Hyperoxaluria - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Hyperoxaluria occurs when a high concentration of oxalates is present in the urine. Oxalate is a naturally occurring substance in green leafy vegetables and legumes. It is present in the body and obtained from the diet. Normally, oxalates are removed from the body by the kidneys. There is also an enzyme present in the body that does not allow the accumulation of oxalates. However, the problem arises when the kidneys fail to work, and the person lacks the enzyme responsible for oxalate metabolism.

As a result, the oxalate levels increase, and too much oxalate is excreted in the urine resulting in hyperoxaluria. The presence of excessive oxalates in the urine increases the risk of kidney stones. It is because calcium and oxalates in the urine clump together to form calcium oxalate stones. The oxalates might build up in other body tissues, resulting in a systemic condition known as oxalosis. The condition must be treated at the earliest to prevent kidney stones and infections.

What Are the Causes of Hyperoxaluria?

Hyperoxaluria has been classified into different types based on its causes. The causes and the types of hyperoxaluria have been described below:

1. Primary Hyperoxaluria - It is a rare condition present since birth. In this type of hyperoxaluria, the liver fails to produce the enzyme that inhibits the production of oxalates. As a result, the oxalates are present at high levels in the body and get eliminated by the kidneys in the urine. This oxalate combines with calcium in the urine and forms calcium oxalate crystals or stones. The symptoms of kidney stones are experienced during childhood. However, if the stones form repeatedly, permanent kidney failure occurs when the child reaches adulthood. Sometimes, the kidneys are unable to function from birth. Gene defects (mutation) are responsible for the inability of the liver to produce the enzyme required for oxalate metabolism.

2. Enteric Hyperoxaluria - Certain conditions of the digestive tract increase the oxalate levels of urine. The conditions have been described below:

   1. Crohn’s Disease - In this condition, the patient experiences abdominal pain, vomiting, diarrhea, and weight loss due to the digestive tract's inflammation. If the condition becomes severe, an ulcer forms in the intestine, and the infection spreads to nearby organs like the anus, rectum, and urinary bladder. Excess oxalates are absorbed and excreted in the urine of patients suffering from Crohn's disease.

   2. Short Bowel Syndrome - In this condition, the body cannot absorb the essential nutrients from food. As a result, the food combines with calcium, and the oxalates are left behind in the intestine. These oxalates travel from the intestine to the kidneys and exit the body through the urine.

3. Oxalosis - Kidney stones repeatedly form if primary hyperoxaluria is left untreated for a long time. As a result, the kidneys get permanently damaged and fail to function, resulting in the deposition of oxalates in the eyes, skin, muscles, bones, and heart. This condition is known as oxalosis.

4. Oxalate-Rich Food - The foods rich in oxalates include spinach, rhubarb, almonds, chocolates, beets, and okra.

What Are the Symptoms of Hyperoxaluria?

Kidney stones are the first symptom of hyperoxaluria. The other symptoms experienced by the patient due to kidney stones are listed below:

• The patient experiences severe pain in the sides and lower back. The pain persists for some time and subsides later. It increases when the person goes to the toilet to urinate.

• Pain is accompanied by fever, vomiting, and nausea.

• Hematuria, or the presence of blood in the urine, is commonly seen due to kidney stones.

• Inability to empty the bladder at once.

• The urine flow becomes restricted.

• Pain and a burning sensation while urinating is the most common finding.

• The urine smells bad and looks cloudy.

• Feeling the desire to urinate frequently.

What Methods Are Used to Diagnose Hyperoxaluria?

The diagnosis of hyperoxaluria is based on medical history, laboratory tests, and imaging tests. The diagnostic methods have been described below:

1. Medical History - The medical history provides an idea about the patient's general health, the symptoms of the condition, the duration of their onset, and family history. The medical history helps to check whether the disease runs in the family or has been acquired by the individual during his lifetime.

2. Laboratory Tests - The health care provider usually recommends the laboratory tests described below:

   1. Urine Test - In this procedure, the patient’s urine sample is examined by a laboratory technician for oxalates, stones, or crystals. The test reports indicate high oxalate levels in patients suffering from hyperoxaluria.

   2. Stone Analysis - The patient is given a container and a strainer. The urine is supposed to be collected in the container and filtered through the strainer. If stones are present, they appear as small particles on the strainer. It is then sent to the laboratory for further evaluation.

   3. Blood Test - The doctor might ask the patient to undergo a blood test to check the oxalate levels and general health of the kidneys.

3. Imaging Tests - The imaging tests listed below are used for confirming the diagnosis:

   1. Ultrasound - It is a diagnostic test that helps to obtain images of the body's internal organs without exposing the patient to X-rays. The doctor moves the transducer over the abdomen, and the images are obtained on the computer screen. The ultrasound helps to check kidney stones and other problems in the urinary system.

