Cystinuria: Causes, Symptoms, Diagnosis and Treatment

Written by Medicover Team and Medically Reviewed by Dr Ramchander Thorrem , Nephrologist

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Cystinuria is a rare genetic disorder characterized by the formation of cystine stones in the kidneys, ureters, and bladder. This condition arises due to a defect in the transport of specific amino acids, leading to their increased excretion in urine. Understanding cystinuria, its causes, symptoms, and available treatments is crucial for managing this condition effectively.

What is Cystinuria?

Cystinuria is an inherited (genetic) disorder that affects the way your kidneys handle certain amino acids, especially cystine. Normally, these amino acids are filtered by your kidneys and reabsorbed into the body. In people with cystinuria, cystine isn't reabsorbed well and spills into the urine, where it can form hard stones.

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What Are the Different Types of Cystinuria?

Cystinuria is not a one-size-fits-all condition. It can be classified into three distinct types based on the specific genetic mutation involved. These types affect how your body handles certain amino acids and how much cystine builds up in your urine.

Type A Cystinuria

Type B Cystinuria

Type AB Cystinuria

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What Are the Common Causes of Cystinuria?

Understanding the causes of cystinuria involves looking at two key factors, the genetic basis and the resulting enzyme deficiency that interferes with normal kidney function.

Genetic Basis

Cystinuria is an autosomal recessive disorder, meaning an individual needs to inherit two copies of the defective gene (one from each parent) to develop the condition. The mutations impair the function of specific transporters in the renal tubules responsible for reabsorbing cystine and other dibasic amino acids (lysine, arginine, and ornithine).

Enzyme Deficiency

A deficiency in the enzymes responsible for amino acid transport leads to the accumulation of cystine in the urine. This enzyme deficiency is a direct consequence of the genetic mutations affecting the SLC3A1 and SLC7A9 genes.

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What are the Cystinuria Symptoms and Warning Signs?

Cystinuria often goes unnoticed until cystine stones begin to form or move within the urinary tract. These stones can cause a range of symptoms, some of which may appear suddenly and be quite painful. Recognizing the early warning signs is key to prompt treatment and avoiding potential complications such as infections or kidney damage.

Common symptoms include:

In some cases, stones can get stuck in the ureters or kidneys, causing serious complications.

Other Symptoms:

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How Cystinuria is Diagnosed?

Diagnosing cystinuria involves identifying the presence of cystine stones and confirming the underlying genetic condition that causes them. Because its symptoms often resemble other types of kidney stones, accurate diagnosis is essential for effective treatment.

Healthcare providers use a combination of urine tests, imaging studies, and sometimes genetic testing to pinpoint the condition and assess its severity.

Urine Tests

Imaging Studies

Genetic Testing

Identifying mutations in the SLC3A1 and SLC7A9 genes can confirm the diagnosis and classify the type of cystinuria.

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What Are the Treatment Options for Cystinuria?

The primary goal is to prevent cystine stones from forming and manage existing ones with a combination of lifestyle changes, medications, and sometimes surgery.

Increased Fluid Intake

One of the most effective ways to prevent cystine stone formation is to maintain high fluid intake. Drinking at least three to four litres of water daily helps dilute the urine, reducing cystine concentration and minimizing stone formation.

Dietary Modifications

Medications

Surgical Interventions

In cases where stones are too large to pass naturally or cause severe symptoms, surgical options may be necessary:

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When to See a Doctor?

Cystinuria is a rare inherited condition that causes kidney stones to form from a substance called cystine, which the body can't filter out properly. These stones can be painful and may come back if not managed.

See a doctor if you experience:

Children and young adults with early signs of kidney stones should also be evaluated for cystinuria.

You should seek urgent medical care if:

Early diagnosis and proper treatment can help reduce stone formation and prevent kidney damage.

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Can Cystinuria Be Prevented?

Since it's genetic, it can not be prevented, but stone formation can be reduced with careful management.

Prevention tips:

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Our Experience Treating Cystinuria

At Medicover, we specialize in treating cystinuria with a focus on long-term kidney health and quality of life. Our team of urologists, nephrologists, and dietitians works closely with each patient to manage symptoms and prevent future stones.

We provide:

At Medicover, we combine medical expertise with caring support, helping you stay informed, in control, and confident in managing cystinuria.

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