The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 75

I get asked a lot about how mast cell disease can affect common blood test results. I have broken this question up into several more manageable pieces so I can thoroughly discuss the reasons for this. The next few 107 series posts will cover how mast cell disease can affect red blood cell count; white blood cell count, including the counts of specific types of white blood cells; platelet counts; liver function tests; kidney function tests; electrolytes; clotting tests; and a few miscellaneous tests.

 

88. How does mast cell disease affect white blood cell counts?

Firstly, remember that while mast cells are technically considered white blood cells, they don’t actually live in the blood. That means that except in very severe malignant cases of aggressive systemic mastocytosis and mast cell leukemia, mast cells won’t directly contribute to white blood cell count in a blood test at all. This means that in a regular white blood cell level blood test, none of those cells are mast cells.

There are a couple of ways in which mast cell disease can cause low white blood cell counts. It can also cause low counts of certain types of white blood cells even if it doesn’t cause low white blood cell count overall.

  • Swelling of the spleen. This can happen in some forms of systemic mastocytosis, and may also happen in some patients with mast cell activation syndrome, although the reason why it happens in MCAS is not as clear. Swelling of the spleen can damage blood cells, including white blood cells, causing lower white blood cell counts. If the spleen is very stressed and working much too hard, a condition called hypersplenism, the damage to blood cells is much more pronounced. This may further lower the white blood cell count. Hypersplenism occurs in aggressive systemic mastocytosis or mast cell leukemia. It is not a feature of other forms of systemic mastocytosis and I am not aware of any cases as a result of mast cell activation syndrome.
  • Medications. Some medications for mast cell disease can cause low white blood cell count. These are not common medications, but are sometimes used, especially in patients with long term symptoms that have not responded to other medications, or where organs could potentially be damaged, like in smoldering or aggressive systemic mastocytosis, or severe mast cell activation syndrome. These include medications like cyclosporine and interferon.
  • Chemotherapy. These medications can also decrease white blood cell count. Chemotherapy is used in smoldering systemic mastocytosis, aggressive systemic mastocytosis, and mast cell leukemia. It is sometimes also used in very aggressive presentations of mast cell activation syndrome. Newer chemotherapies are more targeted and can cause fewer side effects. However, all of the chemotherapies used for mast cell disease can cause the side effect of low blood cell counts, including white blood cell count.
  • Myelofibrosis. Myelofibrosis is a myeloproliferative neoplasm that is related to systemic mastocytosis. In myelofibrosis, the bone marrow becomes filled with deposits of scar tissue so that the body cannot make blood cells correctly or in normal numbers. This can decrease white blood cell counts.
  • Excess fluid in the bloodstream (hypervolemia). In this situation, the body doesn’t actually have too few red blood cells, it just looks like it. If your body loses a lot of fluid to swelling (third spacing) and that fluid is mostly reabsorbed at once, the extra fluid in the bloodstream can make it look like there are too few red cells if they do a blood test. This can also happen if a patient receives a lot of IV fluids.

Even if the overall white blood cell count is normal, mast cell patients sometimes have low levels of certain types of white blood cells.

  • Anaphylaxis. Anaphylaxis can cause basophils to be low.
  • Allergic reactions. These can also cause basophils to be low.
  • Chronic urticaria. Chronic hives and rashes can cause basophils to be low.
  • Use of corticosteroids like prednisone elevates certain types of white blood cells while suppressing others. Lymphocytes, monocytes, eosinophils and basophils can also be low from using corticosteroids like prednisone.
  • Prolonged physical stress. Mast cell disease can cause a lot of damage to the body over time, triggering a chronic stress response. This can selectively lower the amount of lymphocytes and the eosinophils in the body.
  • Autoimmune disease. Autoimmune disease often causes one type of white blood cell to be high and another to be low. Many mast cell patients have autoimmune diseases, so while this is not directly caused by mast cell disease, it often occurs in mast cell patients. For example, rheumatoid arthritis can cause low neutrophils.

