Renal tubular acidosis (RTA) is a condition in which the kidneys cannot properly remove acid from the blood or retain enough bicarbonate, even though overall kidney filtration may be normal. Over time, the extra acid can affect growth, bones, muscles and cause kidney stones. With correct diagnosis, RTA can usually be managed well with long-term treatment.
What Is Renal Tubular Acidosis?
Healthy kidneys help keep the blood's acid-base balance in a narrow range by excreting acid and reabsorbing bicarbonate in the tubules. In RTA, one of these tubular functions is faulty, so acid accumulates in the blood.
There are different types of RTA, and identifying the type helps guide treatment.
- Distal RTA (type 1): the kidney cannot excrete acid properly; often associated with low potassium and kidney stones
- Proximal RTA (type 2): the kidney loses bicarbonate in the urine; may occur with other tubular defects
- Type 4 RTA: linked to low aldosterone effect, often with high potassium; commonly seen in diabetes and chronic kidney disease
Causes
RTA may be inherited or acquired later in life.
- Inherited genetic conditions, often detected in childhood
- Autoimmune diseases such as Sjogren syndrome and lupus
- Certain medicines and toxins
- Diabetes and chronic kidney disease (particularly type 4)
- Multiple myeloma and other conditions affecting the tubules
- Long-standing urinary blockage
Symptoms
Symptoms vary with age and type, and some adults have few symptoms.
- Poor growth or failure to thrive in children
- Muscle weakness or episodes of paralysis due to low potassium
- Tiredness and reduced appetite
- Recurrent kidney stones or calcium deposits in the kidneys
- Bone pain, rickets in children or weak bones in adults
- Excessive thirst and urination
Diagnosis
RTA is suspected when blood tests show acidosis with a normal anion gap. Your nephrologist may check blood gases, electrolytes including potassium, and urine pH and electrolytes. Specialised urine tests may be used to identify the type of RTA. An ultrasound may show kidney stones or calcium deposits, and tests for underlying causes such as autoimmune disease may be needed.
Treatment
Treatment is usually long term and aims to correct acidosis and electrolyte imbalances, protect bones and prevent stones.
Treatment works best when medicines are taken regularly and at the prescribed times, as alkali preparations are often needed several times a day. Blood tests are repeated periodically to check that acid, bicarbonate and potassium levels remain in range, and doses may be adjusted as children grow. Adults may also be advised on bone health and on keeping up fluid intake to reduce the chance of new stones forming.
- Alkali therapy, such as bicarbonate or citrate preparations, prescribed by your doctor
- Potassium supplements when potassium is low
- Managing high potassium and reviewing medicines in type 4 RTA
- Treating the underlying cause, such as an autoimmune condition
- Adequate fluid intake and dietary advice to reduce stone risk
- Regular monitoring of blood tests, growth in children and kidney function
When to See a Nephrologist
Consult a nephrologist if you have recurrent kidney stones at a young age, unexplained low potassium or muscle weakness, poor growth in a child, or blood tests showing acidosis. Early treatment can prevent many complications.
Frequently Asked Questions
Is renal tubular acidosis curable?
Inherited forms usually need lifelong treatment, while acquired forms may improve if the underlying cause is treated. In most cases, RTA can be controlled well with regular medicines.
Can RTA cause kidney failure?
RTA does not always lead to kidney failure, but untreated disease, recurrent stones and calcium deposits may damage the kidneys over time. Good control helps protect kidney function.
Will my child grow normally with RTA?
With early diagnosis and consistent treatment, many children with RTA show improved growth. Regular follow-up with the paediatric and kidney team is important.
Can I stop the medicines once I feel better?
No. Stopping alkali or potassium supplements may cause acidosis and low potassium to return. Always discuss any change with your nephrologist.
Consult Dr. Satarupa Deb
If you or your child has been diagnosed with, or is suspected to have, renal tubular acidosis, book a consultation with Dr. Satarupa Deb at Bombay Hospital, South Mumbai.
This page is for general information only and is not a substitute for a medical consultation. Please consult a qualified doctor for diagnosis and treatment.