title: Positive pregnancy tests in a nongravid, premenopausal woman due to hCG beta-chain production by multiple myeloma.
abstract: Positive pregnancy test results occurred in a nongravid, premenopausal woman while she was receiving chemotherapy for multiple myeloma. We tested 2 hypotheses to account for this finding: (1) Heterophil antibodies caused positive interference in the immunoassays. (2) Genuine human chorionic gonadotropin (hCG) originated from a nonsyncytiotrophoblastic source. Paraprotein was eliminated as a source of positive interference because 3 different instruments with unique capture and signal antibodies gave similar results (83, 90, and 97 mIU/mL [83, 90, and 97 IU/L]). Human antimouse antibodies (HAMAs) were unlikely to cause positive interference because immunoreactivity was maintained after serum was treated to neutralize heterophil antibodies. Immunoassays performed after gel filtration of serum indicated that immunoreactivity was due to genuine hCG. The high-molecular-weight fraction (heterophil antibody) had 6 mIU/mL (6 IU/L) of hCG. The low-molecular-weight fraction (hCG) had 86 mIU/mL (86 IU/L) of hCG. Immunohistochemical stains revealed that myeloma cells expressed immunoreactive hCG. Hence, multiple myeloma caused positive pregnancy test results in a nongravid woman.
authors.affiliation: Department of Pathology and Laboratory Medicine, School of Medicine, University of Louisville, Louisville, KY 40292, USA.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Slone
authors.forename: Zakaria
authors.initials: Z
authors.lastname: Ahmed
authors.forename: Laurence A
authors.initials: LA
authors.lastname: Cole
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Elin
authors.forename: Alvin W
authors.initials: AW
authors.lastname: Martin
authors.forename: Roger H
authors.initials: RH
authors.lastname: Herzig
authors.forename: Geoffrey P
authors.initials: GP
authors.lastname: Herzig
authors.forename: James J
authors.initials: JJ
authors.lastname: Miller
mesh_terms: D000328:Adult; D001853:Bone Marrow / Q000378:metabolism / Q000473:pathology; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000096:biosynthesis* / Q000097:blood; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D009101:Multiple Myeloma / Q000378:metabolism*; D010950:Plasma Cells / Q000378:metabolism / Q000473:pathology; D011247:Pregnancy; D011258:Pregnancy Tests; D017697:Premenopause
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human