The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, part 49

60. Is anaphylaxis the same as anaphylactic shock?

No. Anaphylaxis can result in anaphylactic shock but it often doesn’t. When talking about anaphylactic shock, people are referring to circulatory shock that was caused by anaphylaxis. Circulatory shock occurs when there is not enough blood to carry oxygen to all the tissues that need it. When the tissues don’t get enough oxygen, your organs stop working correctly.

Circulatory shock is usually caused by low blood pressure. Anaphylaxis commonly causes low blood pressure and that can cause shock. However, anaphylaxis does not always cause low blood pressure, and it does not always cause shock.

61. If a tryptase level over 10.9 ng/mL is high, why is one of the criteria for systemic mastocytosis a tryptase level of 20.0 ng/mL or higher?

Tryptase level is used in two ways in assessing mast cell patients: as a marker for activation, and as a marker for how many mast cells are in the body.

There are two primary methods of using tryptase to indicate mast cell activation.

The first way is to compare a tryptase level when a patient is reacting to a tryptase level when they are not reacting (baseline). Mast cells release more tryptase when they are activated. For mast cell patients, an increase of 20% + 2 ng/mL is considered evidence of mast cell activation. So if a patient has a baseline tryptase of 5 ng/mL when they are not reacting, anything 8 ng/mL (20% of 5 ng/mL is 1 ng/mL, then add 2 ng/mL = 8 ng/mL) or higher is considered evidence of activation.

The second way is to count anything over 10.9 ng/mL as evidence of activation.

When you are using tryptase as a measure of how many mast cells are in the body, the patient should not be reacting beyond their normal day to day symptoms. This is because you don’t want an increase in tryptase from activation to make the baseline level look higher than it is. Tryptase is used to measure how many mast cells are present because mast cells release some tryptase all the time, even when they aren’t activated.

Anything over 10.9 ng/mL is considered an elevation of tryptase. The reason that 20 ng/mL is the cutoff for the SM criterion is that patients are likely to have a positive bone marrow biopsy when the tryptase level is twice normal (21.8 ng/mL). They round the number down to 20 ng/mL because all tests have a margin of error. By rounding down to 20 ng/mL, they catch patients that might not have made the cutoff before because of an error in the test. This means that a patient who has a tryptase level of 20 ng/mL or higher is likely to have a bone marrow biopsy that will be positive for systemic mastocytosis.

For more detailed reading, please visit these posts:

Anaphylaxis and mast cell reactions

The Provider Primer Series: Mediator Testing

Patient questions: Everything you wanted to know about tryptase

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

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 48

59. Is systemic mastocytosis a form of cancer? Why do some papers say the life expectancy for systemic mastocytosis patients is much shorter?

Systemic mastocytosis is a term that different people use in different ways, often without defining them for the audience. This can lead to some confusion.

In its broadest sense, systemic mastocytosis is actually a disease category rather than one specific diagnosis. The subtypes of systemic mastocytosis are indolent systemic mastocytosis (ISM), smoldering systemic mastocytosis (SSM), systemic mastocytosis with associated hematologic disease (SM-AHD), aggressive systemic mastocytosis (ASM), and mast cell leukemia (MCL).

When patients talk about systemic mastocytosis without specifying which diagnosis, they almost always mean indolent systemic mastocytosis (ISM), the most common form of SM. ISM is benign and has a normal life expectancy. But when providers and researchers talk about systemic mastocytosis, they usually mean the disease category that includes all of these diagnoses.

I just recently explained in another post what a neoplasm is. It is essentially when the body grows something that doesn’t belong there, like extra cells or a tumor. Cancers are neoplasms but not all neoplasms are cancerous. Indolent systemic mastocytosis is not cancerous. Even without taking drugs to kill off lots of mast cells, the prognosis is excellent with a normal life span. However, aggressive systemic mastocytosis and mast cell leukemia are considered cancerous. Without taking drugs to kill off mast cells, the body would be unable to cope with the huge number of mast cells and the damage they cause. Smoldering systemic mastocytosis is sort of a bridge between ISM, which is benign, and ASM, which is not.

If you are not aware that research papers usually use the term systemic mastocytosis to mean all forms of systemic mastocytosis and not just indolent systemic mastocytosis (ISM), it is easy to get confused and misunderstand what is being said. There was a paper published in 2009 that discussed expected survival for the various forms of systemic mastocytosis. It provides a very jarring statistic for patients who may not understand the context. This study found that many patients with systemic mastocytosis died 3-5 years after diagnosis.