There are many more ways that mast cell disease can trigger high white blood cell counts, or high amounts of certain types of white blood cells.

  • Inflammation. Any type of chronic inflammation can cause high white blood cell counts and mast cell disease causes a lot of inflammation.
  • Medications. Use of corticosteroids especially can cause high white blood cell counts. Epinephrine and beta-2 agonists like salbutamol/albuterol, used to open the airway, can also cause high white blood cell counts.
  • Autoimmune disease. Many mast cell patients have autoimmune diseases, so while this is not directly caused by mast cell disease, it often occurs in mast cell patients.

There are several instances where mast cell disease can trigger elevated levels of certain subsets of white blood cells.

  • Swelling of the spleen. I mentioned above that spleen swelling can damage blood cells, causing their levels to be low. Paradoxically, sometimes having a swollen spleen can cause lymphocytes to be high. There are several theories about why this may occur but there is no definitive answer currently.
  • GI inflammation. Chronic inflammation in the GI tract can cause the body to overproduce monocytes. Certain types of inflammatory bowel disease, like ulcerative colitis, can cause high basophils.
  • Allergies. Allergic reactions of any kind will elevate both basophils and eosinophils.
  • Mast cell activation of eosinophils. Mast cells activate eosinophils, which activate mast cells. It is a nasty cycle that causes a lot of symptoms and can be very damaging to organs affected. It is not unusual for mast cell patients to have high numbers of circulating eosinophils. It is also not unusual for mast cell patients to have higher than expected numbers of eosinophils in biopsies, especially GI biopsies. Eosinophilic GI disease also has some overlap with mast cell disease so some patients have both.
  • Mast cell activation of basophils. Basophils are closely related to mast cells and also degranulate in response to allergic triggers and during anaphylaxis.
  • Autoimmune disease. Autoimmune disease often causes one type of white blood cell to be high and another to be low. Many mast cell patients have autoimmune diseases, so while this is not directly caused by mast cell disease, it often occurs in mast cell patients. For example, lupus can cause eosinophilia.
  • Anemia. Iron deficiency is common in mast cell disease. Iron deficiency anemia can increase basophil levels.
  • Vascular inflammation. Mast cell activation has been repeatedly linked to inflammation of blood vessels. This can elevate blood monocyte level.
  • Medication. Use of corticosteroids like prednisone directly increase neutrophil levels.
  • Proliferation of myeloid cells. Overproduction of certain types of blood cells by the bone marrow, including mast cells, can elevate basophils.
  • Obesity. Obesity has been linked many times to chronic inflammation. Mast cell disease can directly cause weight gain by causing high levels of the hormone leptin. Obesity may cause high levels of monocytes.
  • Third spacing. If a lot of fluid from the bloodstream becomes trapped in tissues (third spacing), there is less fluid in the bloodstream so it makes it look like there are too many cells. As I mentioned above, this is not really a scenario where you are making too many white blood cells, it just looks like that on a blood test.

For additional reading, please visit the following posts:

Allergic effector unit: The interactions between mast cells and eosinophils

Anemia of chronic inflammation

Effect of anemia on mast cells

Explain the tests: Complete blood cell count (CBC) – White blood cell count

Explain the tests: Complete blood cell count (CBC) – High white blood cell count

Explain the tests: Complete blood cell count (CBC) – Low white blood cell count

Mast cell disease and the spleen

MCAS: Anemia and deficiencies

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 72

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 73

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The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 74

I get asked a lot about how mast cell disease can affect common blood test results. I have broken this question up into several more manageable pieces so I can thoroughly discuss the reasons for this. The next few 107 series posts will cover how mast cell disease can affect red blood cell count; white blood cell count, including the counts of specific types of white blood cells; platelet counts; liver function tests; kidney function tests; electrolytes; clotting tests; and a few miscellaneous tests.

