Medical Conditions

Renal Tubular Acidosis (RTA) in Children

Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist

Content reviewed against published NIDDK, AAP, ASN guidelines

Editorial policy

Last reviewed:

If your baby has been diagnosed with or you suspect renal tubular acidosis (rta) in children, here is what the evidence says.

The short answer

Renal tubular acidosis (RTA) is a condition in which the kidneys cannot properly acidify the urine, leading to a buildup of acid in the blood (metabolic acidosis). In children, this can cause failure to thrive, vomiting, poor growth, and sometimes rickets or kidney stones. Treatment with oral bicarbonate or citrate supplementation to correct the acidosis usually restores normal growth and development.

Key takeaways

  • Renal tubular acidosis (RTA) is a condition in which the kidneys cannot properly acidify the urine, leading to a buildup of acid in the blood (metabolic acidosis). In children, this can cause failure to thrive, vomiting, poor growth, and sometimes rickets or kidney stones. Treatment with oral bicarbonate or citrate supplementation to correct the acidosis usually restores normal growth and development.
  • Usually normal when: Your baby is growing along their expected growth curve and has normal blood work at checkups
  • Call your doctor if: Your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours
  • Varies by age — see the age-by-age breakdown below
“Fever itself is not an illness — rather, it is a sign or symptom that the body is fighting an infection. Fever stimulates certain defenses, such as the white blood cells, which attack and destroy invading bacteria.”
— Fever and Your Child, American Academy of Pediatrics (AAP)

Parents everywhere have the same worry. You are doing the right thing by looking into it.

What Parents Should Know

According to NIDDK, AAP, ASN guidelines, renal tubular acidosis (RTA) is a condition in which the kidneys cannot properly acidify the urine, leading to a buildup of acid in the blood (metabolic acidosis). In children, this can cause failure to thrive, vomiting, poor growth, and sometimes rickets or kidney stones. Treatment with oral bicarbonate or citrate supplementation to correct the acidosis usually restores normal growth and development. At 0-6 months, rTA in young infants often presents with poor weight gain, frequent vomiting, and dehydration. Babies may feed poorly and seem fussy or lethargic. Distal RTA (Type 1) is the most common form in infants and may be inherited (autosomal recessive or dominant). An unexplained metabolic acidosis found on blood work in an infant who is not growing well should prompt evaluation for RTA. Early treatment with alkali supplementation can restore normal growth. It is generally considered normal when your baby is growing along their expected growth curve and has normal blood work at checkups. However, you should contact your pediatrician promptly if your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours.

Sources: [1], [2], [3]

Normal vs. Concerning

Usually Normal
Worth Discussing
Your baby is growing along their expected growth curve and has normal blood work at checkups
Your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours
Your child has occasional vomiting with a viral illness but is otherwise thriving
Your child has severe vomiting with lethargy and appears very ill, which could indicate a dangerous level of acidosis
Your child's electrolytes and kidney function tests have been normal
Your child passes a kidney stone or has severe flank pain with blood in the urine
Your child has normal energy levels, appetite, and development for their age
Your child with known RTA has run out of or stopped taking their bicarbonate or citrate medication and is becoming increasingly unwell with vomiting or lethargy

When to Seek Immediate Care

  • Your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours
  • Your child has severe vomiting with lethargy and appears very ill, which could indicate a dangerous level of acidosis
  • Your child passes a kidney stone or has severe flank pain with blood in the urine
  • Your child with known RTA has run out of or stopped taking their bicarbonate or citrate medication and is becoming increasingly unwell with vomiting or lethargy

By Age

What to expect by age

0-6 months

RTA in young infants often presents with poor weight gain, frequent vomiting, and dehydration. Babies may feed poorly and seem fussy or lethargic. Distal RTA (Type 1) is the most common form in infants and may be inherited (autosomal recessive or dominant). An unexplained metabolic acidosis found on blood work in an infant who is not growing well should prompt evaluation for RTA. Early treatment with alkali supplementation can restore normal growth.

