Total Daily Production and Periodicity of Melatonin Metabolite in Critically Ill Children*
Bibliographic record
Abstract
OBJECTIVES: To determine whether total daily 6-sulfatoxymelatonin excretion and diurnal variation of melatonin secretion was maintained during the early phase of PICU admission through examination of the melatonin urinary metabolite, 6-sulfatoxymelatonin. DESIGN: Exploratory prospective, observational study. SETTING: Twelve-bed medical-surgical PICU of a Children's Hospital. PATIENTS: Fifty children 3 months to 18 years old enrolled within 24 hours of PICU admission with access for urinary sampling. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Urine samples were collected at 4-hour intervals for 24 hours and stored at -80C. 6-sulfatoxymelatonin was determined in duplicate by direct enzyme-linked immunosorbent assay. Patients were heterogeneous for diagnosis, had a mean age of 8.1 years (SD = 6.1 yr), and median (interquartile range) Pediatric Risk of Mortality III of 10 (4-13). Mean (SD) total daily 6-sulfatoxymelatonin production was 30.0 µg (25.6 µg) for the first 24 hours, which did not differ significantly from the means on days 2 (p = 0.56) or 3 (p = 0.29), and was similar to literature controls. Mean 6-sulfatoxymelatonin production for the population fit a periodic function well, with a reliable amplitude of 326 ng/hr and peak excretion from 04:00 to 08:00 (F = 4.4, p = 0.01), even when 6-sulfatoxymelatonin was corrected for body weight (F = 3.4, p = 0.03) and when sedation was included in the model (F = 3.95, p = 0.004). There was no significant correlation between lighting and 6-sulfatoxymelatonin excretion at any time period (R values: 0.11-0.25, p = 0.10-0.94). Mean 6-sulfatoxymelatonin excretion did not fit the model for a periodic function well for the subpopulations studied (sepsis [n = 18, F = 1.1, p = 0.32], respiratory failure requiring deep sedation [n = 10, F = 0.4, p = 0.66], and neurologic injury [n = 7, F = 0.6, p = 0.55]). CONCLUSIONS: Total daily and diurnal variation of 6-sulfatoxymelatonin excretion is heterogeneously maintained early in pediatric critical illness. However, this may not hold true for specific diagnostic categories.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| 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".