Let’s pull this apart. We know there are five forms of SM: indolent SM, the most common form, which usually has a normal life span; smoldering SM, which usually has a shortened life span; aggressive SM, which can have a very shortened life span; mast cell leukemia, which has a very shortened life span; and SM with an associated hematologic disorder, which may have a shortened life span. When you average the life expectancies for a mixed group of patients with these various diagnoses, it shows that overall, SM patients are more likely to die 3-5 years after diagnosis when compared to healthy people of the same age.

Additionally, a lot of the patients in this study group were older and died of causes unrelated to systemic mastocytosis. However, because they were part of the study, their deaths of unrelated causes were still included in this data.

Let’s recap: in a research paper, the term systemic mastocytosis includes forms of SM that are malignant and can really shorten your life expectancy as well as forms that are benign and do not shorten your life expectancy. When you average the life expectancies of all of these forms together, it looks like patients are more likely to die 3-5 years after diagnosis. A bunch of other papers then used the data from this study in 2009 without explaining the details behind it. However, most patients with SM have normal life spans.

For more detailed information, please visit these posts:

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

The Provider Primer Series: Natural history of SM-AHD, MCL and MCS

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 46

56. Why do I react every time I eat?

When you swallow food, your nervous system sends signals to tell the cells in the stomach that food is on the way. As a result of this neurologic signal, hormones are released to tell your stomach to get ready to digest. These hormones cause histamine to be released by cells in the stomach. The histamine tells your stomach to make acid to digest your food. Solid food is more activating to the stomach in this way than liquids are.

This is a normal function of the body and happens in everyone, not just people with mast cell disease. However, histamine released in the stomach can activate mast cells and cause typical mast cell symptoms. Like everything else in mast cell disease, how much this affects patients varies a lot. But something to keep in mind is that a lot of mast cell patients who are “allergic to everything they eat” are actually reacting to the normal histamine release that contributes to digestion. They are essentially allergic not just to what they are eating, but to the process of eating.

57. Do I have to go to the hospital every time I use an epipen?

Unless you have received very explicit instructions not to do so from a health care provider that is familiar with the particulars of your life and your health, you need to go to the hospital every time you use an epipen. The reason for this is because an epipen is a temporary measure. The purpose of the epipen is to give you time to get to a hospital for more advanced care. Epinephrine is broken down by your body in a matter of minutes so it only provides a small window of protection. While many patients only need one epipen, there is no way to know if you will have another wave of anaphylaxis after the first one. Additionally, many patients require other medications and IV fluids to treat anaphylaxis. These can be provided at a hospital.

The reason you have to go to the hospital is to give you access to more comprehensive care, not because using an epipen is dangerous.

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 47

  1. 58. What is mastocytic enterocolitis?

A high powered field (hpf) is what you see through a microscope when you use powerful magnifying lenses. With very few exceptions, high powered fields using the same lenses are the same size. Since they are the same size, you can directly compare results from various groups all over the world.

In 2006, a paper was published that coined the term “mastocytic enterocolitis”. The author described mastocytic enterocolitis as more than 20 mast cells per high powered field. This paper was about people with severe chronic diarrhea that did not improve with treatment. The author found that healthy people had about 13 mast cells/hpf while people with severe chronic diarrhea had about 20 mast cells/hpf. The author felt that the extra mast cells were responsible for the diarrhea and inflammation so they called the extra mast cells in the colon and the small intestine “mastocytic enterocolitis”. Enterocolitis is the term for inflammation in the small intestine and colon.

The author felt that 20 mast cells/hpf was the cutoff between a normal amount of mast cells in the GI tract and an abnormal amount. Under 20 was considered normal while 20 and above was considered abnormal. However, there have been a number of papers since that look at how many mast cells are present in the GI tract for patients with different conditions as well as healthy people. There are several conditions that can cause you to have 20 or more mast cells/hpf. (I wrote an exhaustive series on this in 2015-2016. Links are below.)

Additionally, in some situations, people have over 20 mast cells/hpf without having any symptoms. Sometimes healthy people without any GI conditions have over 20 mast cells/hpf. For this reason, there is not agreement about how many mast cells in the GI tract is too many. (If you’re looking for my opinion, I think the number for what is too many is around 25-30/hpf. This is just my opinion.)

