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Licensed Unlicensed Requires Authentication Published by De Gruyter June 17, 2022

Cross-reactivity in assays for prolactin and optimum screening policy for macroprolactinaemia

  • Thomas P. Smith EMAIL logo , Sinead Kelly and Michael N. Fahie-Wilson



Macroprolactin cross-reacts in immunoassays for prolactin causing apparent hyperprolactinaemia (macroprolactinaemia) and consequent misdiagnosis and mismanagement of patients.


We determined the prevalence of macroprolactinaemia using prolactin immunoassays with reported “high” (Tosoh) or “low” cross-reactivity (Roche) with macroprolactin. We additionally modelled the effects of increasing the screening threshold on workload and sensitivity in the detection of macroprolactinaemia.


A review of routine requests for prolactin received in a 12 month period identified 670 sera with hyperprolactinaemia (Tosoh assay). Treatment with polyethylene glycol (PEG) precipitation demonstrated normal levels of monomeric prolactin in 165 sera (24.6%) indicating macroprolactinaemia. In the macroprolactinaemic cohort, total prolactin levels were lower with the Roche assay (473 ± 132 mU/L; mean ± SD) compared to the Tosoh assay (683 ± 217 mU/L), p < 0.005. The prevalence of macroprolactinaemia was also lower with the Roche assay (6.2%). The number of samples that required screening for macroprolactinaemia fell by 14% when Roche gender specific total prolactin reference limits were applied. Use of a higher screening threshold (700 mU/L) reduced the screening workload considerably (Roche by 45%, Tosoh by 37%) however, the sensitivity of detection of macroprolactinaemia decreased markedly (Roche 90%, Tosoh 59%).


Macroprolactin interferes in both Tosoh and Roche prolactin immunoassays. Use of an assay with a relatively low cross reactivity with macroprolactin, e.g. Roche, will lead to a modest reduction in the screening workload. Increasing the screening threshold above the upper limit of the assay reference interval will also reduce the screening workload but leads to disproportionate increases in the number of cases of macroprolactinaemia which are missed.

Corresponding author: Thomas P. Smith, Department of Investigative Endocrinology, St. Vincent’s University Hospital, Elm Park, Dublin 4, Ireland, Phone: 00-353-221-4629, E-mail:

  1. Research funding: Some reagents for this study were kindly provided by Roche Diagnostics.

  2. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  3. Competing interests: Authors state no conflict of interest.

  4. Informed consent: Not Applicable.

  5. Ethical approval: Approval for this study was obtained from the Research Ethics Committee, St. Vincent’s University Hospital.


1. Fahie-Wilson, M, Smith, TP. Determination of prolactin: the macroprolactin problem. Best Pract Res Clin Endocrinol Metab 2013;27(5):725–42, in Google Scholar

2. Wallace, IR, Satti, N, Courtney, CH, Leslie, H, Bell, PM, Hunter, SJ, et al.. Ten-year clinical follow-up of a cohort of 51 patients with macroprolactinemia establishes it as a benign variant. J Clin Endocrinol Metab 2010;95(7):3268–71, in Google Scholar

3. McKenna, TJ. Should macroprolactin be measured in all hyperprolactinaemic sera? Clin Endocrinol (Oxf) 2009;71(4):466–9, in Google Scholar

4. Hattori, N, Aisaka, K, Shimatsu, A. A possible cause of the variable detectability of macroprolactin by different immunoassay systems. Clin Chem Lab Med 2016;54:603–8. in Google Scholar

5. Hattori, N, Ishihara, T, Saiki, Y. Macroprolactinaemia: prevalence and aetiologies in a large group of hospital workers. Clin Endocrinol (Oxf) 2009;71:702–8. in Google Scholar

6. Smith, TP, Suliman, AM, Fahie-Wilson, MN, McKenna, TJ. Gross variability in the detection of prolactin in sera containing big big prolactin (macroprolactin) by commercial immunoassays. J Clin Endocrinol Metab 2002;87:5410–5. in Google Scholar

