Blood Biomarker Profiling & Monitoring

Blood tests for athletes - Why, when, what and where to measure, as well as additional information and resources.

By Noa Deutsch 9 min read
Blood Biomarker Profiling & Monitoring

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Now that this is out of the way, lets get into it.

Blood Biomarker Profiling & Monitoring

Under ‘normal’ circumstances, blood tests are done clinically, for diagnostic purposes. But doing routine blood work for athletes can be quite helpful for a variety of reasons which I will get into below. Before we do that, here is the story about how regular testing helped me many years ago, way before it was a more common practice.

Towards the end of 2004, I was diagnosed with Chronic Fatigue Syndrome at 23 years old. I won’t go into the entire story, so here are the Coles notes: Between the stress of university, working, volunteering, and training at a high level - I was not doing well. My coach at the time was also a sports doctor and he was adamant that all his athletes got blood work done regularly.

I had iron issues so bad that the only thing that helped was injections multiple times a week (I do not recommend), but even when my iron levels were consistently high, I still had issues and could not train the way I wanted to. I was stubborn, so I pretended that everything was okay… We did another round of blood work ( I recall the previous tests were approx. 3 months earlier) and I got a phone call from my coach/doctor’s receptionist once the results were in. The conversation went something like this:

  • Her: I scheduled you in for an appointment with an Endocrinologist next week at XYZ time
  • Me: I can’t make that time, I have classes!
  • Her: She books almost a year in advance. We sent her your latest blood work and she cleared her schedule for that day/time.
  • Me: F%$#ck. So, I guess I’m not good?

The main things that jumped out as abnormal were my Testosterone (very high), Cortisol (very high) and liver protein levels (extremely low). The symptoms were headaches, extreme fatigue, brain fog, muscle & join pain, insomnia and short term memory challenges.

The Endocrinologist was absolutely amazing. She spent hours with me over the next few months, leaving no stone unturned doing a test after test after test. She was patient, kind, supportive and answered my million questions (as a sport science student, I have A LOT of questions). As a side note - Because I was an international student (in New Zealand), I had to purchase health insurance as a requirement of my student visa, which was great as everything was covered (there is no way I could have been able to afford that otherwise).

The interesting thing was that when looking at blood work from a year before, 6 months before, etc - nothing was too much out of the ordinary or a major cause for concern, and the things that were got taken care of right away (like my iron levels). It was only until that last round of tests before starting to work with the endocrinologist that the results showed very large abnormalities. The thing is, if we did not have blood work data from 3 months, 6 months, 12 months prior, there is a very good chance I would not have been able to get in to see a specialist that fast. We would have made adjustments, but I doubt that would have been enough... Having a baseline of what my normal is, and then the ability to see the progressive decline and progression of my issues leading up to that point provided us a much clearer picture of what was going on.

Needless to say, that experience all those years ago taught me the value of monitoring blood markers and the insight they could provide. It also sparked an interest in learning more about which biomarkers are important for athletes - Being a sport science student with access to various publications helped a lot and then came grad school (sports nutrition), where we covered this in more detail.

Why bother with blood biomarker profiling & monitoring?

  • Some blood biomarkers can be used for the purpose of profiling and monitoring in athletes
  • These biomarkers can be personalized based on the individual and the demand of their sport, goals and health background
  • It is not a ‘once and done’ - It is recommended to establish individualized ranges to be able to track changes over time. Changes don’t happen overnight so you need to retest to see the progression and if the interventions are working or not
  • Some biomarkers can be provide information relevant to recovery status, training load, nutrition status, injury risk (ie. stress fractures) and of course - general health and wellbeing.

Screening & Monitoring and when to get tested

Screening vs monitoring depends on how often you get tested. Screening can be defined as measuring specific biomarkers infrequently to identify if there are deficiencies or excesses. Monitoring can be defined as measuring frequently as a way to have ongoing data to assess recovery and adaptation. The more data is accumulated, the better, as that will allow for establishing individualized baselines.

When to get tested? The answer to this is my favorite one - It depends! Like everything else, it is personal and should be tailored to your needs and goals and if you are screening or monitoring. The best time to start is in the pre season, to begin establishing a baseline, then repeat in intervals that are appropriate for the length of your season, your event schedule, goals, etc. If you don’t necessarily have events in mind and are training for health, fun, fitness, personal challenge, etc - I suggest getting tested every 6 months or so, again depending on your personal goals and needs. On the other end of the spectrum if you are a higher level athlete, every 3 months can be useful.

As far as timing goes, the key thing is to test in a way that will allow you to establish personalized baselines vs the clinical ranges (which might not be relevant to you), and also give you enough time to make necessary adjustments - Think preventative vs reactive, keeping in mind that changes take time to see a meaningful effect.

What is normal, anyways?

If I got a few dollars every time an athlete I was working with got tested for iron levels and told me their results were within the normal range so everything is fine… I would be able to buy a brand new bike. Or at least a very nice frame. I have worked with far too many athletes who were hovering at the very low end of the normal range, expecting their bodies to perform high levels of exercise. Just because the results did not indicate a clinical deficiency, does not mean they are optimal for the individual’s goals and activity level.

Another example is a GP’s getting worried about an athlete’s CK levels (Creatine Kinase is a muscle damage indicator) after said athlete competed in an Ironman event a few days prior. 1) That was not a great time to measure that marker and 2) of course there will still be traces of muscle damage after this kind of a hard and long event!

