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The Dose Transcript for September 19, 2024

Host: Dr. Brian Goldman

BRIAN GOLDMAN: Hi, I'm Dr. Brian Goldman. Welcome to The Dose. In Canada, iron deficiency has been described by some physicians as a public health problem, so it's time we talked about it. And this week we're asking: what do I need to know about iron deficiency? Hi, Michelle. Welcome to The Dose. Michelle Sholzberg

MICHELLE SCHOLZBERG: Thanks for having me, Brian.

BRIAN GOLDMAN: Michelle, have you ever had low iron levels?

MICHELLE SCHOLZBERG: Oh, for sure. And I was shocked when I did. Because I'm somebody who has a diet that's rich in meats, I'm somebody who takes reasonably good care of themselves. And when I first found out that I had iron deficiency, I was totally shocked.

BRIAN GOLDMAN: Was it your pediatrician or was it your family doctor who diagnosed you?

MICHELLE SCHOLZBERG: Oh, no, no. I was first diagnosed with iron deficiency at the age of 34 when I was pregnant. So I had never previously had a ferritin check.

BRIAN GOLDMAN: I suspect that a lot of people listening to this conversation now have not had their ferritin levels checked or their iron levels checked. And of course, we're also talking to a much wider audience, including people at risk who don't have primary care. So, I'm really looking forward to this conversation. But before we begin, can you give us a hi, my name is? Tell us what you do and where you do it. Just ad lib.

MICHELLE SCHOLZBERG: Hi, my name is Michelle Scholzberg. I'm a hematologist at St Michael's Hospital. I'm a clinician scientist with a focus on women's hematological health and bleeding problems. And I'm the director of hematology at the University of Toronto.

BRIAN GOLDMAN: You're the right person to be asking these questions. Let's begin with the basics. How do we define iron deficiency?

MICHELLE SCHOLZBERG: So we define iron deficiency in adults with a blood test called the serum ferritin. And when the result is below 30, that's absolutely in keeping with iron deficiency. In pediatric patients -- so children, adolescents -- when the ferritin is below 20, that is in keeping with iron deficiency. There are other circumstances, of course, where the ferritin isn't the best test to indicate iron deficiency. But for the majority of people, those are really the unrefuted numbers.

BRIAN GOLDMAN: I certainly remember measuring ferritin, but I also remember measuring iron levels. What's the connection between measuring your iron level in the bloodstream and ferritin?

MICHELLE SCHOLZBERG: Ferritin is the storage form of iron. It binds to thousands of iron atoms and it stores iron in a bunch of our organs in our body, including our liver, our bone marrow, spleen. And iron studies, which includes serum iron, something called transferrin, which is the carrier protein for iron. So when you eat something and iron is broken off of the food, that iron then goes to a TAXI protein that gets absorbed through the blood and brings it to the storage sites for iron. What's interesting is that TAXI protein, the transferrin, can only bind to two iron atoms at any one time. So it's really susceptible to what you just ate. So, if somebody had, I don't know, like a breakfast sausage or an egg for breakfast, that can influence the transferrin saturation, which is really the best way that we assess iron status using those iron studies, which is why it's so susceptible to being inaccurate. Which is why the serum ferritin is a far better indicator of true iron stores.

BRIAN GOLDMAN: If you have inadequate iron stores, you're a sitting duck for iron deficiency.

MICHELLE SCHOLZBERG: Yeah, exactly. Iron deficiency just means that you have low total body iron stores. And you'll notice that I haven't even talked about hemoglobin or anemia when you asked me to define iron deficiency. That's a separate issue. So anemia develops after and sometimes as a result of iron deficiency that has been present for a long time. Or if somebody has active bleeding then they can develop anemia, which is when there's not enough red blood cells. And iron is a really key part of the oxygen-carrying protein in our red blood cells called hemoglobin.

BRIAN GOLDMAN: I'm going to warn you just how outdated a lot of my information is going to be. You know, I got my medical degree when dinosaurs ruled the earth. I was taught that menstruating women are most affected by iron deficiency because of recurring blood loss. What percentage of menstruating women and girls have iron deficiency and iron deficiency anemia?

MICHELLE SCHOLZBERG: At least 40%. And that's in the province of Ontario. And closer to 50% of pregnant women have iron deficiency in the province of Ontario.

BRIAN GOLDMAN: Michelle, you quoted Ontario figures. Would those be fairly reflective of the rest of Canada?

