What Is Hyperviscosity Syndrome?

Medically Reviewed by Sabrina Felson, MD on May 29, 2023
Written by WebMD Editorial Contributors
3 min read

Hyperviscosity syndrome is a condition that occurs when your blood becomes so thick that your body's overall blood flow decreases. Hyperviscosity can be caused by your blood cells changing shape or by an increase in serum proteins, red blood cells, white blood cells, or platelets. The reduced blood flow caused by hyperviscosity syndrome is a dangerous phenomenon and can have far-reaching effects on the whole body.

Hyperviscosity syndrome is a symptom of other blood-related conditions. Conditions involving increased levels of red blood cells or a higher volume of plasma coursing through the blood can lead to hyperviscosity syndrome. Some of these conditions are:‌

  • Waldenström's macroglobulinaemia (WB). This is the most common cause of hyperviscosity syndrome; around 10-30% of patients who are diagnosed with hyperviscosity have WB. WB is a blood cancer that occurs within the bone marrow and the lymphatic tissues. In response to the cancer, a large number of white blood cells are produced within the body, thickening the blood. 
  • Multiple myeloma. This is a type of cancer that infects plasma cells. Cancerous plasma cells push out the healthy cells that work to protect you from infection. The cancerous plasma cells thicken the blood. 
  • Polycythaemia rubra vera. This blood cancer affects the bone marrow and creates a surplus of red blood cells. This surplus significantly thickens the bone and is the catalyst for hyperviscosity.
  • Leukemia.Leukemia cancer cells invade bone marrow cells, producing irregularly shaped blood cells. These irregular blood cells clog and congest the body. 
  • Connective tissue disorders. Rheumatoid arthritis is an example of a connective tissue disorder that leads to hyperviscosity. This disorder causes your body to emit a serum protein that thickens the blood. However,  hyperviscosity associated with connective tissue disorders is rare.
  • Retinoic acid therapy. This cancer treatment involves giving patients low and high doses of vitamin A, which has been found to suppress cancer. Retinoic acid causes the body to produce an excess of white blood cells. 
  • Cryoglobulinaemia. This branch of rare blood disorders causes inflammation of the blood vessels in your body. When you are suffering from one of these disorders, your body releases a specific protein into the blood that causes large clumps to form. 
  • Chronic hypoxia. Often, chronic hypoxia is the symptom of another disease called cyanotic heart disease. This disease causes the release of a particular plasma into the blood that thickens and clogs your arteries. 
  • Paraneoplastic syndromes. This is a group of rare syndromes in which white blood cells attack healthy cells. This disruption leads to hyperviscosity.

Hyperviscosity can affect your entire body. The symptoms of hyperviscosity can look very different depending on the cause of the syndrome. Some of the symptoms manifest as: 

  • Lethargy
  • Headaches
  • Deafness
  • Convulsions
  • Issues with sight 
  • Loss of vision
  • Hypertension
  • Heart failure
  • Abnormal bleeding 
  • Easy bruising
  • Mucosal bleeding
  • Rectal bleeding
  • Sepsis
  • Thrombosis
  • Kidney failure

Hyperviscosity is treated by a team of specialists, including a hematologist, nephrologist, oncologist, internist, and intensivist. It is technically classified as a medical emergency and it is vital to treat it quickly. Gone untreated, hyperviscosity can have severe repercussions for your health, such as serious organ failure (organs aren't getting oxygenated, and without proper blood flow they will die).

Typically, your treatment plan will consist of two levels. The first is to give you immediate, short-term treatment in order to control your symptoms. Quite often, this short-term treatment is plasmapheresis. Plasmapheresis is a treatment that removes the plasma from your blood and replaces it with a plasma replacement fluid or water-based solution.

To do this, your treatment team will draw blood from a central vein. Your blood will enter a machine that separates your white and red blood cells. The machine will then re-insert your blood back into your vein. However, every case is different, and your treatment team will know whether or not this treatment is safe and vital for you. 

Your doctors will also help you to treat the underlying condition that is causing your hyperviscosity. Depending on the condition that is causing hyperviscosity syndrome, you could receive numerous types of therapies, plasma exchanges, or even chemotherapy.