Determination of urinary norandrosterone excretion in females during one menstrual cycle by gas chromatography/mass spectrometry
Bibliographic record
Abstract
Conjugated norandrosterone is the main urinary metabolite of anabolic steroids like nandrolone, norandrostenedione and norandrostenediol. Nandrolone traces of endogenous origin have been identified in human follicular fluid, and further investigations revealed urinary excretion of norandrosterone in pregnant and non-pregnant females and even males. A threshold level for the norandrosterone concentration in urine has been established when controlling the administration of prohibited nandrolone or its precursors in human doping control. This level has been set to 2 ng/mL for males and females. To investigate the excretion of conjugated norandrosterone in females more systematically, we collected daily urine samples from 12 female volunteers during a whole menstrual cycle. These samples were analysed for norandrosterone down to a limit of quantification and identification of 0.05 ng/mL (180 pmol/L). The results clearly show that all the volunteers excreted norandrosterone glucuronide in a characteristic pattern during one menstrual cycle. Concentrations in urine were considerably lower at the beginning of the follicular and the end of the luteal phases than midcyclic. Peak concentrations up to 0.8 ng/mL (2.9 nmol/L) were recorded and they were three to four times higher than the values at the beginning and end of the cycle. The time of the peak concentration was clearly related to the increased excretion of luteinizing hormone. These results strongly support the possibility of endogenous nandrolone production as a side reaction to enzymatic aromatisation. However, a threshold value of 2 ng/mL for reporting adversed findings in doping control of females was never reached in any of the samples.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".