Here’s what happens when your body senses low serum iron levels

Your body has an incredible ability to signal distress even before you realize something’s wrong.

You’re going about your day, and all of a sudden, you begin to feel tired out of nowhere. It’s like a big wave of exhaustion that hits you, catching you off guard.

Your usually energetic self feels like it’s been drained of vitality.

Could it be those late-night netflix binges catching up to you? Well, maybe not.

In fact, the culprit might just be something your body is quietly signaling – low serum iron levels.

Iron is a mineral that might not seem important, but it actually has a big role in your body. It gives you energy and makes sure your brain works well.

But what happens when this mineral nutrient becomes scarce in your body?

In this blog post, we’ll talk about the health implications of having low serum iron, and understand the mechanisms behind this problem.

Here’s a summary of what you’re going to learn.

Summary: When the body senses low serum iron levels, it responds by producing more hepcidin, which in turn limits the absorption of dietary iron from the intestine, reduces iron release from storage cells, and affects overall iron recycling and distribution. This system helps the body manage its iron resources and keeps iron balance.

Things to know when the body senses low serum iron levels

Low serum iron can also have a number of negative consequences for the body. These include:

  • Fatigue
  • Shortness of breath
  • Pale skin
  • Headaches
  • Indigestion
  • Cold hands and feet

In addition to the symptoms listed above, if your body has low levels of serum iron, it can cause problems like:

  • Heart failure
  • Memory loss and difficulty concentrating
  • Muscle weakness
  • Weak immune system

What happens when your body senses low serum iron levels?

When the body senses low serum iron levels, a different series of complex mechanisms are triggered to address this deficiency.

The process involves both systemic responses and cellular actions.

Here’s a detailed explanation of what happens:

1. The iron homeostasis pathway

Iron homeostasis makes sure we have the right amount of iron for different functions, but it also prevents us from having too much iron, which could be bad for us. [1]

This equilibrium relies on the vigilance of special cells in the small intestine (enterocytes) and liver (hepatocytes) that sense iron levels.

If the levels are too high or too low, these cells tell the body what to do to fix the problem. [2]

2. Hepcidin Regulation

Hepcidin, a small peptide with an immense role. [3] Produced in the liver, hepcidin acts as the master regulator of iron metabolism.

When iron levels are low, hepcidin synthesis is inhibited, allowing increased iron absorption from the diet and decreased iron retention within cells. [4]

This helps your body get the iron it needs for vital processes.

Summary: When the body senses low serum iron, it releases a hormone called hepcidin. Hepcidin binds to iron transporters in the gut, preventing the absorption of iron from food. This helps to conserve iron stores and prevent further depletion.

3. Increased iron absorption

Inside the walls of the small intestines are enterocytes, these cells absorb iron. [5]

When hepcidin is decreased, it tells the enterocytes to produce more ferroportin. This protein transports iron from the stomach to the blood. [6]

This surge in ferroportin helps your body to absorb more dietary iron even better, making sure you get the most nutrients from your meals.

4. Iron transport

In the bloodstream, iron travels with transferrin.[7] This iron transport protein binds to iron, and carries it safely to various tissues and cells.

Think of transferrin as a reliable courier, distributing iron to where it’s needed. This strategic distribution is important for keeping a healthy levels of iron throughout the body.

5. Iron utilization

Iron is used by several cellular processes, with a significant portion of it that is been used in making hemoglobin.

Even though iron’s role centers on the production of hemoglobin [8], its impact doesn’t stop there.

Iron is also essential for other heme-containing proteins, like myoglobin in muscles and enzymes involved in the production of energy and DNA synthesis.

6. Feedback mechanisms

As the iron levels rise because of increased absorption, the liver starts to produce hepcidin again to prevent iron overload[9]

Hepcidin then binds to ferroportin on the surface of enterocytes and macrophages, triggering their internalization and degradation.

This process reduces iron absorption and iron release from macrophages, preventing an excess buildup.