In the last several years, some doctors have begun linking mastocytic enterocolitis to mast cell disease. This makes sense because we know that in those people, mast cell inflammation drives GI symptoms and damage. Mast cell patients certainly have a lot of inflammation in the GI tract so having extra mast cells there makes sense. Some experts think that mastocytic enterocolitis is a sign of mast cell activation syndrome and that patients with mastocytic enterocolitis all have mast cell activation syndrome.

Mastocytic enterocolitis is absolutely a real phenomenon. In these people, mast cells cause a lot of GI symptoms and damage the GI tract. Experts have not all agreed upon whether or not everyone with mastocytic enterocolitis has mast cell disease. Also, there are some researchers that feel that mastocytic enterocolitis is actually its own mast cell disease rather than just a feature of another mast cell disease like mast cell activation syndrome.

Currently, mastocytic enterocolitis is not recognized by the WHO as its own disorder. However, that could certainly change. It was only last year that MCAS was recognized by the CDC even though it was routinely recognized by researchers and providers. (Author’s note: This was initially published stating that the WHO recognized MCAS, rather than the CDC. MCAS has not yet been recognized by the WHO. This is a whopper mistake on my part. Many thanks to the reader who saw this. Sorry!) I personally expect this to change in the next few years as more mast cell patients are diagnosed and mastocytic enterocolitis is better recognized. I think it is suggestive of mast cell disease but I also think providers need to eliminate other possible causes for the extra mast cells in the GI tract.

For more detailed information, please visit these posts:

Mast cells in the GI tract: How many is too many? (Part One)

Mast cells in the GI tract: How many is too many? (Part Two)

Mast cells in the GI tract: How many is too many? (Part Three)

Mast cells in the GI tract: How many is too many? (Part Four)

Mast cells in the GI tract: How many is too many? (Part Five)

Mast cells in the GI tract: How many is too many? (Part Six)

Mast cells in the GI tract: How many is too many? (Part Seven)

Mast cells in the GI tract: How many is too many? (Part Eight)

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

54. How does mast cell disease affect clotting?

Heparin is a very potent blood thinner and inhibits the body’s ability to form clots.  Mast cells are full of heparin. Mast cells stores chemicals like heparin in little pouches inside them called granules. In the granules, histamine is stuck to heparin. This means that when mast cells open their granules and release histamine, heparin comes out with it. This can contribute to things like bruising or bleeding more than expected.

Mast cells release other chemicals that can affect clotting. Platelet activation factor and thromboxane A2 both encourage the body to make clots. Some chemicals that help to regulate when to make a clot can activate mast cells, like complement C3a and C5a.

55. How many people have mast cell disease?

It is hard to know exactly how many people have a rare disease because they are not reported if they are recognized and correctly diagnosed. As recognition and diagnosis improves, rare diseases are often found to be more prevalent than previously thought. The numbers below are current estimates.

Systemic mastocytosis is thought to affect around 0.3-13/100000 people. In one large study, indolent systemic mastocytosis (ISM) makes up 47% of cases. Aggressive systemic mastocytosis (ASM) has been described in various places as comprising 3-10%. Systemic mastocytosis with associated hematologic disease could count for as many of 40% of cases of SM. Mast cell leukemia is extremely rare and accounts for less than 1% of SM cases.

Systemic mastocytosis accounts for about 10% of total mastocytosis cases. This means that total mastocytosis cases come in at around 3-130/100000 people. The remaining 90% of mastocytosis cases are cutaneous with incidence roughly around 2.7-117/100000 people.

We do not have yet have a great grasp upon how many people have mast cell activation syndrome (MCAS) but from where I am sitting, it’s a lot and that number is likely to grow. We know that genetic studies have found mutations that might be linked to MCAS in up to 9% of the people in some groups. However, having a mutation is not the same thing as having a disease. As we learn more about MCAS, we will gain some clarity around how many people have it.

For more detailed reading, please visit the following posts:

Progression of mast cell diseases: Part 2

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

The Provider Primer Series: Natural history of SM-AHD, MCL and MCS

The Provider Primer Series: Cutaneous mastocytosis/Mastocytosis in the skin

 

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 44

53.  How do I get effective care from providers that don’t know anything about mast cell disease?

One of the most frustrating and concerning issues for mast cell patients is the need for involved specialty care when there are only a handful of experts worldwide. Many of us need so much care that there could be dozens of providers involved. Obviously there are no hard and fast rules that will guarantee a positive interaction with providers that don’t know about mast cell disease, but I will tell you what works for me.