MICHELLE SCHOLZBERG: I think so. I don't think there's anything special about Ontario. And one thing as well, Brian, just for you to know, when I was quoting the 50% of pregnant women, that's 50% of pregnant outpatients. When we looked at St Mike's to look at the proportion of women at labour and delivery who had iron deficiency, it's above 80%.

BRIAN GOLDMAN: That's incredible. Because we're living in a Western society where we have certainly adequate diet. And I know diet is not everything, but it is important. To what do you attribute those figures?

MICHELLE SCHOLZBERG: There are estimates that up to 60% of people who menstruate have heavy menstrual bleeding. The trouble is, is that in medicine we have a really hard time, for good reason, to quantify the amount of blood that a woman loses with her menstrual cycles. In fact, women themselves, including myself, have a really hard time quantifying how much blood we're losing every month. We don't have the best tools available to us to quantify how much blood we're losing. And menstrual products over the years have been designed to hold more and more blood to help us feel dry, right, and to interrupt our lives less. So 60% of all women have heavy menstrual bleeding. Okay, fine. The blood holds 70% of our total body iron. So the more blood you lose, the more likely you are to become iron deficient. And then it becomes a bit of a cycle because you need iron to make red blood cells. And so, if you're bleeding too much, you're losing too much iron. And your bone marrow, which is the factory for the blood, doesn't have enough iron to make more red blood cells. So that's the heavy menstrual bleeding piece. But what about people who don't have heavy menstrual bleeding? There's a lot of iron that is lost even with a normal menstrual period each month. And we know, despite us living in a high-income setting, that our diets are relatively poor in iron. Iron-rich foods are expensive. We know in the United States that the daily iron consumption of a woman of reproductive age who's menstruating, is below what she requires to maintain her iron needs, based on how much iron she's losing monthly. So even for people with normal periods, they're still not taking in enough iron to address their needs.

BRIAN GOLDMAN: And I'm assuming that would include vegetarians and vegans.

MICHELLE SCHOLZBERG: Exactly. But even people who are, you know, follow vegetarian or vegan diet aside. Like, iron rich foods can be hard to come by. And we get a lot of mixed messages, of course. You know, for cardiovascular health, you don't want to eat too much red meat, you don't want to clog your arteries, etc., thinking about the amount of fats that are in food, etc. But we're evolutionarily rigged to absorb the iron that is present in animal protein better than we are at absorbing the iron from plant-based foods. Even though, you know, pound for pound, spinach has more iron compared with a steak, we absorb every drop from the steak and we don't absorb it as well from the spinach.

BRIAN GOLDMAN: One thing that I was taught by a wise ob-gyn years ago in the emergency department: as an emergency physician, don't advise women to return if their bleeding gets worse, if their menstrual bleeding gets worse. Actually quantify it. Tell them to put on a full thickness pad. And if, you know, they're changing it, say, in an hour, to note: is it saturated? Is it heavy like a sponge now saturated with blood? If that happens two or three times over two or three hours, you're bleeding too much and you need to come back. So at least there was some effort to try to quantify, you know, how much bleeding. It was a more specific piece of advice and a bit of a game changer in how I advised women.

MICHELLE SCHOLZBERG: That's amazing that you had that conversation and that somebody went through that with you. We recently conducted a study of medical students, residents and fellows at the University of Toronto, across a variety of different specialties -- from family medicine to ob-gyn, to emergency medicine, hematology and internal medicine -- to get a sense of how comfortable they are or not in diagnosing heavy vaginal bleeding. And we found something really interesting. That people actually felt pretty comfortable diagnosing heavy menstrual bleeding and primary post-partum hemorrhage. They felt less comfortable diagnosing a secondary post-partum hemorrhage, meaning the bleeding that happens beyond 24 hours after childbirth. But what was most remarkable is that when we asked them about the tools that are available to quantify vaginal bleeding, very few of them had used them in clinical practice, which we interpreted as inappropriate confidence. And the truth is that the bar keeps sort of changing. So if we define heavy menstrual bleeding as greater than 80 ml of blood loss in your menstrual cycle, that's the true definition of heavy menstrual bleeding. And that's based on that amount of blood is associated with risk of developing iron deficiency. If a woman saturates two heavy pads, that's 100 ml of blood. So right there, she's met the criteria.

BRIAN GOLDMAN: Question I gotta ask you: can males be affected by iron deficiency anemia?

