Central vs. Peripheral Access Samplings in Patients on Hemodialysis Induce Variations in Parathyroid Hormone Levels
Bibliographic record
Abstract
Background: Parathyroid hormone (PTH) levels are routinely measured in dialysis patients, but international guidelines do not specify the optimal site from which PTH should be drawn. Previous findings suggest that centrally drawn PTH may significantly vary from peripherally sampled PTH1. This study aimed to compare PTH levels drawn from central venous catheters (C-PTH), peripheral veins (P-PTH) and arteriovenous fistula (AVF-PTH) in hemodialysis patients. Methods: C-PTH, P-PTH and/or AVF-PTH were simultaneously measured in hemodialysis patients at the CHU de Québec (cohort A) and CISSS Chaudières-Appalaches (cohort B) in Canada from January 1st to February 28th, 2024. Architect Intact PTHTM (Abbott, normal range 25 to 115 ng/L) was used in cohort A and IMMULITE Intact PTHTM (Siemens, normal range 20 to 100 ng/L) in cohort B. Demographic data were collected and mineral biochemistry were measured according to local standard. PTH levels were classified as “on target” according to sampling site if they were between two and nine times the upper limit of normal. Results: Cohort A included 69 hemodialysis patients (mean age 69 ± 13 years, dialysis vintage 69 ± 13 months, 86% with a central venous catheter). Mean C-PTH, P-PTH and AVF-PTH were respectively 546 ± 309 ng/L, 409 ± 227 ng/L and 533 ± 325 ng/L. Classification of PTH levels being “on target” were different between C-PTH and P-PTH in 29% of patients. Cohort B included 50 hemodialysis patients (mean age 67 ± 13 years, dialysis vintage 50 ± 60 months, 54% with a central venous catheter). Mean C-PTH, P-PTH and AVF-PTH were respectively 357 ± 264 ng/L, 352 ± 236 ng/L and 475 ± 255 ng/L. Similarly to cohort A, “on target” PTH levels were different between C-PTH and P-PTH in 18.3% of patients. Conclusion: Our results suggest that sites of sampling may influence PTH levels and could impact the treatment of hyperparathyroidism in hemodialysis patient. Standardization of sampling site should therefore be recommended. 1-Vulpio C, et al. Influence of blood sampling site on intact parathyroid hormone concentrations in hemodialysis patients. Clin Chem. 2010;56(3):489-90. Funding: Government Support – Non-U.S.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 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 | 0.001 |
| 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 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".