ICD-10: E72.01

Cystinuria, classified under the ICD-10-CM code E72.01, is a genetic disorder characterized by the abnormal excretion of cystine, an amino acid, in the urine. This condition arises due to a defect in the renal tubular transport of cystine and other dibasic amino acids, leading to elevated levels of cystine in the urine, which can precipitate and form stones in the urinary tract.

Clinical Features

Pathophysiology

Cystinuria is primarily caused by mutations in the SLC3A1 or SLC7A9 genes, which encode for the transporters responsible for reabsorbing cystine and other dibasic amino acids in the kidneys. The defective transport leads to excessive cystine in the urine, which can crystallize, forming stones that may cause renal colic, hematuria, and urinary tract infections[1].

Symptoms

Patients with cystinuria may experience a range of symptoms, including:
- Recurrent kidney stones: The most common manifestation, often leading to severe pain and complications.
- Hematuria: Blood in the urine, which can occur due to stone formation and irritation of the urinary tract.
- Urinary tract infections: Increased risk due to the presence of stones and urinary stasis.
- Abdominal pain: Often associated with the passage of stones.

Diagnosis

Diagnosis of cystinuria typically involves:
- Urine tests: A 24-hour urine collection may reveal elevated levels of cystine.
- Genetic testing: Identifying mutations in the SLC3A1 or SLC7A9 genes can confirm the diagnosis.
- Imaging studies: Ultrasound or CT scans may be used to visualize kidney stones.

Management and Treatment

Medical Management

The management of cystinuria focuses on preventing stone formation and managing symptoms:
- Hydration: Increasing fluid intake to dilute urine and reduce cystine concentration.
- Medications: Thiol drugs such as tiopronin (THIOLA® EC) can help to reduce cystine levels by converting cystine into a more soluble compound[2].
- Dietary modifications: Reducing sodium and protein intake may help lower cystine levels in the urine.

Surgical Intervention

In cases where stones are large or cause significant obstruction, surgical options may be necessary, including:
- Ureteroscopy: A minimally invasive procedure to remove stones.
- Extracorporeal shock wave lithotripsy (ESWL): A non-invasive technique that uses shock waves to break stones into smaller pieces.

Prognosis

With appropriate management, individuals with cystinuria can lead normal lives, although they may require ongoing monitoring and treatment to manage their condition effectively. Regular follow-up with a healthcare provider is essential to monitor for complications and adjust treatment as necessary.

In summary, cystinuria (ICD-10-CM code E72.01) is a significant metabolic disorder that requires a comprehensive approach to diagnosis and management, focusing on preventing complications associated with kidney stones and maintaining renal health[3].

[1] Cystinuria: Pathophysiology and Clinical Features.
[2] Treatment Options for Cystinuria.
[3] Overview of Cystinuria Management.

Cystinuria, classified under ICD-10 code E72.01, is a genetic disorder characterized by the excessive excretion of cystine and other amino acids in the urine due to a defect in renal tubular reabsorption. This condition can lead to the formation of cystine stones in the kidneys, which can cause significant clinical issues. Below is a detailed overview of the clinical presentation, signs, symptoms, and patient characteristics associated with cystinuria.

Clinical Presentation

Signs and Symptoms

1. Renal Colic: Patients often experience severe flank pain due to the passage of kidney stones. This pain can be intermittent and may radiate to the lower abdomen or groin[1].

2. Hematuria: The presence of blood in the urine is common, which may be visible (gross hematuria) or detectable only under a microscope (microscopic hematuria)[1].

3. Urinary Tract Infections (UTIs): Recurrent UTIs may occur due to the obstruction caused by stones, leading to symptoms such as dysuria (painful urination), urgency, and frequency[1].

4. Nausea and Vomiting: These symptoms can arise from severe pain or as a response to the obstruction caused by stones[1].

5. Chronic Kidney Disease: Over time, recurrent stone formation can lead to kidney damage and chronic kidney disease, which may present with fatigue, swelling, and changes in urine output[1].

Patient Characteristics

1. Genetic Background: Cystinuria is an autosomal recessive disorder, meaning that it typically manifests in individuals who inherit two copies of the mutated gene, one from each parent. It is more prevalent in certain populations, including those of Mediterranean descent[1][2].

