Abstract

Calcium (Ca2+) and magnesium (Mg2+) are essential divalent cations whose homeostasis is essential for cardiovascular, muscular and metabolic function. Absolute or relative imbalances between Ca and Mg can lead to cardiovascular, metabolic and neurological pathologies. Ionized calcium (Ca2+) is a biologically active fraction of plasma calcium that is tightly regulated by protein binding, phosphate complexation, magnesium modulation and acid–base status. Ionized calcium plays a central role in multiple physiological processes and is strongly influenced by plasma pH, phosphate concentration and magnesium levels. However, the combined effects of these parameters are difficult to evaluate intuitively because of their nonlinear interactions. In this study, a numerical simulation framework was used to explore how simultaneous variations in pH, phosphate and magnesium may influence ionized calcium under typical physiological plasma conditions as a phenomenological framework linking ionic equilibrium with viscosity-dependent flow parameters under well-mixed plasma conditions. The simulations reveal phenomenological changes in which concurrent increases in pH and phosphate or reductions in magnesium produce disproportionately large decreases in ionized calcium. Within the physiological ranges examined, the results also indicate a region of relative stability for ionized calcium corresponding to Ca/Mg ratios close to 3, while this value should be interpreted as an emergent feature of the modeled parameter space rather than a universal physiological constant. These findings illustrate the importance of considering multiple electrolyte interactions simultaneously when evaluating calcium homeostasis and may provide a conceptual framework for further experimental investigation.

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