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JohnWBurns (@johnwburns)

Hyponatremia: Anyone else have low sodium?

Heart & Blood Health | Last Active: Jun 18, 2022 | Replies (17)

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Thanks for feeding my thought machine, Jim, but as usual, your own expertise puts you beyond any advice I could provide. I checked my recent sodium levels and found them all to be around 140 (my HMO’s target range is 135-145 right now, and I’m regularly dead-center). But that’s not lifelong with me. It’s where I’ve come to over 20 years of steadily improving medical therapy for hypertension. I’ve used a variety of diuretics, and some had to be abandoned because they left too much water in my tissues, ironically irrespective of sodium levels recorded in Chem-7 lab tests. My case may be unusual; it is essentially kidney-based, and my serum sodium levels go up at the same time as potassium levels go down pretty reliably.

Pulse rate is another matter. My natural heart rate was about 50 bpm most of my life, but jumped to as high as 90 when a-fib set in two years ago. Now it’s pretty reliably in the 65-75 bpm range while my sodium is normal and my potassium is too as a result of a potassium-sparing diuretic.

I don’t have symptoms of bradycardia — weakness or breathlessness or dizziness. Could it be that my hypertension is preventing those symptoms by having my heart work harder? What are your suspects for causing bradycardia? Something to think about for sure.

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Replies to "Thanks for feeding my thought machine, Jim, but as usual, your own expertise puts you beyond..."

You are too generous. I’m selfishly looking for ideas. But, I appreciate the kind words.
Sounds like you have a fundamentally good pump and things are under control. Your hypertension is controlled right? Otherwise I would guess that the strain would cause your heart rate to eventually augur downward as the veins and arteries stiffened. The emphasis is on guess.
I got hit with abrupt bradycardia almost 2 months ago. heart rate was always a little on the high side, 80’s, but varied with thyroid replacement. Last year I was diagnosed with mild hypertension that was deemed more critical due to the simultaneous findings of an aneurysm on my ascending aorta (small, 4.3) and a murmur traced to mild aortic stenosis. The bradycardia was and is symptomatic, fatigue, diminished exercise capacity mainly. Multiple things changed around the time it developed: much hotter weather in which I kept hiking the mesas around here, prescription of duloxetine for pain, prescription of plaquenil for Sjogren’s. Turns out that both duloxetine and plaquenil can interfere with the enzyme which clears metoprolol which I am also on, CYP2D6. Since metoprolol, and other beta blockers, are known for triggering bradycardia I thought that I had the smoking gun. But cutting out both duloxetine and plaquenil for a trail period did nothing to get the HR up. Finally the cardiologist at Mayo cut my already low dose of metoprolol in half and things improved somewhat, but not much. I have come to know that beta blockers can sometimes cause a bradycardia which does not recover after drug removal. I wish that they would have shared that sooner. So, I’m going through a vetting process and one thing that I stumbled on was mild hyponatremia. I take a thiazide so I’ll be curious to see what my blood work is on 8/11. Past sodium pre-thiazide has dipped to 137 but never cracked normal. Duloxetine is known to cause hyponatremia but stopping it didn’t matter. We’ll see. Sjogren’s can cause heart block as well, as can just plain aging.

Anyway, per that link I posted the symptoms of even mild hyponatremia are somewhat surprising, including falls and attention issues. Maybe some people are over looking a relatively pedestrian cause for their seemingly complex complaints.