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The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 14

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

22. Is MCAS an early form of SM?

• MCAS is not viewed as an early form of SM but the diagnosis of MCAS may precede a later diagnosis of SM.
• In the last few years, we have learned a lot about the genetics associated with mast cell diseases and how it occurs in families. As a result, we are beginning to understand that mast cell diseases occur more along a spectrum than as distinct categories. This means that there is a lot of overlap between conditions.
• While it is certainly not a new disorder, MCAS is a pretty recent diagnostic entity. The last decade has seen a large increase in diagnosis as it has been more frequently described. Because of how new it is, and also the fact that there aren’t uniform criteria for what MCAS is, there will be a level of uncertainty about how this disease tends to progress for some time.
• That uncertainty aside, we know that at least some patients with a long history of MCAS have continued to have symptoms without developing markers of systemic mastocytosis.
• However, some patients with history of MCAS do develop markers of systemic mastocytosis.
• Many patients do not receive bone marrow biopsies when they are diagnosed with MCAS because there is not always a reason to have one. It often doesn’t affect treatment. If there is no sign of organ damage, the patient has a negative blood test for the CKIT D816V mutation, and their baseline tryptase is below 20 ng/mL, most doctors do not order a bone marrow biopsy. This means that some patients who are diagnosed with MCAS may have had SM all along but it wasn’t found until a biopsy was performed later.
• In 2007, monoclonal mast cell activation syndrome was described in scientific literature. This condition is diagnosed when a patient meets some criteria of systemic mastocytosis but not enough for a diagnosis of SM.
• Monoclonal mast cell activation syndrome is more often viewed as a “pre-SM”. I personally view it this way. Before it had a name, researchers called it “pre-diagnostic SM.” Literally, SM before they could diagnose it as SM.

For more detailed reading, please visit these posts:

The Provider Primer Series: Mast cell activation syndrome (MCAS)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 13

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

21. Why do people care so much about diagnostic criteria?
• Historically speaking, the medical establishment tends to draw very explicit borders around diagnoses. There are several reasons for this.
• It is partly to help diagnose things correctly. There are thousands and thousands of diseases and disease states. The most effective way of getting as many people as possible correctly diagnosed with a disease is to define what that disease is and how you diagnose it. That doesn’t mean that every person who has this disease will always be diagnosed correctly. It also doesn’t mean that every person who doesn’t have this disease will be diagnosed with something else. It just means that this is the best way to diagnose the largest point of people all over the place.
• It is also to strength any research done around these diagnoses. As a scientist, who has to operate within the trappings of specific diagnoses with specific criteria, it is 100% necessary for me to do my job well.
• We have to know that all the patients in a study meet the same criteria. It’s not enough for their doctor to give them a diagnosis because they think that’s what they have even if they don’t meet the criteria. Let’s look at this a little more closely below, under the heading “Blue Disease.”
• The bottom line is that diagnostic criteria is the foundational bedrock of the Western medicine establishment (and some Eastern traditions as well).
• Diagnostic criteria also help determine what insurance companies will pay for. If you are a provider caught saying a bunch of patients have a diagnosis that they don’t have, you can be charged with insurance fraud. That can carry significant penalties including fines, loss of license and even prison time.
• Furthermore, if a doctor is caught misdocumenting diagnosis, insurance companies will crack down on patients with the same diagnosis in other places, making it harder for everyone to get treatment. There have been situations in recent history where patients getting a very expensive treatment were required to stop treatment to prove that they needed it since doctors were prescribing it for many other conditions without documenting it correctly.
• The last reasons why everyone cares about diagnostic criteria are related more to the experiences of patients within this community. Most of us have been misdiagnosed more than once. It can really complicate things and it can endanger people. It can also really scare people, too.
• Finally, most of us in this community have been lied to someone impersonating a rare patient at least once and usually more. It is exhausting and insulting.
• I want to be very clear that the reason a lot of people get stuck on diagnostic criteria is NOT because people who don’t meet one or the other set are not deserving of treatment or are not as sick. That is not the case at all.

