Serum norethisterone (NET) levels in NET-enanthate (NET-EN) injectable contraception users substantially interfere with testosterone immunoassay measurements and confound interpretation of biological outcomes
Abstract Background The progestin norethisterone (NET), which is structurally related to testosterone, and its enanthate form (NET-EN), are used in contraception in women. Oral NET has been shown to interfere with testosterone measurements by some chemiluminescence microparticle immunoassays (CMIA)....
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BMC
2025-08-01
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| Series: | Contraception and Reproductive Medicine |
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| Online Access: | https://doi.org/10.1186/s40834-025-00388-x |
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| author | Chanel Avenant Johnson Mosoko Moliki Alexis J. Bick Sigcinile Dlamini Mandisa Singata-Madliki G. Justus Hofmeyr Pai-Lien Chen Karl-Heinz Storbeck Donita J. Africander David W. Erikson Janet P. Hapgood |
| author_facet | Chanel Avenant Johnson Mosoko Moliki Alexis J. Bick Sigcinile Dlamini Mandisa Singata-Madliki G. Justus Hofmeyr Pai-Lien Chen Karl-Heinz Storbeck Donita J. Africander David W. Erikson Janet P. Hapgood |
| author_sort | Chanel Avenant |
| collection | DOAJ |
| description | Abstract Background The progestin norethisterone (NET), which is structurally related to testosterone, and its enanthate form (NET-EN), are used in contraception in women. Oral NET has been shown to interfere with testosterone measurements by some chemiluminescence microparticle immunoassays (CMIA). However, whether serum NET in NET-EN users interferes with these assays is unknown. Methods Serum samples were obtained from women randomized to the injectable contraceptives NET-EN or depo medroxyprogesterone acetate intramuscular (DMPA-IM) in a clinical trial conducted in South Africa. Testosterone concentrations were compared after measurement by Abbott Architect CMIA and ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), from matched samples collected at baseline (D0) and 25 weeks (25W) after initiation. Results At 25W, testosterone concentrations in the NET-EN arm were significantly higher (271%) using the CMIA compared to the UHPLC-MS/MS method. Contrary to the UHPLC-MS/MS results showing a significant decrease in testosterone concentrations in the NET-EN arm from D0 to 25W, a significant increase was determined by CMIA. Conversely, in the DMPA-IM arm at 25W, no significant difference in testosterone concentrations between the two methods was detected, and both methods showed a significant decrease in testosterone from D0 to 25W. Conclusions We show for the first time that physiological concentrations of NET in premenopausal NET-EN users interfere with testosterone quantification using a CMIA method. The degree of interference is much higher and occurs at lower concentrations of NET than has previously been reported for oral NET and confounds the biological outcome of NET-EN use on testosterone concentrations, individually and relative to DMPA-IM. Trial registration The WHICH trial was retrospectively registered with the Pan African Clinical Trials Registry (PACTR 202009758229976). |
| format | Article |
| id | doaj-art-56e44df6ee3b47a2b1667beb14007b2a |
| institution | Kabale University |
| issn | 2055-7426 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | BMC |
| record_format | Article |
| series | Contraception and Reproductive Medicine |
| spelling | doaj-art-56e44df6ee3b47a2b1667beb14007b2a2025-08-24T11:56:15ZengBMCContraception and Reproductive Medicine2055-74262025-08-0110111110.1186/s40834-025-00388-xSerum norethisterone (NET) levels in NET-enanthate (NET-EN) injectable contraception users substantially interfere with testosterone immunoassay measurements and confound interpretation of biological outcomesChanel Avenant0Johnson Mosoko Moliki1Alexis J. Bick2Sigcinile Dlamini3Mandisa Singata-Madliki4G. Justus Hofmeyr5Pai-Lien Chen6Karl-Heinz Storbeck7Donita J. Africander8David W. Erikson9Janet P. Hapgood10Department of Molecular and Cell Biology, University of Cape TownDepartment of Molecular and Cell Biology, University of Cape TownDepartment of Molecular and Cell Biology, University of Cape TownDepartment of Molecular and Cell Biology, University of Cape TownEffective Care Research Unit, Eastern Cape Department of Health/Universities of the Witwatersrand and Fort HareEffective Care Research Unit, Eastern Cape Department of Health/Universities of the Witwatersrand and Fort HareFamily Health International (FHI) 360Department of Biochemistry, Stellenbosch UniversityDepartment of Biochemistry, Stellenbosch UniversityEndocrine Technologies