My general recommendations about how to increase your chances of good care from providers are as follows:

  1. Do not expect most providers to know about mast cell disease or how to treat it. Patients are often upset to discover that healthcare providers know nothing about mast cell disease or how to treat it. There are currently over 7000 rare diseases described in literature. About 25,000,000 Americans have at least one rare disease. That is a lot of rare. It is impossible to know the ins and outs of so many diseases. Furthermore, medical education in recent years hinges not upon knowing everything but knowing where to find the knowledge you need. It is less important for your provider to know about mast cell disease than it is to know where they can find reliable information about it.
  • I never expect any provider to have heard of mast cell disease because it made me so mad so often when I did. I also find that I feel less hostile towards providers when I don’t expect them to have prior knowledge about my diseases. Less hostility improves any interaction.
  1. Have a script prepared for when you meet a provider that you don’t know. This is what I say after we exchange pleasantries:
  • “Before we get started, I want to make sure that you know that I have a rare blood disorder called systemic mastocytosis. Have you ever seen a patient with that before?”
  • If they have seen a patient with it before, great! Either way, I say this next:
  • “The hallmark of mast cell disease is severe allergic reaction or anaphylaxis to a variety of triggers without the involvement of IgE. It would really help me a lot if you could be really clear about what you’re doing and exactly what medications or materials I am being given. Also, if I feel anaphylaxis starting, I will use my Epipen first and then call for help.” (Please note that I administer epi myself immediately as directed by my immunologist. Speak with your doctor to find out what is the best course of action for you.)
  • This script does several things. Firstly, it lets them know that I have a reasonable understanding of my disease and the risks I face. This makes me a partner in my care. Secondly, it gives the provider a clear understanding of my expectations. They understand that I expect them to tell me everything they are doing and what materials and medications they are using. They understand there is the risk of anaphylaxis and that I have been given an Epipen to manage that. They understand that I will use this first and then call for help. In particular, the part about the Epipen is really important. Patients sometimes run into trouble when they use their own Epipen because providers are not expecting that and don’t react to it well. This conversation helps to avoid such a confrontration.
  • If I have seen this provider before, but it has been a while, or I remember them as being particularly unaware of mast cell disease, my script is basically the same. Something like,
  • “I just want to remind you that I have a rare blood disorder called systemic mastocytosis. The hallmark of mast cell disease is severe allergic reaction or anaphylaxis to a variety of triggers without the involvement of IgE. It would really help me a lot if you could be really clear about what you’re doing and exactly what medications or materials I am being given. Also, if I feel anaphylaxis starting, I will use my Epipen first and then call for help.”
  1. If you have a scheduled appointment or test somewhere you have not been seen before, call ahead a week or two before the appointment. Leave a message for the provider or their surrogate asking them to call you. This is the script I use:
  • “Hi, my name is Lisa Klimas, and I have an appointment with Dr. Yahoo at Some Date at Some Time Somewhere. I was just calling to make sure Dr. Yahoo is aware that I have a rare blood disorder called systemic mastocytosis. This disorder can cause allergic reactions to common things so there are certain precautions for mast cell patients. I would appreciate it if you could call me at your earliest convenience. Additionally, my mast cell specialist Dr. Mast Cell is available at Dr. Mast Cell’s number if you have any questions or concerns.”
  • Once again, we are clearly communicating our expectations. This also gives them extra time to learn a bit about mast cell disease or consult with your specialist so that they are comfortable seeing you.
  1. Be pleasant. This is hard to do sometimes, especially if you are scared. But if you can do this, things go much smoother. Nobody likes to be told what to do, even if they need to. Nobody likes to feel stupid. Be respectful. They will be much more likely to view you as an intriguing rare patient as opposed to some bitchy lady with masto (not speaking from personal experience, of course.)
  2. Do not argue. This is so, SO difficult sometimes but it is critical that you do not argue. Mast cell patients require a degree of control in order to mitigate the risk of reactions or anaphylaxis. Once you start arguing, you are no longer in control. You have given that control up. You will be viewed as an adversary. That is not going to get you anywhere.
  3. If you break rule 4 or 5, apologize.
  4. Be knowledgeable about your disease. You are your own best defense against dangerous health situations. You do not have to know everything but you should know where to direct providers for the information they need.
  5. When you give information about your disease, it has to be correct. This is so, so important. If you do not know the answer to something, do not invent one. Just say that you don’t know and that you can find out, or suggest a place where they can get that information.
  6. Limit the drama and intrigue when you are telling providers about your disease. There is a very fine line between being informative and scaring them. Help providers to feel comfortable about treating you.
  7. Have handy literature to educate providers about mast cell disease and how to manage mast cell patients safely. The literature should be short and comprehensive. They are much more likely to read something if it’s short and to the point. I let them know if that they are interested in further resources that I can provide those as well. I personally prefer to email literature to providers but hard copies are okay, too.
  • There are a few concise, effective papers that are great for this. This paper by Molderings and Afrin is one of my favorites. This one by Valent is good, too.
  • There are also materials prepared by organizations that are helpful for this. The Mastocytosis Society has materials for providers. On this site, I wrote the Provider Primer series for this specific purpose.
  1. Know the premedication and rescue medication protocols by heart. Also carry them in hard copy. You can find that here. If your protocols vary a lot from the general recommendations, ask for your doctor to write a letter describing your protocol that can be given to providers as needed.
  2. Know the difference between inconvenience and danger. This is critical. You have to know when a situation is dangerous and not just frustrating. There’s a big difference between refusing to give you epi during flagrant anaphylaxis and a provider making a stupid comment that being too hot can’t cause anaphylaxis. Your end game is always to get the care you need in a safe environment. Not every provider is going to be nice about your needs but if they are getting met, it’s not always worth it to argue.
  3. Remember that providers are doing their job. I have seen people report doctors who see multiple mast cell patients because the doctor was rude. I cannot stress enough that there is not a limitless pool of providers willing to treat mast cell patients. We do not want to give providers a reason to refuse to treat us. As much as possible, if you really can’t let a situation go, try to resolve it directly with the provider.
  4. Strongly encourage that your local providers establish a relationship with experts. This improves communication and encourages your local providers to seek help when they are unsure about how to help you.

