What is hyperoxaluria?

Primary Hyperoxaluria

a hereditary disease (passed on from one family member to another) more

Secondary Hyperoxaluria

Caused by excessive intake of oxalate from the intestines or due to high food intake or other disease (usually something related to the intestines) more

What is Primary Hyperoxaluria?

Primary Hyperoxaluria (PH) is a group of genetic conditions, this means that the conditions are caused by a change in your DNA and are often passed on in families.

These are rare conditions (around 4 people in a million).

Because it is so rare it can take a while to find the diagnosis.

PH happens because a substance called oxalate builds up in the kidneys.

Oxalate is made from a chemical called glyoxylate, usually this is very controlled so that only a small amount of oxalate is made. In a person with PH, the enzymes from the liver that control how much oxalate is made do not work normally. This means there is too much oxalate in the body and the body cannot get rid of it all. When there is too much oxalate in the body it makes solid crystals together with calcium.

Primary Hyperoxaluria (PH) is associated with genetic conditions. A genetic condition is caused by one or multiple changes in the DNA. These changes can be inherited or can happen during cell division. Having those genetic conditions is rare. Only roughly 4 people in a million show these genetic changes. Because it is so rare, an early diagnosis is difficult.

Primary Hyperoxaluria causes high oxalate levels in the blood.

Endogenous oxalate (aka oxalate in the body) comes from a substance called glyoxylate. Glyoxylate is broken down by an enzyme from the liver. Normally, this enzyme is regulated and only produces small quantities of oxalate. In a patient with primary Hyperoxaluria, this enzyme is malfunctioning, leading to an uncontrolled production of oxalate.

The body is now overloaded with oxalate and struggles to remove it from the body. Excessive amounts of oxalate build up in the kidney. Here they react with calcium and form crystalline structures which are the cause of kidney stones.

How does it affect people?

Primary Hyperoxaluria (PH) mainly affects the kidneys.

The accumulation of crystalline structures in the kidney as a result of high oxalate levels in the blood can cause kidney stones. Most patients with PH develop kidney stones before the age of 20.

The symptoms of kidney stones vary from each person to another. Sometimes even two members of the same family can have completely different symptoms even though they both have PH.

Possible symptoms are pain in the abdomen, pain and difficulties passing urine as well as fever.

The urine can appear turbid (cloudy) or bloody. Children with PH can suffer from growth disorders.

It is also possible that patients with primary Hyperoxaluria live with no symptoms. Then the diagnosis of PH can only happen by chance during other checkups.

Besides kidney stones, PH can cause chronic kidney disease and it can destabilize the bones leading to fractures.

What can be done?

What is Secondary Hyperoxaluria

Secondary or enteric hyperoxaluria is when the urine and blood oxalate levels are high because someone is eating a lot of food which is rich in oxalate or if they have another condition or illness which affects the gut.

In enteric hyperoxaluria there are three main ways that the oxalate levels in the body become high:

  1. Too much oxalate in your diet (click here for more information about food and oxalate). see dietary advice
  2. In some illnesses fat is not absorbed properly in the gut, this means your gut finds it easier to absorb oxalate so more oxalate stays in the body. In these conditions you often have stools which are pale and oily.
    Some of the conditions that can cause fat malabsorption are pancreatic disorders, Roux-en-Y bypass (gastric bypass) surgery, short bowel disease, Crohn´s disease, or if you take a drug called Orlistat. Click here for a full list of conditions which can affect oxalate in the gut.
  3. The oxalate in your gut doesn´t get broken down as easily because of changes to the „friendly“ bacteria which live in your gut. This can sometimes happen if you have had multiple courses of antibiotics or gastrointestinal infections.

    The cause can also be a combination of these things.

Secondary Hyperoxaluria: What can be done?