Calcium has roles in cell signalling and skeletal structure. Dietary calcium intake and serum calcium are distinct quantities: physiological regulation means a change in one need not correspond to an equivalent change in the other.
Serum calcium is the concentration of calcium in blood serum. It can be an exposure in an observational study or Mendelian randomization, but genetically changing it need not reproduce the effect of changing dietary calcium intake.
Hypercalcaemia is an abnormally elevated serum calcium concentration. A diagnosis in medical records depends on testing and diagnostic practice, which can introduce selection bias into an observational study.
Calcium intake is the amount of calcium consumed, including food and supplements. It is an exposure that can be changed by an intervention, and should not be identified automatically with serum calcium in a causal inference analysis.
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Calcium is a chemical element with the symbol Ca and atomic number 20. In biology, calcium plays several critical roles: 1. **Structural Component**: Calcium is a major component of bones and teeth in vertebrates; it forms calcium phosphate, which provides strength and structure. 2. **Cell Signaling**: Calcium ions (Ca²⁺) act as important signaling molecules in various biological processes.