About cystinosis

What is nephropathic cystinosis?

Cystinosis is a very rare genetic condition that affects small structures inside the cells called lysosomes.In healthy cells, lysosomes store protein building blocks and break them down into smaller pieces called amino acids. Cystine is one of these amino acids. Cystine and other amino acids are then transported out of the lysosome to make room for new proteins, and the cycle repeats itself.2

But in people with cystinosis, cystine isn’t able to move efficiently, so it gets trapped and builds up inside lysosomes. This is why cystinosis is called a lysosomal storage disorder.1 If left untreated, cystine will build up to toxic concentration within hours, and over time can cause serious, long-term, irreversible damage to organs and tissue.1,3-6

Cystinosis is rare, affecting about 500 people in the US and approximately 2,000 worldwide.7 Nephropathic or “classic infantile” cystinosis is the most common and most severe form of the disease.1,6 Symptoms of nephropathic cystinosis typically appear within a baby’s first year. The disease may affect more males than females, 1.4:1 according to one study.4 Nephropathic cystinosis is classically associated with blond-haired, blue-eyed children of European descent, but all races and ethnic backgrounds may be affected.1

Cystinosis and the cells7,8

Normal Lysosome

In a normal lysosome, cystine and lysine are produced and then transported away through the lysosomal membrane by their own transporters.

Untreated Cystinotic Lysosome

In people with nephropathic cystinosis, the transport system doesn’t work properly. While lysine is able to pass through the lysosome membrane, cystine is not.

In an untreated cystinotic lysosome, cystine is unable to exit the lysosome and its accumulation leads to irreversible cell damage.

As toxic accumulation of cystine continues, crystals may form within the lysosome. Increased and sustained cystine concentration can eventually lead to cell destruction. Although nephropathic cystinosis affects the entire body, the kidneys and eyes are typically affected first.1 Patients with nephropathic cystinosis usually show symptoms of Fanconi syndrome, a disorder of the kidney tubules that causes patients to lose important nutrients and minerals in the urine, between 6 and 12 months of age.

Treated Cystinotic Lysosome

Fortunately, cystine-depleting medications are available to treat nephropathic cystinosis. These medications effectively “modify” cystine, allowing it to pass through the membrane, which slows accumulation and crystallization. This may help delay disease progression.

In a treated cystinotic lysosome, cystine-depleting medications modify cystine to resemble lysine, thus enabling it to go through the lysine transporter. Cystine-depleting medications do not appear to remove previously accumulated crystals in the body or reverse previous damage to the cells.

What are the symptoms of cystinosis?

Although nephropathic cystinosis affects the entire body, the kidneys and eyes are typically affected first.9 Patients with nephropathic cystinosis usually show symptoms of Fanconi syndrome, a disorder of the kidney tubules that causes patients to lose important nutrients and minerals in the urine, between 6 and 12 months of age.1,6

In the eyes, cystine crystals form on the cornea. This can cause people with cystinosis to experience severe light sensitivity, which means that a bright sunny day can be painful. They may want to avoid bright lights or wear sunglasses to be more comfortable, and sometimes they may need to wear sunglasses indoors.1,9

In addition to forming in the kidneys and eyes, cystine crystals can also form in such organs and tissue as the liver, spleen, lymph nodes, thyroid, intestines, muscle, brain, and bone marrow.1 Nephropathic cystinosis is a progressive disease, which means it gets worse over time if left untreated, and can lead to damage to the heart, central nervous system, and muscle tissue.1 Before the availability of cystine-depleting medication, nephropathic cystinosis would progress to kidney failure and sometimes death, usually between 9 and 10 years of age.5,6

Multiple organ systems are affected in patients with cystinosis and as time progresses and without treatment, toxic levels of cysteine can lead to irreversible organ damage.1 Today, people with cystinosis have treatment options in the form of cystine-depleting medications. Ongoing, regular treatment is needed to keep cystine concentration in check.5 In order to determine how effectively treatment is working, it is important that people with nephropathic cystinosis test their white blood cell cystine concentration on a regular basis.10

Managing Cystinosis

Maintaining healthy cystine concentration over time

ManagingCystinosisCystinosis is a progressive, incurable disease that gets worse over time. Without treatment, cystine can elevate to toxic concentration very quickly—sometimes within hours—and eventually lead to severe and irreversible organ damage. Keeping cystine concentration under control is the only way to limit or prevent this kind of damage.1,3-6

