Renal handling of phosphorus and magnesium.

The kidney is a major regulator of phosphate and magnesium levels. Phosphate reabsorption occurs primarily in the proximal tubule, driven by sodium reabsorption. Phosphate excretion is regulated by dietary adaptation and is stimulated by parathyroid hormone (PTH). Magnesium reabsorption occurs predominately in the thick ascending limb, driven by the lumen-positive voltage. Its excretion varies with many factors. Increases in extracellular volume, dietary intake, and calcium and the use of thiazide diuretics enhance magnesium excretion.