The diagnostic efficacy of urinary fractionated metanephrines measured by tandem mass spectrometry in detection of pheochromocytoma
Bibliographic record
Abstract
BACKGROUND: There are limitations to currently available biochemical tests for pheochromocytoma. Our objective was to evaluate the diagnostic efficacy of a novel tandem mass spectrometry assay for the measurement of fractionated urinary metanephrines in patients suspected to have a pheochromocytoma. We also developed clinically based cut-offs for positivity of this measurement. METHODS: We examined the medical records of 506 patients (including 102 patients with a catecholamine-producing tumour) who underwent measurement of 24-h urinary fractionated metanephrines using tandem mass spectrometry as well as adrenal imaging at Mayo Clinic, Rochester. The cut-offs for positivity were defined as follows: total metanephrines (sum of the metanephrine fractions) 5163 nmol/day, normetanephrine fraction 4001 nmol/day, metanephrine fraction 1531 nmol/day. Receiver operating characteristic (ROC) curves were constructed. RESULTS: The diagnostic efficacy was as follows: normetanephrine fraction sensitivity 87.3% [(95% confidence interval (CI) 79.4-92.4%], specificity 95.0% (92.5-96.8); metanephrine fraction sensitivity 56.9% (47.2-66.1), specificity 95.0% (92.5-96.8); elevation of either normetanephrine or metanephrine fraction sensitivity 97.1% (91.7-99.0) and specificity 91.1% (87.9-93.5). Areas under the ROC curves (AUCs) were 0.972 (95% CI 0.955-0.990) for the normetanephrine fraction, 0.800 (0.741-0.858) for the metanephrine fraction, 0.991 (0.985-0.996) for total metanephrines, and 0.991 (0.985-0.996) for a regression-derived ROC curve incorporating both the metanephrine and normetanephrine fractions. CONCLUSION: Measurement of 24-h urinary fractionated metanephrines by a tandem mass spectrometry assay appears to be an effective biochemical technique in the investigation of pheochromocytoma.
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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 | 0.007 | 0.022 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".