Hyperoxaluria Explained

Hyperoxaluria Explained

Hyperoxaluria leads to increased excretion of oxalic acid in the urine. The oxalic acid precipitates with calcium to form the poorly soluble calcium oxalate and causes calculus to form in the kidneys. The disease can cause renal failure and systemic impairment of various tissues.

What is hyperoxaluria?

When the kidneys stop working effectively, blood oxalate concentrations also rise, which can lead to oxalosis developing in various tissues. Cardiac arrhythmias, high blood pressure, partial tissue necrosis (gangrene) and restricted mobility of the joints then occur. See AbbreviationFinder for abbreviations related to Hyperoxaluria.

Hyperoxaluria is a serious condition characterized by increased urinary excretion of oxalic acid. Oxalic acid is a metabolic end product that is normally rapidly broken down into carbon dioxide and water. However, if this degradation does not work properly or if too much oxalic acid gets into the organism through the food, poorly soluble calcium oxalates can form with calcium, which can settle as urinary stones in the urinary organs.

This damages the kidneys in particular. There are both primary and secondary forms of hyperoxaluria. Primary hyperoxaluria is always genetic and can be divided into three types. All three types have enzyme defects that lead to increased oxalic acid formation or reduced oxalic acid degradation in the organism. The oxalic acid must be excreted in the urine.

It combines with calcium to form calcium oxalate, which crystallizes in the kidneys and sometimes in other organs. Secondary hyperoxaluria is often associated with other metabolic diseases that lead to increased calcium concentrations in the blood. It is also caused by an increased intake of foods containing oxalic acid.


Genetic defects are present in primary hyperoxaluria. Type I primary hyperoxaluria is an autosomal recessive metabolic disease characterized by a defect in the liver enzyme glyoxylate aminotransferase. The enzyme is responsible for converting glyoxylate into glycine.

When this enzyme is dysfunctional, glyoxylate builds up, which is then broken down into oxalic acid. The oxalic acid concentration is also increased in primary hyperoxaluria type II (PH II). Here the enzyme glyoxylate reductase/hydroxypyruvate reductase is defective. As a result, oxalate accumulates because glyoxylate can no longer be converted.

In PH III, the enzyme 2-keto-4-hydroxyglutarate aldolase is inoperative, which also leads to an increased concentration of oxalic acid. The oxalic acid must be excreted in the urine. At very high oxalic acid concentrations, however, it precipitates as a calcium salt and forms urinary stones in the kidneys. The constant build-up of calcium oxalate causes kidney inflammation and scarring reactions that eventually impair the functioning of the kidneys.

Systemic oxalosis also occurs. In the context of oxalosis, calcium oxalate precipitates form in many other organs because the oxalic acid concentration in the blood is increased. Among other things, it affects vessel walls, eyes, heart muscle, skin, bones or the central nervous system. This results in typical impairments of the affected organs such as blindness, bone oxalosis, cardiac arrhythmia or anemia.

There is even a risk of death due to organ failure. The secondary forms of hyperoxaluria are often based on other metabolic diseases that are associated with an increased release of calcium. Calcium then binds more strongly with existing oxalic acid to form oxalates, which in turn can precipitate.

This occurs, among other things, in hyperparathyroidism, Cushing’s disease, sarcoidosis, [[bone metastases]), multiple myeloma or an overdose of vitamin D. Furthermore, secondary hyperoxaluria can also develop with excessive intake of oxalic acid through food. Rhubarb, sorrel, spinach and cocoa products contain a particularly large amount of oxalic acid.

Symptoms, Ailments & Signs

The symptoms of hyperoxaluria can be varied. The course of the disease can vary greatly in the individual affected, even with the same form. The increased concentration of oxalates in the urine is typical. Stone formation usually occurs in the urinary organs.

In primary hyperoxaluria, oxalate formation in the kidneys and other organs can be so massive that significant kidney and other tissue damage occurs even in childhood. Other people with primary hyperoxaluria may develop kidney stones only occasionally as they get older. Overall, symptoms appear that are characterized by severe renal dysfunction, urinary stone formation, renal colic, hematuria, fever and renal failure.

When the kidneys stop working effectively, blood oxalate concentrations also rise, which can lead to oxalosis developing in various tissues. Cardiac arrhythmias, high blood pressure, partial tissue necrosis (gangrene) and restricted mobility of the joints then occur.

Diagnosis & course of disease

Hyperoxaluria is diagnosed by measuring the concentration of oxalic acid in the urine. Oxalic acid excretion should not exceed 40 milligrams per day.


Hyperoxaluria causes kidney problems in most patients. Other tissues in the patient’s body can also be affected by the disease. This leads to increased stone formation in the kidneys and thus to considerable pain in the patient. The tissue in the kidneys and other organs can be severely damaged by hyperoxaluria, so that restrictions in these organs can be expected.

Most patients also suffer from fever and a general feeling of illness. In the worst case, complete kidney failure can occur if the hyperoxaluria is not treated early by a doctor. High blood pressure also occurs, which in the worst case can lead to a heart attack. Untreated hyperoxaluria leads to a reduced life expectancy.

