Hyperviscosity Syndrome

Hyperviscosity syndrome occurs when blood thickens and doesn’t flow freely through blood vessels. Without treatment, this condition could lead to severe complications, including reduced blood flow to your vital organs. With timely treatment, many people recover fully from the syndrome.


What is hyperviscosity syndrome?

Hyperviscosity syndrome occurs when your blood thickens so much that it doesn’t flow freely through your blood vessels. It may happen because you have too many red blood cells, white blood cells or blood proteins. It may also develop if you have irregularly shaped red blood cells.

Hyperviscosity syndrome is a serious condition. Without treatment, it can lead to artery blockages and reduced blood flow to your vital organs. In children, reduced blood flow can affect growth and development.


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Who is most likely to get hyperviscosity syndrome?

People who have a rare condition called Waldenstrom macroglobulinemia are much more likely to develop hyperviscosity syndrome. People with this condition have atypically high levels of a blood protein called macroglobulin. More than 30% of people with Waldenstrom macroglobulinemia develop hyperviscosity syndrome at some point in their lives.

Symptoms and Causes

What are the symptoms of hyperviscosity syndrome?

Most often, hyperviscosity syndrome causes:

Less commonly, it may also cause:


What causes hyperviscosity syndrome in infants?

Hyperviscosity in a newborn may develop due to:

What causes hyperviscosity syndrome in adults?

The most common cause of hyperviscosity syndrome is Waldenstrom macroglobulinemia. Other causes may include:


Diagnosis and Tests

How is hyperviscosity syndrome diagnosed?

Healthcare providers typically diagnose hyperviscosity syndrome with blood tests. They may use:

  • Arterial blood gas test to measure oxygen and carbon dioxide in your blood.
  • Bilirubin test to check bilirubin levels, the yellowish substance that your body develops when red blood cells break down.
  • Blood sugar test to check blood sugar (glucose) levels.
  • Complete blood count (CBC) to measure the levels of all blood components, including red blood cells, white blood cells and proteins.
  • Creatinine test to evaluate kidney function.
  • Liver function test to evaluate liver proteins.
  • Serum viscosity or whole blood viscosity tests to evaluate blood thickness.
  • Protein tests to measure the amount of proteins.

Management and Treatment

How is hyperviscosity syndrome treated?

Treatment for hyperviscosity syndrome may vary based on the underlying cause. Hyperviscosity syndrome worsens dehydration, so your provider may prescribe intravenous (IV) hydration. In severe cases, healthcare providers may use:

  • Partial exchange transfusions, where they remove a small amount of blood and replace it with saline solution.
  • Plasmapheresis, where they remove and replace a small amount of plasma, the clear liquid part of your blood.


How can I prevent hyperviscosity syndrome?

There’s no way to prevent hyperviscosity syndrome. If you are pregnant, you may take certain steps to lower the risk of your baby doesn't get the condition. You may:

  • Complete genetic testing to understand the chances of having a child with a genetic disease.
  • Eat a nutritious diet and exercise regularly to lower your risk of gestational diabetes.
  • Visit your healthcare provider for regular prenatal care visits and screenings.

Outlook / Prognosis

What is the outlook for hyperviscosity syndrome?

Hyperviscosity syndrome requires prompt treatment. Without treatment, it can lead to life-threatening complications and organ failure.

Babies and adults who receive timely treatment often fully recover from hyperviscosity syndrome. If hyperviscosity syndrome is related to a chronic underlying condition, you may need ongoing treatment to prevent it from developing again.

Living With

What questions should I ask my doctor?

If you or your child have hyperviscosity syndrome or you think you could, you may also want to ask your healthcare provider:

  • What is the most likely cause of hyperviscosity syndrome?
  • What tests diagnose hyperviscosity syndrome?
  • How is hyperviscosity syndrome treated?
  • Do I need long-term treatment for hyperviscosity syndrome?
  • What are the chances that I’ll have another child with hyperviscosity syndrome?

Additional Common Questions

What does hyperviscosity feel like?

Hyperviscosity may feel different to different people. Thickened blood leads to poor brain circulation, which can cause headaches, dizziness or confusion. Some people may also feel short of breath or have blurry vision.

What causes blood viscosity to increase?

Multiple factors can increase blood viscosity. Your blood may thicken if you have irregularly shaped red blood cells. It may also thicken if you have irregularly high levels of any blood component, including red blood cells, white blood cells or blood proteins.

A note from Cleveland Clinic

Hyperviscosity syndrome occurs when your blood thickens and doesn’t flow properly through your body. The syndrome may develop in people who have certain types of blood disorders. Sometimes, it develops in infants who have certain genetic or hereditary disorders. Hyperviscosity syndrome is serious and requires treatment. Many people who receive timely treatment experience a full recovery.

Medically Reviewed

Last reviewed on 07/28/2022.

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