Blue Disease:

• Let’s say that I am running a study on a disease called Blue Disease. Blue Disease is a condition that strikes people on their 25th birthday. On this day, people with this disease just wake up completely blue. They are never not blue again. I am interested in Blue Disease and so I design a study for it.
• In order to fund my study, I have to get grant funding. This money may be from a private foundation or a university or the government. I have to convince them to care about Blue Disease. More importantly, I have to convince them that the money they give me will be used intelligently and not wasted.
• Let’s say that I let in 100 people who all tell me they have Blue Disease. They are all blue. They all are older then 25. I let them in to my study to research a medicine to treat this disease.
• At the end of my study, I have found that if I give most of them a medicine called anti-Blue, their blue goes away. There is gladness and rejoicing. I find that 90 out of 100 respond to the medicine. Hooray! That’s a 90% success rate.
• Except then I find out that not all of those people actually had Blue Disease. Some of them turned blue before their 25th birthday. Some of them started purple, then became blue, then green. And so instead of having a 90% success rate for Blue Disease, we find that it’s much less effective than 90% for Blue Disease. We know that it has helped some other people not be blue but we don’t even know what disease they have. And I am in a hell of pickle as a researcher because I don’t know what these data mean.
• Because the medication seems not very effective for Blue Disease, it doesn’t get approved or prescribed to people who have Blue Disease.
• Because my study was not controlled enough, no one wants to give me any more money to research this disease. In certain situations, I could actually have to pay back the money, would almost certainly lose my job, and could be prosecuted because I have an ethical obligation to only research the disease I say I will research in a study.

For more detailed reading, please visit these posts:

The Provider Primer Series: Mast cell activation syndrome (MCAS)

The Provider Primer Series: Cutaneous Mastocytosis/ Mastocytosis in the Skin

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

Difference

You build your life around your secrets. Around other things too, but never more than your secrets. They are always there, in every place, the silent beat at the end of your words, the air you take in when you gasp. They are a comfort in their familiarity, a bane in their power. When you go to bed, it is just you and them, whispering to each other in the dark.

I have plenty of secrets. Most of us do. Most of them don’t matter. They remain secret only because I have never had occasion or need to reveal them to another person. But those aren’t the secrets I am talking about.

My biggest secret is that I am hopeful but I am afraid all the time. I have been this way a long time and so I am skilled at working around. I can talk myself into most things, even if I’m scared. But the doubt and uncertainty can be overwhelming sometimes.

I have another secret, too. I am scared that I have enough health to follow my dreams but not enough to achieve them. I grapple with this every time I have some wins and gain any measure of control. My mind immediately starts planning, lays out these paths to things I want badly but that my body could never accomplish. It is painful and frightening.

I think I’m finally coming to the end of this rough season. I am eating some solids again. I am reacting less. My mind continues to make plans that I don’t know I can achieve.

We so often equate success with results. That’s why we feel like a failure when we can brings these things we want to fruition.

But success is more than that. You have to try. The result may be the same but your heart knows the difference.

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

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

20. Why do a lot of mast cell patients get intravenous (IV) fluids?
• Use of IV fluids is becoming increasingly common for mast cell patients as word spreads that it helps with fatigue, overall energy, and general reactivity.
• There have not been any studies showing that IV fluids work directly for mast cell disease. However, there have been papers demonstrating that it helps with deconditioning (when your body is out of shape from being sick), POTS (which a lot of mast cell patients have), and other chronic illnesses.
• A lot of chemicals that mast cells release can cause some of the liquid in your bloodstream to fall out through the walls of the bloodstream and become trapped in the tissues there. This phenomenon is called third spacing.
• The term “third spacing” is derived from the idea that fluids like blood or other fluids can be in one of three “spaces” in the body. One space is inside the cells, where cells can use it. Another space is right outside the cells, where cells can still use it. When fluids are stuck in a place that can’t be used by cells, and therefore is not useful to the body, it is said to be in a third space. So third spacing is when the fluids your body needs is stuck in the wrong place.
• Third spacing is the cause of most types of swelling and edema.
• When you have fluid that should be in your bloodstream stuck in a third space, you are functionally dehydrated. This is important because bloodwork may not always show that you are truly dehydrated when you have a lower amount of third spacing but you will still have a lot of the symptoms of it.
• IV fluids puts more fluids back into the blood to compensate for the fluids that get sucked out of the bloodstream and aren’t useful to the body. When this fluid is replaced, it helps stabilize blood pressure and heart rate. It also takes stress off many other cells so they calm down too, calming down mast cells.

For more detailed reading, please visit this post:

Third spacing

I also wrote a seven part series on third spacing and IV fluids. The first post is here.