2. Age of Onset: Symptoms often begin in childhood or early adulthood, with many patients experiencing their first stone episode by the age of 20[2].

3. Family History: A significant number of patients have a family history of cystinuria or related kidney stone diseases, indicating a genetic predisposition[2].

4. Gender: While cystinuria can affect both genders, some studies suggest a slightly higher prevalence in males, particularly in the context of stone formation[2].

5. Dietary Factors: Patients may have dietary habits that contribute to stone formation, such as high protein intake, which can exacerbate cystine levels in the urine[2].

Conclusion

Cystinuria is a complex condition that requires careful management to prevent complications such as kidney stones and chronic kidney disease. Understanding the clinical presentation, including the signs and symptoms, as well as the patient characteristics, is crucial for timely diagnosis and treatment. Patients with a family history of the disorder or those presenting with recurrent kidney stones should be evaluated for cystinuria, and appropriate genetic counseling may be beneficial for affected families. Regular follow-up and lifestyle modifications, including dietary changes and increased fluid intake, are essential components of managing this condition effectively.

Cystinuria, classified under the ICD-10-CM code E72.01, is a genetic disorder characterized by the excessive excretion of cystine in the urine, leading to the formation of kidney stones. Understanding alternative names and related terms for this condition can enhance clarity in medical documentation and communication. Below are some of the key alternative names and related terms associated with cystinuria.

Alternative Names for Cystinuria

1. Cystine Urolithiasis: This term refers specifically to the formation of stones (uroliths) in the urinary tract due to high levels of cystine.
2. Cystinuria Type I: This designation is sometimes used to specify the most common form of cystinuria, which is caused by a defect in the renal tubular transport of cystine and other dibasic amino acids.
3. Cystinuria Syndrome: This broader term may encompass the various clinical manifestations and complications associated with cystinuria, including recurrent kidney stones and potential renal damage.

Related Terms

1. Amino Aciduria: A general term that refers to the presence of amino acids in the urine, which can include cystine in the case of cystinuria.
2. Dibasic Amino Acid Transport Disorder: This term describes the underlying mechanism of cystinuria, where the renal tubules fail to reabsorb dibasic amino acids, including cystine, lysine, arginine, and ornithine.
3. Renal Tubular Acidosis: While not synonymous with cystinuria, this condition can occur alongside it, as both involve renal tubular dysfunction.
4. Cystinosis: Although distinct from cystinuria, cystinosis is another disorder involving cystine metabolism, characterized by the accumulation of cystine within lysosomes, leading to different clinical outcomes.

Conclusion

Cystinuria is a complex condition with various alternative names and related terms that reflect its clinical features and underlying mechanisms. Understanding these terms is crucial for healthcare professionals in diagnosing, treating, and communicating about the disorder effectively. If you have further questions or need more specific information regarding cystinuria or related conditions, feel free to ask!

Cystinuria, classified under ICD-10 code E72.01, is a genetic disorder characterized by the excessive excretion of cystine in the urine, leading to the formation of kidney stones. The diagnosis of cystinuria involves several criteria and diagnostic methods, which are essential for confirming the condition and guiding treatment.

Diagnostic Criteria for Cystinuria

1. Clinical Presentation

• Symptoms: Patients may present with symptoms such as recurrent kidney stones, hematuria (blood in urine), flank pain, and urinary tract infections. The clinical history of stone formation is a significant indicator of cystinuria[1].
• Family History: Since cystinuria is an autosomal recessive disorder, a family history of the condition can support the diagnosis[1].

2. Urine Analysis

• Urinary Cystine Levels: A 24-hour urine collection is performed to measure the levels of cystine. Elevated levels of cystine (greater than 250 mg per day) are indicative of cystinuria[1][2].
• Urine pH: The urine pH may be assessed, as cystine solubility decreases in acidic urine, which can contribute to stone formation[2].

3. Genetic Testing

• Molecular Genetic Testing: Genetic testing can confirm mutations in the SLC7A9 or SLC3A1 genes, which are responsible for cystinuria. This testing is particularly useful in ambiguous cases or when there is a need for definitive diagnosis[1][2].