   2. Computerized Tomography (CT) Scans - This procedure provides three-dimensional (3D) images of the body's internal organs. The patient is laid on a table, and the X-rays are taken when this table goes into a tunnel-like device. These images help to detect kidney stones and other abnormalities.

4. Other Tests - In addition to the tests mentioned earlier, the following tests help to diagnose hyperoxaluria:

   1. Genetic Tests - The patient's deoxyribonucleic acid (DNA) sample is taken to check the presence of defective genes. It is because genetic mutations (defective genes) cause primary hyperoxaluria.

   2. Kidney Biopsy - It is a procedure in which a mass of tissue is taken from the kidneys to check oxalate deposits.

   3. Eye Test - An ophthalmologist does it to detect oxalate crystals in the eyes.

   4. Liver Biopsy - A piece of liver tissue is taken to detect the enzyme responsible for oxalate metabolism. The enzyme is absent in patients suffering from hyperoxaluria.

How Is Hyperoxaluria Managed?

The treatment depends upon the causes, severity, and type of hyperoxaluria the patient suffers from. The treatment options have been described below:

• Medications - The medications, mainly Lumasiran and vitamin B6, help treat primary hyperoxaluria. These drugs reduce the production of oxalates in adults and children. As a result, a small amount of oxalate passes into the urine. A combination of magnesium and orthophosphate and orally administered potassium citrate help prevent calcium oxalate crystals' formation. Thiazide diuretics also help to deal with primary hyperoxaluria.

• Drinking Water - The patient needs to drink sufficient water daily to flush out the oxalates from the body. Water does not allow the buildup of oxalates in the blood.

• Modifications In the Diet - Patients suffering from secondary hyperoxaluria must avoid salty foods, sweets, chocolates, nuts, butter, french fries, and animal proteins (milk and fish). The patient must avoid a diet that requires him to stay on juices alone. These juices also contain oxalate-rich materials and increase the risk of hyperoxaluria. Eat calcium-rich foods because calcium binds with oxalates and reduces the levels. The oxalate exits the body through the stools and does not pass through urine.

• Treatment of Kidney Stones - The oxalates and calcium in the urine combine to form calcium oxalate stones. These procedures can manage kidney stones:

  • Shock Wave Lithotripsy - In this procedure, stones are broken down into smaller pieces with the help of shock waves sent to the body so that they quickly pass through the urine.

  • Percutaneous Nephrolithotomy: If the stone has become very large and the pain is unbearable, an incision is made in the back region to remove the stones, usually greater than 2 centimeters. A tube is passed through the incision with a telescope to remove the stone directly or break it down into smaller fragments for removal.

• Management of Severe Hyperoxaluria - If the kidneys have failed to work due to hyperoxaluria, dialysis and kidney transplant is usually recommended. The treatment options have been described below:

  • Dialysis - It is a procedure in which a machine is attached to the body to remove blood. This blood is then filtered by the dialyzer (artificial kidney), and the fresh blood obtained is sent to the body. If the kidneys do not heal, the patient must repeatedly undergo dialysis.

  • Kidney Transplant: A healthy kidney from one person (friend or relative) is transferred to the infected person's body to replace the infected one. It is a good option as the new kidney works better than dialysis.

What Are the Complications of Hyperoxaluria?

Hyperoxaluria must be treated at the earliest as it damages the kidneys to a large extent. The complications of hyperoxaluria are listed below:

1. Urosepsis - It is one of the most serious complications of a urinary tract infection, pyelonephritis (kidney infection), and hyperoxaluria. Sepsis is dangerous because it damages the healthy tissues of the body.

2. Anuria - It is a condition in which the kidneys fail to produce urine. It is because they have got damaged due to the presence of calcium oxalate crystals.

3. Anemia - Anemia might occur due to the accumulation of oxalate crystals in the blood and other parts of the body. The skin color appears pale due to anemia.

4. Heart Diseases - Oxalate crystals enter the heart membranes of the heart, making it difficult to pump blood. As a result, the heart is damaged and fails to function.

5. End-Stage Renal Disease - When the calcium oxalate stones repeatedly form, the kidneys fail to function permanently. It is known as end-stage renal disease, and the patient has to be on dialysis or undergo a kidney transplant.

Conclusion:

Hyperoxaluria occurs when the oxalates are present in high concentrations in the body. Normally, the kidneys remove the oxalates to maintain a balance. Dialysis and kidney transplants treat end-stage renal disease or kidney failure. If the diagnostic tests show the presence of stones, lithotripsy and percutaneous nephrolithotomy are of great help. It can be concluded that there are treatments available for all the problems associated with hyperoxaluria. Therefore, the patient must consult the doctor soon to learn more about hyperoxaluria and the treatment options.