Children's Hospital Colorado

Pediatric Oxalosis

What is oxalosis?

Oxalosis is a condition that affects the kidneys and can damage them, leading to kidney stones and kidney failure (end-stage renal disease). The name of this kidney disorder is derived from the chemical, oxalate, which occurs naturally in many foods. With oxalosis, the body is overloaded with oxalate and the body is unable to break down the chemical. When the kidneys are unable to break down the oxalates, they can overload the kidneys and damage them.

What causes oxalosis?

Oxalosis is a caused by a buildup of oxalate. There is typically an enzyme that breaks down oxalate so it cannot build up. However, some people are born with a genetic mutation that affects these enzymes. The change in function of these enzymes is caused by a group of rare genetic disorders known as primary hyperoxalurias (PHs).

The enzymes that are affected by PH aid in the digestion process, helping to break down the foods we eat. Oxalates are usually broken down along with the food, but because the enzymes have a mutation due to PH, they are not able to break down the oxalates. Instead of being digested and passed through stool or urine, the oxalates build up in the kidneys and other organs.

This buildup of oxalates can also occur in people who have certain types of gastrointestinal (GI) illnesses, such as short bowel syndrome. In people with these types of GI illnesses, the buildup of oxalate is usually milder than with oxalosis brought on by genetically mutated enzymes.

Who gets oxalosis?

The conditions associated with enzyme mutations are rare but have been found across all genders and ethnicities. Like other genetic mutations, primary hyperoxalurias can be passed down through the parents.

What are the signs and symptoms of oxalosis?

An excess of oxalates can affect many parts of the body, such as the kidneys, blood vessels, heart, bones and eyes. As a result, children with oxalosis may experience a variety of signs and symptoms, including:

  • Kidney stones, resulting in painful or bloody urination
  • Skin problems such as rashes or ulcers, due to high levels of oxalates in the blood vessels
  • Poor circulation due to impaired heart function
  • Bone fractures and bone marrow dysfunction leading to anemia (low red blood cell count)
  • Eye irritation or impaired vision

What tests are used to diagnose oxalosis?

Measurement of urinary oxalate and related substances may suggest the diagnosis of oxalosis. These are paired with blood tests to measure oxalate levels in the circulatory system and to assess kidney function.

We may also perform renal imaging (examine images of the kidney) using ultrasound imaging, magnetic resonance imaging (MRI) or computerized tomography (CT) scans.

A genetic test will tell us if your child has a genetic disorder associated with oxalosis, which we can do by taking a blood sample or by swabbing the inside of the cheek. We may also perform a liver biopsy, which will help us to clarify what type of enzyme is being affected.

What to expect from a liver biopsy

We use a liver biopsy to confirm and classify oxalosis, as there are several different types based on what enzyme is being affected. We can do a liver biopsy as an outpatient procedure, so your child won’t have to stay overnight.

We ask that your child not eat anything for 4 to 8 hours before the procedure. Once your child arrives, we will place them on an IV to administer medication. Depending on each case, we either sedate your child for the procedure or give them anesthesia so they are fully asleep to eliminate as much stress and pain as possible.

We use a minimally invasive technique, inserting a needle through your child’s side and onto the surface of their liver. We use a very small camera to guide us through the entire procedure, which enables us to be very accurate. Using the needle, we remove a small amount of tissue, then examine it under a microscope and analyze it, which takes a few days.

The biopsy procedure takes about one hour, after which your child will wake up. We will monitor your child for several hours to ensure there are no complications such as bleeding. Once we ensure everything is fine, you can take your child home. Make sure they avoid strenuous activities for about three days. After a few days, we will contact you to discuss the biopsy results and begin to develop a treatment plan.

How do we make a diagnosis of oxalosis?

We make a diagnosis based on a combination of things. Sometimes a family history of kidney stones can tell us if your child’s condition may be hereditary. The results of urine and blood tests also help us decide if further evaluation needs to be done. This evaluation may sometimes include a 24-hour urine collection, a kidney stones analysis, a kidney ultrasound, or sometimes even a detailed eye exam. However, the results of genetic testing and a liver biopsy will always give us a definitive answer and allow us to give a final diagnosis.

Why choose us to diagnose oxalosis?

We have extensive experience testing for and diagnosing oxalosis. Our doctors and nurses are trained to work exclusively with children. Some of the tests can be scary, even for adults, so we make an extra effort to explain the procedures in a way that children and families can understand and help them feel safe and comfortable throughout their time in our care.

From uniquely designed instruments, to our pediatric anesthesiologists and Child Life team, we plan everything we do around caring for children, so that they can focus on feeling better and getting back to what kids do best.

How is oxalosis treated?

If we can diagnose your child with primary hyperoxaluria early enough, sometimes we can avoid the damaging buildup of oxalate in the tissues (oxalosis). In some cases, vitamin supplements and a careful diet can be very effective. We would also prescribe certain medications to reduce oxalate absorption in the body and to dissolve oxalate in the urine as it is eliminated.

However, not all children respond to these measures and some can experience irreversible organ damage from oxalate overload. The kidney as well as the liver can be severely damaged by oxalosis. If the kidney becomes damaged, we may need to plan for kidney dialysis treatment and perhaps, eventually kidney transplantation. In serious cases, we may also require liver transplantation to replace the mutated oxalate-processing enzyme that causes the disease and that is mostly found in the liver.

Why choose us for treatment of oxalosis?

Primary hyperoxaluria and oxalosis require highly specialized multidisciplinary care. We provide this care specifically for children at Children’s Hospital Colorado by combining our expertise in urology, nephrology and metabolic medicine. For severely affected children, we have an expert team to provide intensive dialysis until transplantation (either of a liver, kidney, or both) is needed. We offer the only child-specific dialysis, as well as provide the highest ranked kidney transplant and liver transplant programs in the region.

Helpful resources

The Oxalosis & Hyperoxaluria Foundation (OHF) is dedicated to finding treatments and a cure for all forms of hyperoxaluria. They support healthcare professionals, patients and their families with the aim of sharing knowledge so that everyone has accurate information about the advances in this disease.