In this episode, I break down an iron panel and explain why it’s important to also measure serum ferritin and transferrin, and when you should use transferrin saturation instead of iron saturation as a marker of your short-term iron status.
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This is how to use an iron panel, serum ferritin, and transferrin in order to assess your iron status.
Hi, I’m Dr. Chris Masterjohn of chrismasterjohnphd.com. This is Chris Masterjohn Lite where the name of the game is “Details? Shmeetails. Just tell me what works!”
And today we’re going to talk about blood work for managing iron status.
There’s a whole lot to unpack in the topic of iron that I’m not talking about today, and that includes anemia, and that includes many medical disorders. What I want to talk about today is how to make sure that you’re not suffering from iron overload using these iron tests, and in particular why it’s important to look at ferritin and transferrin on top of the iron panel when looking at this. If you look on the screen, you’ll see the list of iron tests that I got for my most recent blood analysis. We’ll look at the numbers in the next video.
We have iron and TIBC. TIBC means total iron-binding capacity, and that breaks down into TIBC, UIBC, which is unbound iron-binding capacity, iron, and iron saturation. Then as separate tests, I have added on here serum ferritin and serum transferrin. The things that we’re really interested with these tests are serum ferritin, which is a marker of your long-term iron storage, and transferrin saturation, which is not the same as serum transferrin. It’s the number of transferrin molecules in your blood that have their iron binding sites bound to iron. Transferrin is your short-term store of iron, distinct from ferritin, which is your long-term store of iron, and together serum ferritin and transferrin saturation give a good picture of your short- and long-term iron status.
When you are subject to iron overload, what happens early on is transferrin saturation increases above what it normally would increase to before ferritin kicks in. Normally you eat iron, your serum transferrin saturation goes up, that kicks in ferritin to take some of that iron and put it in long-term storage. When you have iron overload conditions because of a genetic predisposition, the transferrin saturation goes up, and it doesn’t kick iron over into ferritin until much later. If you have a late-stage iron overload condition, you will see ferritin rise, and you can see it rise very, very high.
In the iron binding panel, what we’re looking at is measures of iron saturation, and this is a cheaper estimate of transferrin saturation. What they do here is they say, “You know, it’s mostly transferrin in the blood that’s binding iron, so let’s just throw iron at the blood and see how much sticks.” By doing that, you can estimate the total iron-binding capacity of the blood, that’s how much can stick when the iron is removed; the unbound iron-binding capacity, that’s how much sticks when you don’t remove the natural iron present in the blood; and then how much iron is in the blood, and you can use all this to estimate the iron saturation, all as a means of getting a cheaper estimate of transferrin saturation, which is what we’re really interested in.
What we want is for the transferrin saturation to be between 30% and 40%. The range that they give for iron saturation is bigger than that, 15% to 55%, but when we’re looking for an optimal range, 30% to 40% is the optimal range. In the case of serum ferritin, the ranges are controversial, and the ranges vary from laboratory to laboratory and over time. In my opinion, we generally want to keep serum ferritin between 60 and 150. In cases where someone has a long experience of being subject to iron overload, it might make sense to go under 60, maybe even go down to 20 or 30. But in cases where someone’s predisposed to anemia, that’s a good reason for trying to keep it above 60 and maybe even get towards 100 to 150. Because in one case, you’re trying to drain iron that’s been overloaded out of the body, and in the other case, you’re trying to replete iron stores, and so it makes sense to be on the higher or lower end of that accordingly. For transferrin saturation, the way that we estimate—the way that we calculate this when we’ve measured transferrin is to take this serum iron, divide it by the serum transferrin, and multiply it by 0.79.
Now, you might ask, “Why should you bother with that if you have already estimated it with the iron saturation?” And the reason is that there are other things in the blood besides transferrin that bind to iron. Albumin, for example, is the most prevalent protein in the blood, and it can bind to iron. And there are studies suggesting that in some people with iron overload, iron saturation is often an underestimate of the transferrin saturation. And it’s the transferrin saturation that you want between 30% and 40%.
So here’s what I would suggest. Given the fact that measuring serum transferrin is more expensive than the iron panel, it does make sense to be conservative about ordering the test when you don’t need to. But you don’t know if you need to until you order the ntest at least once. So what I would do is at least once or maybe three times, get all of these measured and compare the transferrin saturation when calculated as serum iron divided by serum transferrin times 0.79 to the iron saturation. If they diverge consistently, then you probably want to continue measuring your transferrin saturation by getting transferrin and making the calculation as long as you continue to have iron-related issues that you believe need to be managed.
If, on the other hand, your transferrin saturation as calculated that way always looks like your iron saturation, then I think you can conclude from that that iron saturation is a good enough proxy to use going forward, and going forward, you can limit this to the iron panel and to the ferritin.
You can find more details on managing and monitoring iron status in my e-book, Testing Nutritional Status: The Ultimate Cheat Sheet.