between Two Different Second-Generation Parathyroid Hormone Assays

• Kang JK
• Jeon JH
• Park JH
• Kee SJ
• Choi HW

• KMID: 2552760
• DOI: http://doi.org/10.47429/lmo.2023.13.4.332

Abstract

Background
Accurate measurement of parathyroid hormone (PTH) levels is crucial for the diagnosis and treatment of hyperparathyroidism and hypoparathyroidism. Given the existence of various PTH forms in the bloodstream, it is well-known that there are variations in PTH levels depending on the measurement method. This study aimed to evaluate two different second-generation PTH assays.
Methods
A total of 56 residual samples originally requested for PTH testing were utilized for comparing the two methods. Each sample was subjected to analysis using an immunoradiometric assay (ELSA-PTH; Cisbio Bioassays, France) and a chemiluminescence microparticle immunoassay (Alinity i Intact PTH; Abbott, USA). Precision and linearity were analyzed, and reference interval and limit of quantitation (LoQ) were verified to investigate the performance of the Alinity i Intact PTH assay.
Results
The median PTH values of ELSA-PTH and Alinity i Intact PTH were 69.0 pg/mL and 101.9 pg/mL, respectively, with significantly higher PTH values for Alinity i Intact PTH (P < 0.0001). The Pearson correlation coefficient was 0.959, and the average difference between the two tests was 78.57 pg/mL. For Alinity i Intact PTH, the coefficient of variation obtained at three concentrations was 1.9%, 2.4%, 1.8% for repeatability, and 2.0%, 2.7%, 2.7% for within-laboratory precision. Linearity was observed in the range of 3–3,000 pg/mL. The reference interval and LoQ reported by the manufacturer were verified.
Conclusions
The PTH results of the ELSA-PTH and Alinity i Intact PTH assays showed a strong correlation, and the Alinity i Intact PTH assay demonstrated acceptable analytical performance.

Keyword

Parathyroid hormone; Immunoassay; Comparison; Performance

Figure

• 

  Fig. 1 Schematic diagram of PTH assays by generation. (A) First generation (radioimmunoassay, RIA): Human PTH in the sample under analysis competes with, and displaces, the radiolabeled bovine PTH bound to immobilized capture antibody. (B) Early second generation (immunoradiometric assay, IRMA): Anti-PTH [39-84] antibody coated on the tube captures PTH in the sample and radioactivity subsequently measured through the bound I125-labelled anti-PTH [1-34] antibody. (C) Second generation (chemiluminescent microparticle immunoassay, CMIA): An anti-PTH [39-84] antibody coated on a paramagnetic microparticle captures PTH in the sample and the emitted light is subsequently measured through an acridinium-labelled anti-PTH [1-34] antibody bound to the captured PTH. (D) Third generation (chemiluminescent immunoassay, CLIA): Same method applied as second-generation CLIA, except for the use of anti-PTH [1-4] as the tracer antibody to increase the specificity for the whole (bio-intact) 1-84 PTH. Abbreviation: PTH, parathyroid hormone.

• 

  Fig. 2 Box and whisker plots of the two second-generation PTH assays compared in this study. The median values of ELSA-PTH and Alinity i Intact PTH were 69.0 pg/mL and 101.9 pg/mL, respectively. Abbreviation: PTH, parathyroid hormone.

• 

  Fig. 3 Comparison of ELSA-PTH and Alinity i Intact PTH using Passing-Bablok regression and identity line. The Pearson correlation coefficient (r) was 0.959 and the average difference was 78.57 pg/mL. The 95% confidence interval of the slope and y-intercept ranged from 1.4333 to 1.5833 and from 4.1954 to 15.0667, respectively. Abbreviation: PTH, parathyroid hormone.

• 

  Fig. 4 Bland-Altman plots were used to assess the difference (A) and percentage difference (B) between ELSA-PTH and Alinity i Intact PTH. The results consistently showed higher measurements with the Alinity i Intact PTH test method, and as the measured value increased, the disparity between both assays also increased. The percentage difference remained constant irrespective of the measured value. Abbreviations: PTH, parathyroid hormone; SD, standard deviation.

• 

  Fig. 5 Linearity of Alinity i Intact PTH assay. The black dotted line represents ± ADL. For all proportionally mixed samples, the absolute value of deviation from linearity (blue dots) was less than or equal to ADL, or the CI of deviation from linearity intersected within the ADL range. Abbreviations: ADL, allowable deviation from linearity; CI, confidence interval; PTH, parathyroid hormone.