4. Imaging Studies

• Ultrasound or CT Scan: Imaging studies may be conducted to visualize kidney stones and assess their size and location. This can help in evaluating the extent of the disease and planning treatment[1].

5. Differential Diagnosis

• It is crucial to differentiate cystinuria from other types of stone-forming conditions, such as calcium oxalate stones or uric acid stones. This may involve additional urine tests and imaging studies to rule out other causes of nephrolithiasis[2].

Conclusion

The diagnosis of cystinuria (ICD-10 code E72.01) is multifaceted, involving clinical evaluation, urine analysis, genetic testing, and imaging studies. Early diagnosis is essential to manage symptoms effectively and prevent complications associated with kidney stones. If you suspect cystinuria based on symptoms or family history, consulting a healthcare provider for appropriate testing and evaluation is recommended.

Cystinuria, classified under ICD-10 code E72.01, is a genetic disorder characterized by the excessive excretion of cystine in the urine, leading to the formation of cystine stones in the kidneys and urinary tract. This condition arises from a defect in the renal tubular reabsorption of cystine and other amino acids, which can result in significant morbidity due to recurrent kidney stones and associated complications. Here, we will explore the standard treatment approaches for managing cystinuria.

Treatment Approaches for Cystinuria

1. Dietary Modifications

Dietary management is a cornerstone of cystinuria treatment. The following dietary changes are typically recommended:

• Increased Fluid Intake: Patients are advised to drink plenty of fluids to dilute urine and reduce the concentration of cystine, thereby minimizing stone formation. A target of at least 3 to 4 liters of fluid per day is often suggested[1].
• Low Sodium Diet: Reducing sodium intake can help decrease cystine excretion. High sodium levels can lead to increased calcium and cystine in the urine, promoting stone formation[1].
• Protein Restriction: Limiting dietary protein, particularly animal protein, may help reduce the amount of cystine produced by the body. A diet low in methionine, an amino acid that can be converted to cystine, is often recommended[1][2].

2. Medications

Several medications can be utilized to manage cystinuria and prevent stone formation:

• Cystine-Binding Drugs: Medications such as tiopronin or penicillamine can help to reduce cystine levels in the urine by binding to cystine and forming a more soluble compound, which is easier to excrete[2][3].
• Potassium Citrate: This medication can help to alkalinize the urine, which increases the solubility of cystine and reduces stone formation. It is often prescribed to patients with acidic urine[2][3].
• Thiazide Diuretics: These can be used to reduce urinary calcium excretion and may help in some cases of cystinuria, particularly when there is a concurrent calcium stone formation[3].

3. Surgical Interventions

In cases where patients develop large cystine stones or experience recurrent urinary tract infections, surgical intervention may be necessary:

• Ureteroscopy: This minimally invasive procedure allows for the removal of stones from the urinary tract using a small scope[2].
• Percutaneous Nephrolithotomy (PCNL): For larger stones, PCNL may be performed, which involves making a small incision in the back to remove stones directly from the kidney[2][3].
• Extracorporeal Shock Wave Lithotripsy (ESWL): This non-invasive technique uses shock waves to break stones into smaller pieces that can be passed more easily[2].

4. Regular Monitoring and Follow-Up

Patients with cystinuria require ongoing monitoring to assess kidney function and the presence of stones. Regular follow-up appointments may include:

• Urine Tests: To monitor cystine levels and assess the effectiveness of dietary and pharmacological interventions[1].
• Imaging Studies: Ultrasounds or CT scans may be performed periodically to check for the presence of stones and evaluate kidney health[2].

Conclusion

Managing cystinuria involves a multifaceted approach that includes dietary modifications, pharmacological treatments, and, when necessary, surgical interventions. The primary goal is to prevent stone formation and associated complications while maintaining kidney function. Regular follow-up and monitoring are essential to adapt treatment plans as needed and ensure optimal patient outcomes. For individuals diagnosed with cystinuria, a collaborative approach involving healthcare providers, dietitians, and possibly urologists is crucial for effective management of this condition.