7. Schneider, W, Marcovitz, S, Al-Shammari, S, Yago, S, Chevalier, S. Reactivity of macroprolactin in common automated immunoassays. Clin Biochem 2001;34:469–73. in Google Scholar

8. Cavaco, B, Prazeres, S, Santos, MA, Sobrinho, LG, Leite, V. Hyperprolactinemia due to big big prolactin is differently detected by commercially available immunoassays. J Endocrinol Invest 1999;22:203–8. in Google Scholar PubMed

9. Fahie-Wilson, MN. Detection of macroprolactin causing hyperprolactinemia in commercial assays for prolactin. Clin Chem 2000;46:2022–3. in Google Scholar

10. de Soárez, PC, Souza, SC, Vieira, JG, Ferraz, MB. The effect of identifying macroprolactinemia on health-care utilization and costs in patients with elevated serum prolactin levels. Value Health 2009;12:930–4. in Google Scholar PubMed

11. Gibney, J, Smith, TP, McKenna, TJ. Clinical relevance of macroprolactin. Clin Endocrinol (Oxf) 2005;62:633–43. in Google Scholar

12. Suliman, AM, Smith, TP, Gibney, J, McKenna, TJ. Frequent misdiagnosis and mismanagement of hyperprolactinemic patients before the introduction of macroprolactin screening: application of a new strict laboratory definition of macroprolactinemia. Clin Chem 2003;49:1504–9. in Google Scholar

13. Olukoga, AO, Dornan, TL, Kane, JW. Three cases of macroprolactinaemia. J R Soc Med 1999;92:342–4. in Google Scholar

14. Heaney, AP, Laing, I, Walton, L, Seif, MW, Beardwell, CG, Davis, JR. Misleading hyperprolactinaemia in pregnancy. Lancet 1999;353:720. in Google Scholar

15. Guay, AT, Sabharwal, P, Varma, S, Malarkey, WB. Delayed diagnosis of psychological erectile dysfunction because of the presence of macroprolactinemia. J Clin Endocrinol Metab 1996;81:2512–4. in Google Scholar

16. Overgaard, M, Pedersen, SM. Serum prolactin revisited: parametric reference intervals and cross platform evaluation of polyethylene glycol precipitation-based methods for discrimination between hyperprolactinemia and macroprolactinemia. Clin Chem Lab Med 2017;55:1744–53. in Google Scholar PubMed

17. Šostarić, M, Bokulić, A, Marijančević, D, Zec, I. Optimizing laboratory defined macroprolactin algorithm. Biochem Med (Zagreb) 2019;29:020706. in Google Scholar

18. Saleem, M, Martin, H, Coates, P. Prolactin biology and laboratory measurement: an update on physiology and current analytical issues. Clin Biochem Rev 2018;39:3–16.Search in Google Scholar

19. Che Soh, NAA, Yaacob, NM, Omar, J, Mohammed Jelani, A, Shafii, N, Tuan Ismail, TS, et al.. Global prevalence of macroprolactinemia among patients with hyperprolactinemia: a systematic review and meta-analysis. Int J Environ Res Publ Health 2020;17:8199. in Google Scholar PubMed PubMed Central

20. Vilar, L, Vilar, C, Albuquerque, JL, Thé, AC, Gadelh, P, Borges, T, et al.. The importance of routine screening for macroprolactin in symptomatic patients with idiopathic hyperprolactinemia. An Fac Med Olinda, Recife 2018;1:2. in Google Scholar

21. Fahie-Wilson, MN, Soule, SG. Macroprolactinaemia: contribution to hyperprolactinaemia in a district general hospital and evaluation of a screening test based on precipitation with polyethylene glycol. Ann Clin Biochem 1997;34:252–8. in Google Scholar PubMed

22. Beltran, L, Fahie-Wilson, MN, McKenna, TJ, Kavanagh, L, Smith, TP. Serum total prolactin and monomeric prolactin reference intervals determined by precipitation with polyethylene glycol: evaluation and validation on common immunoassay platforms. Clin Chem 2008;54:1673–81. in Google Scholar PubMed