 

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 11

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

19. How do other conditions affect mast cell disease?
• Mast cell activity can affect literally every system in the body.
• Mast cells are found throughout the body and live in many tissues and organs in significant numbers.
• There are essentially three types of damaging mast cell activity:
–Normal mast cells are getting bad signals from other cells and they do bad things. This is not mast cell disease because these mast cells are not broken. They are getting signals from other broken cells.
–Abnormal mast cells do bad things and tell other nearby cells to do bad things. This is mast cell disease, specifically mast cell activation syndrome and sometimes monoclonal mast cell activation syndrome.
–You make way too many mast cells, they are abnormal, they do bad things, and they tell other nearby cells to do bad things. This is mast cell disease, specifically all forms of mastocytosis (systemic, cutaneous, and mast cell leukemia), sometimes monoclonal mast cell activation syndrome and mast cell tumors (mastocytoma and mast cell sarcoma).
• Generally speaking, if you have mast cell disease, any other condition you have will irritate your mast cell disease. This can also work the other way around and mast cell disease can irritate your other conditions.
• Many conditions naturally trigger higher level mast cell activation.
• Any disease that causes your body to make a lot of cells very quickly is likely to trigger to mast cell activation. Cancers are mast cell activating. Non cancerous diseases where you make too many blood cells at once, like polycythemia vera or essential thrombocythemia, are are mast cell activating.
• Mast cells are usually found very close to tumors. Sometimes, they are found inside tumors. Mast cells are important for tumors to survive because they can make blood vessels to bring tumors the blood they need.
• Diseases affecting the immune system are triggering to mast cells. In fact, many patients have mast cell activation syndrome caused by the immune disease irritating their mast cells so much. Many mast cell patients have autoimmune diseases like lupus or rheumatoid arthritis. Many patients also have deficiencies in their immune system. Because mast cells are immune cells, they are very responsive to signals from other immune cells. Mast cells think those cells need help from them to fight an infection or disease so they respond strongly to “help”.
• Diseases that cause inflammation also trigger mast cells. This can happen whether the inflammation is local or not. Systemic inflammation is more irritating to mast cells since that kind of inflammation can find more mast cells throughout the body. Local inflammation can irritate mast cells nearby. It can also call mast cells from other parts of the body to that location.
• Mast cells are actively involved in fighting infections from viruses, bacteria, fungi, and parasites. This is the reason many mast cell patients find they are more reactive when they have even a minor illness, like a cold.
• Any type of physical stress can activate mast cells. This can be something as simple as exercise or something more traumatic such as a car accident, a surgery, or childbirth. Even things that should be easy to recover from can activate mast cells, like a small cut, dehydration, or getting overheated. This also includes stress caused by another disease.
• Emotional stress can activate mast cells, even if the big emotion is joy.
For more detailed reading, please visit this page:

Symptoms and effects of mast cell disease

 

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 10

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

17. Does mast cell disease impact mood, anxiety, and depression?
• Yes. This has been described in literature for over 30 years. In 1986, a paper described a series of patients with systemic mastocytosis who had severe psychiatric symptoms as a result of their disease. It was called “mixed organic brain syndrome”.
• Depression, anger, bipolar disorder, attention deficit disorders, anxiety, irritating, and panic disorders have all been associated with mast cell disease.
• One study found that in a group of patients with cutaneous mastocytosis and systemic mastocytosis, 75% of the patients had symptoms of depression. In another study, 60% had symptoms of depression or anxiety.
• Many patients have been diagnosed with a psychiatric condition before learning that they have mast cell disease. For many mast cell patients, managing their diseases lessens the severity of their psychiatric symptoms. Antihistamines have been reported many times to improve these symptoms.
• Mast cells are often sitting right next to nerve cells throughout the body. Mast cells are found in large numbers in the brain. Chemicals released by mast cells can cause psychiatric symptoms.
• Some of the chemicals released by mast cells are specifically intended to talk to nerve cells. Histamine is one such chemical. When histamine is not released in the right amounts at the right times, it can affect how other chemicals are released. Some of these chemicals are also for cells to talk to nerves, like serotonin and dopamine. Mast cells can also release serotonin.

