Ferritin 101: Ironing Out a Major Concern for Distance Runners

This week I had originally planned to post the next installment on our summer conditioning, looking at training groups, volume, and paces.  However, I decided to put that on hold momentarily to discuss something .

Iron deficiency is a topic that in the eyes of many elite coaches is highly important and lowly discussed.  Before going any further, I did want to say from the outset that I am not a medical professional, so please take all of the information below in consultation with a physician.  That being said, I hope this post can prove helpful in addressing an issue I do think is probably affecting a number of our runners.  Monitoring iron levels can help our runners remain healthy and reach their goals. The main points can be summarized as follows:

• Low iron levels are a common issue in distance runners with impact on performance and potentially overall health.
• The best way to measure iron levels is through a serum ferritin test.  This test must be ordered by a doctor for minors.  It is best to also request a CBC and iron panel as well.  
• Testing should ideally be performed at the start of summer in the morning following twelve hours without food or exercise and 48 hours since a hard workout or race.  Avoid testing if you've been sick.
• The minimum acceptable ferritin level for distance runners is 30 ng/mL, but 50 or above would be even better.  Ask the doctor to see the actual numbers.  Don't just accept their word that levels are fine.
• Low iron levels can be addressed through diet changes and/or supplements in consultation with a physician. ​

If you have any questions feel free to reach out!  

Jonathan Dalby ran high school cross country with Matt Tegenkamp, arguably the most successful male runner from Missouri. Currently Dalby is the coach at Mountain Vista in Colorado, where his boys have finished as high as third and his girls have won a title at Nike Nationals. One of the things he preaches to both his runners and anyone else willing to listen is the importance of ferritin testing.

What Is Ferritin?

I'm going to try not to turn this into biology class.  I'm not the one for that job, so let's keep things simple.  90-95% of the energy used in a 5k comes from the aerobic system, but this process requires oxygen, and quite a bit of it.  Obviously that oxygen enters your bloodstream through your lungs when you breathe, but then it has to get transported throughout your body to the cells in all of your muscles.

How does that happen?  Red blood cells.  But on a smaller scale. the oxygen bonds to the protein hemoglobin within those cells.  The central structural component of hemoglobin is iron.  So a distance runner needs lots of iron because they need lots of hemoglobin in lots of red blood cells transporting lots of oxygen to produce lots of energy over lots of time.  That's lots of lots.

The lifespan of a red blood cell is roughly four months, so the body is constantly producing new ones.  But to make matters worse, endurance running tends to expedite the destruction of red blood cells, requiring the body to make even more.  All of that production takes iron.

So what happens when someone's body doesn't have enough iron?  Besides a number of other issues, it struggles to produce the required energy levels, especially during periods of high demand (like maybe a cross country race).  That's going to put runners in jeopardy of not only decreased performance in training and competition, but ultimately a host of other health risks.

That's why it's immensely important for runners to maintain adequate iron levels.  But how does someone know that those are up to par?  A blood test can be done for hemoglobin (the Red Cross does a bunch of them at blood drives).  However, the problem is that such a test only detects the iron in active use.  It doesn't measure the iron the body has on reserve.  Someone could have sufficient hemoglobin levels at the moment of testing, but it their reserves are low and they begin exercise that destroys red blood cells, the hemoglobin levels will drop. 

Furthermore, iron plays a role in a number of other parts of the aerobic process.  Even having enough iron for hemoglobin might not leave enough for these other needs.  To determine the amount of iron on reserve in someone's body, one needs to look to ferritin, a different protein used to store (and in some cases transport) iron.  

Low ferritin levels indicate iron deficiency.  Ultimately this can lead to low hemoglobin and thus a low red blood cell count, a condition many are familiar with as anemia. 

During John Davis's tenure as an assistant coach at Edina High School, their boys made Nike Nationals four years in a row. Since then he's completed his PhD in biomechanics and become one of the leading nerds in the sport. He's a favorite source on the science of running, and his articles have greatly helped me understand the role of ferritin.

Is Iron Deficiency
​That Big of a Deal?

From the perspective of both prevalence and impact, low ferritin levels are a serious concern.  Studies place the incident rate in cross country runners as high as 1 in 6 for males and 1 in 2 for females.  The most likely explanation for the higher rates in women is blood loss during menstruation.  

Growing teenagers not only need to replace existing red blood cells.  Their increased blood capacity demands an expansion, and that takes even more iron relative to an adult of the same size.  That puts high school runners at even greater risk of deficiencies.

When that happens, runners experience a decrease in performance.  This is seen most clearly in difficulty recovering during workouts and ultimately sub-par race times.  With a goal of helping runners reach their potential, this is certainly a concern.  However, as iron deficiency advances, its effects appear in everyday life.  This can include general fatigue, difficulty sleeping, lack of focus/concentration, mood instability, and hair loss.  

Given the severity of these concerns, MSHSAA actually issued a position statement in 2019 on iron deficiency in endurance athletes,  authored by Dr. Kim Colter, then member of their Sports Medicine Advisory Committee.

How Is Iron
​Deficiency Identified?