Cysteamine, a cystine-depleting therapy, is critical to the management of cystinosis.1,3,4 Cysteamine helps by effectively reducing the toxic concentration of cystine in cells.3

Maintaining healthy cystine concentration is as important for you today as it was when you were first diagnosed, even if you’ve had a kidney transplant and even if you look or feel fine. Even brief interruptions in cysteamine dosing allow cystine concentration to become toxic again.5

The importance of white blood cell cystine testing

Along with careful adherence to a treatment plan, white blood cell (WBC) cystine testing can play an important part in helping you manage cystinosis. WBC cystine testing helps you see any changes in your cystine concentration, which helps you and your doctor determine the effectiveness of a given cystine-depletion medication and determine if you are titrated to maximum clinical benefit.10,11

The goal of cystine-depleting medications is to keep cystine concentration to less than 1 nmol ½ cystine/mg of protein. To achieve continuous cystine control, regular WBC cystine tests may be needed—as often as every 3 months, and sometimes more frequently.10,12

In a research study, people with cystinosis who took PROCYSBI every 12 hours as directed maintained WBC concentration and kidney function during 24 months or more of treatment.9,10,13

Taking PROCYSBI® (cysteamine bitartrate) delayed-release capsules as directed and having regular WBC cystine tests may help you stay in control of your cystine concentration.10

Healthy habits

Create a routine that’s right for you

Managing cystinosis can be complicated and challenging. At times, you may feel overwhelmed by all the medicines you need to take and the rules and routines you need to remember.

But remember that there is help. Simple lifestyle changes and healthy habits may help make managing cystinosis a little easier.

Track your cystine concentration with regular white blood cell cystine testing

Testing your white blood cell (WBC) cystine concentration on a regular basis is one of the most important habits to build when trying to manage cystinosis. WBC cystine testing helps you see any changes in your cystine concentration, which helps you and your doctor determine the effectiveness of a given cystine-depletion medication and determine if you are titrated to maximum clinical benefit. Because controlling cystine concentration is the only way to limit or prevent organ and tissue damage, it is essential to know if your medication or therapy is working the way it should be.10,11

WBC cystine testing is important even if you’ve had a kidney transplant and even if you look or feel fine. Even brief interruptions in your cystine-depleting therapy allow cystine concentration to become toxic again.5

To achieve continuous cystine control, it may be necessary to test WBC cystine concentration as often as every 3 months, and sometimes more often.10,12 Frequent WBC testing is an important way to combat high cystine concentration. WBC cystine testing gives you and your healthcare professional more information to help you manage your disease.


Cystinosis affects the diets and nutritional needs of patients throughout the course of their lives, from onset and diagnosis through adulthood. Certain cystinosis-related medical complications, such as dialysis and kidney transplantation, can make proper nutrition even more difficult. Depending on factors like age and severity of disease, different kinds of foods, drinks, or eating habits may be needed or recommended. Of course, just like anyone else, people with cystinosis must receive the right nutrition and give their bodies what they need to stay as healthy as possible.1

Continue reading for some advice on how to handle some nutritional challenges particular to cystinosis. Always consult your doctor or healthcare professional when making a treatment and nutrition plan.

Dehydration and nutrient loss

Cystinosis is one of the most common causes of Fanconi syndrome, a kidney disorder.6 In Fanconi syndrome, important nutrients don’t get reabsorbed by the kidneys and instead get passed into the urine.1,6 Without the right amounts of these nutrients and minerals, patients with Fanconi syndrome and cystinosis often display symptoms like poor growth rates, bone deformities, and excessive thirst.3

In general, it is important that patients with Fanconi syndrome and cystinosis always have easy access to fresh water, because they will need larger quantities to make up for what they’re losing through their urine. Potassium and phosphate supplements may also be recommended.14

Kids with cystinosis often crave salty foods. This is because they’re losing extra salt through their urine.11 In the absence of other health issues, there is no need to restrict the amount of salt they consume.14

Growth impairment and eating problems

For people with cystinosis, mealtimes can sometimes be difficult and uncomfortable. This is especially true for children and adolescents. Some common complaints include choking, gagging, and vomiting; overly sensitive gag reflex; reflux issues; slow gastric emptying; oral aversion; and complaints relating to texture. If not properly managed, these difficulties can prevent patients from eating enough, which results in calorie, protein, and nutrient shortages.14