MICHELLE SCHOLZBERG: Absolutely. Causes, of course, are different. For men you have to think about things like are they losing iron from their gut, meaning are they bleeding. Even if they're not seeing blood in the stool or black tarry stool -- which suggests that the blood is being absorbed in the higher-up parts of the gastrointestinal tract -- that's one thing that we ask patients about, if they're having any gastrointestinal symptoms. So, it could range from a bleeding ulcer to an infection called H. pylori that interferes with the absorption of iron; to blood vessels that are too close to the surface of the stomach or the small intestine that can intermittently bleed; to a polyp or even to colon cancer. It's really, really important to investigate the cause of iron deficiency in males and in females. Because you never want to just say, 'oh, you have iron deficiency, let's treat it,' and not talk about the cause. You always need to identify the cause because it could be a dangerous thing that's contributing to somebody's iron deficiency.

BRIAN GOLDMAN: As an emergency physician, I tend to equate the symptoms of iron deficiency anemia with the typical symptoms of blood loss -- so, weakness, fatigue, shortness of breath, lightheadedness. But what are some of the other symptoms that I may not be aware of?

MICHELLE SCHOLZBERG: Absolutely. And that makes total sense because your perspective is not of an emerg doc. And so you're dealing with true emergencies where you're dealing with people who have anemia. Right? So iron deficiency anemia, where you're going to have those cardiac and respiratory symptoms. But iron deficiency, even in the absence of anemia, is associated with symptoms, including fatigue, decreased exercise tolerance and endurance, decreased cognition. So iron deficiency is associated with lower IQ, that is reversible with treatment. It's associated with mood disorders, including post-partum depression. It's associated with sleep issues, including restless leg syndrome. It's associated with the urge to eat inedible things like ice or other weird things. So, it kind of makes you rethink the cravings that women have when they're pregnant.

BRIAN GOLDMAN: You can also get brittle nails from iron deficiency anemia.

MICHELLE SCHOLZBERG: Absolutely. Brittle nails, hair loss, cracking around the corners of your mouth. All of those things.

BRIAN GOLDMAN: What are some of the long-term repercussions of untreated iron deficiency?

MICHELLE SCHOLZBERG: So, the long-term repercussions can be pretty significant and also can cross generations. And the reason I'm saying that is because people who are most vulnerable are at greater risk of iron deficiency. We showed this in Ontario. The people of lower socioeconomic status are less likely to even be tested for iron deficiency, so they have diminished access to care. But also because iron-rich foods are expensive. So it affects the most vulnerable, and it's also vulnerable making. So, you know, something that negatively affects your IQ -- because iron is important to make, you know, neurotransmitters in our brain like serotonin and dopamine, in addition to making red blood cells and components of our muscle cells -- can also make people more vulnerable. And a mother transmits her iron status to the baby that's in her belly. So, in addition to influencing and potentially interfering with somebody's potential and productivity, it also can, if it's severe, cause anemia, increase their risk of blood transfusions, impact their cardiovascular health, even cause heart failure if untreated. It increases the risk of blood transfusions. And the last people we want to transfuse are women of reproductive age because it increases the risk of, you know, their future pregnancies. And really, red blood cell transfusions should be reserved for the emergency settings. That should not be, you know, the mainstay treatment for iron deficiency. In addition, we know that babies that are born to mothers that are anemic have a greater risk of intellectual disability, ADHD and autism spectrum disorders. So this is a correctable problem with unnecessary consequences.

BRIAN GOLDMAN: I know you're not a pediatrician, but I feel like we need to touch on this issue. Children can get iron deficiency and they have a lower level of ferritin that would indicate that. I'm assuming that's, in part, because kids are growing and they need more iron because they're growing.

MICHELLE SCHOLZBERG: Exactly. So, iron is really important for growth and development, including neurodevelopment. And so that's why children and adolescents and pregnant people are at increased risk of iron deficiency, because it takes a lot of iron to make all of those various tissues within our bodies. So the iron demands of children are high. And also, some foods directly interfere with the absorption of iron. And some foods also can make children feel full faster so that they're less likely to eat iron-rich foods. So, one common cause of iron deficiency in younger children is drinking too much cows' milk. Because, again, the calcium in the cows' milk interferes with the absorption of iron. And also drinking too much cows' milk makes you feel really full and less likely to eat the solid foods that contain more iron.

BRIAN GOLDMAN: We've talked at length about the issues related to iron deficiency. What's the best way to address it through iron supplementation?

