Objective Urinary steroid metabolomics by GC-MS is an established method in both clinical and research settings to describe steroidogenic disorders. However, population-based reference intervals for adults do not exist. Methods We measured daytime and night time urinary excretion of 40 steroid metabolites by GC-MS in 1128 adult participants of European ancestry, aged 18 to 90 years, within a large population-based, multicentric, cross-sectional study. Age and sex-related patterns in adjacent daytime and night time urine collections over 24 hours were modelled for each steroid metabolite by multivariable linear mixed regression. We compared our results with those obtained through a systematic literature review on reference intervals of urinary steroid excretion. Results Flexible models were created for all urinary steroid metabolites thereby estimating sex- and age-related changes of the urinary steroid metabolome. Most urinary steroid metabolites showed an age-dependence with the exception of 6β-OH-cortisol, 18-OH-cortisol, and β-cortol. Reference intervals for all metabolites excreted during 24 hours were derived from the 2.5 th and 97.5 th percentile of modelled reference curves. The excretion rate per period of metabolites predominantly derived from the adrenals was mainly higher during the day than at night and the correlation between day and night time metabolite excretion was highly positive for most androgens and moderately positive for glucocorticoids. Conclusions This study gives unprecedented new insights into sex- and age-specificity of the human adult steroid metabolome and provides further information on the day/night variation of urinary steroid hormone excretion. The population-based reference ranges for 40 GC-MS-measured metabolites will facilitate the interpretation of steroid profiles in clinical practice.

during minipuberty favors the backdoor pathway over the classic pathway: insights into enzyme activities and steroid fluxes in healthy infants during the first year of life from the urinary steroid metabolome, Journal of Steroid Biochemistry and Molecular Biology http://dx.doi.org/10. 1016/j.jsbmb.2016.07.009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights-Male androgen biosynthesis shows a significant peak at week 7 during minipuberty -Androgens in minipuberty are (at least in part) produced through the backdoor pathway -Steroid enzyme activities in the first year of life are all age-, some sex-specific -Steroid enzyme ratios obtained from urine GC-MS are comparable between laboratories AbstractThe steroid profile changes dramatically from prenatal to postnatal life. Recently, a novel backdoor pathway for androgen biosynthesis has been discovered. However, its role remains elusive. Therefore, we investigated androgen production from birth to one year of life with a focus on minipuberty and on production of androgens through the backdoor pathway. Additionally, we assessed the development of the specific steroid enzyme activities in early life. To do so, we collected urine specimens from diapers in 43 healthy newborns (22 females) at 13 time points from birth to one year of age in an ambulatory setting, and performed in house GC/MS steroid profiling for 67 steroid metabolites. Data were analyzed for androgen production through the classic and backdoor pathway and calculations of diagnostic ratios for steroid enzyme activities were performed. Analysis revealed that during minipuberty androgen production is much higher in boys than in girls (e.g. androsterone (An)), originates largely from the testis (An boysAn girls ), and uses predominantly the alternative backdoor pathway (An/Et; Δ5<Δ4 lyase activity).Modelling of steroid enzyme activities showed age-related effects for 21-, 11-, 17-hydroxylase and P450 oxidoreductase activities as well as 3β-hydroxysteroid dehydrogenase, 11β-hydroxylase type 1/2 and 5α-reductase activities. Sex-related characteristics were found for 21-hydroxylase and 5α-reductase activities.Overall, our study shows that androgen biosynthesis during minipuberty favors the backdoor pathway over the classic pathway. Calculations of specific diagnostic ratios for enzyme activities seem to allow the diagnosis of specific steroid disorders from the urinary steroid metabolome.

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