Core, Oregon National Primate Research Center, Oregon Health and Science UniversityDepartment of Molecular and Cell Biology, University of Cape TownAbstract Background The progestin norethisterone (NET), which is structurally related to testosterone, and its enanthate form (NET-EN), are used in contraception in women. Oral NET has been shown to interfere with testosterone measurements by some chemiluminescence microparticle immunoassays (CMIA). However, whether serum NET in NET-EN users interferes with these assays is unknown. Methods Serum samples were obtained from women randomized to the injectable contraceptives NET-EN or depo medroxyprogesterone acetate intramuscular (DMPA-IM) in a clinical trial conducted in South Africa. Testosterone concentrations were compared after measurement by Abbott Architect CMIA and ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), from matched samples collected at baseline (D0) and 25 weeks (25W) after initiation. Results At 25W, testosterone concentrations in the NET-EN arm were significantly higher (271%) using the CMIA compared to the UHPLC-MS/MS method. Contrary to the UHPLC-MS/MS results showing a significant decrease in testosterone concentrations in the NET-EN arm from D0 to 25W, a significant increase was determined by CMIA. Conversely, in the DMPA-IM arm at 25W, no significant difference in testosterone concentrations between the two methods was detected, and both methods showed a significant decrease in testosterone from D0 to 25W. Conclusions We show for the first time that physiological concentrations of NET in premenopausal NET-EN users interfere with testosterone quantification using a CMIA method. The degree of interference is much higher and occurs at lower concentrations of NET than has previously been reported for oral NET and confounds the biological outcome of NET-EN use on testosterone concentrations, individually and relative to DMPA-IM. Trial registration The WHICH trial was retrospectively registered with the Pan African Clinical Trials Registry (PACTR 202009758229976).https://doi.org/10.1186/s40834-025-00388-xNorethisterone enanthate (NET-EN)Depo medroxyprogesterone acetate intramuscular (DMPA-IM)TestosteroneTestosterone quantificationChemiluminescent microparticle immunoassay (CMIA)Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) |
| spellingShingle | Chanel Avenant Johnson Mosoko Moliki Alexis J. Bick Sigcinile Dlamini Mandisa Singata-Madliki G. Justus Hofmeyr Pai-Lien Chen Karl-Heinz Storbeck Donita J. Africander David W. Erikson Janet P. Hapgood Serum norethisterone (NET) levels in NET-enanthate (NET-EN) injectable contraception users substantially interfere with testosterone immunoassay measurements and confound interpretation of biological outcomes Contraception and Reproductive Medicine Norethisterone enanthate (NET-EN) Depo medroxyprogesterone acetate intramuscular (DMPA-IM) Testosterone Testosterone quantification Chemiluminescent microparticle immunoassay (CMIA) Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) |
| title | Serum norethisterone (NET) levels in NET-enanthate (NET-EN) injectable contraception users substantially interfere with testosterone immunoassay measurements and confound interpretation of biological outcomes |
| title_full | Serum norethisterone (NET) levels in NET-enanthate (NET-EN) injectable contraception users substantially interfere with testosterone immunoassay measurements and confound interpretation of biological outcomes |
| title_fullStr | Serum norethisterone (NET) levels in NET-enanthate (NET-EN) injectable contraception users substantially interfere with testosterone immunoassay measurements and confound interpretation of biological outcomes |
| title_full_unstemmed | Serum norethisterone (NET) levels in NET-enanthate (NET-EN) injectable contraception users substantially interfere with testosterone immunoassay measurements and confound interpretation of biological outcomes |
| title_short | Serum norethisterone (NET) levels in NET-enanthate (NET-EN) injectable contraception users substantially interfere with testosterone immunoassay measurements and confound interpretation of biological outcomes |
| title_sort | serum norethisterone net levels in net enanthate net en injectable contraception users substantially interfere with testosterone immunoassay measurements and confound interpretation of biological outcomes |
| topic | Norethisterone enanthate (NET-EN) Depo medroxyprogesterone acetate intramuscular (DMPA-IM) Testosterone Testosterone quantification Chemiluminescent microparticle immunoassay (CMIA) Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) |
| url | https://doi.org/10.1186/s40834-025-00388-x |
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