Validation of urine citrate and oxalate measurement on the Roche Cobas® c502 chemistry analyzer
Bibliographic record
Abstract
Background: Evaluation of citrate and oxalate in 24-hour urine specimens can help determine the cause of stone formation which may guide treatment as well as urolithiasis prophylaxis. We validated measurement of both of these analytes in urine using third-party reagents on the Roche Cobas® c502 instrument. Methods: Patient specimens (n=41 for citrate and n=46 for oxalate) were collected in 24-hour urine containers and processed for analysis on a Roche Cobas® c502 instrument using an enzymatic method. Imprecision was determined by testing quality control (QC) material twice per day for 20 days and a patient sample five times daily for 5 days. Bias was determined by comparing results to a commercial referral laboratory. Linearity was assessed by diluting a high patient sample into five levels and measuring each level in triplicate. The limit of quantification (LoQ) was determined by diluting a patient sample and performing replicate measurement. Lastly, both refrigerated (4 ℃) and frozen (−20 ℃) stability was assessed over a 14-day period. Results: The coefficient of variation (CV) was <5.0% for QC material and patient specimens for both citrate and oxalate assays. Minimal bias was observed between results on the c502 and the reference laboratory (citrate average bias =1.5%, slope =1.043, and y-intercept =−0.094; oxalate average bias −0.467%, slope =0.934, and y-intercept =0.023). The citrate assay was linear from 0.05–4.50 mmol/L while the oxalate assay was linear from 0.11–1.17 mmol/L. The LoQ was 0.05 and <0.12 mmol/L for citrate and oxalate, respectively. Both assays demonstrated acceptable stability for 14 days at the temperatures tested. Conclusions: Validation of third-party reagents on the Roche Cobas® c502 for measurement of urinary citrate and oxalate yielded acceptable results and provided an attractive alternative for measurement of these two important urinary biomarkers.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.000 | 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 teacher head, 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".