Fanconi Syndrome

What is Fanconi syndrome?

A syndrome is a group of symptoms that occur at the same time that might not have a specific cause. Fanconi syndrome affects the proximal tubules in your kidneys and their ability to reabsorb electrolytes and other substances. Healthy proximal tubules reabsorb certain molecules into your bloodstream. These particular electrolytes and other substances are necessary for your body to function. If you have Fanconi syndrome, these molecules excessively leave your body through your urine (pee).

The molecules include:

• Phosphorus.
• Glucose.
• Potassium.
• Bicarbonate.
• Uric acid.
• Amino acids.

Who does Fanconi syndrome affect?

Fanconi syndrome can affect anybody. You can inherit the condition from one of your biological parents (inherited Fanconi syndrome). You can also develop it at some point during your life (acquired Fanconi syndrome).

What are the symptoms of Fanconi syndrome?

Symptoms of inherited Fanconi syndrome include:

• Peeing more than usual.
• Dehydration.
• Being thirstier than usual (polydipsia).
• Pain in your bones.
• Muscle weakness.
• Bone weakness.
• Bone fractures.
• Well below average height (small stature).

Symptoms of acquired Fanconi syndrome include:

• Muscle weakness.
• Low blood phosphate levels (hypophosphatemia).
• Low blood potassium levels (hypokalemia).
• More amino acids in your pee (hyperaminoaciduria).
• A buildup of acids in your bodily fluids (metabolic acidosis).
• Peeing more than usual.
• Dehydration.
• Being thirstier than usual.

What causes Fanconi syndrome?

The following conditions affect your kidney tubules and may cause Fanconi syndrome:

• Cystinosis. Cystinosis is a disease that causes the amino acid cystine to build up in your body. It may affect your kidneys, eyes, muscles, heart and brain. Cystinosis is a rare disease, and it’s the most common cause of inherited Fanconi syndrome. Cystinosis typically presents by adolescence if it causes Fanconi syndrome.
• Lowe syndrome. Lowe syndrome is a rare genetic condition that relates to your X chromosome. It affects your eyes, kidneys and brain. Lowe syndrome is a rare disease, and symptoms are typically present at birth.
• Wilson’s disease. Wilson’s disease is a genetic condition that prevents your body from adequately removing copper. As copper builds up, it may affect your liver, brain, kidneys and eyes.
• Inherited fructose intolerance. Inherited fructose intolerance is a disease that affects your metabolism because you don’t have the enzyme aldolase B. If you have inherited fructose intolerance, when you eat fructose (sugar from fruit) or sucrose (sugar from plants, especially sugarcane and sugar beets), it causes low blood sugar (hypoglycemia), which can affect your liver.
• Dent disease. Dent disease is a rare kidney disorder that causes small proteins to spill into your pee, increased amounts of calcium in your pee, calcium deposits in your kidney tubules (nephrocalcinosis), kidney stones and chronic kidney disease. It mainly affects boys, men and people assigned male at birth (AMAB).
• Glycogenosis. Glycogenosis is a genetic disorder that causes a defect in a sugar transporter (GLUT2). It affects how your intestines, liver, pancreas and kidneys handle glucose. Another name for glycogenosis is Fanconi Bickel syndrome.
• Hereditary tyrosinemia type I. Hereditary tyrosinemia type I is a genetic disease that affects how your liver, nerves and kidneys metabolize the amino acid tyrosine. In these patients, an abnormal byproduct of tyrosine may build up and cause Fanconi syndrome.

Causes of acquired Fanconi syndrome include:

• Certain drugs. Certain antibiotics, antiretrovirals, chemotherapy drugs and anticancer drugs can have toxic side effects that damage your kidneys and cause Fanconi syndrome.
• Kidney transplant. Fanconi syndrome may develop after a kidney transplant for a variety of reasons, including medications, injury to the kidney during surgery and rejection.
• Multiple myeloma. Multiple myeloma is a blood cancer that affects your plasma cells. Fanconi syndrome may develop due to the plasma cells making an abnormal protein that affects the kidneys or after stem cell transplantation treatment.
• AL amyloidosis (primary amyloidosis). AL amyloidosis is a disorder in which a protein in your plasma cells mutates. It can affect many organs, including your kidneys.
• Light chain proximal tubulopathy (LCPT). LCPT is a disorder in which your body deposits abnormal proteins in your kidneys.
• Lead poisoning. Exposure to high levels of lead may cause Fanconi syndrome.
• Toluene exposure. Toluene exposure can cause Fanconi syndrome. Toluene is a clear, colorless liquid that becomes a gas after exposure to room-temperature air. Products that may contain toluene include glue, paint, metal cleaners and adhesives. Toluene exposure often occurs from sniffing glue.
• Certain herbal therapies. Some herbal medicines that contain aristolochic acid may have a link to Fanconi syndrome. Medical doctors typically don’t prescribe these therapies.

Which drug causes Fanconi syndrome?

The following drugs are commonly associated with causing Fanconi syndrome:

• Cisplatin.
• Ifosfamide.
• Tenofovir.
• Valproic acid.
• Aminoglycoside antibiotics like gentamicin.
• Deferasirox.

Is Fanconi syndrome contagious?

No, Fanconi syndrome isn’t contagious. You can’t pass it on to someone else through close contact.

How is Fanconi syndrome diagnosed?

A healthcare provider will ask about your symptoms, conduct a physical examination and ask what medications you’re taking. They’ll order tests to help confirm the diagnosis. They may also refer you to a nephrologist. A nephrologist is a doctor who specializes in kidney conditions.

What tests will be done to diagnose Fanconi syndrome?