6-12 months

If untreated, RTA can cause significant growth failure by this age. Parents may notice that their baby is not keeping up on the growth chart despite adequate intake. Constipation, poor appetite, and recurrent vomiting are common. Some infants with distal RTA may develop nephrocalcinosis (calcium deposits in the kidneys) visible on ultrasound. Proximal RTA (Type 2) may present as part of Fanconi syndrome with loss of glucose, amino acids, and phosphate in the urine.

1-5 years

Toddlers and young children with undiagnosed RTA may present with short stature, rickets (bowed legs, widened wrists), or recurrent kidney stones. Distal RTA (Type 1) can cause calcium-containing kidney stones due to alkaline urine and low citrate excretion. A child with unexplained poor growth, rickets, or kidney stones should be evaluated with blood gases, electrolytes, and urine studies. Treatment with citrate supplementation corrects the acidosis and promotes catch-up growth.

5 years+

Older children with RTA may have been diagnosed earlier or may present with recurrent kidney stones or growth concerns. With appropriate treatment, most children achieve normal growth. Some forms of proximal RTA may improve with age. Regular monitoring of blood electrolytes, kidney function, and growth is important. Medication adherence is essential as stopping alkali therapy will cause the acidosis to recur.

What to Tell Your Pediatrician

  • Describe when you first noticed renal tubular acidosis (rta) in children and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if your baby is consistently falling off the growth chart despite adequate feeding.
  • Mention if your child has chronic or recurrent vomiting without an obvious cause.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

What Should You Do?

When to take action

Probably normal when...
  • Your baby is growing along their expected growth curve and has normal blood work at checkups
  • Your child has occasional vomiting with a viral illness but is otherwise thriving
  • Your child's electrolytes and kidney function tests have been normal
  • Your child has normal energy levels, appetite, and development for their age
Mention at your next visit when...
  • Your baby is consistently falling off the growth chart despite adequate feeding
  • Your child has chronic or recurrent vomiting without an obvious cause
  • Your child has been found to have an unexplained metabolic acidosis on blood work
  • Your child has bowed legs, widened wrists, or other signs that could suggest rickets
Act now when...
  • Your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours
  • Your child has severe vomiting with lethargy and appears very ill, which could indicate a dangerous level of acidosis
  • Your child passes a kidney stone or has severe flank pain with blood in the urine
  • Your child with known RTA has run out of or stopped taking their bicarbonate or citrate medication and is becoming increasingly unwell with vomiting or lethargy

What You Can Do at Home

  • Keep track of when you notice renal tubular acidosis (rta) in children — noting the time of day, duration, and any triggers can help your pediatrician.
  • Remember that your baby is growing along their expected growth curve and has normal blood work at checkups — this is generally within the range of normal.
  • At 0-6 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
  • Follow any care instructions from your pediatrician. Keep a written log of symptoms to bring to appointments.
  • While monitoring at home, seek immediate care if your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours.

Signs of Failure to Thrive in Babies

Failure to thrive (now often called growth faltering) refers to a baby or child who is not gaining weight as expected. It is typically defined as weight falling below the 2nd percentile, or crossing down two or more major percentile lines on the growth chart. While it sounds alarming, most cases are related to feeding difficulties, inadequate calorie intake, or transient illness, and can be successfully treated. Early identification and intervention are important for optimal outcomes.

Baby Not Growing Fast Enough - Failure to Thrive

Slow weight gain (falling across percentile lines on the growth chart) can have many causes, ranging from simple (not getting enough calories, growth pattern recalibration) to medical (feeding difficulties, food allergies, malabsorption, or underlying conditions). "Failure to thrive" is a clinical term for weight that falls below the 2nd percentile or drops across two major percentile lines. The most common cause is insufficient caloric intake - the baby is not eating enough, not absorbing enough, or burning too many calories. Early evaluation is important because nutrition affects brain development.

Rickets in Babies (Vitamin D Bone Disease)

Rickets is a condition in which bones become soft and weak due to severe deficiency of vitamin D, calcium, or phosphorus. Signs include bowed legs, widened wrists and ankles, delayed closure of the fontanelle, and poor growth. Exclusively breastfed babies with darker skin tones and limited sun exposure are at highest risk. Rickets is preventable with vitamin D supplementation (the AAP recommends 400 IU daily for all breastfed infants) and is treatable when caught early.

