Reference intervals for circulating steroid hormones in healthy infants: a longitudinal LC-MS/MS study

Alexander S. Busch; Ljubicic Marie Lindhardt; Emmie N. Upners; Fischer Margit Bistrup; Casper P. Hagen; Christa E. Fluck; Johannsen Trine Holm; Hanne Frederiksen; Anders Juul

doi:10.1530/endoabs.118.PO57

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Endocrine Abstracts (2026) 118 PO57 | DOI: 10.1530/endoabs.118.PO57

IDSD2026 Poster Abstracts Poster Abstracts (93 abstracts)

Reference intervals for circulating steroid hormones in healthy infants: a longitudinal LC–MS/MS study

Alexander S. Busch ^1,2,3,* , Marie Lindhardt Ljubicic ^2,3,* , Emmie N. Upners ^2,3 , Margit Bistrup Fischer ^2,3 , Casper P. Hagen ^2,3 , Christa E. Flück ^4,5 , Trine Holm Johannsen ^2,3 , Hanne Frederiksen ^2,3 & Anders Juul ^2,3,6

Author affiliations

¹Department of General Pediatrics, University of Münster, Münster, Germany; ²Department of Growth and Reproduction, Copenhagen University Hospital – Rigshospitalet, Copenhagen, Denmark; ³International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark; ⁴Pediatric Endocrinology, Diabetology and Metabolism, Bern University Hospital, 3010 Bern, Switzerland; ⁵Department of BioMedical Research (DBMR), University of Bern, 3012 Bern, Switzerland; ⁶Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark. Correspondence to: [email protected]

Background: Infancy is characterized by profound endocrine adaptation, including postnatal remodeling of the adrenal cortex and transient activation of the hypothalamic–pituitary–gonadal axis during minipuberty. Although these processes are reflected in the circulating steroid metabolome, longitudinal serum data generated by liquid chromatography–tandem mass spectrometry (LC–MS/MS) remain limited.

Objective: To characterize the temporal dynamics of the serum steroid metabolome during the first year of life in healthy term infants and to establish sex- and age-specific reference curves for clinical use.

Methods: This study was embedded in the prospective COPENHAGEN Minipuberty Study and included healthy, term, singleton infants followed longitudinally during the first year of life. Serum concentrations of 16 steroid hormones were quantified by isotope dilution on-line TurboFlow LC–MS/MS in 446 samples from 189 infants (88 girls, 101 boys), collected between 5 and 485 days of age. Free testosterone was calculated using the Vermeulen equation. Age-specific reference curves were modelled using generalized additive models for location, scale and shape (GAMLSS). Repeated measures were analyzed using linear mixed-effects models, and estimated steroidogenic enzyme activities were derived from steroid ratios.

Results: The serum steroid metabolome showed marked age-dependent remodeling across infancy. Most progestins, adrenal androgen precursors, and several glucocorticoid- and mineralocorticoid-related steroids declined after birth, including progesterone, 17-hydroxyprogesterone, 17-hydroxypregnenolone, dehydroepiandrosterone sulfate, dehydroepiandrosterone, androstenedione, and aldosterone. In contrast, cortisol, corticosterone, 11-deoxycorticosterone, and 11-deoxycortisol displayed an initial rise before declining later in infancy, consistent with maturation of adrenal steroidogenesis. Sex differences were limited for most analytes, indicating broadly similar adrenal developmental patterns in girls and boys. As expected, testosterone, dihydrotestosterone, and free testosterone were significantly higher in boys, reflecting minipuberty. Estimated enzyme activities were largely comparable between sexes, although 17β-hydroxysteroid dehydrogenase and 17α-hydroxylase activities were higher in boys, whereas 5α-reductase activity was higher in girls.

Conclusions: This study provides comprehensive longitudinal LC–MS/MS-based reference data for serum steroid metabolome in healthy infants during the first year of life. These sex- and age-specific reference curves may support earlier recognition, diagnosis, and monitoring of rare disorders of steroidogenesis and improve interpretation of steroid profiles in pediatric endocrine practice.