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 43

52. Is it true that it can take up to six bone marrow biopsies to diagnose systemic mastocytosis?

Sort of. This has become sort of an urban legend in the mast cell community. I am partly to blame for this as I have offered this information up several times without explaining it, which is lazy on my part.

Systemic mastocytosis is diagnosed by biopsy. While a positive biopsy in any organ that’s not skin can be used to diagnose SM, bone marrow biopsies are overwhelmingly what is used to diagnose.

In 2004, a paper was published that discussed how well bone marrow biopsies worked for diagnosing SM in a group of 23 patients. These patients had bilateral bone marrow biopsies taken, so each patient had one on each side. In 19 of those patients, both of the biopsies showed mastocytosis. In 4 of those patients, only one of their two biopsies was positive. 4/23 is 17%, which is roughly 1/6. Based upon this figure, it means that theoretically, in a patient who has SM, they could have five negative biopsies before getting a positive biopsy.

It’s important to two things in mind when you think about this 1/6 thing. Firstly, this is a very small patient group. Things that you see in a small group don’t always translate to what really happens in larger groups. Another thing is that the criteria they used in 2004 to diagnose SM are not the same as the criteria we use now. It’s possible that with changes in diagnostic criteria that this 1/6 number is no longer accurate.

In reality, I have never met a person who needed six bone marrow biopsies to get a positive biopsy for SM. But I do know a few who needed two or three. It’s not impossible that it could take six to get a positive biopsy but it’s unlikely.

However, it’s also important to realize that every expert acknowledges that you can have a negative biopsy while having SM. The reason for this is that you can’t tell by looking whether or not a biopsy site will give you a positive biopsy for SM. You have to just hope that the mast cells are clustered where they stick the needle. Mast cells don’t cluster evenly throughout your bone marrow when you have SM. If you get a biopsy site where the mast cells didn’t happen to cluster, you are out of luck. For this reason, some doctors advocate getting bilateral bone marrow biopsies (two at once) to increase the chances of catching a positive biopsy.

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 42

51. What is the difference between mast cell activation syndrome and histamine intolerance?

Histamine intolerance is not widely accepted by the mainstream medical establishment. I haven’t been able to find much about it in the way of peer reviewed literature. That said, it doesn’t seem ridiculous to me. It feels plausible, I just haven’t seen convincing evidence of that yet.

Histamine intolerance is when a patient has symptoms from ingesting something that has a lot of histamine in it, that causes the body to release histamine, or that interferes with the body’s ability to break down histamine. In histamine intolerance, the problem is what is being put into your body rather your body itself. The problem is external, not internal.

