Iron and inflammation: why hepcidin blocks absorption

There is a form of iron deficiency in which the stores are not empty. The iron is present in the body, sometimes even plentiful. And the tissue still goes hungry. The reason often sits in a silent process that has nothing to do with the amount of iron supplied: an inflammation that locks the iron away through a hormone called hepcidin.

This article does not pursue the question of which number makes a ferritin count as normal, nor the question of where an iron deficiency basically comes from. Separate posts go deeper on functional iron deficiency despite normal ferritin and on the causes of iron deficiency. Here it is about the mechanism behind it: how a chronic or low-grade inflammation slows iron absorption and iron recycling. And why iron tablets then often run into nothing.

The gatekeeper is called hepcidin

Many people with lasting exhaustion know the feeling of doing everything right and still not moving forward. Eating iron-rich food, taking tablets, and the value barely moves. To understand why this happens, it is worth looking at a small hormone from the liver.

Hepcidin is the central regulator of iron balance. You can picture it as a gatekeeper who decides how much iron is allowed into the blood. Iron leaves every cell only through a single door, a transport protein called ferroportin. When hepcidin rises, this door is broken down. The iron then stays trapped where it is: in the gut cells that just wanted to take it up, and in the scavenger cells that recycle old iron.

According to the work of Ganz and Nemeth, hepcidin attacks at three places at once. It throttles absorption in the gut, it holds iron back in the storage cells of the liver and it blocks the release from the scavenger cells that break down spent red blood cells. This last place is decisive, because the largest part of the daily iron requirement comes not from food, but from this internal recycling.

How an inflammation instructs the gatekeeper

What drives hepcidin up? Besides the iron status itself, it is above all one thing: inflammation. When the immune system activates, immune cells release messengers. One of them, interleukin-6, gives the liver the signal to make more hepcidin. Within hours, the gatekeeper can tighten its shift this way.

At first this sounds like a fault of the body. But it is the opposite. This reaction is ancient and sensible. Many pathogens need iron to multiply. By pulling the iron out of the blood during an infection and locking it in the cells, the body deprives the invaders of a basis of life. Researchers around Nemeth and Ganz therefore describe hepcidin as part of immune defence, as a kind of starvation strategy against intruders.

With a one-off infection this is a clever, temporary protection. The problem arises when the inflammation no longer stops. A chronic inflammatory disease, a rheumatic underlying condition, a chronic kidney or lung disease, a weak heart or also pronounced obesity keep the immune system on a low flame permanently. The gatekeeper then no longer works a shift, but stays on duty for good.

Anemia of inflammation: when the protection becomes a permanent brake

In medicine this picture has a name. It is called anemia of inflammation or anemia of chronic disease. Weiss, Ganz and Goodnough describe it as one of the most frequent forms of low blood count in the chronically ill. The core is always the same: inflammation-related messengers and the high hepcidin block iron absorption in the gut and hold iron back in the storage cells. The result is an iron-poor blood formation, although iron is present in the body.

Important is the distinction from the classic notion of iron deficiency. Here two different bottlenecks are at work, which can also overlap.

Both forms can occur together. That is exactly what makes the classification difficult. Someone can have a silent inflammation and additionally a real shortage in the stores. Weiss and colleagues point out explicitly that the diagnosis becomes especially demanding when an anemia of inflammation overlaps with an additional real iron deficiency.

Why iron tablets often run into nothing during inflammation

Now it becomes understandable why swallowed iron often disappoints during an inflammation. The tablet lands in the gut. But exactly there sits the hepcidin brake that throttles absorption. A large part of the iron is not taken up, stays in the gut and can irritate it, instead of arriving in the body. Which side effects can arise from this is explored in the post on iron tablets and side effects.

On top of that comes a twist from research: iron drives hepcidin up itself. One iron dose raises the hepcidin level for about a day and thereby lowers the absorption of the next dose. With an additional inflammation, hepcidin is already high anyway. So the brake is on twice.

Why the infusion can bypass the bottleneck

When the hepcidin brake sits above all at the gut absorption and at the store release, a logical consideration follows. An iron infusion gives the iron directly into the vein. It bypasses the gut and thereby one of the places where the brake grips most strongly. With an absorption blockade this can be a path to reach the stores at all.

This is exactly the reason why an infusion can make more sense in some situations than ever higher doses of tablets. Important to me here is the clean classification. An infusion is never the first reflex. It comes into question when the oral absorption demonstrably does not suffice, the deficiency is clearly proven and no contraindications are present. Before every administration, an iron overload and a hereditary iron storage disease belong excluded, an acute infection wants to be considered, and the administration belongs well monitored. This care is not a trimming, it is the condition.

The ferritin problem: high value, empty tank

There is a value that becomes especially tricky during inflammation: ferritin. It counts as a storage marker for iron, and low usually means really empty. But ferritin is at the same time an acute-phase protein. That means it rises during inflammation, infection or stress, independent of how full the usable iron reserves are.

From this a trap arises. With an anemia of inflammation, high hepcidin and high ferritin can exist side by side. Weiss, Ganz and Goodnough describe the combination of low available iron and elevated ferritin as a typical pattern. The ferritin looks reassuring, but the tank is locked for the cells. A value of 150 can, with silent inflammation, still mean too little usable iron.

In practice this means: an inflammation value such as CRP belongs to iron diagnostics. If the CRP is elevated and the ferritin normal or high, the ferritin can be shifted upward. Then a low transferrin saturation often says more about the actual supply. Also the soluble transferrin receptor can help, because it is less influenced by the inflammation. Which values are worth it for a self-check is explored in the post iron deficiency self-test: which blood values count.

What this means for you when nothing kicks in

This is not about recipes, but about directions. If you eat iron-rich food, take tablets and still little moves, the most important step is to complete the picture instead of simply raising the dose.

Ask about a silent inflammation. A low-grade inflammation often causes no obvious symptoms. But it can shift iron metabolism in the background. An inflammation value in the lab helps to make this background noise visible.

Do not read ferritin in isolation. Precisely during inflammation a normal or high value can mislead. The transferrin saturation and the soluble transferrin receptor complete the picture. This way a seemingly reassuring ferritin can be interpreted better.

Think along about the cause of the inflammation. Where an inflammation blocks iron, it is worth looking at its origin. Gut health, stress, sleep and the whole lifestyle play into it. Filling up iron without minding the inflammation is like trying to give gas with the brake running.

Adapt the path to the bottleneck. When the gut absorption is demonstrably blocked and a deficiency clearly proven, another route can make sense. In practice at ViveCura, for example, via a modern, well-monitored iron infusion, always only after exclusion of the contraindications. When this comes into question is in the overview article on iron deficiency and iron infusions.

Classic medicine rightly looks first at the underlying disease and at the anemia with these patterns, that is sensible and important. What a functional-medicine view can add is the early attention for the in-between zone: inflammation in the background, iron blocked, symptoms present, standard values unremarkable. Our work moves here at the intersection of the three areas that make up ViveCura: physical health and metabolism, mental health and a conscious, healthy lifestyle.

And now you know why sometimes it is not too little iron that is the problem, but a closed door. Your body does not reckon in swallowed milligrams. It reckons in what the cells actually reach in the end.

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