Hyperuricosuria - Causes, Symptoms, Diagnosis, and Treatment

What Is Hyperuricosuria?

Uric acid is a substance that forms when purines are used by the body cells to carry out their activities. Purine is a chemical substance in the body or obtained from food items like dried beans, peas, beer, and anchovies. Normally, 300 to 400 milligrams of uric acid is produced daily, most of which is made by the liver. An enzyme known as uricase converts uric acid to allantoin, but this enzyme is inactive in humans. Hence, the end-product formed as a result of purine metabolism is uric acid. The kidneys maintain the levels of uric acid in the blood. When the uric acid reaches the filtration units of the kidneys, it is reabsorbed, and only ten percent of it is allowed to be excreted. Some uric acid goes into the intestine and converts into ammonia. This ammonia is utilized by the bacteria of the gut for metabolic activities. However, the problem arises when more than 750 to 800 milligrams of uric acid pass into the urine. This condition is known as hyperuricosuria and causes severe problems in the urinary tract. Uric acid might get deposited in the bones, joints, and other organs and cause severe complications.

What Are the Causes of Hyperuricosuria?

If the uric acid is in excess in the urine, the risk of calcium oxalate and uric acid stones (uroliths) increases. It is because the urine becomes saturated with monosodium urate that initiates the formation of calcium oxalate stones. The causes of hyperuricosuria are listed below:

1. Gouty Diathesis - Gouty is a form of arthritis that occurs due to the deposition of uric acid in bones and joints. When uric acid stones form in people suffering from gout, the condition is known as gouty diathesis. However, the exact cause of uric acid stones in these patients is still unknown, but the urine shows a low pH (potential of hydrogen) upon examination.

2. Purine-Rich Diet - Purine is a chemical substance responsible for the formation of uric acid. If purine-rich food items like meat, fish, anchovy, and alcohol are consumed in excess, more uric acid builds up in the body resulting in hyperuricosuria.

3. Diabetes - The exact relation between diabetes and hyperuricosuria is unknown. However, diabetics tend to develop acidic urine and uric acid stones due to insulin resistance. In addition, as ammonia is not produced in sufficient quantities, the uric metabolism gets impaired, resulting in hyperuricosuria.

4. Crohn’s Disease - It is a type of inflammatory bowel disease that causes severe abdominal pain, diarrhea, fatigue, and weight loss. Patients suffering from this disease tend to produce less urine and lose essential fluids and electrolytes. In addition, the person becomes dehydrated due to Crohn’s disease, and the functions of the kidneys become impaired.

5. Genetic Disorders - Patients suffering from genetic disorders like Lesch-Nyhan syndrome and type 1 collagen disorders tend to produce uric acid in large amounts. As a result, large quantities of it get excreted in the urine resulting in hyperuricosuria.

6. Medications - Certain medications interfere with the reabsorption of uric acid in the kidneys. These drugs do not allow the kidneys to reabsorb uric acid. As a result, a large quantity of uric acid passes from the kidneys to the urine, and the risk of stone formation increases.

7. Malignancy - People with cancer and undergoing radiotherapy or chemotherapy tend to suffer from hyperuricosuria.

What Are the Signs and Symptoms of Hyperuricosuria?

The symptoms of hyperuricosuria appear when the uric acid crystals combine with calcium and form stones. The signs and symptoms of hyperuricosuria are listed below:

• Pain - The patient experiences severe pain in the lower back and sides (flank). The pain slowly radiates to the abdomen and the pubic region. As the pain starts suddenly, it does not subside even if the patient changes his position. Patients suffering from renal colic (severe kidney pain) find it difficult to stay still.

• General Problems - Vomiting, nausea, and fever are commonly seen if the patient develops urinary tract infections due to stones.

• Urinary Tract Problems - If the stone is present near the urinary bladder, the following symptoms are usually seen:

  • The presence of blood in the urine, also known as hematuria, is commonly seen due to kidney stones.

  • 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 Hyperuricosuria?

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

1. Medical History - Medical history plays an important role in patients suffering from hyperuricosuria. It gives information about the patient's general health, symptoms, duration of onset, family history, drug history, and other conditions the patient is suffering from. For example, hyperuricosuria can be suspected if the patient has a history of diabetes or gout, is on medications like Probenecid or Sulfinpyrazone, and consumes a purine-rich diet.

2. Physical Examination - The patient will be in distress due to pain during the physical examination. If he is suffering from renal colic along with hyperuricosuria, the patient will not be able to sit or stand still. The doctor will also check for tenderness between the 12th rib and spine (costovertebral angle).

