Cystinosis: Causes, Symptoms, and Treatment
Medically reviewed by Sumiran Racherla, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Cystinosis?
A kidney doctor called a nephrologist often leads care for cystinosis. An eye doctor called an ophthalmologist is often on the team. Children often see a pediatrician too. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is cystinosis?
Cystinosis is a condition in which an amino acid called cystine builds up inside cells. Cystine is a building block of proteins. Extra cystine damages cells. It often forms crystals that cause problems in many organs. The kidneys and eyes are especially vulnerable to damage. There are three types of cystinosis. They are nephropathic, intermediate, and ocular. The nephropathic type is the most severe.
Symptoms
Nephropathic cystinosis is the most common and most severe form. It begins in infancy, causing poor growth and a type of kidney damage called renal Fanconi syndrome. The body loses minerals, salts, and fluids in the urine.
Other signs in nephropathic cystinosis include:
- Passing a lot of urine, thirst, and dehydration.
- Soft, bowed bones, called rickets, especially in the legs.
- Pain and sensitivity to light.
- Crystals of cystine build up in the clear covering of the eye, called the cornea.
Without treatment, these children have complete kidney failure by about age 10. In untreated people with the nephropathic type, other problems can include muscle deterioration, blindness, diabetes, and thyroid and nervous system problems, especially after adolescence. The intermediate type has the same signs. They start later, usually in adolescence. The ocular type usually causes sensitivity to light. It usually does not cause kidney problems.
Causes and who gets it
All three types are caused by mutations, or changes, in the CTNS gene. These changes lead to a shortage of cystinosin, a protein that normally moves cystine out of lysosomes. Lysosomes are parts of the cell that break down and recycle materials. When cystinosin is defective or missing, cystine builds up and forms crystals. It is inherited. Both copies of the gene in each cell have mutations. The parents each carry one copy of the changed gene but typically do not show signs of the condition.
How doctors diagnose it
Doctors look at symptoms, health history, an exam, and special tests. A test of cystine in certain white blood cells can confirm the diagnosis. An eye doctor can use a special microscope, called a slit lamp, to see cystine crystals in the cornea. Genetic testing can also confirm it by finding changes in the CTNS gene. A prompt diagnosis helps medicines that lower cystine work best.
Treatment
Treatment targets each person's symptoms and may need a team of specialists. The main medicine is cysteamine, which lowers the levels of cystine in the cells of the body. Cysteamine slows kidney damage and helps children grow. It can significantly delay the need for a kidney transplant. Cysteamine should start right after diagnosis. It should continue throughout life. Taken by mouth, it can cause nausea, vomiting, and stomach discomfort. It also causes extra stomach acid. Cysteamine taken by mouth does not reach the cornea well. Cysteamine eye drops are approved to treat crystals in the cornea.
Other treatments help with problems caused by the disease:
- Drinking plenty of fluids to prevent dehydration.
- Phosphates and vitamin D to prevent rickets.
- Growth hormone, which has helped many patients grow.
- Thyroid hormone for an underactive thyroid.
- Insulin for diabetes.
Even with early treatment, people with the infantile and intermediate types eventually reach end stage kidney disease, when the kidneys stop working. They then need a kidney transplant. People generally respond very well to a kidney transplant. Cystine does not build up in the donated kidney, but it still builds up in other tissues and organs. Genetic counseling is recommended for families.
When to see a doctor
Poor growth and kidney trouble, such as a lot of thirst and urination, are usually the first signs, so talk to a doctor if a child has them. Dehydration can be severe in some people with this disease. Call 911 or go to the emergency room if someone has any of these signs:
- Severe or persistent vomiting or diarrhea.
- Trouble breathing.
- A seizure.
- Fainting or loss of consciousness.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. These doctors can watch for early signs and order basic blood and urine tests. They can refer you to specialists and help with long-term follow-up.
Common questions
Is cystinosis inherited?
Yes, it is inherited. Both copies of the gene in each cell have mutations. Both parents carry one changed copy of the gene but typically do not show signs of the condition.
Is cystinosis life threatening?
It can be. Without treatment, nephropathic cystinosis leads to kidney failure by about age 10, but treatment with cysteamine and kidney transplants has extended life well into adulthood.
Does cystinosis affect intelligence?
Usually not. Intelligence is usually normal. But many children have learning disabilities.
Does cysteamine reverse kidney damage?
No. Kidney damage that happens before treatment cannot be undone. Cysteamine can slow the loss of kidney function and delay the need for a transplant.
Sources
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