  1. How does mast cell disease affect red blood cell counts?

There are several ways in which mast cell disease can make red blood cell count lower.

  • Anemia of chronic inflammation. This is when chronic inflammation in the body affects the way the body absorbs and uses iron. It can result in iron deficiency. Iron is used to make hemoglobin, the molecule used by red blood cells to carry around oxygen to all the places in the body that need it. If there’s not enough iron to make hemoglobin, the body will not make a normal amount of red blood cells.
  • Vitamin and mineral deficiencies. Like I mentioned above, chronic inflammation can affect the way your body absorbs vitamins and minerals through the GI tract, and the way it uses vitamins and minerals that it does absorb. While iron deficiency is the most obvious example of this, deficiency of vitamin B12 or folate can also slow red cell production.
  • Swelling of the spleen. This can happen in some forms of systemic mastocytosis, and may also happen in some patients with mast cell activation syndrome, although the reason why it happens in MCAS is not as clear. Swelling of the spleen can damage blood cells, including red blood cells, causing lower red blood cell counts. If the spleen is very stressed and working much too hard, a condition called hypersplenism, the damage to blood cells is much more pronounced. This may further lower the red blood cell count. Hypersplenism occurs in aggressive systemic mastocytosis or mast cell leukemia. It is not a feature of other forms of systemic mastocytosis and I am not aware of any cases as a result of mast cell activation syndrome.
  • Medications. Some medications that are used to manage mast cell disease can cause low red blood cell count. Chemotherapies, including targeted chemotherapies like tyrosine kinase inhibitors, can cause low red blood cell count. Medications that specifically interfere with the immune system can do the same thing, including medications for autoimmune diseases like mycophenolate. Non steroidal anti-inflammatory drugs (NSAIDs) are used by some mast cell patients to decrease production of prostaglandins. They can interfere with red blood cell production in the bone marrow and also cause hemolytic anemia, when the immune system attacks red blood cells after they are made and damages them.
  • Excessive bleeding. Mast cell disease can cause excessive bleeding in several ways. Mast cells release lots of heparin, a very potent blood thinner that decreases clotting. This makes it easier for the body to bleed. It is not unusual for mast cell patients to have unusual bruising. Bleeding in the GI tract can also occur. Mast cell disease can cause ulceration, fissures, and hemorrhoids, among other things. Mast cell disease can contribute to dysregulation of the menstrual cycle, causing excessive bleeding in this way.
  • Excessive production of other types of blood cells. In very aggressive forms of systemic mastocytosis, aggressive systemic mastocytosis or mast cell leukemia, the bone marrow is making huge amounts of mast cells. As a result, the bone marrow makes fewer cells of other types, including red blood cells. Some medications can also increase production of other blood types, causing less production of red cells. Corticosteroids can do this.
  • Excess fluid in the bloodstream (hypervolemia). In this situation, the body doesn’t actually have too few red blood cells, it just looks like it. If your body loses a lot of fluid to swelling (third spacing) and that fluid is mostly reabsorbed at once, the extra fluid in the bloodstream can make it look like there are too few red cells if they do a blood test. This can also happen if a patient receives a lot of IV fluids.

There are also a couple of scenarios where mast cell disease can make the red blood cell count higher. This is much less common.

  • Chronically low oxygen. If a person is not getting enough oxygen for a long period of time, the body will make more red blood cells in an effort to compensate for the low oxygen. This could happen in mast cell patients with poor oxygenation.
  • Third spacing. If a lot of fluid from the bloodstream becomes trapped in tissues (third spacing), there is less fluid in the bloodstream so it makes it look like there are too many cells. As I mentioned above, this is not really a scenario where you are making too many red blood cells, it just looks like that on a blood test.

