Chronic Sodium Urate Nephropathy- Causes, Symptoms, Diagnosis, and Treatment

What Is Chronic Sodium Urate Nephropathy?

Gout nephropathy, also called sodium urate nephropathy, is caused when there is excessive production of urate, reduced uric acid excretion, and a high level of uric acid in the body. The deterioration of the kidney function occurring in the patient suffering from gout is called gout nephropathy. It is a form of chronic inflammation of tubulointerstitial cells which is caused by the deposition of monosodium urate crystals in the distal collecting tubules and medullary interstitium. The presence of a chronic increase in uric acid and gout is responsible for chronic urate nephropathy.

What Is Gout?

It is a form of arthritis that is caused due to high levels of uric acid in the body. These urate crystals deposit in the joints leading to gout arthritis. It is a purine metabolism disorder leading to increased levels of uric acid (hyperuricemia) and urate crystal deposition inside and around the joints. It is characterized by tenderness in joints, inflammation, and severe pain. It generally affects the toes of the foot. On blood examination, mild to moderate proteinuria, a little increase in serum creatinine, and a marked increase in serum uric acid levels can be found.

What Is Uric Acid?

• Uric acid is a water-insoluble compound and can be found in acidic environments. It is an end product of purine metabolism formed in the liver by the action of xanthine oxidase.

• Uric acid requires the uricase enzyme for it to be converted into a water-soluble form. As human lacks uricase enzyme, the water-soluble form cannot be made inside the body. Therefore in a condition of increased uric acid, the crystals deposit inside the distal tubule of the nephron due to its acidic environment. The deposition of this crystal can cause potential damage to the nephron.

• Nephrons are the filtering units of the kidney which excrete all the waste products from the blood into the urine. The uric acid crystals, when deposited in the distal tubules, lead to the formation of uric acid stones. These stones block the kidneys and impair kidney function by removing waste, fibrosis of the kidneys, and infection.

• About 90 % of the uric acid filtered is excreted from the renal tubules.

• Hyperuricemia is the condition when the circulating levels of uric acid are in the range of more than 6 to 7 mg/dL.

What Are the Symptoms of Chronic Sodium Urate Nephropathy?

The sodium urate nephropathy is asymptomatic until it leads to kidney failure. The sign and symptoms include -

• Hematuria (blood in the urine).

• Lethargy (lack of energy).

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• Pain in the abdominal region.

• Severe pain in joints.

• Reduced urine output.

• Pain while urinating.

• Seizures.

• Kidney failure symptoms like:

  • High blood pressure.

  • Fluid retention inside the body due to the uric acid deposition in the distal tubule.

  • Hyperkalemia-high level of potassium in the blood.

  • Cardiovascular diseases can lead to stroke.

  • Foot sores.

  • Anemia.

  • Irreversible damage to the kidneys, which finally needs dialysis or a kidney transplant.

How to Diagnose Chronic Sodium Urate Nephropathy?

• Blood Tests: These can be done to detect the presence of abnormal levels of uric acid in the blood.

• Urine Tests: This can be done to detect the presence of hematuria, proteinuria, and decreased amount of uric acid.

• Kidney Biopsy: This can be done to detect impairment in kidney function caused by uric acid deposition.

• Imaging Tests: Computerized tomography (CT) and magnetic resonance imaging (MRI) can be used to assess the size and structure of the kidneys.

• Arthrocentesis: This is aspirating the fluid from the joints called the synovial fluid to detect the presence of uric acid. It is a helpful method for diagnosing gout.

• Glomerular Filtration Rate (GFR): This is done to test kidney functioning.

• Albumin to Creatinine Ratio: This is done to test if the level of albumin protein is high, which indicates kidney damage.

How to Treat Chronic Sodium Urate Nephropathy?

The treatment modality includes relieving the pain and symptoms and reducing the risk of complications and the recurrence of symptoms.

• To Reduce Pain and Inflammation - NSAIDs (non-steroidal anti-inflammatory drugs) are the drugs used to control pain and inflammation. Corticosteroids are also used to relieve pain and swelling. NSAIDs like Colchicine can be used to reduce pain.

• Uric Acid-Lowering Drugs - These drugs help to reduce or prevent the further deposition of uric acid in the body. Drugs like Allopurinol and Febuxostat can be used.

• Treat Kidney Failure - Prompt treatment would be dialysis or a kidney transplant. The disease progression cannot be stopped but can be limited.

Who Is at the Risk of Getting Chronic Sodium Urate Nephropathy?

• Patients on drugs containing high levels of uric acid.

• Obesity.

• Advanced age.

• Family history.

• Prolonged dehydrated condition.

• Patients have a history of gout.

• Excessive intake of foodstuffs containing increased levels of uric acid like red meat.

• Patients who are suffering from uric acid stones inside the kidney.

• Chronic arthritis.

What Are the Preventive Measures for Chronic Sodium Urate Nephropathy?

• Dietary Changes - Drinking plenty of water can help the kidneys to function better and avoid dehydration. Eating healthy food to avoid weight gain. Regular exercise can help in extra weight management. Avoiding alcohol consumption, red meat, and shellfish can increase the uric acid in the body. Avoid drinks containing high levels of fructose. Protein from animal sources elevates uric acid levels. Avoiding it can prevent elevation in the level of circulating uric acid.

• Medications - Such as Diuretics and immunosuppressants are found to elevate uric acid levels. These medications should be altered after the physician's opinion.

Conclusion

Patients suffering from obesity, hypertension, and diabetes mellitus are at a higher risk of developing sodium urate nephropathy. Dietary changes and maintaining a healthy lifestyle are two preventive measures for any type of kidney disease. Symptoms of gout nephropathy can be managed by drinking plenty of water. Putting ice on the affected joints can relieve the pain temporarily. Limiting the stress on the joints can further prevent inflammation and pain in the joints. In the case of gout nephropathy, food containing high levels of uric acid should be avoided. The risk of further complications can be prevented by following a healthy lifestyle.