Medical Oncologist
CION Cancer Clinics
Metabolic problems after bowel-based diversion | CION Cancer Clinics
After a urinary diversion the blood can become slightly more acidic, because the piece of bowel now carrying urine absorbs acid and salts back into the body. It is common, often causes no symptoms, is found on a routine blood test, and is treated with a daily alkali tablet. This page explains why it happens, the related problems with bones, vitamin B12 and stones, and what you can do. CION Cancer Clinics’ surgical oncologists in Hyderabad can talk this through with you.
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Medically reviewed by Dr. Muralidhar MuddusettyConsultant Surgical Oncologist · MBBS (AIIMS), MS (Surgery, AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh) · last reviewed September 2026, next review due September 2027
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On this page
- What is acidosis after a urinary diversion?
- What other problems come from using bowel to carry urine?
- The words on the blood report, in plain language
- Four things families tell us about the tablets and the tests
- How is it treated, and what can I do myself?
- Common questions about acidosis and metabolic problems
The short answer
What is acidosis after a urinary diversion?
Acidosis means the blood has become slightly more acidic than it should be. It happens after a urinary diversion because the piece of bowel now carrying urine does what bowel is built to do: it absorbs. It takes some of the acid and salts back out of the urine and into the blood. It is common, it is found on a routine blood test, and it is treated with tablets.
Why bowel and urine do not mix well
The bladder was a waterproof bag. Bowel is a lining designed to soak things up. The longer urine sits against it, the more is absorbed. So the problem is milder with a short ileal conduit, where urine passes straight through into a bag, and more likely with a neobladder or a continent pouch, where urine is stored for hours. Poor kidney function makes it worse, because the kidneys cannot clear the extra acid.
How it feels, if it is felt at all
Often there is nothing to feel. When there is, it is vague: tiredness, weakness, loss of appetite, feeling sick, or breathing a little faster than usual. The blood test at each follow-up is what actually finds it.
Why it is worth treating even when you feel well
Acid that is left uncorrected is buffered by the bones, which slowly lose calcium and weaken. It also makes kidney stones more likely and puts extra strain on the kidneys. A simple tablet prevents all three, which is why your team will ask you to take it long-term.
The full name on your report may be "hyperchloraemic metabolic acidosis". The chloride part describes which salt was absorbed. The treatment is the same.The wider picture
What other problems come from using bowel to carry urine?
Acidosis is the main one. These four travel with it and are checked at the same visits.
Weaker bones
Bone is the body's reserve of alkali. Years of mild acidosis draw on it and bone density falls. Correcting the acid balance, enough calcium and vitamin D, and a bone density scan if your team suggests one, are the answer.
Low vitamin B12
The last part of the small bowel is where B12 is absorbed, and it is often the part used to build a conduit or neobladder. Stores run down slowly over years. A low level causes tiredness, a low haemoglobin and numbness or tingling in the hands and feet, and is checked with a blood test.
Stones
Acid urine, mucus, still urine and lost calcium together make stones more likely, in the kidneys and inside a pouch. Enough water and the alkali tablet are the main prevention.
Salt and water loss
Where a longer piece of bowel was used, or part of the large bowel, loose motions and dehydration are more common, especially in summer or with a stomach upset. Both make the acidosis worse quickly.
Low potassium can come with it. It shows on the same blood test.Not sure whether this applies to you?
Ask an oncologistOn your report
The words on the blood report, in plain language
- Bicarbonate
- The body's main alkali. A low bicarbonate is the usual sign of acidosis and the number the tablet is meant to bring back up.
- Chloride
- A salt absorbed from the urine by the bowel segment. It runs high in this type of acidosis.
- Potassium
- A salt the body can lose in the urine and in loose motions after a diversion. Too low causes weakness and cramps.
- Base excess or pH
- Two ways of describing how acidic the blood is, used when the team wants a more precise measure than bicarbonate alone.
- Creatinine and eGFR
- Measures of kidney function. They are read alongside the acid balance, because a struggling kidney clears less acid.
- Vitamin B12
- Checked periodically because the part of the bowel that absorbs it may have been used in the diversion.
!
One thing that cannot wait
Vomiting, loose motions or a fever that stop you keeping fluids down, with growing weakness, drowsiness, confusion or fast deep breathing, can tip a mild acidosis into a severe one within a day. Go to the nearest emergency department the same day, say you have a urinary diversion, and take your tablet packets and discharge summary. Do not stop the alkali tablet on your own.
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Commonly believed
Four things families tell us about the tablets and the tests
"He feels fine now, so we stopped the soda tablets."
The tablet is doing its job precisely when he feels fine. The damage from untreated acidosis is to bones and kidneys, over years, without symptoms. Stopping it is a decision for the team, made on a blood result, not a decision for the family made on how he looks.
"Acidosis means the operation went wrong."
