What is Potassium?

The gap in potassium between the inside and the outside of a cell gives its membrane an electrical charge. Nerve and muscle cells use that charge to fire and contract, the heart among them.

Cells run a pump that pushes potassium in and sodium out, so a fault in it shows in both markers. Potassium leaves the body through the kidneys, and eGFR estimates how much filtering capacity is there to remove it, so potassium and eGFR read together separate a shift caused by intake from one caused by weaker clearance.

Diet supplies it, mainly through fruit and vegetables. Movement between blood and cells shifts it faster than diet does, driven by insulin, exercise and how acid or alkaline the blood is. The kidney does the balancing, matching what it passes out to what arrives so that the blood amount holds while intake varies.

The movement in and out of cells and the kidney's balancing both work within hours, so blood potassium stays inside a narrow band across a day of uneven eating. A yearly measurement therefore tests the balancing itself: if the kidney is clearing less, potassium rises while intake carries on as it was. This is Do Health's monitoring schedule, not a general recommendation for everyone.