MICHELLE SCHOLZBERG: First line therapy is oral iron. So iron pills or tablets. And there are a ton of different iron supplements out there. I would be lying if I said that I knew which iron supplement was best. The truth is, nobody knows the answer to that. Part of the issue is that because iron supplements fall into the health supplements category as opposed to the treatment category as medications, that means that the level of evidence -- that is, the level of scientific evidence -- that is required to get those drugs on the market is lower. That's why the data that we have is kind of few and far between. But what I tell my patients is the best iron supplement is the one that you tolerate and take consistently. I never, almost never tell somebody to take an iron pill more than once a day. There's some emerging evidence that the less iron you take, the better, actually. That you absorb more if you take less of it. So there's no value in taking, like, three iron supplements a day, for example. I just encourage people to take an iron supplement before bed, on an empty stomach, with a glass of water and hope that my patient tolerates it. Thirty per cent of people have gastrointestinal symptoms when they take iron supplements. That ranges from constipation, diarrhea, nausea, vomiting, abdominal pain.

BRIAN GOLDMAN: I do want to touch on the side effects from iron supplementation, which are, of course, legendary. As you've said, 30% of people who take iron supplements will have these side effects. Is there anything that can be done to help lessen them?

MICHELLE SCHOLZBERG: That's the biggest barrier to iron pills, right? Nobody wants to take a treatment and then feel worse for it, right. So, there are ways to manage constipation for sure. And I often will speak to my patients about laxatives like PEG -- so an odorless, tasteless powder that you can mix into your water and chug it and it'll help you go to the bathroom. The diarrhea really is not something that is easily managed. I typically suggest that patients either decrease their iron supplement to every other day, or to switch the pill, see if they tolerate it better. Similarly, the nausea and vomiting, abdominal pain. Again, I suggest that people try something else. So, managing the iron deficiency isn't as simple as handing out iron pellets. It requires a lot of knowledge translation. A lot of counselling. A lot of speaking to the patient about their symptoms; why it's important to treat the iron deficiency. And then going through how to manage symptoms should they occur and helping them toggle through different iron supplements until they find the right one. It's tough.

BRIAN GOLDMAN: Is there a best time of day to take an iron supplement?

MICHELLE SCHOLZBERG: The reason why I suggest to take it at night before bed is that if the patient is going to have any abdominal symptoms, they'll be sleeping through it. Which is why I try to encourage them to do so. And also, I suggest that they don't eat for, you know, one to two hours before bed. So oftentimes it's an easy time to sort of address the multiple foods that also interfere with the absorption of iron. Like dairy and lots of grains, and tea and coffee interferes with the absorption of iron. There's some emerging evidence that if you were to take your iron supplement perhaps after you eat meat, that you might actually absorb the iron in the supplement better. But generally I just say empty stomach before bed.

BRIAN GOLDMAN: Can you remind us again of what are the foods that hamper absorption of iron?

MICHELLE SCHOLZBERG: So the foods that interfere with the absorption of iron include dairy. So, stuff that contains a lot of calcium interferes with the absorption of iron. Tannins -- so if somebody drinks a ton of tea, that absolutely will interfere with the absorption of iron. Coffee can, potentially, as well. Foods that are rich in grains also can interfere with the absorption of iron. So, those are the biggies. But that's kind of the reason why telling somebody to cook in a cast iron pot isn't always the solution, because it depends what you're cooking. So if you're having something that contains dairy that's being cooked in a cast iron pan, then, I mean, you're not going to absorb whatever iron leaches into your food from the cast iron.

BRIAN GOLDMAN: Intravenous iron, it's, it's something that we have in the emergency department where I work. It's been a game changer for people who have significant blood loss and often obviates the need for blood transfusions. When do you recommend that patients receive intravenous iron?

MICHELLE SCHOLZBERG: Intravenous iron absolutely should be considered for somebody with iron deficiency anemia that is not responding to oral iron supplements. It could also be considered for somebody with non-anemic iron deficiency not responding to oral iron supplements, if the patient has the means to cover the cost and accepts the risks. But absolutely it should be given to people with anemia. So in the emergency setting, I think it's really important for us to be very mindful that blood is a precious resource and we should really be reserving transfusion of red blood cells for true emergencies. Meaning for patients with ongoing active blood loss who have cardiovascular symptoms or signs. So somebody who's tachycardic, hypotensive, that is the person who should be getting the red blood cell transfusion. Somebody with a massive hemorrhage, absolutely. That is somebody who should get a red blood cell transfusion. But if you see a patient who comes to the emergency department with a hemoglobin of 70 grams per litre, who feels really tired, who happened to have bloodwork done through their family physician, for example, and the family physician understandably got worried about seeing the hemoglobin of 70. And they come and see you in emerg and they say, 'I'm just feeling really tired,' that means that that person's been anemic for a while and is tolerating their anemia. So that person should get the intravenous iron. I would say the exact same thing if their hemoglobin was 60. I would say the exact same thing even if their hemoglobin was 50. If they're tolerating the anemia, give them IV iron. And ensure, of course, that they have close outpatient followup so they can get a full repletion dose of intravenous iron. Because what you're going to give them in the emerg probably isn't going to completely address the iron deficit.

