Preanalytical Influences on DPC IMMULITE 2000 Intact PTH Assays of Plasma and Serum from Dialysis Patients
Bibliographic record
Abstract
Measurement of intact parathyroid hormone (PTH) is essential to the diagnosis and management of metabolic bone disease (1), hypercalcemia, hypocalcemia (2), and renal osteodystrophy (3). The effects of specimen type, collection temperature, and storage temperature on the in vitro stability of PTH differ by method and platform (4)(5)(6)(7)(8)(9)(10). Characterization of preanalytical effects unique to each method, platform, and patient population is important to prevent potential clinical misclassification. The Diagnostics Product Corporation (DPC) IMMULITE 2000 intact PTH assay is a solid-phase two-site chemiluminescent immunoassay with a monoclonal mouse capture antibody and a polyclonal goat signal antibody conjugated to alkaline phosphatase. The effects of preanalytical factors on this assay have been partially investigated. Underfilling of EDTA-plasma tubes decreased measured PTH in samples from both healthy persons and those with chronic kidney disease (CKD) (11). Storage of SST serum samples for 3 days at room temperature decreased measured PTH in SST serum samples, an effect not seen with EDTA plasma (6). Results from EDTA plasma paradoxically increased after storage at 4 °C (12). Despite evidence that PTH is more stable in EDTA-anticoagulated specimens (5)(6)(7)(9)(10), the manufacturer describes an instability associated with EDTA-plasma samples and therefore recommends cold (2–8 °C) collection, centrifugation, and storage until analysis (13).
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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 | 0.010 | 0.026 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".