I’m currently on holiday in Sicily. It’s ridiculously hot, and despite promising myself I’d switch off, I’ve discovered something that many ADHD clinicians (and probably many people with ADHD) are familiar with: I can still get a bit addicted to work, even on holiday.
So instead of reading my novel, I found myself going down a rabbit hole about POTS, salt, hydration, and emotional dysregulation.
One of the most common pieces of advice given to people with POTS is to “drink more water”. It’s good advice, but it’s often incomplete.
What caught my attention was the evidence suggesting that sodium may be doing much of the heavy lifting.
POTS is associated with reduced effective circulating blood volume. Water alone doesn’t necessarily correct that. Without enough sodium, much of what we drink is simply excreted. Sodium helps retain fluid within the circulation and supports blood volume when we’re upright.
The more interesting finding, though, was the link between low sodium and the nervous system.
Studies have shown that hyponatraemia is associated with increased sympathetic nervous system activity. In simple terms, the body’s fight-or-flight system becomes more active. Even more intriguing, animal studies suggest that chronic low sodium can affect brain chemistry within the amygdala, increasing anxiety-like behaviours and emotional reactivity, with these changes improving when sodium levels are corrected.
That immediately made me think about some of the patients I see who describe a combination of orthostatic symptoms, brain fog, anxiety, emotional overwhelm, and fatigue. We often think about these symptoms separately when perhaps they’re sometimes more connected than we realise.
There is also good clinical evidence that increasing sodium intake in POTS can improve blood volume, reduce standing heart rate, and improve orthostatic tolerance.
The takeaway isn’t that everyone should start taking large amounts of salt. Clearly that isn’t appropriate for people with hypertension, heart disease, kidney disease, and some other conditions.
Rather, it reminded me that when someone with POTS tells me they’re drinking litres of water and still feeling dreadful, the next question may not be “How much are you drinking?” but “How much sodium are you getting?”
Sometimes the issue isn’t hydration.
It’s whether your body can hold on to the fluid you’re drinking.
Now, if you’ll excuse me, I’m going to attempt something radical and return to being on holiday.
Educational content only and not individual medical advice.