Fanconi Syndrome

Fanconi syndrome is a group of disorders that affect the proximal tubules in your kidneys. It affects the tubules’ ability to reabsorb electrolytes and other substances.

Healthy proximal tubules reabsorb certain molecules into your bloodstream. Your body needs these electrolytes and other substances to function. But if you have Fanconi syndrome, too much leaves your body through your pee.

The molecules include:

• Phosphate
• Glucose
• Potassium
• Bicarbonate
• Uric acid
• Amino acids

Fanconi syndrome can affect anyone, and there are two different types:

• Inherited Fanconi syndrome: You get it from one of your biological parents.
• Acquired Fanconi syndrome: You develop it at some point in your life.

What are the signs and symptoms of Fanconi syndrome?

Signs and symptoms of inherited Fanconi syndrome include:

• Peeing more than usual (frequent urination)
• Dehydration
• Being thirstier than usual (polydipsia)
• Bone pain
• Muscle weakness
• Bone weakness
• Bone fractures
• Well below average height (small stature)

Symptoms of acquired Fanconi syndrome include:

• Muscle weakness
• Low 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

Fanconi syndrome causes

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

• Cystinosis: This causes the amino acid cystine to build up in your body. It’s the most common cause of inherited Fanconi syndrome. If it causes Fanconi syndrome in your child, symptoms usually start during infancy or early childhood — typically between six and 18 months.
• Lowe syndrome: This is a rare genetic condition that relates to your X chromosome.
• Wilson disease: This is a genetic condition that prevents your body from removing copper well.
• Inherited fructose intolerance: This condition affects your metabolism because you don’t have the enzyme aldolase B. If you have it, you get low blood sugar (hypoglycemia) when you eat sugars from fruits or plants. This can affect your liver.
• Dent disease: This is a kidney condition. It causes small proteins to spill into your pee and increased amounts of calcium in your pee. It also causes calcium deposits in your kidney tubules, kidney stones and chronic kidney disease.
• Glycogenosis (Fanconi Bickel syndrome): This is a genetic disorder that causes a defect in a sugar transporter (GLUT2). It helps move glucose between your liver and blood. It affects how your intestines, liver, pancreas and kidneys handle sugar.
• Hereditary tyrosinemia type I: This is a genetic disease that affects how your liver, nerves and kidneys break down the amino acid tyrosine. An abnormal byproduct of tyrosine may build up and cause Fanconi syndrome.

Causes of acquired Fanconi include:

• Certain drugs: Some antibiotics, antiretrovirals, chemotherapy drugs and anticancer drugs can damage your kidneys and cause Fanconi syndrome.
• Kidney transplant: Fanconi syndrome may develop after a transplant for many reasons. These include medications, a kidney injury during surgery or kidney transplant rejection.
• Multiple myeloma: Fanconi syndrome may develop when multiple myeloma affects your plasma cells. The plasma cells make an abnormal protein that affects your kidneys. Fanconi syndrome may also develop after stem cell transplantation
• AL amyloidosis: This is when a protein in your plasma cells changes. It can affect many organs, including your kidneys.
• Light chain proximal tubulopathy (LCPT): This causes your body to deposit abnormal proteins in your kidneys.
• Lead poisoning: Exposure to high levels of lead may cause Fanconi syndrome.
• Toluene exposure: Toluene is a clear, colorless liquid that becomes a gas after exposure to room-temperature air. It may be in products like glue, paint, metal cleaners and adhesives. Toluene exposure often occurs after sniffing glue.
• Certain herbal therapies: Some herbal medicines that contain aristolochic acid may have a link to Fanconi syndrome. Providers usually don’t prescribe these therapies.

What drugs can cause it?

The following drugs commonly associate with Fanconi syndrome:

• Cisplatin: This is a type of chemotherapy medication.
• Ifosfamide: This is a testicular cancer treatment.
• Tenofovir: This treats long-term (chronic) hepatitis B and HIV.
• Valproic acid: This is a type of antiseizure medication.
• Aminoglycoside antibiotics: These treat serious bacterial infections. One example includes gentamicin.
• Deferasirox: This treats high levels of iron in your blood.

Complications

Cystinosis is the most common cause of inherited Fanconi syndrome. In addition to affecting your kidney tubules, cystinosis can affect your:

• Eyes (light sensitivity)
• Liver (hepatomegaly)
• Thyroid (hyperthyroidism)

How doctors diagnose Fanconi syndrome

A healthcare provider will:

• Review your health history
• Ask about your symptoms
• Conduct a physical exam
• Ask about any medications you’re taking

They may recommend tests to help confirm their diagnosis, including:

• Pee (urine) tests
• Blood tests

They may also refer you to a kidney specialist (nephrologist).

Is there a cure?

It depends on the cause.

The inherited causes of Fanconi syndrome usually don’t have a cure. But certain lifestyle changes may help.

You may be able to recover from acquired causes of Fanconi syndrome. But there isn’t a guarantee. Proper treatment can help manage your symptoms and limit damage to your kidneys, muscles and bones.

What are the treatment options for Fanconi syndrome?

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

You can restore lost fluids and electrolytes through:

• Changes to your eating patterns
• Oral supplements
• Peripheral IV

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

Low phosphate levels may cause bone pain and weakness. If you have low phosphate levels, your provider may prescribe a phosphate supplement and vitamin D. Vitamin D helps build and maintain bone health.

If you have inherited Fanconi syndrome, you may need to make changes to what you eat. This may include avoiding sugars, like fructose (fruits and vegetables) and galactose (milk and other dairy products). You may also need to avoid foods that have tyrosine (seeds, nuts and meats).

You may also need to stop using or reduce the dosage of any drugs that cause acquired Fanconi syndrome.

Recovery time

How soon you feel better after Fanconi syndrome treatment varies a lot depending on the cause. Some acquired cases of Fanconi syndrome may improve in days to weeks. But both types of Fanconi syndrome can be long-term conditions.

When should I see my healthcare provider?

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

During your appointment, you may want to ask:

• What tests do you recommend to diagnose Fanconi syndrome?
• Do I have inherited Fanconi syndrome or acquired Fanconi syndrome?
• What caused it?
• Should I see a specialist?
• What supplements should I take?
• What’s 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?
• Can you recommend a support group?

What is the prognosis for Fanconi syndrome?

Experts 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 pretty normal lives.

Most inherited Fanconi syndrome symptoms appear during infancy. If cystinosis causes Fanconi syndrome in your child, it’s common for them to experience growth faltering and delayed growth. Kidney failure often develops early. It may also affect their eyes, liver, bones and other organs.

For acquired Fanconi syndrome, your kidneys may have the potential to recover once your provider figures out the cause. But some kidney damage may be permanent.

What is the life expectancy of someone 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. But if you develop kidney failure, your life expectancy may decrease.

The inherited causes of Fanconi syndrome are different situations. How they affect your life expectancy varies.

What is the difference between Fanconi anemia and Fanconi syndrome?

Fanconi syndrome and Fanconi anemia are two different conditions.

Fanconi syndrome affects how your kidneys reabsorb substances your body needs 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. You have an increased risk of developing blood disorders and certain types of cancer.