Reference

1. Naveh-Many T, Silver J, et al. Bilezikian JP, Martin TG, editors. 2019. Parathyroid hormone molecular biology. Principles of bone biology. 4th ed. San Diego, CA: Elsevier;p. 575–94.

2. Gardella TJ, Axelrod D, Rubin D, Keutmann HT, Potts JT Jr, Kronenberg HM, et al. 1991; Mutational analysis of the receptor-activating region of human parathyroid hormone. J Biol Chem. 266:13141–6. DOI: 10.1016/S0021-9258(18)98816-2. PMID: 1649179.

3. D'Amour P, Brossard JH, Rousseau L, Nguyen-Yamamoto L, Nassif E, Lazure C, et al. 2005; Structure of non-(1-84) PTH fragments secreted by parathyroid glands in primary and secondary hyperparathyroidism. Kidney Int. 68:998–1007. DOI: 10.1111/j.1523-1755.2005.00493.x. PMID: 16105030.

4. D'Amour P, Brossard JH, Rousseau L, Roy L, Gao P, Cantor T. 2003; Amino-terminal form of parathyroid hormone (PTH) with immunologic similarities to hPTH(1-84) is overproduced in primary and secondary hyperparathyroidism. Clin Chem. 49:2037–44. DOI: 10.1373/clinchem.2003.021592. PMID: 14633875.

5. Fraser WD. 2009; Hyperparathyroidism. Lancet. 374:145–58. DOI: 10.1016/S0140-6736(09)60507-9. PMID: 19595349.

6. Bilezikian JP, Khan A, Potts JT Jr, Brandi ML, Clarke BL, Shoback D, et al. 2011; Hypoparathyroidism in the adult: epidemiology, diagnosis, pathophysiology, target-organ involvement, treatment, and challenges for future research. J Bone Miner Res. 26:2317–37. DOI: 10.1002/jbmr.483. PMID: 21812031. PMCID: PMC3405491.

7. Nussbaum SR, Thompson AR, Hutcheson KA, Gaz RD, Wang CA. 1988; Intraoperative measurement of parathyroid hormone in the surgical management of hyperparathyroidism. Surgery. 104:1121–7.

8. Bhangu JS, Riss P. 2019; The role of intraoperative parathyroid hormone (IOPTH) determination for identification and surgical strategy of sporadic multiglandular disease in primary hyperparathyroidism (pHPT). Best Pract Res Clin Endocrinol Metab. 33:101310. DOI: 10.1016/j.beem.2019.101310. PMID: 31409538.

9. Cavalier E, Vasikaran S, Bhattoa HP, Heijboer AC, Makris K, Ulmer CZ. 2021; The path to the standardization of PTH: is this a realistic possibility? A position paper of the IFCC C-BM. Clin Chim Acta. 515:44–51. DOI: 10.1016/j.cca.2020.12.022. PMID: 33412144. PMCID: PMC7920929.

10. Cavalier E. 2019; Parathyroid hormone results interpretation in the background of variable analytical performance. J Lab Precis Med. 4:1–10. DOI: 10.21037/jlpm.2018.12.03.

11. Nawrot I, Woźniewicz B, Szmidt J, Śladowski D, Zając K, Chudziński W. 2014; Xenotransplantation of human cultured parathyroid progenitor cells into mouse peritoneum does not induce rejection reaction. Cent Eur J Immunol. 39:279–84. DOI: 10.5114/ceji.2014.45937. PMID: 26155136. PMCID: PMC4440013.

12. González-Casaus ML, Fernández-Calle P, Buño Soto AB. 2021; Should clinical laboratories adapt to the reality of chronic kidney disease in the determination of parathyroid hormone? Adv Lab Med. 2:342–51. DOI: 10.1515/almed-2021-0046. PMID: 37362408. PMCID: PMC10197458.

13. Censi S, Iacobone M, Simmini S, Manso J, Franceschet G, Plebani M, et al. 2020; PTH: redefining reference ranges in a healthy population-The role of interfering factors and the type of laboratory assay. Int J Endocrinol. 2020:1053719. DOI: 10.1155/2020/1053719. PMID: 32148482. PMCID: PMC7054804.

