title: A Case With Immunoassay Interferences in the Measurement of Multiple Hormones.
abstract: BACKGROUND
  Commonly used immunoassays are not free from interference, which can be a confounder in the interpretation of test results. We present a case with extremely high multiple hormone levels due to such interference.
  
  
  METHODS
  A 33-year-old woman with no specific symptoms had markedly elevated TSH with normal free T4 and free T3 levels. Repeated measurements revealed discordantly high TSH, ACTH, FSH, PTH, IGF-1, prolactin, β-human chorionic gonadotropin, and calcitonin levels without the associated clinical pictures. The measurements were repeated with the same patient sample on four different analytical platforms using chemiluminescence immunoassays/electrochemiluminescence immunoassays, and the results were divergent on each platform. Serial dilutions of serum samples revealed nonlinearity, suggesting assay interference. All hormonal measurements were in the normal range when heterophile antibody blocking tubes were used. The serum of the patient was then subjected to polyethylene glycol precipitation. The post-polyethylene glycol recovery resulted in hormone levels in the normal range. The patient did not receive any medications and has been under follow-up without any signs and symptoms for 24 months.
  
  
  CONCLUSIONS
  This report illustrates a rare case of falsely elevated hormone levels due to assay interference caused by heterophile antibodies. We point out the importance of a close collaboration between clinicians and the laboratory to avoid unnecessary clinical investigations as well as inappropriate treatments.
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Ozlem
authors.initials: O
authors.lastname: Gulbahar
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Ceyla
authors.initials: C
authors.lastname: Konca Degertekin
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Mujde
authors.initials: M
authors.lastname: Akturk
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Mehmet Muhittin
authors.initials: MM
authors.lastname: Yalcin
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Isilay
authors.initials: I
authors.lastname: Kalan
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Gokce Filiz
authors.initials: GF
authors.lastname: Atikeler
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Alev Eroglu
authors.initials: AE
authors.lastname: Altinova
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Ilhan
authors.initials: I
authors.lastname: Yetkin
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Metin
authors.initials: M
authors.lastname: Arslan
authors.affiliation: Departments of Biochemistry (O.G., G.F.A.) and Endocrinology and Metabolism (C.K.D., M.A., M.M.Y., I.K., A.E.A., I.Y., M.A., F.T.), Gazi University Faculty of Medicine, 06100 Ankara, Turkey.
authors.forename: Fusun
authors.initials: F
authors.lastname: Toruner
mesh_terms: D000328:Adult; D000910:Antibodies, Heterophile / Q000097:blood*; D016477:Artifacts; D003429:Cross Reactions; D003940:Diagnostic Techniques, Endocrine / Q000592:standards; D005189:False Positive Reactions; D005260:Female; D006728:Hormones / Q000032:analysis*; D006801:Humans; D007118:Immunoassay / Q000379:methods; D049590:Postpartum Period / Q000097:blood / Q000276:immunology
chemical_list: D000910:Antibodies, Heterophile; D006728:Hormones