Triage

Vomiting Decision Tree

Evaluate vomiting severity and decide when to call the doctor.

Tool

Growth Percentile Calculator

Plot your baby's weight, length, and head circumference on WHO/CDC growth charts.

Milestone

Month-by-Month Development

Detailed monthly development guides from birth through 24 months.

Guide

When to Call the Doctor

General guide on when to call the pediatrician, visit urgent care, or go to the ER.

Frequently asked questions

Is renal tubular acidosis (rta) in children normal?
Renal tubular acidosis (RTA) is a condition in which the kidneys cannot properly acidify the urine, leading to a buildup of acid in the blood (metabolic acidosis). In children, this can cause failure to thrive, vomiting, poor growth, and sometimes rickets or kidney stones. Treatment with oral bicarbonate or citrate supplementation to correct the acidosis usually restores normal growth and development.
When should I call the doctor about renal tubular acidosis (rta) in children?
Your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours Your child has severe vomiting with lethargy and appears very ill, which could indicate a dangerous level of acidosis Your child passes a kidney stone or has severe flank pain with blood in the urine
When is renal tubular acidosis (rta) in children normal?
Your baby is growing along their expected growth curve and has normal blood work at checkups Your child has occasional vomiting with a viral illness but is otherwise thriving Your child's electrolytes and kidney function tests have been normal
What causes renal tubular acidosis (rta) in children?
Renal tubular acidosis (RTA) is a condition in which the kidneys cannot properly acidify the urine, leading to a buildup of acid in the blood (metabolic acidosis). In children, this can cause failure to thrive, vomiting, poor growth, and sometimes rickets or kidney stones. Treatment with oral bicarbonate or citrate supplementation to correct the acidosis usually restores normal growth and development. Common explanations include: Your baby is growing along their expected growth curve and has normal blood work at checkups. Your child has occasional vomiting with a viral illness but is otherwise thriving.
What should I mention to my pediatrician about renal tubular acidosis (rta) in children?
You should mention renal tubular acidosis (rta) in children at your next visit if: Your baby is consistently falling off the growth chart despite adequate feeding. Your child has chronic or recurrent vomiting without an obvious cause. Your child has been found to have an unexplained metabolic acidosis on blood work.
Is renal tubular acidosis (rta) in children normal at 0-6 months?
RTA in young infants often presents with poor weight gain, frequent vomiting, and dehydration. Babies may feed poorly and seem fussy or lethargic. Distal RTA (Type 1) is the most common form in infants and may be inherited (autosomal recessive or dominant). An unexplained metabolic acidosis found on blood work in an infant who is not growing well should prompt evaluation for RTA. Early treatment with alkali supplementation can restore normal growth.
Is renal tubular acidosis (rta) in children normal at 6-12 months?
If untreated, RTA can cause significant growth failure by this age. Parents may notice that their baby is not keeping up on the growth chart despite adequate intake. Constipation, poor appetite, and recurrent vomiting are common. Some infants with distal RTA may develop nephrocalcinosis (calcium deposits in the kidneys) visible on ultrasound. Proximal RTA (Type 2) may present as part of Fanconi syndrome with loss of glucose, amino acids, and phosphate in the urine.
Should I go to the ER for renal tubular acidosis (rta) in children?
Seek emergency care if your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours, or if your child has severe vomiting with lethargy and appears very ill, which could indicate a dangerous level of acidosis. When in doubt, call your pediatrician's after-hours line for guidance.
Does renal tubular acidosis (rta) in children go away on its own?
In many cases, renal tubular acidosis (rta) in children resolves on its own, especially when your baby is growing along their expected growth curve and has normal blood work at checkups. By 5 years+, older children with RTA may have been diagnosed earlier or may present with recurrent kidney stones or growth concerns. With appropriate treatment, most children achieve normal growth. Some forms of proximal RTA may improve with age. Regular monitoring of blood electrolytes, kidney function, and growth is important. Medication adherence is essential as stopping alkali therapy will cause the acidosis to recur.
NIDDKAAPASN