BRIAN GOLDMAN: Last question I want to ask. Like all good things, sometimes too much of a good thing is harmful. Can you ever consume too much iron?

MICHELLE SCHOLZBERG: In the absence of having a condition that increases your risk of iron overload, so, something called hereditary hemochromatosis. Or there are certain inherited red blood cell disorders where people can develop iron overload. Theoretically, yeah, there's a thing about having too much iron, and those people actually have to get blood taken off. But I would say for the majority of the population, like, the really gross majority of the population, there's really no such thing. But it is important for patients when they're on iron supplements to have their blood work checked on the regular. Because we don't want anybody to take something that they don't need to be taking, especially intravenous iron. Because you certainly could, theoretically, iron overload somebody if you're giving them a ton of intravenous iron and not checking their blood work. So that requires monitoring oral iron supplements. Yeah, I mean, you could theoretically as well be taking stuff that you don't need anymore. Typically, if that were to occur, that would happen in somebody who's not menstruating or somebody who doesn't have big iron demands. So, somebody who's not pregnant. So I would say that it's probably pretty close to impossible just with pills or diet for sure, and somebody who's menstruating or pregnant to become iron overloaded. But in people who aren't menstruating, people who aren't pregnant or growing, it's really hard to iron overload oneself.

BRIAN GOLDMAN: Well, Dr. Michelle Scholzberg, you know, I thought I knew a lot about iron deficiency, and you've convinced me that I have a lot to learn. And I want to thank you for sharing your knowledge with us on The Dose.

MICHELLE SCHOLZBERG: Thank you for having me. It's a pleasure being here.

BRIAN GOLDMAN: Dr. Michelle Scholzberg is a hematologist at St. Michael's Hospital in Toronto and division director of hematology at the University of Toronto's Department of Medicine. Here's your dose of smart advice: iron deficiency is a condition caused by a decrease in the total amount of iron in the body. Iron is a major component of hemoglobin found in red blood cells. Iron deficiency and iron deficiency anemia are related, though not synonymous. Iron deficiency anemia is defined as low hemoglobin caused by not having enough iron in your body to make the red blood cells your body requires. Iron deficiency is the most common cause of anemia worldwide, and the most common cause of iron deficiency is blood loss. Not surprisingly, the condition occurs most often in menstruating women. However, men and women can also develop iron deficiency through gastrointestinal bleeding. Iron deficiency can also happen when your diet is low in iron and when the iron you consume is poorly absorbed through the gastrointestinal tract. You can also have a deficiency when your body requires more iron than usual. That happens during pregnancy and lactation and also happens to children and adolescents during growth spurts. The most common symptoms of iron deficiency are those of anemia, and include fatigue, lack of energy and shortness of breath. Other symptoms include irritability, pale skin complexion, brittle nails, slow thinking, swollen or sore tongue, and cravings for peculiar things like ice and dirt. Doctors confirm the diagnosis by measuring ferritin levels in the bloodstream. The test is used to find out how much iron the body stores. Note that there are different ferritin levels that are considered abnormal in pregnancy and in children. The main treatment for iron deficiency is oral iron supplementation. There are many different kinds of iron to take and there's insufficient evidence to say which is best. You may need to try several of them to find the one you tolerate the most. Side effects like constipation, abdominal distress and diarrhea are common. Intravenous iron supplementation is indicated for people with symptomatic iron deficiency, who don't respond to oral iron and in those who cannot tolerate oral iron. If low iron is caused by blood loss, it's important for doctors to find and treat the underlying cause. When recognized, iron deficiency is treatable. Not treating it can lead to health problems down the road. If you have topics you'd like discussed or questions answered, our email address is thedose@cbc.ca. If you like this episode, please give us a rating and review wherever you listen. This edition of The Dose was produced by Sameer Chhabra. Our senior producer is Colleen Ross. The Dose wants you to be better informed about your health. If you're looking for medical advice, see your health-care provider. I'm Dr. Brian Goldman. Until your next dose.

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What do I need to know about iron deficiency? - Transcript

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