Biology of calcium homeostasis regulation in intestine and kidney
Bibliographic record
Abstract
Calcium (Ca2+) is an essential divalent cation involved in many bodily functions including bone composition, cell growth and division, blood clotting, and muscle contraction. The bone, intestine and kidneys are important for the maintenance of Ca2+ homeostasis. Ninety-nine percent of body Ca2+ is stored in the skeleton as hydroxyapatite. The small, and to a lesser extent the large intestine absorbs Ca2+ from the diet. Once in the circulation, Ca2+ is filtered by the glomerulus and the majority, >95%, is reabsorbed along the nephron. The remainder is excreted in the urine. Two general (re)absorptive pathways contribute to the vectorial transport of Ca2+ across renal and intestinal epithelia: (i) a paracellular pathway, which is reliant on claudins in the tight junction of epithelium and the electrochemical gradient, and (ii) a transcellular pathway, which requires different influx, intracellular buffering/shuttling and basolateral efflux mechanisms, to actively transport Ca2+ across the epithelial cell. Blood Ca2+ levels are maintained by hormones including parathyroid hormone, 1,25-dihydroxyvitamin D3 and fibroblast growth factor 23, and through effects of Ca2+-sensing receptor (CaSR) signaling. Disruption of Ca2+ homeostasis can result in altered blood Ca2+ levels and/or hypercalciuria, the latter is a phenomenon closely linked to the formation of kidney stones. Genetic alterations affecting renal Ca2+ handling can cause hypercalciuria, an area of expanding investigation. This review explores the molecular mechanisms governing Ca2+ homeostasis by the intestine and kidneys and discusses clinical aspects of genetic disorders associated with Ca2+-based kidney stone disease.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".