Potassium keeps the heart's electrical system working. When it rises too high, the heart can stop — sometimes with no warning symptoms beforehand.
A potassium of 7.0 in a patient who feels completely well is an emergency.
"Stop eating bananas" is not a diagnosis
It is what most patients are told, and it is almost never the reason.
Diet does not cause hyperkalemia in a kidney that can excrete potassium. A person with normal kidneys can eat an enormous potassium load and clear it without difficulty. The number rises when something is preventing excretion — and that something is what nobody looks for.
So the real question is never what did you eat. It is why is your body not getting rid of it.
Urinary obstruction is the answer that gets missed. A bladder that does not empty. An enlarged prostate. A neurogenic bladder in a long-standing diabetic. Obstruction impairs the distal tubule's ability to secrete potassium, and the potassium climbs while the creatinine may look almost normal. It is found with a post-void residual and an ultrasound, and it is not found by asking about bananas.
Medications are the other common answer — and the ones most often blamed are frequently the ones that should stay.
Type 4 renal tubular acidosis, common in diabetes, impairs potassium excretion specifically. Adrenal insufficiency. Metabolic acidosis, which drives potassium out of cells.
If your potassium is high and nobody has looked at your bladder, your medications, or your acid-base status, the cause has not been established.
Board-certified nephrology at Remix Medical in Houston. Call (713) 597-5131 or book online.
The medication bind
The drugs that protect kidneys — ACE inhibitors, ARBs, spironolactone, finerenone — all raise potassium. They are also the drugs that slow progression and reduce cardiovascular death.
So the potassium rises, and someone stops the ACE inhibitor. The patient loses the medication extending the life of their kidney, in order to fix a number.
That trade is usually unnecessary. Potassium binders — patiromer and sodium zirconium cyclosilicate — lower potassium reliably and let these drugs continue at full dose. The older binder, sodium polystyrene sulfonate, is poorly tolerated and of questionable benefit.
Keeping a patient on kidney-protective therapy by managing the potassium around it is among the more valuable things a nephrologist does, and it happens far less often than it should.
But note the order. The binder is not a substitute for finding the cause. A patient on patiromer with an undiagnosed obstructed bladder still has an obstructed bladder.
Where the kidney fits
The kidney excretes roughly ninety percent of the potassium you consume. When kidney function falls, that capacity falls with it, and an eGFR under 30 leaves little margin.
This is true, and it is also the trap. A low eGFR is a plausible cause, and a plausible cause is what stops people from finding the real one. Chronic kidney disease and an obstructed bladder look identical on a basic metabolic panel.
What else raises it
NSAIDs. Trimethoprim. Heparin. Beta blockers. Tacrolimus and cyclosporine after transplant.
Uncontrolled diabetes. Tissue breakdown from injury, hemolysis, or tumor lysis.
And potassium chloride salt substitutes — a genuinely frequent and unrecognized source, particularly in patients who were told to cut sodium and reached for a substitute nobody asked about.
A falsely high result is common
A tight tourniquet, a clenched fist during the draw, a hemolyzed sample, or a very high platelet or white cell count can all raise the measured potassium without the patient's potassium being high at all.
Before treating an unexpected result in someone who feels well with a normal ECG, we repeat it. Treating a spurious value carries its own risks.
Treating it
Severe, with ECG changes: calcium to stabilize the heart, then insulin with glucose and albuterol to drive potassium into cells, then something to remove it. Calcium protects the heart within minutes and removes no potassium — that distinction is the entire logic of the treatment.
Chronic: find the cause. Then a binder, correction of acidosis, a hard look at every medication, and dietary counseling last rather than first.
Dialysis when the kidney cannot do it.
What we do
Confirm the value is real. Get an ECG. Then establish why potassium is not being excreted — bladder, medications, acid-base status, adrenal function, tubular defect.
Then manage the potassium so the kidney-protective therapy can stay.
A high potassium is a question about excretion, not about diet. If yours was answered with a food list, it was not answered.
Call (713) 597-5131 or book online.