18. Are medications for depression, anxiety or other psychiatric conditions used in mast cell patients?
• Yes. As with every medication, only you and your care team can decide if a medication is safe for you. No medication is universally safe or always dangerous.
• Benzodiazepines are usually well tolerated in mast cell patients. Benzodiazepines actually interact with mast cells and can make them release fewer chemicals. (Be aware that the IV forms of these medications sometimes have alcohol in them).
• SSRIs are sometimes taken by mast cell patients. Mast cell patients should be cautious because they can increase serotonin levels and mast cells can also release serotonin.
• Tricyclic antidepressants are more commonly used in mast cell patients. Tricyclic antidepressants actually work as antihistamines, too.
• Other drugs that can manage psychiatric symptoms, like mirtazapine, olanzapine, and quetiapine, also have antihistamine properties.
For more detailed reading, please visit these posts:

 

Neuropsychiatric features of mast cell disease: Part 1 of 2

Neuropsychiatric features of mast cell disease: Part 2 of 2

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 9

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

15. How is mast cell disease treated?
• There are a number of medications to treat mast cell disease. Mast cells release so many chemicals, some in a large quantity. We are not able to totally stop mast cells from releasing the chemicals so we need to use many medications to block their effects on the body.
• The baseline regimen for mast cell patients include antihistamines and mast cell stabilizers. Specifically, patients are usually prescribed two antihistamines that work two different ways. These are called H1 antihistamines and H2 antihistamines. The H in these meds stand for histamine. There are many antihistamine options. Antihistamines stop the histamine from working in the body. Even still, many patients experience histamine driven symptoms
• Mast cell stabilizers work by making mast cells less likely to release chemicals. There are fewer options for mast cell stabilizers. Cromolyn is a very common mast cell stabilizer. Ketotifen is both a mast cell stabilizer and an antihistamine. Ketotifen that you can take as a pill is not approved in the US because there was not a market for it so it was never submitted to the FDA. However, patients can get ketotifen in pill form through compounding pharmacies in the US.
• Other types of medication commonly used for mast cell disease that block the effect of mast cell chemicals include leukotriene inhibitors and PAF blockers.
• Some medications can stop mast cells from making specific chemicals. These include COX inhibitors, lipoxygenase inhibitors, and corticosteroids like prednisone.
• Many patients are deficient in some vitamins or minerals because they don’t absorb them well in the GI tract. Vitamin D and iron are commonly low. Patients often take supplements to replace these deficiencies.
• Chemo drugs are sometimes used to treat severe mast cell disease. These drugs can kill mast cells and/or decrease the amount of chemicals released.
• IV fluids are reported by patients to help with symptoms such as fatigue and swelling.
• There are many other medications that can be used to treat other symptoms.

16. Do I have to take medication if I feel okay?
• Mast cell patients are usually recommended to take baseline medications like antihistamines and mast cell stabilizers even if they feel okay. This is for two main reasons: mast cells can damage your body even if you don’t feel it; and if you do not take baseline medications, you will have less protection from a severe reaction and anaphylaxis.
• Many patients have other medications prescribed to be taken as needed. These medications are given when symptoms are bad and do not necessarily have to be taken daily.
• Please speak with your provider to clarify what meds are taken as needed and what meds are taken every day.
For more detailed reading, please visit these posts:

The Provider Primer Series: Management of mast cell mediator symptoms and release

The Provider Primer Series: Mast cell activation syndrome (MCAS)