Mast cell activation syndrome is when a patient’s mast cells are fundamentally dysfunctional. The problem is internal, not external. There is no evidence at this point that patients with MCAS can’t break down histamine normally with enough time, there’s just so much of it that it takes longer.

Many patients with MCAS (and other mast cell diseases) often have symptoms when they ingest something that has a lot of histamine in it or that causes the body to release histamine. There are two theoretical ways in which ingestion of histamine can cause symptoms: either the histamine released/ingested makes it way to other parts of the body and causes symptoms there directly; or, the histamine released/ingested makes mast cells release more histamine.

Regardless of exactly what is happening, patients with MCAS and histamine intolerance can have identical symptoms to ingesting a trigger. Importantly, MCAS patients may have histamine symptoms from lots of other things, not just ingesting something.

Histamine intolerance is much more commonly discussed in holistic and alternative medicine groups, which is definitely not where my expertise is. If you are aware of some recent data on histamine intolerance, or if I have made a mistake in this post, please let me know so that I can correct it.

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 41

50. How does mast cell disease affect hearing?

For readers who don’t know, I lost the majority of my hearing in 2009. I am profoundly deaf in my left ear and have moderate to severe hearing loss in my right. This happened years before I was diagnosed with systemic mastocytosis or Ehlers Danlos Syndrome.

Mast cell disease affects hearing in multiple ways. Some related diagnoses also affect hearing.

Mast cells are involved in sensorineural hearing loss. The exact role of mast cells is still being researched but hearing loss is not an unusual complaint for mast cell patients. Mast cell disease can also cause auditory processing disorder. This condition makes it difficult to understand speech. Ringing in the ears (tinnitus) is also a symptom of mast cell disease.

Many mast cell patients also have Ehlers Danlos Syndrome (EDS), a disease in which the body makes defective connective tissue. EDS patients are vulnerable to both sensorineural hearing loss, in which the nerves don’t correctly transmit sound from the ear to the brain, and conductive hearing loss, in which the ear is not able to carry the sound waves correctly to the inner ear. Having both types of hearing loss, sensorineural and conductive, is called mixed hearing loss.

Many mast cell patients are deconditioned. This means that their body has undergone lots of changes as the result of not being active. Sensory processing is affected in deconditioned patients. In particular, sounds must be louder to be heard correctly. POTS patients sometimes experience something similar.

Having certain autoimmune disorders can increase the risk of autoimmune inner ear disease, resulting in hearing loss. Many mast cell patients also have autoimmune disease.

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 40

49. What is the relationship between FPIES and MCAS?

FPIES is food protein induced enterocolitis syndrome, a severe type of food allergy. It causes continuous vomiting and diarrhea upon ingestion of a trigger. FPIES reactions can cause dehydration and dangerous drop in blood pressure. I cannot emphasize enough that FPIES can be extremely serious and that the reactions can be life threatening if they are not managed properly.

FPIES almost exclusively affects children starting in infancy and resolves around the age of 5. The reasons for this are unknown. FPIES is a diagnosis of exclusion. There are no tests to identify FPIES.

An important point is that trigger avoidance is generally sufficient for management in children with FPIES. When the child is not being exposed to a trigger, they should not have lingering symptoms.

If a child with FPIES continues to have symptoms, the conventional thinking is often that there must be a trigger that has not yet been eliminated from their diet. In children with continuing symptoms, they frequently have more traditional allergy type symptoms than the profuse GI issues seen with FPIES exposures. This is where FPIES starts to overlap with MCAS. MCAS can cause the same reactions to foods seen in FPIES. MCAS can also cause daily symptoms even if food triggers are avoided. Increasingly, children who were initially diagnosed with FPIES are later diagnosed with MCAS.

There are a few possible scenarios here. Firstly, it is possible that the child has FPIES and has MCAS secondarily to the FPIES. It is also possible that the child was misdiagnosed with FPIES and had MCAS all along. It may also be that FPIES is some form of MCAS. They have a lot in common.

Because there is no test for FPIES, and it is very difficult to accurately perform mediator testing to look for mast cell disease in infants, it is hard to be definitive at that age anyway. In some cases, investigation of MCAS as a possible diagnosis for these children only occurs when they fail to “grow out of” FPIES around age 5. Having anaphylaxis also provides a clue towards MCAS as a potential diagnosis.

For more detailed reading, please visit these posts:

Food allergy series: FPIES (Part 1)

Food allergy series: FPIES (Part 2)

Food allergy series: Mast cell food reactions and the low histamine diet

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