Normal ranges for the general population and normal ranges for athletes are not always the same… Also, normal is not always optimal.

Who should I work with to Interpret the results?

Data alone can be helpful, but I think we can all agree that the interpretation and application of the data is what is important. This should be done with a sport scientist / sport nutritionist as well as a sports doctor because working collaboratively as a team is always the best approach, as well as the obvious need for medical expertise if abnormalities requiring medical intervention show up.

If you scroll down, you’ll see a list of companies offering testing services. Many of them also offer recommendations as a part of the package and while that could be helpful, you might want to work with a professional who knows you and your individual needs and will work with you on an ongoing basis.

Pre Testing Considerations

There are several things to take into account before getting tested, depending on the tests getting done:

  • Hydration status - Haematocrit, electrolytes
  • Day of menstrual cycle or birth control use - female hormones, oxidative stress, cortisol
  • Fasting - Glucose, nutrients
  • Psychological stress - Cortisol, hormones
  • Time of the day - Cortisol, hormones
  • Posture - Haematocrit, Haemoglobin
  • Exercise - All cell counts, haematocrit, haemoglobin, inflammation, Creatine Kinase, hormones and more

So, what should you do / not do before a test, other than the obvious, which is to follow the the specific recommendations provided by the lab?

  • Get tested in the morning, after an overnight fast, before exercise.
  • Take into account the time of the month and type of birth control used if you are a women. For example, if you are on the pill, you might want to do a 24hr urine cortisol test as opposed to a blood test.
  • Between the time you wake up and your test, drink to thirst to a max of 7ml/kg. So, if you weigh 70km, drink a max of 490ml before the test.
  • Keep exercise easy and a relatively short duration the day before the test
  • Sit for ~10 minutes before the test

What should you test?

That really depends on your individual needs. For a figure showing some of the common tests, click here (the article the figure is from is reference #4 below). You can also refer to the ‘where to get tested’ section below and browse the tests offered by each company, as they all offer fairly comprehensive panels. Of course, for best results I highly suggest you consult a sports doctor before getting testing done.

An additional point of consideration: In some cases, a blood test might not be the best way to go, like the cortisol example above, magnesium and calcium.

I am adding a bit of extra info on RED-S screening here because I think its an important topic. An indirect screening for energy availability through blood tests is recommended for this purpose. This includes female and male sex hormones, thyroid and free triiodothyronine as well as total triiodothyronine.

I shared an introduction to RED-S in a previous article, so for a bit of a primer, click on the article below.

Calories & Introduction to RED-S
Before we get into it, welcome to all new subscribers! I am so glad you are here and hope to engage with you in the comment section of this and/or future articles.

What are some of the common interventions post testing?

Changes to Nutrition - If there are deficiencies in various micronutrients, macronutrients, need to improve health markers (ie. cholesterol, liver function, thyroid, glucose, etc) and overall energy availability, you will be able to make the necessary dietary changes.

Recovery and/or adjustment to training schedule - Interventions due to muscle damage markers, various hormones imbalances, inflammation and immune function. Typical for many, training load might need to be adjusted and a larger emphasis will need to be placed on building more recovery time into the schedule. Of course, nutrition strategies are almost always a part of this.

Supplements might be recommended in addition to dietary changes, depending on needs. It is very common in the case of Vitamin D and Iron.

Where can I get tested?

Traditionally, you had to get your doctor to order tests… And for the most part, depends on where you are in the world, that is still very much the case. I am not completely sure of what things are like everywhere around the world, but in British Colombia, Canada (my home province), blood tests are a part of our health care system, which has pros and cons. The pro is that it is free when needed. The con is that you need a doctor to give you a lab requisite and you might not be able to get the tests you want done unless there is a medical reason for that… So you might need to pay privately after all.

Here are several companies offering blood tests specifically for athletes, in the USA, Canada and the UK:

  • Athlete Blood Test - USA only
  • Inside Tracker - USA & Canada
  • Biostarks - Home test, ships to most of the USA
  • Forth Edge - UK only. Note - They offer a specific female hormone panel accompanied by a relevant FAQ section. Kudos to them!

I am sure there are more companies around the world - Feel free to share those in the comments.

Additional Resources / References

The goal of this article is not to give you ALL the information - This is a complex topic so we will be here for a very long time if I tried… Also, I am not a doctor specializing in this. I have a high level of understanding from my sport science / sports nutrition education and experience (both personal and practical working with athletes) and I am able to make some recommendations based on the data, but when examining athlete blood work, I always work with a sports doctor as well. No one can, or should, do everything themselves!

If you are interested in reading more, here are a few resources for you:

  3. Pedlar, C.R., Newell, J. & Lewis, N.A. Blood Biomarker Profiling and Monitoring for High-Performance Physiology and Nutrition: Current Perspectives, Limitations and Recommendations. Sports Med 49 (Suppl 2), 185–198 (2019).
  4. Lee EC, Fragala MS, Kavouras SA, Queen RM, Pryor JL, Casa DJ. Biomarkers in Sports and Exercise: Tracking Health, Performance, and Recovery in Athletes. J Strength Cond Res. 2017 Oct;31(10):2920-2937.

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