3. Laboratory Tests - The following laboratory tests are usually recommended to diagnose hyperuricosuria:

   • Urinalysis - In this test, the patient collects the urine in a container or a sterile bag provided by the hospital. The urine sample is examined in the laboratory microscopically, visually, or by using a dipstick. First, the urine is tested with a dipstick which changes color if the pH is acidic. Acidic urine is indicative of uric acid stones. Next, the urine sample is examined under the microscope to detect pus cells, bacteria, blood, and crystals. If the urine shows the presence of diamond-shaped crystals, uric acid stones are present.

   • 24-Hour Urine Test - As the name suggests, the patient must collect urine in a container throughout the day. The urine sample is sent to the laboratory for examination under a microscope the next day. This test is only recommended for patients who develop stones repeatedly.

   • Blood Test - The doctor might ask the patient to undergo a blood test to check sodium, potassium, calcium, and uric acid levels. If the uric acid levels are high, the person might suffer from gout or hyperuricosuria.

   • 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 to check if they are uric acid stones.

4. Imaging Tests - The following imaging tests are usually recommended to check the presence of stones:

   • Computerized Tomography (CT) Scans - It is one of the most specific and highly recommended tests to diagnose uric acid stones. This procedure provides three-dimensional (3D) images of the body's internal organs. The patient is laid on a table that slides into a tunnel-like device where the X-rays are taken. The uric acid stones appear bright white on the images obtained after the scan.

   • 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 advantage of the procedure is that the patient is not exposed to the X-rays, so it can be safely used on children and pregnant females. The patient is laid on a table, and the sound waves are sent to the body with the help of a transducer. 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.

How Is Hyperuricosuria Managed?

The treatment depends upon the causes and severity of the condition. The treatment options have been described below:

• Medications - Patients suffering from hyperuricosuria have acidic urine, increasing the risk of stone formation. Therefore, it is important to increase the urine's pH (potential of hydrogen) to make it alkaline. Potassium citrate therapy is the most effective medication used to treat uric acid stones. Sodium and potassium bicarbonate salts also work to alkalinize the urine. Theobromine is also an effective agent that inhibits the growth of uric acid crystals. Allopurinol is also recommended in hyperuricosuria. Ultrasound and 24-hour urine tests are done to check the effectiveness of these medications.

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

• Lifestyle Changes - Patients suffering from diabetes and other metabolic disorders need to exercise regularly to maintain a healthy weight. Consumption of salty and purine-rich foods should be avoided.

• Surgery - If the stones are large and block the urine flow, surgical intervention is required to remove them. The surgical options have been described below:

  • 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 two 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.

  • Ureteroscopy - In this procedure, a small telescope-like instrument known as a ureteroscope is inserted into the urinary bladder through the urethra. The stones can be easily located with the help of a camera. They are removed directly or broken into fragments to allow them to pass through the urine.

What Are the Complications of Hyperuricosuria?

Hyperuricosuria can cause severe complications if left untreated for a long time. The complications of hyperuricosuria are listed below:

1. Hydronephrosis - It is a condition in which the kidneys swell due to the backflow of urine. Suppose the uric acid stone is large and blocks the urine flow, the pressure on the kidneys increases, resulting in swelling and permanent failure.

2. End-Stage Renal Disease - When uric acid stones repeatedly form, the kidneys fail to function permanently. It is known as an end-stage renal disease; the patient must be on dialysis or undergo a kidney transplant.

3. Urinary Tract Infection - Hyperuricosuria increases the risk of urinary tract infections as the urine remains in the body. The bacteria quickly enter the body and multiply in the urine.

4. Obstructive Pyelonephritis - It is a life-threatening condition that occurs due to a bacterial infection. The urine needs to be drained from the body at the earliest.

5. Ureteral Strictures - If the stones travel from the kidneys to the ureters, they become narrow, resulting in ureteral strictures.

6. Chronic Kidney Disease - If the uric acid levels keep on rising, the kidneys lose their ability to reabsorb them and get damaged permanently.

Conclusion:

Hyperuricosuria is when uric acid is present in large amounts in the urine. Uric acid forms when the body uses purines for various activities. Several causes of hyperuricosuria include gout, genetic disorders, diabetes, and Crohn's disease. Also, a diet rich in purine increases the risk of hyperuricosuria. The patient experiences severe flank pain, which does not subside easily and increases during the day and night. Stones form when uric acid crystals clump together. These stones block the urine flow and interfere with the ability of the kidneys to reabsorb uric acid. Though the condition is serious, it is not incurable. Medications are available that reduce uric acid levels and make the urine's pH (potential of hydrogen) alkaline. The patient need not worry, as surgical intervention is required only when uric acid stones are present. Consult the doctor at the earliest for diagnosis and treatment of the condition.