The Provider Primer Series: Cutaneous Mastocytosis/ Mastocytosis in the Skin

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, part 8

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

14. Are there any special instructions for the tests to diagnose mast cell disease?
• There are a lot of tests used to diagnose mast cell disease. There are certainly people who slip through the cracks with the current diagnostic criteria.
• Remember this as you read the following: DO NOT, UNDER ANY CIRCUMSTANCES, EVER, DISCONTINUE MEDICATION FOR TESTING WITHOUT EXPLICIT INSTRUCTIONS TO DO FROM A DOCTOR THAT UNDERSTANDS MAST CELL DISEASE. Stopping medications for mast cell disease can be very dangerous.
• The biopsy forms the centerpiece of diagnosis of both cutaneous and systemic forms of mastocytosis.
• You can increase your chance of positive skin biopsy by choosing either a permanent lesion or an area of skin that is frequently reactive.
• For internal organs, including bone marrow, you can’t always tell where to biopsy just by looking. The area may look normal but show inflammation when viewed with a microscope.
• If patients do not need to take daily corticosteroids because they do not make their own (adrenal insufficiency or Addison’s disease), they are often recommended to not use corticosteroids (prednisone or similar) for five days before a bone marrow biopsy. Taking corticosteroids can tell your body to make a lot of extra white blood cells which can make it harder to give a correct diagnosis.
• The CKIT D816V mutation test is often done on a blood sample. It is much more accurate when a bone marrow biopsy is tested because there are many more mast cells. Mast cells do not live in the blood so the blood test is less accurate. If the test is positive in blood, we assume that the patient is truly positive. If the test is negative in blood, we are not sure if the patient is truly negative.
• Serum tryptase is a test with a lot of caveats. It is influenced heavily by timing and patient factors like weight. Many people with mast cell disease have normal serum tryptase. It is good for tracking progression of disease in patients with systemic mastocytosis.
• About 85% of patients with systemic mastocytosis have a baseline tryptase value over 20 ng/mL. Patients with monoclonal mast cell activation syndrome may also have baseline tryptase value over 20 ng/mL. For these patients, they should have two different tests from days when they are not especially reactive, or have had anaphylaxis.
• For patients with mast cell activation syndrome, we are often looking for an increase in tryptase during a reaction or anaphylactic event. In these patients, experts recommend having blood drawn 15 minutes to 4 hours after onset of the event.
• Another sample should be drawn 1-2 days later so that you have a sample to compare with the tryptase level during the event. Many experts accept a level increased by 20% plus 2 ng/mL above the baseline to be indicative of mast cell activation. (I made a typo on this that said 20% to 2 – sorry!)
• As we have previously discussed, many mast cell mediators should be kept cold because they break down quickly. 24 hour urines for n-methylhistamine, prostaglandin D2, 9a,11b prostaglandin F2, and leukotriene E4 should be kept cold.
• Performing a 24 hour urine when you are having a reaction event can increase the likelihood of mediator release.
• COX inhibitors will interfere with prostaglandin production. Some patients stop these meds before giving 24 hour urines for prostaglandin testing. DO NOT STOP MEDS WITHOUT BEING ADVISED BY AN EXPERIENCED MAST CELL PROVIDER.
• Lipoxygenase inhibitors will interfere with leukotriene production. Some patients stop these meds before giving 24 hour urines for leukotriene testing. DO NOT STOP MEDS WITHOUT BEING ADVISED BY AN EXPERIENCED MAST CELL PROVIDER.
• Heparin is very heat sensitive. Plasma heparin must be kept cold. One study reported that a tourniquet on the upper arm for ten minutes before drawing the sample increased the change of detecting mast cell activation with this test.
• Chromogranin A is influenced by many other conditions and medications. It is important that those other conditions be ruled out. This may require lengthy body scans and other tests. Chromogranin A is influenced by proton pump inhibitors, meds that are commonly taken by mast cell patients. DO NOT STOP MEDS WITHOUT BEING ADVISED BY AN EXPERIENCED MAST CELL PROVIDER.

For more detailed reading, please visit these posts:

The Provider Primer Series: Mediator testing

Patient questions: Everything you wanted to know about tryptase

The Provider Primer Series: Mast cell activation syndrome (MCAS)

The Provider Primer Series: Cutaneous Mastocytosis/ Mastocytosis in the Skin

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, part 7

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

 

13. What do these biopsy tests look for?
• They look for the shape, quantity, and distribution of mast cells.
• They also look for specific proteins on the outside of mast cells and tissue damage around mast cells.
• Systemic mastocytosis and cutaneous mastocytosis are generally diagnosed by biopsy. With very, very few exceptions, you cannot meet the criteria for systemic mastocytosis without having a positive biopsy. Sometimes people with monoclonal mast cell activation syndrome are diagnosed by having a biopsy that looks like a very early phase of systemic mastocytosis.
• The diagnostic criteria for mast cell activation syndrome are hotly contested. Most doctors do not use biopsies to diagnose MCAS because there are not uniform criteria. Some doctors feel that more than 20 mast cells in a field when you look through the microscope is a sign of MCAS.
• Cutaneous mastocytosis is having too many broken mast cells in your skin. For this condition, they are looking for either 20 mast cells to be present in the microscope field (hpf) when looking at the skin, or for there to be at least one cluster of at least fifteen mast cells.
• Clustering is a very important feature of mastocytosis. When mast cells bunch together in a cluster, it is easier to damage the tissue. They are essentially punching holes in the tissue by clustering.
• Systemic mastocytosis is having too many broken mast cells made by the bone marrow. Systemic mastocytosis is usually diagnosed by a positive bone marrow biopsy. However, sometimes people are diagnosed by biopsies of other organs. Skin biopsy is NOT enough to diagnose systemic mastocytosis.
• For systemic mastocytosis, there are three key things they are looking for in the biopsy.
• They are looking for at least one cluster of at least fifteen mast cells.
• They are looking for some of the mast cells to be shaped like spindles, sort of smushed at the ends and round in the middle. You see this shape a lot when cells are trying to stick together in a cluster.
• They are looking for special proteins that are only found when a patient has systemic mastocytosis or monoclonal mast cell activation syndrome. They are called CD25 and CD2. These are like flags that the mast cells fly to tell us they are broken. One of them, CD25, actually helps mast cells cluster together.
• In biopsies, they usually also look for the protein CD117. This is a normal flag for mast cells to fly and just allows us to know that we are looking at mast cells.

