Seasonal Variance in Serum Levels of Vitamin D Determines a Compensatory Response by Parathyroid Hormone: Study in an Ambulatory Elderly Population in Quebec
Bibliographic record
Abstract
BACKGROUND: Although the seasonal variance in serum levels of vitamin D in the elderly is well known, its significance on parathyroid hormone (PTH) remains controversial. OBJECTIVE: To identify the variability and correlation between serum levels of vitamin D and PTH in a sample of community-dwelling elderly patients in the Province of Quebec, Canada, where vitamin D and calcium are supplemented in the food. METHODS: Cross-sectional study in an ambulatory elderly population in the Province of Quebec. Samples were analyzed at the Metabolic and Calcium Research Centre, Royal Victoria Hospital, Montreal, Quebec. 256 healthy men and women aged 65-94 (mean age +/- SD: 72.8 +/- 5.6) were analyzed. Serum levels of 25-hydroxyvitamin D (25(OH)D3) and PTH were determined between 1994 and 1999 using commercial radioimmunoassay kits to measure calciotropic hormones. We examined data in different seasons of the year and observed the behavior of the data through time. A cut-off level of 25 nmol/l for 25(OH)D3 was established to define vitamin D deficiency. A correlation between vitamin D levels vs. PTH levels was also obtained. RESULTS: There is a predominance of females with a 75% of the population. Among them, 32% showed levels of vitamin D <20 nmol/l as compared to 51% of the male population (p < 0.02). A seasonal variance in the levels of vitamin D was observed with the lower levels happening in early spring with a recovery at the end of the summer (p < 0.004). These low levels of vitamin D corresponded with an inverse pattern in the levels of PTH more importantly in early spring. CONCLUSION: This study not only confirms previous reports that despite vitamin D food supplementation a vitamin D deficiency is still a finding in elderly population in the Northern hemisphere, but also that a compensatory change in PTH levels concurrently occurs with a potential significance on bone strength and risk of fractures.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".