Managing electrolytes

Hydration is really an electrolyte question, not a water question. Plain water passes through quickly; what keeps fluid in your bloodstream — and keeps your nerves and heart steady — is the balance of the salts dissolved in it. “Managing electrolytes” is a more accurate goal than “loading salt.”

The cast, and what each one does

• Sodium — the main volume lever. It holds water in the bloodstream, which is why it eases standing symptoms in POTS and counters low blood volume. It is the electrolyte most often increased in POTS — but also the one most often restricted for heart, kidney, or blood-pressure reasons. It cuts both ways.
• Potassium — sodium’s partner. The two work in balance to run nerve signals and a steady heartbeat. fludrocortisone and some diuretics lower potassium (so it is monitored on those), while kidney disease can let it rise too high — which is dangerous. Potassium is not something to supplement on your own.
• Magnesium — supports nerve conduction, muscle and vascular tone, and sleep, and often runs low; it is frequently relevant alongside mast cell activation and migraine. Like potassium, it can accumulate in kidney disease, so it also belongs in a monitored plan rather than open-ended self-dosing.
• Chloride and bicarbonate — travel with sodium and potassium and keep your acid–base balance steady. They are usually managed indirectly rather than targeted on their own.

Why balance beats loading any single one

Because sodium and potassium operate as a pair, pushing one hard while ignoring the other can backfire — and flooding the system with plain water can dilute sodium to dangerous lows (hyponatremia). This is exactly why a blanket “add more salt” is too blunt: the target is the right balance for your body and your other conditions, not the maximum of any single ion.

Getting fluid to actually absorb

There is a reason sipping plain water can feel like it goes straight through you. The gut absorbs sodium and water fastest through a shared doorway — the sodium–glucose cotransporter (SGLT1) — where a small amount of glucose pulls sodium across the gut wall, and water follows. That is the principle behind oral rehydration solution (ORS): a balance of sodium, a little glucose, and potassium (osmolarity around 250–310 mOsm/kg) that can rival intravenous saline for raising blood volume in some people with POTS.⁴

It also means commercial drinks vary enormously. Many sports drinks are low in sodium and high in sugar; “hydration” tablets differ widely; ORS-style mixes are built for volume. Sodium is the number that matters most for this purpose — and the one you and your team can dial to fit your limits.

When sodium must be limited

Salt loading is the usual companion to fluids, but it is not universally safe. If you have high blood pressure, heart failure, kidney disease, or a medication or condition that already makes you retain fluid — or any other reason to limit sodium — then “just add more salt” is the wrong default for you, and that deserves to be said plainly. It is a real and common tension: the advice that helps orthostatic symptoms can collide with the advice that protects your heart or kidneys.

The reassuring part is that the goal — keeping enough volume in the circulation — does not depend on salt loading alone. What changes is the route:

• Manage the whole panel, not just sodium, with your clinical team — especially when conditions or medications pull in different directions.
• Choose fluids and any rehydration products with your team, so they fit your sodium limits instead of ignoring them.
• Lean on the salt-free volume tools. Compression garments and midodrine improve standing tolerance without adding any dietary salt; fludrocortisone raises volume through the kidneys but shifts sodium and potassium, so it is used under monitoring.

Monitoring, and individualizing with your team

Electrolytes are measurable. A simple blood panel (a basic metabolic panel, or U&Es) checks sodium, potassium, and kidney function, and it matters most when you are on fludrocortisone or a diuretic, or when kidney or heart disease is in the picture. The right targets are individual and can shift over time, so this is something to steer with your clinicians rather than chase on your own. Symptoms worth flagging promptly include worsening headache, nausea, or confusion (which can signal low sodium) and new palpitations or muscle weakness (which can signal a potassium problem).