Acute emergencies can usually be treated with a large intake of fluids. In serious cases, however, the transplantation of various organs in the patient is necessary. This can lead to complications or other problems. However, these depend on the exact circumstances of the disease and cannot be generally predicted.

When should you go to the doctor?

If symptoms and symptoms such as urinary stones, renal colic or fever are noticed, hyperoxaluria may be the cause. A doctor should be consulted if symptoms persist for more than two to three days. If other symptoms develop over the course of the disease, such as signs of hematuria or renal dysfunction, the family doctor must be consulted immediately. In the case of serious complications such as cardiac arrhythmias or tissue necrosis, a visit to the hospital is indicated.

In severe cases, an ambulance should be called immediately. This is especially true when the symptoms occur suddenly and are associated with failure symptoms. In this case, it is best to seek medical advice immediately. People who have been found to have the relevant genetic defects are particularly susceptible to the development of hyperoxaluria. Likewise people with Cushing’s disease, sarcoidosis or hyperparathyroidism. If you belong to one of these risk groups, it is best to see a doctor immediately if you have the symptoms mentioned. In addition to the family doctor, a specialist in internal medicine or a nephrologist can be consulted.

Treatment & Therapy

Hyperoxaluria is initially treated by increasing fluid intake. In addition, inhibitors are administered which prevent the crystal formation of calcium oxalate. These include magnesium, citrate or bicarbonate. The urine is kept as alkaline as possible to keep calcium oxalate in solution.

In patients who are very sensitive to vitamin B6, pyridoxine is substituted to reduce oxalate production. These treatments can delay the course of severe primary hyperoxaluria. In many cases, however, a combined kidney-liver transplantation is already necessary in childhood in order to prevent enzyme-induced oxalate formation and to save the patient’s life.

Outlook & Forecast

The prognosis of hyperoxaluria varies greatly. If left untreated, it can take a very serious course. Type I primary hyperoxaluria has a particularly poor prognosis. Like the other two primary forms of the disease, it is genetic. Secondary hyperoxaluria is based on another disease.

What all hyperoxaluria have in common, however, is the deposit of calcium oxalate in the organism. Due to the high degree of saturation with calcium oxalate in the urine, the crystals precipitate, especially in the kidneys, and over time cause severe kidney dysfunction. The oxalates manifest themselves as kidney stones, which constantly damage kidney tissue. However, the disease can also take a mild course into old age, with only isolated kidney stones being diagnosed again and again. In other cases, such as type I primary hyperoxaluria, severe kidney damage occurs in early childhood. Left untreated, hyperoxaluria is often fatal.

Oxalosis (deposition of oxalate crystals) often spreads to the entire organism after the kidneys have become increasingly impaired. Heart muscles, blood vessels, eyes, skin, bones and the central nervous system are often affected. As a result, complications such as cardiac arrhythmias, blindness, untreatable anemia, vascular diseases or oxalate bone diseases occur. Sometimes the diseases are fatal. In many cases, even intensive therapy with high fluid intake and drug inhibition of crystal formation can only delay the course of the disease, but not prevent it. Sometimes a combined liver-kidney transplant must be performed.


It is not possible to prevent primary hyperoxaluria because it is genetic. If you are predisposed to this, foods containing oxalic acid should be avoided. Overall, the consumption of very large amounts of rhubarb, spinach or products containing cocoa should be restricted, as these can lead to secondary hyperoxaluria.


In the case of hyperoxaluria, the person affected is primarily dependent on a quick diagnosis with subsequent treatment in order to prevent further complications and symptoms from this disease. The sooner a doctor is consulted, the better the further course of this disease. The person concerned should therefore contact a doctor as soon as the first symptoms and signs of hyperoxaluria appear, since in the worst case it can even lead to death.

Self-healing cannot occur with this disease, so treatment is always necessary. Aftercare measures are limited. In most cases, hyperoxaluria is treated with medication. It is important to ensure that the dosage is correct and that it is taken regularly.

Especially with children, parents must check the correct intake and dosage. In the case of side effects or interactions, a doctor should be contacted first. Furthermore, regular examinations of the internal organs are very important in order to detect damage to the internal organs and to treat them in good time. Hyperoxaluria may also limit or significantly reduce the life expectancy of those affected.

You can do that yourself

In most cases, the symptoms can be avoided relatively easily by changing your diet. However, early detection of the disease also has a very positive effect on the course and can prevent problems and damage to the kidneys.

As a rule, the affected person with hyperoxaluria should avoid foods containing oxalic acid. Products containing cocoa should also be limited as much as possible. Furthermore, the affected person must avoid spinach or rhubarb in his diet. In most cases, hyperoxaluria does not represent a major limitation in the patient’s everyday life and food intake. Those affected can reduce the oxalate in the body by taking pyridoxine. You just have to make sure you take it regularly to avoid further problems.

The acute symptoms of the disease are usually treated with an increased intake of fluids. Since the disease can also damage the kidneys or heart, those affected should have regular check-ups. In the case of psychological complaints or depression, talking to other people affected by hyperoxaluria or to close friends and parents often helps.