What is Cystinuria? Causes, Symptoms Diagnosis of Cystinuria

Genetic inheritance of characteristics is a concrete fact. Just like the color of your hair, your height, and your skin tone, some diseases can also be passed from parents to offspring. Cystinuria is one such disease in which both parents having this condition pass the necessary genetic information to their offspring that is responsible for the expression of Cystinuria in a person. To completely understand Cystinuria, it is necessary to have basic knowledge of the field of genetics. In this blog, we will see the underlying cause of Cystinuria, its symptoms, diagnosis, and treatment options.

What is Cystinuria?

In terms of prevalence, Cystinuria is a rare genetic condition. One in every 10,000 people gets affected by it. Both males and females are affected by Cystinuria in equal numbers. In a cystinuria-affected person, the risk of formation of cystine kidney stones always remains high. In 85% of cystinuria-affected patients, the first kidney stone appearance occurs at the age of 20.

Cystine kidney stones differentiate themselves from other kidney stones by being larger, harder, and more frequently occurring. Cystine kidney stones are generally to be surgically removed which again puts the patient at risk of damaging the kidney

Formation of cystine stone

Cystine is a form of amino acid. Amino acids are the units of proteins that are involved in various functions of the body. Cystine in the urine is normally transported back into the blood. People with the genetic disorder of Cystinuria are unable to reabsorb cystine into their bloodstream causing the building up of cystine. This is the basic outline of how cystine stones are formed.

Cause of Cystinuria

The two genes that are mutated to cause Cystinuria are SLC3A1 and SLC7A9. As every gene is responsible in the expression of a protein, these two genes regulate the transport of Cystinuria from urine into the blood. Cystinuria is an autosomal recessive disease which means both the copies of each of these two genes must be affected in an individual to get Cystinuria. Even for the people who are only the carriers of Cystinuria have above-the-normal levels of cystine in their urine.

Symptoms of Cystinuria

Generally, the symptoms of Cystinuria are first prevalent in the affected patient at the age of 20. These symptoms include:

• Flank pain
• Hematuria
• Abdominal pain
• Nausea

The cause of Cystinuria being asymptomatic for 20 years is that the symptoms seen in this condition are associated with the formation of the kidney stones and not merely the presence of this condition

Diagnosis of Cystinuria

The initial step in the diagnosis of Cystinuria is consulting the patient for their symptoms and family or personal medical history. It must also be kept in mind to evaluate other conditions, if any, which have an association with cystine kidney formation. These conditions may include Hematuria, UTI, etc.

After the evaluation for establishing family medical history and links of other conditions with Cystinuria is established, the diagnosis is taken to the level of testing the patient with various methodologies such as:

• Urinalysis: In this test method, a urine sample from the patient is examined in the lab for its color and composition. The sample is examined under a microscope and by involving the sample in chemical testing. For urinalysis, it is necessary to bring a sample which is not more than 24 hours old
• Pyelogram: In this method, the movement of a dye, that is intravenously injected, is examined by X-Ray
• CT scan: This method is used to picture the sharper images of the abdominal area to examine the changes caused by the kidney stones in the kidney or even to establish the presence of kidney stones  

Treatment of Cystinuria

Management and treatment of Cystinuria is done by following steps:

• Taking general precautions to avoid the formation of kidney stones which will mainly include restricting the intake of salt.
• Taking the sources of alkalinizing agents as cystine becomes highly soluble at high PH levels.
• Taking prescribed drugs such as tiopronin helps in the prevention of crystallization of cystine
• If the above-mentioned treatment options fail to help the condition of the patient suffering from Cystinuria to get better, then the patient must get surgically treated. Some of the surgical methods that can be used to treat extreme cases of Cystinuria are
  • Lithotripsy
  • Endoscopic basket extraction
  • Dissolving the kidney stones from laser techniques
  • Genetic therapy

Conclusion

No doubt Cystinuria is a rare condition, but the treatment of every condition starts with the seeking help of a doctor who can help you manage it. Nephrologists are the doctors who specialize in dealing with the kidney conditions like these.

At Alfa Kidney Care, we let our patients be diagnosed and treated only by experienced professionals. To know more about your kidney, contact us at Alfa Kidney Care