A healthcare provider may order urine or blood tests. High levels of glucose, amino acids and phosphates in your pee help confirm a Fanconi syndrome. Low blood levels of phosphate, bicarbonate and potassium may also be signs of Fanconi syndrome.

Urine tests

During a urinalysis, you’ll pee into a special cup at a healthcare provider’s office. The provider will then send it to a laboratory where a lab technician will analyze the chemical components of your pee.

A urine test should only take a few minutes to complete.

Blood tests

Blood tests also help provide important information about the chemicals in your blood. A healthcare provider will use a thin needle (21 gauge, about the size of a small earring) to withdraw a small amount of blood from a vein in your arm. They’ll then send it to a laboratory for analysis.

You may feel a pinch or some discomfort from the needle. You may also notice a bruise, soreness or light bleeding where the needle went into your arm. These symptoms usually go away within a day or two.

Is Fanconi syndrome curable?

This depends on the cause of Fanconi syndrome.

The inherited causes of Fanconi syndrome often have no cure, though certain dietary changes may be helpful.

The acquired causes of Fanconi syndrome may have the potential to recover. However, there isn’t a guarantee. You can control your symptoms and limit damage to your kidneys, muscles and bones with proper treatment.

How is Fanconi syndrome treated?

Treatment depends on the cause and severity of Fanconi syndrome. A healthcare provider will first identify and treat any underlying causes. They’ll also restore substances that leave your body through your pee.

You can restore lost fluids and electrolytes through dietary changes, oral supplements or intravenous (IV) infusion. During IV infusion, you receive the substances through a needle in your vein.

Many people with Fanconi syndrome often have metabolic acidosis. A provider may give you sodium bicarbonate to help restore a healthy blood pH balance. The pH scale is the levels of acids and bases in your blood.

Low phosphate levels may cause bone weakness and bone pain. If you have low phosphate levels, a provider may prescribe a phosphate supplement plus vitamin D.

If your child has inherited Fanconi syndrome, they may need a specially tailored diet, such as avoiding fructose, galactose or tyrosine.

If a genetic condition is responsible for your Fanconi syndrome, you may need to make other adjustments to your diet. For example, if you have inherited fructose intolerance, you must limit the amount of fructose and sucrose you consume.

You may need to stop using or reduce the dosage of any drugs that are responsible for acquired Fanconi syndrome.

How soon after treatment will I feel better?

How soon you feel better after Fanconi syndrome treatment may vary widely depending on the cause. Some acquired causes of Fanconi syndrome may improve in days to weeks. However, Fanconi syndrome can be a long-term condition in its acquired and inherited forms.

How can I prevent Fanconi syndrome?

You can help prevent acquired Fanconi syndrome by:

• Avoiding exposure to lead.
• Discussing herbal supplements with a healthcare provider.
• Discussing medication risks with a healthcare provider, such as antibiotics and chemotherapy medications.

What can I expect if I have Fanconi syndrome?

Healthcare providers and medical researchers know more about Fanconi syndrome and how to treat it now than they did just a few years ago. New therapies and treatments allow many people to live relatively normal lives.

Most inherited Fanconi syndrome symptoms appear during infancy. If your child has Fanconi syndrome due to cystinosis, failure to thrive (inability to gain weight despite having a good appetite and consuming enough calories) and arrested growth (slow or delayed growth) are typical. Kidney failure tends to develop early. It may also involve your eyes, liver, bones and other organs.

For acquired Fanconi syndrome, once a healthcare provider determines its cause, your kidneys may have the potential to recover. However, some kidney damage may be permanent.

How long can you live with Fanconi syndrome?

There isn’t a fixed life expectancy if you have Fanconi syndrome. You may have a relatively normal life expectancy with proper treatment and a consistent medical plan. However, if you develop kidney failure, your life expectancy may decrease.

The inherited causes of Fanconi syndrome are different situations. The effect they have on your life expectancy varies.

How do I take care of myself?

A healthcare provider will work with you to develop a treatment plan, including taking supplements, changing your diet and adjusting your lifestyle.

When should I see a healthcare provider?

Contact a healthcare provider if you have any symptoms of Fanconi syndrome or symptoms of a condition that may cause Fanconi syndrome.

What questions should I ask a healthcare provider?

• How do you know that I have Fanconi syndrome?
• What tests will you conduct to diagnose Fanconi syndrome?
• Do I have inherited Fanconi syndrome or acquired Fanconi syndrome?
• What caused my Fanconi syndrome?
• Should I see a specialist?
• What supplements should I take?
• What is my risk of kidney failure?
• Do I need a kidney transplant?
• Should I get genetic testing?
• How often should I schedule appointments to monitor my Fanconi syndrome?
• Are there any support groups for people who have Fanconi syndrome?

What is the difference between Fanconi syndrome and Fanconi anemia?

Fanconi syndrome and Fanconi anemia are two different conditions.

Fanconi syndrome affects how your kidneys reabsorb necessary substances for your body to function.

Fanconi anemia is a rare inherited condition that affects your bone marrow. Your bone marrow can’t create healthy blood cells and platelets, and you have an increased risk of developing blood disorders and certain types of cancer.

A note from Cleveland Clinic

Fanconi syndrome is a condition that affects how your kidneys reabsorb minerals and nutrients that you need to function. It’s a rare condition, and you may inherit faulty genes from your biological parents that cause it. You can also acquire it from certain drugs or lead poisoning. You may feel anxious or scared if you have Fanconi syndrome. However, emerging treatments allow many people to lead normal lives. If you have any questions, talk to a healthcare provider. They can answer any questions, recommend a specialist or point you toward support groups.