The symptoms of runner's anemia listed above seem problematic for a teenager trying to navigate the baseline demands of high school.  The challenge is that iron deficiency has to progress to a fairly extreme point before these symptoms emerge, and correcting such low levels can take months.  The best way to identify iron deficiency early is through testing.

Unlike hemoglobin, most ferritin resides within tissue cells, but some ends up in the bloodstream, where it can be tested.  These ferritin levels in the blood are reflective of the overall quantities.  Therefore, a lab blood test can determine ferritin levels. 

This test can be ordered by a runner's physician.  The problem is that many doctors don't see such tests as necessary unless more severe symptoms have developed.  They also tend to read test results in light of guidelines for the general population.  This could mean taking levels as low as 6 ng/mL as normal, whereas both Dr. Davis and and Dr. Colter recommend runners maintain levels above 30 ng/mL  To address this, Dr. Colter has actually penned a letter that an athlete can present to their physician explaining the need for serum ferritin testing and how to better interpret results.  

Dr. Kim Colter is a semi-retired physician based out of Washington, MO. For years he has been an advocate of iron testing in high school runners.

​Who Should Get Tested?

​Should every high school runner be tested?  I'm not a doctor, so I will direct you to the advice of professionals.  Certainly a runner should consult with their own physician, but in addition to Dr. Colter, sports medicine physicians at Nationwide Children's in Columbus, OH and the University of Michigan Health West recommend every endurance athlete be tested at least once per year.  For female athletes, those with a personal/family history of anemia, or those following a vegetarian diet, the impetus is even greater.

When Should a
​Runner Get Tested?

Dr. Colter recommends that every endurance runner get tested during each offseason before cross country (or track) training begins.  The rationale is twofold.  First, a runner's ferritin levels tend to decrease as the season progresses.  One reason for this is that during strenuous training, the body produces hepcidin, a hormone which inhibits the body's ability to absorb ingested iron.  If a runner's ferritin level is already low or even borderline in June, they are likely going to end up in an even worse position by October. 

Second, addressing low iron levels takes time.  Identifying them early in the summer hopefully allows a runner to raise them to optimal levels before racing season.  

Following Coach Dalby's lead, my suggestion is for runners to get their sports physical done at the beginning of the summer and to bring up the topic with their physician at that point.  The good news is that a number of the family medicine professionals in our community have connections to our team and should therefore be sympathetic to the matter.  Most physicians can have the blood for the test drawn at their office, or else they can refer you to a lab.

As a final point here, many experts suggest that the test is most accurate in the morning following a twelve-hour period of fasting and minimal exercise.  That might be helpful to keep in mind when scheduling.  If you have been sick recently, you should also postpone testing.

​What If Iron Levels
​Come Back Low?

It's important to see ferritin levels as a continuum.  It isn't as simple as good versus low.  It's more like really good--good--okay--borderline--bad--really bad.  Where a runner's level fits within this spectrum will determine the protocol.  I suggest starting with the least aggressive tactics and then progressing from there in consultation with one's doctor.

I'm always a fan of getting nutrients through food as much as possible before supplements.  The number one source of iron hands down is red meat (well besides the more obscure oysters and duck liver).  However, poultry (especially dark meat), eggs. and seafood are also sources of heme iron.  This iron is more easily absorbed by the body.

Non-heme iron can be found in a number of plant sources.  You just have to consume more of it to have the same effect.  Below are some great sources to consider:

• Leafy greens (especially spinach and chard)
• Asparagus or artichoke
• Beans/lentils (especially white beans and soy beans)
• Nuts/seeds (especially pumpkin seeds and cashews)
• Dried fruit (especially apricots and prunes)
• Whole Grains (especially quinoa, oatmeal, and rice)
• Dark chocolate and blackstrap molasses
• Many cereals are fortified with iron (Multigrain Cheerios and Honey Bunches of Oats are among the best)

Additionally, studies have shown that consuming Vitamin C in conjunction with iron increases absorption, whereas Vitamin D decreases absorption.  And interestingly enough, cooking food in cast iron also seems to add to the iron content as well.

If dietary solutions aren't sufficient, then an athlete could consider an iron supplement such as ferrous sulfate or Proferrin.  However, this should always be done in consultation with a physician.

Meghann Featherstun is a sport-certified dietitian and competitive marathon and triathlon racer. Having dealt with low iron in her own running journey, she now specializes in helping athletes in a similar situation and has been a valuable resource in my own learning on the topic.

Other Questions
on Ferritin Testing

Can you test for ferritin without a doctor visit?
Several labs do allow walk-in ferritin tests for adults.  However, they all require physician's orders before testing minors.

Will health insurance cover the test?
That obviously is going to depend on the provider, but in most cases they will since it is a relatively inexpensive test.

Can someone just skip the testing and start an iron supplement?
In many cases an iron supplement isn't necessary,  Furthermore, there is too much of a good thing.  Excess iron can lead to liver damage and irregular heart rhythms.  This is especially concerning for those with a genetic condition called hemochromatosis that affects 1 in 400 individuals and causes their intestines to absorb unusually high levels of iron.  For all of these reasons, it is best to determine if one's iron levels are deficient before proceeding with supplements.