A low bicarbonate means acid is accumulating faster than your body can clear it.
The reflex is to replace the bicarbonate. The correct first move is to find out why it fell.
The cause has to be established before the treatment
Metabolic acidosis is not one disease. The anion gap splits it into two families, and they have almost nothing in common.
A high anion gap means acid was added. Diabetic ketoacidosis. Lactic acidosis from sepsis or shock. Toxic alcohol ingestion. Kidney failure itself. Each of these is an emergency with its own treatment, and bicarbonate is rarely the answer.
A normal anion gap means bicarbonate was lost, or acid was not excreted. Diarrhea. Renal tubular acidosis. Certain medications. And chronic urinary retention — an obstructed bladder producing a normal-gap acidosis in a patient whose kidney function looks unremarkable, found only if someone thinks to look for it.
That last one is the point. A patient can be handed bicarbonate tablets for years while an obstructed bladder is quietly damaging both kidneys. Nobody checked a post-void residual. Nobody asked about the stream.
If your bicarbonate is low and nobody has calculated your anion gap, the diagnosis has not been made. Something is being treated, but nobody has said what.
Board-certified nephrology at Remix Medical in Houston. Call (713) 597-5131 or book online.
Then, once the cause is known
If chronic kidney disease is the cause — and it often is, as failing kidneys stop excreting the acid ordinary metabolism produces every day — the treatment does real work.
Correcting bicarbonate with oral sodium bicarbonate slows the progression of chronic kidney disease. Trials showed slower eGFR decline, less progression to dialysis, and better nutritional status. The intervention costs almost nothing.
And it is skipped constantly. A bicarbonate of 19 gets noted and left alone, because it produces no symptoms and looks minor next to the creatinine.
What chronic acid does while nobody treats it
The body neutralizes excess acid by pulling alkaline salts out of bone. Over years this demineralizes the skeleton, adding to a fracture risk already elevated in kidney disease.
Muscle is broken down to supply glutamine for acid excretion. The result is protein-energy wasting — the muscle loss common in advanced kidney disease, which independently predicts death.
Acidosis worsens hyperkalemia by driving potassium out of cells. It suppresses thyroid and growth hormone signaling. It contributes to insulin resistance.
And it accelerates the loss of kidney function itself, triggering ammoniagenesis and complement activation in the nephrons that still work.
Where the target sits
Serum bicarbonate at or above 22 mEq/L.
Not higher. Overcorrection causes volume overload from the sodium load, worsening hypertension, and metabolic alkalosis. In heart failure, the sodium in bicarbonate tablets demands real attention.
Diet
Meat and cheese produce acid. Fruits and vegetables produce base. Increasing plant foods lowers acid load and works.
It collides with the potassium restrictions many patients have been given — and that collision is usually resolved in favor of the restriction, without anyone examining whether the restriction was ever necessary.
What we do
Calculate the anion gap. Establish the mechanism before treating the number.
Look for the causes that hide: renal tubular acidosis, gastrointestinal loss, medications, and obstruction — including the post-void residual nobody measured.
Then, if chronic kidney disease is the driver, check bicarbonate at every visit once eGFR falls below 45, treat below 22, and watch sodium load, blood pressure, and volume.
A low bicarbonate is a finding, not a diagnosis. If yours was treated without being explained, the explanation is still worth having.
Call (713) 597-5131 or book online.