FP306PRIOR DIETARY PHOSPHATE EXPOSURE ALTERS THE HORMONAL AND URINARY REPONSE TO AN ORAL PHOSPHATE LOAD IN HEALTHY YOUNG ADULTS
Bibliographic record
Abstract
INTRODUCTION AND AIMS: Dysregulated phosphate metabolism is a risk factor for CVD-related events and mortality in the general population, and becomes particularly evident as kidney function declines. However, circulating phosphate rarely increases above the normal range until GFR is <30mL/min. The excretion profile of phosphate following an oral load and the hormonal response to the challenge reveals impaired excretion in the absence of elevated serum phosphate. Several long-term (vitamin D, fibroblast growth factor 23 (FGF-23)) and short term (parathyroid hormone (PTH)) factors regulate phosphate absorption and urinary excretion. The objective of this study was to determine the impact of dietary phosphate modification on the acute hormonal response and urinary excretion profile of an oral phosphate challenge in healthy individuals. METHODS: In each cycle of this randomized cross-over study, participants (N=15) either consumed a dietician-designed low-phosphorus (LP) diet (750 mg) containing 1500 mg calcium, or the diet plus a 1250 mg phosphorus supplement (HP) for five days. On the sixth morning, fasted participants consumed a 500 mg oral phosphorus challenge. Levels of phosphate, calcium, magnesium, PTH, vitamin D metabolites and FGF-23 were measured in blood samples at baseline and hourly for 3 hours. Phosphate, calcium, magnesium and the fractional excretion of each mineral was assessed in the urine at baseline and for 3 hours following the oral challenge. RESULTS: The mean age of the participants was 23.3±2.5 years, 64% (N=9) were female, and the mean creatinine was 76.5±12.1. During the HP cycle, the 24-hour urine excretion of phosphate increased from 21.5±10.8 to 49.9±14.2 mmol/day (p<0.0001). At baseline, paired analysis revealed FGF-23 (55.2±41.3 vs 63.7±38.8 pg/mL, p<0.01) and PTH (3.8±1.2 vs 4.6±1.5 pmol/L, p<0.05) to be significantly elevated with the HP diet whereas circulating calcium, phosphate and magnesium were similar. Fractional excretion (FE) of phosphate and urinary phosphate-to-creatinine ratio were significantly higher at baseline in response to HP, whereas the FE of calcium and urinary calcium to creatinine ratio did not change. Various vitamin D metabolites were not altered by the phosphate diet, however, the 25-OH-D3:24,25-D3 ratio was decreased significantly with the HP diet (16.9±4.9 vs 14.6±2.7 ng/mL, p<0.05).Following the oral challenge, serum phosphate increased similarly in both diet conditions at 1 hour (+0.15mM, p<0.001) and returned to baseline by 2 and 3 hours. Following the LP diet, there were no differences in PTH whilst fractional excretion of phosphate was significantly increased over baseline at 2 and 3 hours. In contrast, while on the HP diet, PTH decreased significantly from baseline at 1 and 2 hours following the phosphate challenge (-0.7 and 1.1 pmol/L, p<0.05) and FE of phosphate was significantly decreased from baseline at 1 hour. CONCLUSIONS: In healthy people, a chronic high dietary intake of phosphate, while increasing resting fractional excretion, appears to blunt the acute hormonal and functional response to an oral phosphate challenge. The dietary level of phosphate appears to be an important regulator of the hormonal response and urinary excretion of a defined phosphate load. Detection of early onset of phosphate intolerance in otherwise healthy individuals may be early indicator of CVD risk.
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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 | 0.000 |
| 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) | 0.003 | 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".