For additional reading, please visit the following posts:

Anemia of chronic inflammation

Effect of anemia on mast cells

Effects of estrogen and progesterone and the role of mast cells in pregnancy

Explain the tests: Complete blood cell count (CBC) – Low red cell count

Explain the tests: Complete blood cell count (CBC) – High red cell count

Explain the tests: Complete blood cell count (CBC) – Red cell indices

Gastrointestinal manifestations of SM: Part 1

Gastrointestinal manifestations of SM: Part 2

Mast cell disease and the spleen

Mast cells, heparin and bradykinin: The effects of mast cells on the kinin-kallikrein system

MCAS: Anemia and deficiencies

MCAS: Blood, bone marrow and clotting

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 3

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 12

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 19

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 20

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 45

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 72

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 73

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Mast cell disease and the spleen

Spleen is known mostly for having a stupid name, but it actually does a lot of really important things.  It is located in the upper left quadrant of the abdomen.  It is essentially a filter.  It removes old or damaged red blood cells.  It retains a supply of blood that can be used to regulate blood pressure in case of hemorrhage.  It also recycles and conserves iron by metabolizing hemoglobin removed from red blood cells filtered out.  The spleen also produces antibodies and filters out bacteria and blood cells that have been attacked by antibodies and marked for removal.  In this way, it is effectively a very large lymph node. 

Another very important function of the spleen is creation of blood cells.  In cases where the bone marrow is producing fewer blood cells than normal (like myelofibrosis), the spleen can actually compensate to produce red and white blood cells.  About ¼ of the body’s white cells are stored in the spleen at any time. 
Swelling of the spleen is called splenomegaly.  If a swollen spleen can be felt manually, it is at least twice its normal size.  The spleen usually swells when it is working harder than normal.  This can happen for several reasons. 
Swelling of the spleen often has no symptoms.  It can cause abdominal, chest or back pain and the feeling of having a “small stomach,” being able to eat less than normal in one sitting.  Anemia may also be present.  The most common reason is developed countries is mononucleosis, followed by infiltration by benign or neoplastic cells, or portal hypertension.  Bacterial infections like syphilis can also cause a swollen spleen.  In people whose bone marrow is not producing enough cells, the spleen can become swollen by the effort of producing extra cells. 
It is should be stated that swelling of the spleen is pretty common in blood disorders.  It is sometimes found in systemic mastocytosis.  As the spleen gets bigger, it grows beyond the borders of the protective rib cage and can be more easily damaged.  Swollen spleens present an increased risk of rupture. 
In SM, splenomegaly (swollen spleen) is NOT a C finding indicating aggressive disease.  It is a B finding.  This is because mast cells often infiltrate the spleen, causing swelling, but not necessarily impairing function.  Hypersplenism with splenomegaly is a C finding.  Hypersplenism is when the spleen is working too hard. 
Hypersplenism is indicated by swelling of the spleen, reduction in circulating red blood cells, platelets or granulocytes (neutrophils, eosinophils, basophils or mast cells), increased proliferation by the bone marrow to compensate for the decrease in circulating cells, and probable resolution of these symptoms by removal of the spleen.    Hypersplenism can cause additional complications, including portal hypertension and ascites.
Portal hypertension is increased pressure in the vein that connects the GI tract and spleen to the liver.  Ascites is free fluid in the abdomen.  Both portal hypertension and ascites are also mastocytosis C findings.  Removal of the spleen can decrease the patient’s risk of portal hypertension and ascites, thus improving prognosis.  Additionally, in the context of mast cell disease, an infiltrated organ is inflamed, which is in turn activating to mast cells.  Removal of a source of inflammation can cause relief of systemic activation.
People living without a spleen are more susceptible to certain types of infections, including H. influenzae, S. pneumoniae, and Meningococcus spp.  They should receive vaccinations for these organisms and also regular flu vaccinations.  In some cases, long term prophylactic antibiotics are needed.  Often, patients without a spleen develop a stable high white blood cell or platelet count as their numbers are not regulated by the spleen.