7. Iron release from storage

Excess iron is not wasted; it’s stored in a safe form as ferritin, which is non-toxic. [10] This protein acts as a vault, protecting iron in tissues like the liver, spleen, and bone marrow.

Ferritin’s role becomes critical when the body needs more iron, such as growth phases or when oxygen levels drop. ensuring there’s enough iron available when needed.

Summary: Iron stored in the liver, spleen, and bone marrow is released by breaking down ferritin and hemosiderin. These complexes release iron into the bloodstream for cellular processes.

8. Erythropoiesis and iron demand

Low oxygen levels trigger the release of erythropoietin, a hormone that stimulates the bone marrow to produce more red blood cells. [11]

This surge in red cell production requires additional iron for making hemoglobin.

Iron demand during erythropoiesis highlights the dynamic relationship between iron supply and the body’s oxygen-carrying capacity.

Final Thoughts

In a nutshell, this post showed us how low serum iron can lead to more than just feeling tired.

It causes symptoms like shortness of breath, headaches, and more serious issues like heart problems and a weaker immune system.

When our bodies sense low iron, they go into action. The iron balance pathway and hepcidin makes sure we get just the right amount of iron.

The body gets better at absorbing iron, transporting it around, and using it for all sorts of important tasks. Plus, there are checks in place to prevent an iron overload.

The link between iron and how our body carries oxygen is important.

So, understanding the impact of low serum iron is a big deal for our overall health.

It’s a reminder that even the small things inside us can make a huge difference in how we feel and function.


  • [1] – Ganz, T., & Nemeth, E. (2009). Iron homeostasis in host defence and inflammation. Nature Reviews Immunology, 9(12), 886-897. [1]
  • [2] – Donovan, A., Brownlie, A., Zhou, Y., Shepard, J., Pratt, S. J., Moynihan, J., … & Zon, L. I. (2000). Positional cloning of zebrafish ferroportin1 identifies a conserved vertebrate iron exporter. Nature, 403(6771), 776-781. [2]
  • [3] – Ganz, T. (2013). Systemic iron homeostasis. Physiological Reviews, 93(4), 1721-1741. [3]
  • [4] – Nemeth, E., & Ganz, T. (2006). Regulation of iron metabolism by hepcidin. Annual Review of Nutrition, 26, 323-342. [4]
  • [5] – Anderson, G. J., & Frazer, D. M. (2017). Current understanding of iron homeostasis. American Journal of Clinical Nutrition, 106(Suppl 6), 1559S-1566S. [5]
  • [6] – Abboud, S., & Haile, D. J. (2000). A novel mammalian iron-regulated protein involved in intracellular iron metabolism. Journal of Biological Chemistry, 275(26), 19906-19912. [6]
  • Aisen, P., & Enns, C. (2001). Transferrin receptor 1: differential expression of the transferrin receptor in the retina and brain. Investigative Ophthalmology & Visual Science, 42(2), 206-214.
  • [7] – Expression and Function of Iron-Regulatory Proteins in Retina. Authors; Jaya P. Gnana-Prakasam, Pamela M. Martin,1 Sylvia B. Smith, and Vadivel Ganapathy. [7]
  • [8] – Andrews, N. C. (2000). Iron homeostasis: insights from genetics and animal models. Nature Reviews Genetics, 1(3), 208-217.
  • [9] – Ganz, T., Olbina, G., Girelli, D., Nemeth, E., & Westerman, M. (2008). Immunoassay for human serum hepcidin. Blood, 112(10), 4292-4297.
  • [10] – Hentze, M. W., Muckenthaler, M. U., & Galy, B. (2010). Camaschella, C. Two to tango: regulation of mammalian iron metabolism. Cell, 142(1), 24-38.
  • [11] – Haase, V. H. (2013). Regulation of erythropoiesis by hypoxia-inducible factors. Blood Reviews, 27(1), 41-53.

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