Patients with cystinosis need to make sure they’re eating enough to get sufficient nutrients and stay healthy. Supplements can be helpful, as can a growth hormone (if recommended by a doctor). To make mealtime easier, consider replacing the standard three big meals a day with smaller, more frequent meals; taking or giving appetite stimulants; using a feeding tube; or doing occupational therapy. Working with a speech therapist and/or nutritionist may be helpful in resolving certain eating problems.14

Dialysis and diet restrictions

Some people with cystinosis will be required to go on dialysis, which presents its own dietary challenges. Dialysis helps clean waste from the blood of people with kidney disease and malfunction. A dialysis diet tries to limit the amount of waste in the blood, so that less waste needs to be removed by the procedure.15

In general, people on dialysis need to eat more high-protein foods; eat less high-salt, high-potassium, and high-phosphorous foods; and learn how much fluid is safe to drink.15 A common complaint of people on this diet is that it’s unhealthy because of these restrictions.14

The key to managing a dialysis diet is learning correct portion sizes. For example, while fruits and vegetables do contain potassium, they may be safe to eat within certain limits. The right portion size will let patients on dialysis diets eat foods they like and receive important nutrients without compromising their treatment goals.14 It is also important to supplement properly with vitamins when on dialysis because the procedure can remove important vitamins from the blood while cleaning it.14

For more information on dialysis diets, visit Kidney.org.

Kidney transplant

After a kidney transplant, many people with cystinosis begin to feel better. They may start eating more and growing at a more normal rate. However, it is also very common for patients to gain too much weight in the year or so following transplantation. Obesity is linked to many other health complications, so it is best avoided.14

In general, patients with cystinosis who have had kidney transplants should follow “heart-healthy” diets that prevent obesity. Heart-healthy diets include lots of fruits, vegetables, and whole grains and limit portion sizes and unhealthy fats like butter and margarine.


1. Gahl WA, Thoene JG, Schneider JA. Cystinosis. N Engl J Med. 2002;347(2):111-121.

2. Cooper GM. The Cell: A Molecular Approach. 2nd edition. Sunderland (MA): Sinauer Associates; 2000. Available at http://www.ncbi.nlm.nih.gov/books/NBK9953. Accessed July 22, 2015.

3. Brodin-Sartorius A, Tète M-J, Niaudet P, et al. Cysteamine therapy delays the progression of nephropathic cystinosis in late adolescents and adults. Kidney Int. 2012;81:179-189.

4. Gahl WA, Balog JZ, Kleta R. Nephropathic cystinosis in adults: Natural history and effects of oral cysteamine therapy. Ann Intern Med. 2007;147:242-250.

5. Levtchenko EN, van Dael CM, de Graaf-Hess AC, et al. Strict cysteamine dose regimen is required to prevent nocturnal cystine accumulation in cystinosis. Pediatr Nephrol. 2006;21:110-113.

6. Nesterova G, Gahl WA. Cystinosis: The evolution of a treatable disease. Pediatr Nephrol. 2013;28:51-59.

7. Cystinosis Research Foundation. “About Cystinosis.” Available at http://www.cystinosisresearch.org/About-Cystinosis. Accessed December 4, 2015.

8. Genetics Home Reference. “What is a cell?” Available at http://ghr.nlm.nih.gov/handbook/basics/cell. Accessed December 4, 2015.

9. Langman CB, Greenbaum LA, Sarwal M, et al. A randomized controlled crossover trial with delayed-release cysteamine bitartrate in nephropathic cystinosis: Effectiveness on white blood cell cystine levels and comparison of safety. Clin J Am Soc Nephrol. 2012;7:1112-1120.

10. PROCYSBI [package insert]. Lake Forest, IL: Horizon Pharma USA, Inc; 2017.

11. Dalton, Neil. The importance of accurate cystine level testing. Cystinosis Research Network. Available at https://cystinosis.org/images/research/article-library/cystagon/2009_01_Cystine_Level_Testing.pdf. Accessed December 4, 2015.

12. CYSTAGON [package insert]. Morgantown, WV: Mylan Pharmaceuticals Inc.; 2007.

13. Langman CB, Greenbaum LA, Grimm P, et al. Quality of life is improved and kidney function preserved in patients with nephropathic cystinosis treated for 2 years with delayed-release cysteamine bitartrate. J Pediatr. 2014;165(3):528-533.e.1.