References

  1. [1]National Institute of Diabetes and Digestive and Kidney Diseases. Renal Tubular Acidosis. NIH, 2023. NIDDK
  2. [2]American Academy of Pediatrics. Evaluation of the Child with Failure to Thrive. Pediatrics in Review, 2020. AAP
  3. [3]Rodriguez Soriano J. Renal Tubular Acidosis: The Clinical Entity. Journal of the American Society of Nephrology, 2002. ASN

Doctor Visit Checklist

Bring this checklist to your next pediatrician visit to discuss Renal Tubular Acidosis (RTA) in Children.

Things to mention

  • Describe when you first noticed renal tubular acidosis (rta) in children and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if your baby is consistently falling off the growth chart despite adequate feeding.
  • Mention if your child has chronic or recurrent vomiting without an obvious cause.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

Observations to share

  • Your baby is consistently falling off the growth chart despite adequate feeding
  • Your child has chronic or recurrent vomiting without an obvious cause
  • Your child has been found to have an unexplained metabolic acidosis on blood work

Urgent signs to report immediately

  • Your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours
  • Your child has severe vomiting with lethargy and appears very ill, which could indicate a dangerous level of acidosis
  • Your child passes a kidney stone or has severe flank pain with blood in the urine

My notes

From ismybabyalright.com — free, evidence-based baby health guides

All content follows our editorial policy and is reviewed against published clinical guidelines.

2,705 evidence-based guides6 authoritative medical sources5 medical advisory board members

Related Resources

Vomiting TriageWell-Baby Visit PrepGrowth Spurts TimelineGrowth Percentile CalculatorEmergency ContactsBaby Tracker

Bottom line

Most cases of renal tubular acidosis (rta) in children are normal. Talk to your pediatrician if your baby is severely dehydrated with sunken fontanelle, dry mouth, no tears, and no wet diapers for 8 or more hours.

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

Share:FacebookX

Was this page helpful?

Related Medical Concerns

Signs of Failure to Thrive in Babies

Failure to thrive (now often called growth faltering) refers to a baby or child who is not gaining weight as expected. It is typically defined as weight falling below the 2nd percentile, or crossing down two or more major percentile lines on the growth chart. While it sounds alarming, most cases are related to feeding difficulties, inadequate calorie intake, or transient illness, and can be successfully treated. Early identification and intervention are important for optimal outcomes.

Baby Not Growing Fast Enough - Failure to Thrive

Slow weight gain (falling across percentile lines on the growth chart) can have many causes, ranging from simple (not getting enough calories, growth pattern recalibration) to medical (feeding difficulties, food allergies, malabsorption, or underlying conditions). "Failure to thrive" is a clinical term for weight that falls below the 2nd percentile or drops across two major percentile lines. The most common cause is insufficient caloric intake - the baby is not eating enough, not absorbing enough, or burning too many calories. Early evaluation is important because nutrition affects brain development.

Rickets in Babies (Vitamin D Bone Disease)

Rickets is a condition in which bones become soft and weak due to severe deficiency of vitamin D, calcium, or phosphorus. Signs include bowed legs, widened wrists and ankles, delayed closure of the fontanelle, and poor growth. Exclusively breastfed babies with darker skin tones and limited sun exposure are at highest risk. Rickets is preventable with vitamin D supplementation (the AAP recommends 400 IU daily for all breastfed infants) and is treatable when caught early.

My Baby's Head Shape Looks Abnormal

Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.

Achondroplasia (Dwarfism) in Babies

Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.

Adenoid Hypertrophy and Breathing

Adenoids are lymphoid tissue located behind the nose that help fight infection in young children. When adenoids become enlarged (adenoid hypertrophy), they can block the nasal airway, causing chronic mouth breathing, snoring, nasal speech, and sleep-disordered breathing. Enlarged adenoids are most common between ages 2-7 and are a leading cause of obstructive sleep apnea in young children. Treatment ranges from watchful waiting and nasal steroids to surgical removal (adenoidectomy) if breathing or sleep is significantly affected.