It means bowel is doing what bowel does. Some degree of it is expected after any diversion built from bowel, which is why it is checked from the first follow-up. It is a known and managed effect, not a complication of a poor operation.
"Lime water and soda will fix it at home."
Kitchen remedies do not deliver a measured amount of alkali and cannot be adjusted to a blood result. The prescribed tablet is a measured dose that your team changes as the test changes. Take what is prescribed, and ask before adding anything.
"A neobladder avoids all of this because there is no bag."
A neobladder stores urine against bowel for hours, so it absorbs more, not less. People with a neobladder or a pouch are more likely to need the tablet, not less. The bag is a separate question from the chemistry.
Treatment and daily life
How is it treated, and what can I do myself?
With an alkali tablet, usually sodium bicarbonate or a citrate salt, taken every day, and a blood test at each follow-up to adjust it. Your team sets the amount and changes it as the result changes. Most people take it for life.
Water and emptying
Enough plain water that the urine stays pale, spread across the day. With a neobladder or a pouch, empty by the clock so urine does not sit against the bowel for longer than it must. With a conduit, a night drainage bag keeps urine flowing instead of pooling.
Bones and B12
Ask whether you need calcium and vitamin D, and whether a bone density scan is due. Ask for a B12 level at follow-up; if it is low, it is replaced with injections or tablets.
When you are unwell
A stomach upset, a fever or a hot day with too little water can push the acid balance out of range quickly. Drink, keep taking the tablet, and get a blood test early.
What this page cannot tell you
It cannot tell you whether your acid balance is out of range, or how much tablet you need. Both come from your own blood result. It also cannot tell you whether your tiredness is acidosis, low B12, a low haemoglobin or something else. The same blood sample answers all of that at once, so ask for it.
If you have a heart condition or high blood pressure, tell your team before starting a sodium tablet. A different alkali may suit you better.Questions we are asked
Common questions about acidosis and metabolic problems
Will I need to take the alkali tablet for the rest of my life?
Many people do, because the bowel segment keeps absorbing for as long as it carries urine. Some people with a short conduit and good kidneys need it only at times. Your team decides from the blood test, and the amount may go up or down over the years. Never stop it without asking.
Can the tablet upset my stomach or blood pressure?
Sodium bicarbonate can cause bloating and wind, and its salt content matters if you have high blood pressure or a heart condition. Tell your team. A citrate tablet is often used instead. Take it with food and spread the doses if you have been told to, rather than all at once.
Is acidosis dangerous?
Mild, treated acidosis is not. Left untreated for years it weakens bones, encourages stones and strains the kidneys. Severe acidosis, which usually needs a trigger such as vomiting, an infection or dehydration, can make you very unwell quickly and is treated in hospital. The routine tablet and blood test prevent both.
Why am I so tired months after the operation?
Tiredness this long after surgery has several possible causes, and acidosis, low B12 and a low haemoglobin are three of them. All three show on one blood sample. Ask for it rather than assuming it is recovery or age. Each of the three has a simple treatment once found.
Does diet make a difference?
Less than the tablet and the water do. A normal balanced diet with enough calcium, and fewer very salty and very acidic processed foods, is sensible. Do not cut out food groups on your own, and be cautious with high-dose vitamin C, which can push the urine more acidic. Ask a dietitian at your centre if you are unsure.
How is B12 given if it is low?
Usually by injection, because the part of the bowel that absorbs it from food may have been used in the diversion, so tablets may not be taken up well. Your team will say how often. A low B12 develops slowly, over years, which is why it is checked at follow-up rather than waited for.
Can I get a bone density scan in Hyderabad?
Yes. It is a quick, low-dose scan available at larger diagnostic centres in the city. Ask your team whether and when you need one. People with years of acidosis, women after the menopause and anyone with a previous fracture are the ones usually sent for it.
Are the tablets and tests covered by Aarogyasri or insurance?
Follow-up blood tests after cancer surgery are usually part of the treatment pathway, and the alkali tablets are inexpensive and widely available. Aarogyasri, CGHS, ECHS and EHS are accepted and most cashless insurers are empanelled. Call the helpline with your card details and we will check your cover.
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Sources
- National Cancer Institute — Bladder Cancer Treatment (PDQ) - Patient Version
- NICE — Bladder cancer: diagnosis and management (NG2)
- American Cancer Society — Urostomy guide
- NHS — Urostomy
- Cancer Research UK — Living with bladder cancer
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Vitamin B12 After Urinary DiversionThe B12 problem in more detailKidney Function After Urinary DiversionWhy the acid balance and the kidneys are read togetherUrine Infections After Urinary DiversionThe infections that can tip the balanceEating and Bowel Function After CystectomyLoose motions and diet after part of the bowel is usedFollow-Up After Radical CystectomyThe visits where these blood tests are done
Talk to us
A blood result you do not understand?
Send it to us or call the helpline. A surgical oncologist who deals with urinary diversion every week will read it with you and tell you what the next step actually is. One helpline serves every CION centre.