14. Data on file, Horizon Orphan LLC

15. “Kidney diet: Dialysis patients overview.” New York Times. Available at http://www.nytimes.com/health/guides/nutrition/kidney-diet-dialysis-patients/overview.html?print=1#Food-Sources. Accessed July 21, 2015.

What is PROCYSBI (Pro-CIS-bee)?

PROCYSBI® (cysteamine bitartrate) delayed-release capsules is a prescription medicine used to treat a medical condition called nephropathic cystinosis, in adults and children 1 year of age and older.

It is not known if PROCYSBI is safe and effective in children under 1 year of age.

Who should not take PROCYSBI?

Do not take PROCYSBI if you are allergic to penicillamine or cysteamine.

What should I tell my doctor before taking PROCYSBI?

Before you take PROCYSBI, tell your doctor if you:

  • drink alcohol
  • have a skin rash or bone problems
  • have or have had stomach or bowel (intestinal) problems including ulcers or bleeding
  • have a history of seizures, lack of energy, unusual sleepiness, depression or changes in your ability to think clearly
  • have liver or blood problems
  • have any other medical conditions
  • are pregnant or plan to become pregnant. It is not known if PROCYSBI will harm your unborn baby. Tell your doctor right away if you think that you are pregnant. Talk with your doctor about the benefits and risks of taking PROCYSBI during pregnancy.
  • are breastfeeding or plan to breastfeed. You should not breastfeed during treatment with PROCYSBI. Talk with your doctor about the best way to feed your baby if you take PROCYSBI.

Tell your doctor about all medicines that you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Know the medicines you take. Keep a list of them to show your doctor and pharmacist when you get a new medicine.

What should I avoid while taking PROCYSBI?

Do not drive or operate heavy machinery until you know how PROCYSBI affects you. PROCYSBI can make you sleepy or less alert than normal.

Do not drink alcohol if you take PROCYSBI. Drinking alcohol while taking PROCYSBI may change how PROCYSBI works and may cause an increase in the amount of PROCYSBI in your blood that may cause serious side effects.

What are the possible side effects of PROCYSBI? PROCYSBI can cause serious side effects, including:

  • Skin, bone, and joint problems. People treated with high doses of cysteamine bitartrate may develop abnormal changes of their skin and bones. These changes may include stretch marks, bone injuries (such as fractures), bone deformities, and joint problems. Check your skin while taking PROCYSBI. Tell your doctor if you notice any skin changes or problems with your bones or joints. Your doctor will check you for these problems.
  • Skin rash. Skin rash is common with cysteamine bitartrate and may sometimes be severe. Tell your doctor right away if you get a skin rash. Your dose of PROCYSBI may need to be decreased until the rash goes away. If the rash is severe, your doctor may tell you to stop taking PROCYSBI.
  • Stomach and bowel (intestinal) Some people who take other medicines that contain cysteamine bitartrate develop ulcers and bleeding in their stomach or bowel. Tell your doctor right away if you get stomach-area pain, nausea, vomiting, loss of appetite, or vomit blood.
  • Central nervous system symptoms. Some people who take other medicines that contain cysteamine bitartrate develop seizures, depression, and become very sleepy. The medicine may affect how your brain is working (encephalopathy). Tell your doctor right away if you develop any of these symptoms.
  • Low white blood cell count and certain abnormal liver function blood tests. Your doctor should check you for these problems.
  • Benign intracranial hypertension (pseudotumor cerebri) has happened in some people who take immediate-release cysteamine bitartrate. This is a condition where there is high pressure in the fluid around the brain. Your doctor should do eye examinations to find and treat this problem early.

Tell your doctor right away if you develop any of the following symptoms while taking PROCYSBI: headache, buzzing or “whooshing” sound in the ear, dizziness, nausea, double vision, blurry vision, loss of vision, pain behind the eye or pain with eye movement.

The most common side effects with PROCYSBI include vomiting, nausea, stomach (abdominal) pain, breath odor, diarrhea, skin odor, tiredness, skin rash, headache, and problems with body salts or electrolytes.

Tell your doctor if you have any side effect that bothers you or that does not go away. These are not all of the possible side effects of PROCYSBI. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088.

Issued: 12/2017                    Piece number: P-PYB-00032                    Derived from Patient Information approved 12/2017