Here is something almost everyone gets backward.
People believe that if they are urinating a lot, they cannot be blocked. It seems obvious. Urine is coming out, so nothing is stuck.
The opposite is closer to the truth. A blocked bladder often makes you urinate more, not less — small amounts, constantly, day and night. That symptom is not proof you are fine. It is one of the ways obstruction announces itself.
And because almost nobody knows this, a reversible cause of kidney failure gets walked past.
Why a blockage makes more urine, not less
Your kidneys do two separate jobs. They filter waste, and they concentrate urine so you are not up all night.
The concentrating job depends on a delicate pressure gradient deep inside the kidney. A bladder that never empties backs pressure up into the kidneys and damages that gradient.
The kidney loses the ability to concentrate. So it makes large volumes of dilute, watery urine. You go often. You get up several times a night. You feel like you are producing plenty.
Meanwhile, the bladder is still full. It never empties. It simply overflows — leaking small amounts because it has nowhere else to put them. That is called overflow incontinence, and patients are often embarrassed to mention it.
So you have a full bladder, a damaged kidney, and a symptom — frequent urination — that convinces everyone nothing is obstructed.
Board-certified nephrology at Remix Medical in Houston. Call (713) 597-5131 or book online.
What the blockage does to your blood
This is where it stops being a bladder problem and becomes a kidney problem.
The same back-pressure that ruins the concentrating gradient also damages the part of the kidney that gets rid of potassium and acid.
Your potassium rises. Not because you ate a banana. Because the kidney has lost the ability to excrete it. High potassium can stop the heart, and it often produces no symptoms at all beforehand.
Acid builds up in your blood. A low bicarbonate on a lab report — a metabolic acidosis — that gets treated with tablets while nobody asks where it came from. Over time it thins bone and wastes muscle.
Your kidney function falls. Sometimes gradually. Sometimes as a sudden acute kidney injury that lands someone in a hospital.
Three separate abnormalities. One cause. And that cause is a bladder that a two-minute ultrasound would have found.
The two people this happens to most
Men with an enlarged prostate.
The prostate sits around the urethra, the tube urine leaves through. As men age it enlarges and squeezes that tube. The bladder muscle thickens and strains against it for years, and eventually it stops emptying completely.
Weak stream. Hard to start. Dribbling at the end. Getting up two, three, four times a night. Never feeling quite finished.
These get dismissed as normal aging. Sometimes they are. Sometimes the bladder is holding half a liter of urine at all times and the kidneys are quietly failing behind it.
People with diabetes.
Diabetes damages nerves — everyone knows about the feet. Almost nobody is told it damages the nerve that tells your bladder when it is full.
This is called diabetic bladder, or neurogenic bladder. The bladder loses sensation. It stretches, and stretches, and never signals that it needs emptying. You do not feel full because the nerve that reports fullness no longer works.
Many patients with a diabetic bladder have no urinary symptoms at all. They are not straining. They are not uncomfortable. They simply have a bladder holding far more urine than it should, and kidney numbers that are drifting in the wrong direction.
If you have had diabetes for years and your creatinine or potassium is climbing, this deserves to be excluded. It is frequently assumed to be diabetic kidney disease when the actual problem is a bladder that will not empty.
The test is simple, quick, and painless
It is called a post-void residual.
You empty your bladder as completely as you can. Then someone places an ultrasound probe on your lower abdomen and measures what is left behind.
That is the whole test. No needle. No catheter. No preparation. It takes a couple of minutes and costs very little.
A bladder that should be nearly empty holding a substantial amount of urine gives you the diagnosis on the spot.
If your potassium is high, your bicarbonate is low, or your kidney function is falling, and nobody has done this test — ask for it.
The good news, which is considerable
This is one of the most reversible causes of kidney failure there is.
Relieve the obstruction and kidney function often improves, sometimes dramatically, sometimes within days. The potassium comes down. The acidosis corrects. Numbers that looked like permanent kidney disease turn out to have been a mechanical problem.
That is not true of most kidney disease. It is true of this one.
The catch is time. An obstruction relieved early recovers. An obstruction left in place for months causes scarring that does not reverse. The kidney damage becomes permanent, and then it really is chronic kidney disease.
After the blockage is relieved
Sometimes the kidneys respond by producing enormous volumes of urine for a day or two — several liters. This is called post-obstructive diuresis, and it happens as the kidneys unload retained salt and water and recover their concentrating ability.
It is expected. It needs monitoring, because losing that much fluid and electrolytes quickly can cause its own problems. It is not a sign that something went wrong.
What we do
Find it. A post-void residual and an ultrasound of the kidneys, in anyone with unexplained kidney dysfunction, high potassium, or a low bicarbonate — particularly a man over fifty or a person with long-standing diabetes.
Sort out the cause. Prostate, nerve damage, medications that impair bladder emptying, prior surgery, stones, tumors.
Get it relieved, working with a urologist, who performs the procedures that address prostate obstruction.
Manage the kidney through it. Watch potassium and acid-base status. Monitor the diuresis afterward. Determine how much function returns and treat what remains.
And correct what was misattributed. A patient told they have chronic kidney disease, prescribed a phosphate binder and a potassium restriction, may have a bladder problem instead.
The one sentence worth remembering
Urinating frequently does not mean you are not obstructed. It is often exactly what obstruction looks like.
If you are getting up several times a night, if your stream is weak, if you leak small amounts without warning, or if you have diabetes and rising kidney numbers with no urinary symptoms whatsoever — a two-minute ultrasound can answer this.
Call (713) 597-5131 or book online.