For more detailed reading, please visit these posts:

The Provider Primer Series: Management of mast cell mediator symptoms and release

The Provider Primer Series: Mast cell activation syndrome (MCAS)

The Provider Primer Series: Cutaneous Mastocytosis/ Mastocytosis in the Skin

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 6

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

12. What do these blood and urine tests look for?

• There are a lot of tests ordered for mast cell disease. How they are interpreted can depend upon a lot of factors. Some of the tests are unreliable, a fact that will be addressed in detail later in this series. (And has been addressed in detail elsewhere on this blog). Please keep in mind when reading this post that I am being VERY general and assumed the test was performed correctly on a correctly stored sample.
• The most common test ordered for mast cell disease is serum tryptase. Tryptase is a molecule that mast cells release. While it has lots of functions in the body, and is especially important in healing wounds and tissue growth, the amount present in your body at a given moment should be low.
• Tryptase is special because mast cells release it in two ways. Firstly, they make and release a little bit steadily. This is not related to activation. Mast cells just normally release a little tryptase as they go about their work. So the idea is that if you have more mast cells than you should, and each of those mast cells releases a little tryptase all the time, that you will have a higher than normal serum tryptase.
• Patients with a clonal mast cell disease, in which they have too many broken mast cells, usually have elevated baseline tryptase. This means tryptase that is elevated at least two times when you are NOT having a big reaction or anaphylaxis.
• Mast cells also store lots of tryptase in their pockets. When the mast cell is activated and it empties out its pockets, lots of tryptase comes out at once. This is why tryptase can be higher after a reaction or anaphylaxis, because mast cells release a bunch at once.
• Patients with mast cell activation syndrome or cutaneous mastocytosis do not always have elevated tryptase even with a big reaction or anaphylaxis.
• Mast cells have huge amounts of histamine stored in their pockets inside their cells. Histamine has lots of functions inside the body and is required for normal body functions. In particular, it is important to our nervous system. Smaller amounts are released as a normal function of the body.
• A lot of histamine is released when mast cells are activated. The idea is that if your mast cells are more activated than they should be that your histamine level will be higher. However, the test recommended for us to consider the histamine level in mast cell patients is not for histamine. It is for n-methylhistamine. This is a molecule that is formed when the body breaks down histamine, which happens very quickly (within minutes of release). n-methylhistamine is more stable, which is why we look at it.
• The test for n-methylhistamine is most reliable when performed in a 24 hour urine sample. This is because the level in urine can fluctuate throughout the day.
• Mast cells make a lot of prostaglandin D2 (abbreviated PGD2). PGD2 is very important for cell communicating. It can carry a message from one cell to another, allowing cells to work together. Unlike histamine and tryptase, mast cells do not keep PGD2 stored in their pockets. They make it only when they need it and then release it.
• PGD2 is released in large amounts when mast cells are activated. However, because it is not stored in the pockets, it is not always elevated right away when you have a big activation event or anaphylaxis. Prostaglandin D2 is broken down quickly. While we do test directly for PGD2 for mast cell disease, we also test for 9a,11-PGF2, a molecule formed when PGD2 breaks down.
• The tests for PGD2 and 9a,11b-PGF2 are most reliable when performed in 24 hour urine samples. This is because the levels in urine can fluctuate throughout the day.
• Heparin is a blood thinning molecule that is stored in pockets inside mast cells. Mast cells are the only cells that release significant amounts of histamine. When the mast cell is activated and it releases histamine, the histamine comes out stuck to heparin. Heparin is broken down very quickly so it is hard to measure accurately.
• The test to assess heparin level actually looks for a molecule called anti-factor Xa that can interact with heparin. This test is performed in serum.
• Chromogranin A is released by mast cells. It is also released by a lot of other cells. The level of this molecule can be affected by many things, including common medications. It is sometimes tested for and considered a sign of mast cell disease if elevated when all other possible reasons can be excluded.
• Chromogranin A levels are most reliable in serum.

 

For more detailed reading, please visit these posts:

The Provider Primer Series: Management of mast cell mediator symptoms and release

The Provider Primer Series: Mast cell activation syndrome (MCAS)

The Provider Primer Series: Cutaneous Mastocytosis/ Mastocytosis in the Skin

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)