Cystine Stones

What are cystine stones?

Cystine stones are a type of kidney stone. Kidney stones are a hard mass made up of a collection of chemicals in your pee. Cystine stones are made of the chemical cystine, an amino acid in your body. When cystine doesn’t reabsorb into your kidneys, it builds up and causes a cystine stone. Cystine stones tend to be large and sometimes need to be removed surgically to prevent damage to your kidneys or urinary tract. Most people with cystine stones will develop several cystine stones in their lifetimes. There are some treatment options for cystine stones that don’t involve surgery like changing your diet or taking medication to balance the pH of your pee.

What is cystinuria?

Cystinuria is a rare, inherited condition (runs in families) that causes cystine to build up in your pee. About 1 in 10,000 people has the condition. If you have cystinuria, your body has trouble dissolving cystine, which causes it to accumulate and form a cystine stone. Cystinuria can cause you to develop multiple cystine stones throughout your life. Cystinuria is an autosomal recessive gene that runs in your biological family. This means both parents need to have the gene for cystinuria to pass it to their biological child. It’s a lifelong condition with no cure. You can only manage the condition with the right treatments.

How rare are cystine kidney stones?

Cystine stones account for 1% to 2% of all kidney stones. But they make up 6% to 8% of kidney stones in children. In fact, more than 80% of people who get cystine stones get their first stones before age 20. But, you can develop a cystine stone (or multiple stones) at any age.

What are the symptoms of cystine stones?

The symptoms of cystine stones are similar to those of other types of kidney stones. You only feel symptoms if you have a stone.

Symptoms can include:

• Feeling a sharp pain in your side or back (this is typically on one side of your body).
• Feeling pain in your groin or abdomen.
• Seeing blood in your pee.
• Vomiting and upset stomach.
• Pain when you pee (if the stone is near your bladder).

In some cases, a urinary tract infection (UTI) may occur because a cystine stone is stuck. Cystine stones tend to be larger than other types of kidney stones, causing complications like UTIs.

What causes cystine stones?

People with a rare condition called cystinuria get cystine stones. Changes in the SLC3A1 and SLC7A9 genes cause you to be born with cystinuria. Cystinuria makes it harder for your body to process cystine, which leads to it building up and forming stones. Cystine stones can get stuck anywhere in your urinary tract such as your bladder or kidneys.

What are cystine stones made of?

Cystine stones are made of cystine. Cystine is an amino acid. Amino acids are a type of protein that help repair your body’s tissues, build muscle and fight infection. People with cystinuria have a problem with how their kidneys absorb or process this amino acid.

What are the complications of cystine stones?

Cystinuria is a condition you’ll have for life. Your healthcare provider can help you manage the condition with medications, dietary and lifestyle changes and surgery, but you’ll be prone to getting cystine stones for the rest of your life. They can become quite painful, especially if you’re waiting for one to pass.

Complications of cystine stones include:

• Kidney infections.
• Blocked ureter (the tube that carries pee from your kidneys to your bladder).
• Urinary tract infections (UTIs).
• Damage to your kidney.

How are cystine stones diagnosed?

Your healthcare provider diagnoses cystine stones by listening to your symptoms and getting your full medical history, including your family history. Other ways they diagnose it include:

• Ordering imaging tests (ultrasounds and CT scans) and urine tests.
• Sending a stone to a lab for testing. If you can collect a stone that has passed out of your body with your pee, your healthcare provider can send it to a lab for analysis. In the analysis, they can identify what chemical makes up the stone.

How is cystinuria treated?

A major part of treating cystine stones is preventing stones from forming in the first place. A big part of this involves reducing the amount of cystine in your pee. Your healthcare provider will likely recommend a mix of treatment options like medication and changes to your eating habits to reduce the number of stones you get. If medication and a modified eating plan aren’t enough to prevent stones from forming or if the stones become large, surgery is another treatment option.

Medication

If your provider thinks the stone will pass on its own by drinking lots of water, they may recommend over-the-counter (OTC) pain medication like acetaminophen for discomfort. They may recommend medications like tiopronin and d-penicillamine, which can help prevent the development of future stones

Eating Plan

Your provider may recommend changing your eating habits to prevent stones from developing. Some of these recommendations could include:

• Drinking lots of water. This can help pass a cystine stone. Your provider may recommend drinking 96 ounces of water in a day, a glass of water every hour and/or waking up to drink water at night.
• Limiting the amount of sodium (salt) you eat. This could mean eliminating frozen or canned foods.
• Cutting back on how often you eat animal protein (meat) and swapping it for plant-based protein instead.

Surgery

Large stones can cause damage if they can’t pass through your urinary tract. These stones can be very painful and prevent the flow of pee out of your body. There are several options your healthcare provider may use to remove a stone, including:

• Inserting a small, flexible camera up your urethra, bladder and ureter, then locating the stone and removing it (ureteroscopy).
• Making a small incision in the skin of your back and inserting a tube into your kidney to remove the stone (percutaneous nephrolithotomy).

How do I know treatment is working?

Your healthcare provider may order a urinalysis to periodically check your cystine levels. This test can tell them if your treatment plan is working.

Can you dissolve cystine stones?

It's possible to pass a cystine stone, but it requires careful monitoring and ongoing treatment.

What foods help cystinuria?

Research shows that people with cystinuria can benefit from changes in their eating habits. Some of these changes include drinking more water, eating fruits and vegetables and eating less salty foods.

Can cystine stones be prevented?

Cystinuria is an inherited condition (passed down through a family) that you can’t prevent. But you can prevent the formation of cystine stones by following your healthcare provider’s treatment plan.

Is cystinuria life-threatening?

It’s usually not life-threatening and most people don’t end up with kidney failure. It’s important to work with your healthcare provider on a treatment that works for you. Most people respond well to treatment and can find a treatment method that doesn’t lead to kidney, bladder or urinary tract damage.

What is the outlook for cystine stones?

Cystine stones can happen multiple times in your life. If you have cystinuria, you may need food-related changes and medication to prevent the formation of cystine stones. Your healthcare provider will monitor you and make sure you receive proper treatment for any new cystine stones to prevent damage to your urinary tract, kidneys and bladder.

When should I see my healthcare provider?

Talk to your healthcare provider if you experience any signs of a kidney stone. Some of the most common symptoms include:

• Pain in your abdomen, side, back or groin area.
• Nausea and vomiting.
• Painful urination.

A note from Cleveland Clinic

Cystinuria is a lifelong condition that causes you to get cystine stones. Work with your healthcare provider on a treatment plan that prevents stones from developing. Since the condition is genetic, it’s helpful for people who have cystinuria to receive genetic counseling if they wish to expand their families. The good news is that the condition is usually manageable with treatment and typically doesn’t lead to kidney failure or serious damage to your urinary tract.