23. Smith, TP, Fahie-Wilson, MN. Reporting of post-PEG prolactin concentrations: time to change. Clin Chem 2010;56:484–5. in Google Scholar PubMed

24. Melmed, S, Casanueva, FF, Hoffman, AR, Kleinberg, DL, Montori, VM, Schlechte, JA, et al.. Diagnosis and treatment of hyperprolactinemia: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 2011;96:273–88. in Google Scholar PubMed

25. Searell, C, Evans, C. Standards for the Investigation of Macroprolactinaemia. In: A.W.C.B.A. Group, editor. The Association of Clinical Biochemistry & Laboratory Medicine; 2012. Available from: in Google Scholar

26. Whitehead, SJ, Cornes, MP, Ford, C, Gama, R. Reference ranges for serum total and monomeric prolactin for the current generation Abbott Architect assay. Ann Clin Biochem 2015;52:61–6. in Google Scholar PubMed

27. Casanueva, FF, Molitch, ME, Schlechte, JA, Abs, R, Bonert, V, Bronstein, MD, et al.. Guidelines of the pituitary society for the diagnosis and management of prolactinomas. Clin Endocrinol (Oxf) 2006;65:265–73. in Google Scholar PubMed

28. Byrne, B, O’Shea, P, Barrett, P, Tormey, W. The Beckman DxI 800 prolactin assay demonstrates superior specificity for monomeric prolactin. Clin Chem Lab Med 2010;48:205–8. in Google Scholar PubMed

29. Ellis, MJ, Livesey, JH, Soule, SG. Macroprolactin, big-prolactin and potential effects on the misdiagnosis of hyperprolactinemia using the Beckman Coulter Access Prolactin assay. Clin Biochem 2006;39:1028–34. in Google Scholar PubMed

30. Jassam, NF, Paterson, A, Lippiatt, C, Barth, JH. Macroprolactin on the advia centaur: experience with 409 patients over a three-year period. Ann Clin Biochem 2009;46:501–4. in Google Scholar PubMed

31. Vieira, JG, Tachibana, TT, Ferrer, CM, Sá, J, Biscolla, RP, Hoff, AO, et al.. Hyperprolactinemia: new assay more specific for the monomeric form does not eliminate screening for macroprolactin with polyethylene glycol precipitation. Arq Bras Endocrinol Metabol 2010;54:856–7. in Google Scholar PubMed

32. Ellis, MJ, Reed, MR, Livesey, JH. Cross-reactivities of macroprolactin and big-prolactin in three commercial immunoassays for prolactin: a chromatographic analysis. Clin Biochem 2007;40:1285–90. in Google Scholar PubMed

33. Fahie-Wilson, M, Bieglmayer, C, Kratzsch, J, Nusbaumer, C, Roth, HJ, Zaninotto, M, et al.. Roche Elecsys Prolactin II assay: reactivity with macroprolactin compared with eight commercial assays for prolactin and determination of monomeric prolactin by precipitation with polyethylene glycol. Clin Lab 2007;53:485–92.Search in Google Scholar

34. Jeffcoate, SL, Bacon, RR, Beastall, GH, Diver, MJ, Franks, S, Seth, J. Assays for prolactin: guidelines for the provision of a clinical biochemistry service. Ann Clin Biochem 1986;23:638–51. in Google Scholar PubMed

35. Cattaneo, FA, Fahie-Wilson, MN. Concomitant occurrence of macroprolactin, exercise-induced amenorrhea, and a pituitary lesion: a diagnostic pitfall. case report. J Neurosurg 2001;95:334–7. in Google Scholar PubMed

36. Hattori, N, Adachi, T, Ishihara, T, Shimatsu, A. The natural history of macroprolactinaemia. Eur J Endocrinol 2012;166:625–9. in Google Scholar

Received: 2022-05-12
Accepted: 2022-06-02
Published Online: 2022-06-17
Published in Print: 2022-08-26

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