14. Clinical and Laboratory Standards Institute. 2014. User verification of precision and estimation of bias; Approved guideline-Third edition. CLSI document EP15-A3. Clinical and Laboratory Standards Institute;Wayne, PA:

15. Clinical and Laboratory Standards Institute. 2020. Evaluation of linearity of quantitative measurement procedures, 2nd edition. CLSI guideline EP06. Clinical and Laboratory Standard Institute;Wayne, PA:

16. Clinical and Laboratory Standards Institute. 2008. Defining, establishing, and verifying reference intervals in the clinical laboratory; Approved guideline-Third edition. CLSI document C28-A3c. Clinical and Laboratory Standard Institute;Wayne, PA:

17. Berson SA, Yalow RS, Aurbach GD, Potts JT. 1963; Immunoassay of bovine and human parathyroid hormone. Proc Natl Acad Sci U S A. 49:613–7. DOI: 10.1073/pnas.49.5.613. PMID: 16591075. PMCID: PMC299933.

18. Nussbaum SR, Zahradnik RJ, Lavigne JR, Brennan GL, Nozawa-Ung K, Kim LY, et al. 1987; Highly sensitive two-site immunoradiometric assay of parathyrin, and its clinical utility in evaluating patients with hypercalcemia. Clin Chem. 33:1364–7. DOI: 10.1093/clinchem/33.8.1364. PMID: 3608153.

19. Quarles LD, Lobaugh B, Murphy G. 1992; Intact parathyroid hormone overestimates the presence and severity of parathyroid-mediated osseous abnormalities in uremia. J Clin Endocrinol Metab. 75:145–50. DOI: 10.1210/jcem.75.1.1619003. PMID: 1619003.

20. Wang M, Hercz G, Sherrard DJ, Maloney NA, Segre GV, Pei Y. 1995; Relationship between intact 1-84 parathyroid hormone and bone histomorphometric parameters in dialysis patients without aluminum toxicity. Am J Kidney Dis. 26:836–44. DOI: 10.1016/0272-6386(95)90453-0. PMID: 7485142.

21. John MR, Goodman WG, Gao P, Cantor TL, Salusky IB, Jüppner H. 1999; A novel immunoradiometric assay detects full-length human PTH but not amino-terminally truncated fragments: implications for PTH measurements in renal failure. J Clin Endocrinol Metab. 84:4287–90. DOI: 10.1210/jcem.84.11.6236. PMID: 10566687.

22. D'Amour P, Brossard JH, Rousseau L, Roy L, Gao P, Cantor T. 2003; Amino-terminal form of parathyroid hormone (PTH) with immunologic similarities to hPTH(1-84) is overproduced in primary and secondary hyperparathyroidism. Clin Chem. 49:2037–44. DOI: 10.1373/clinchem.2003.021592. PMID: 14633875.

23. Einbinder Y, Benchetrit S, Golan E, Zitman-Gal T. 2017; Comparison of intact PTH and bio-intact PTH assays among non-dialysis dependent chronic kidney disease patients. Ann Lab Med. 37:381–7. DOI: 10.3343/alm.2017.37.5.381. PMID: 28643486. PMCID: PMC5500736.

24. Hecking M, Kainz A, Bielesz B, Plischke M, Beilhack G, Hörl WH, et al. 2012; Clinical evaluation of two novel biointact PTH(1-84) assays in hemodialysis patients. Clin Biochem. 45:1645–51. DOI: 10.1016/j.clinbiochem.2012.08.006. PMID: 23217247.

25. Au DH, Kim JY, Seok JD. 2010; The usefulness according to the incubation time of PTH as prediction index of hypocalcemia. J Nucl Med Technol. 14:138–42.

26. D'Amour P. 2006; Circulating PTH molecular forms: what we know and what we don't. Kidney Int Suppl. 70:S29–33. DOI: 10.1038/sj.ki.5001599. PMID: 16810307.

27. Kidney Disease: Improving Global Outcomes (KDIGO) CKD-MBD Update Work Group. 2017; KDIGO 2017 Clinical practice guideline update for the diagnosis, evaluation, prevention, and treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). Kidney Int Suppl. 7:1–59. DOI: 10.1016/j.kisu.2017.04.001. PMID: 30675420. PMCID: PMC6340919.

28. Youngwirth L, Benavidez J, Sippel R, Chen H. 2010; Parathyroid hormone deficiency after total thyroidectomy: incidence and time. J Surg Res. 163:69–71. DOI: 10.1016/j.jss.2010.03.059. PMID: 20605611.

29. Souberbielle JC, Roth H, Fouque DP. 2010; Parathyroid hormone measurement in CKD. Kidney Int. 77:93–100. DOI: 10.1038/ki.2009.374. PMID: 19812537.

30. Korean Association of External Quality Assessment Service. 2022. 2022년도 01차 신빙도조사 호르몬검사 2 공통 보고서. Korean Association of External Quality Assessment Service (KEQAS);Seoul: