Confused by Your Iron Levels and Chronic Fatigue? Understanding Iron Recycling & Utilization

Most people equate low iron with iron-deficiency anemia, but in practice, iron status is often far more nuanced. Many women experience hallmark low-iron symptoms—fatigue, brain fog, weakness, and reduced exercise tolerance—even when conventional markers such as serum iron or ferritin fall within normal ranges or are unexpectedly elevated. In some cases, there is a clear mismatch between serum iron and ferritin, signaling that the issue is not iron intake, but impaired iron recycling and utilization.

Iron must be absorbed, transported, stored, mobilized, and recycled to be used throughout the body. In this blog, we’ll explore why iron is so essential, how mismatches between iron markers signal recycling and utilization issues, and the deeper factors that influence iron balance like micronutrient status, gut health, and chronic inflammation.

Iron 101: Why Iron and Iron Balance Matter

Iron plays a foundational role in nearly every major body system. It’s required for:

• Red blood cell formation (critical for transporting oxygen throughout the body)
• Thyroid hormone production and conversion of T4 to T3
• Mitochondrial energy production (essential for metabolism and steroid hormone production)
• Immune function (like the production of T-regulatory cells, which control autoimmunity)
• Cognitive performance and focus (to provide brain energy and help produce neurotransmitters)

However, iron is a double-edged sword. Too little available iron can lead to fatigue, dizziness, hair loss, low mood, cold intolerance, and exercise intolerance. Too much iron, on the other hand, drives oxidative stress, liver strain, inflammation, insulin resistance, and hormonal disruption.

This is why true iron health isn’t just about how much total iron you have. It’s about how efficiently your body absorbs, transports, stores, recycles, and utilizes iron every single day. Even with adequate dietary intake, you can still feel iron-deficient if your body struggles at any step of the iron recycling process.

The Iron-Ferritin Mismatch: A Clue to Iron Recycling Dysfunction

Before exploring the mechanics of iron recycling and utilization, it’s important to understand how these issues present in lab work—because this is often where confusion begins. Iron imbalances don’t always follow the textbook narrative of “low iron equals anemia.”

When evaluating iron status, two markers are foundational:

(1) total serum iron, which reflects the amount of circulating iron in the blood

(2) ferritin, which represents iron stored for future use. A disconnect between these two values is a key signal that iron recycling or utilization is impaired.

On one side of the spectrum is the pattern of high ferritin with low serum iron, often referred to as anemia of chronic disease. In this scenario, iron isn’t truly deficient, but factors like chronic inflammation are causing too much iron to be locked into storage form. The result is elevated ferritin alongside low levels of available iron, leaving cells starved of oxygen and energy despite having “adequate” iron reserves.

On the opposite side of the spectrum we have the pattern of low ferritin with high serum iron. This reflects an iron storage and handling issue. And while plenty of iron is circulating freely in the blood, it isn’t able to be stored within the cells for future utilization. Excess free iron in the blood increases oxidative stress, while still failing to meet the body’s functional iron needs.

As you can see, any mismatch between total serum iron and ferritin is problematic, regardless of which is high or low, and signals an iron utilization issue. These imbalances often point back to deeper drivers such as chronic inflammation, ongoing immune activation, or long-standing micronutrient insufficiencies. Now let’s dive into the steps involved in iron recycling to better understand how these iron imbalances may arise.

Understanding the Iron Recycling Process

Step 1: Iron Absorption

Iron absorption occurs primarily in the small intestine, but it’s heavily influenced by gut health, stomach acid levels, and overall digestive efficiency. Conditions such as low stomach acid production (hypochlorhydria), chronic gut inflammation, impaired bile flow, and small intestine bacterial overgrowth (SIBO) can all significantly reduce iron absorption. Under these circumstances, even if you’re consuming plenty of iron-rich foods,  that iron may never make it into circulation.

Stomach acid plays a critical role by freeing iron from food and converting it into a form the body can absorb. Women with low thyroid function have lower baseline levels of stomach acid. Certain micronutrients, such as zinc and B vitamins (especially B1, B6, B12, and folate) support stomach acid production and digestive enzyme activity, making them essential for iron uptake. It’s also important to note that heme iron (from animal foods) is absorbed more efficiently, while non-heme iron (from plant foods) relies heavily on these digestive processes.

Other vitamins like vitamins C and A are natural enhancers of iron absorption, particularly of plant-based non-heme iron, which is more vulnerable to compounds that block iron absorption. These vitamins bind to iron, forming a complex that is better absorbed and protected from common iron inhibitors, including:

• Phytates (found in grains, oats, legumes, nuts, seeds)
  • Fun fact: soaking, sprouting, fermenting, or pressure-cooking these foods reduces phytates 
• Tannins (found in coffee, black tea, wine)
• Calcium (from supplements or dairy products, specifically when consumed with iron-rich meals)

Finally, gut inflammation plays a critical role in iron absorption. Inflammation increases levels of hepcidin, the body’s main iron-regulating hormone. Elevated hepcidin levels can directly block iron absorption within the gut as a protective mechanism. This means that iron intake may be adequate, but absorption is impaired.

Step 2: Iron Transportation

Once absorbed, iron must travel through the bloodstream, either delivered to tissues for immediate use or shuttled into the cells for storage. This process requires a handful of key proteins and micronutrients, and is where many hidden iron issues occur.

Copper is essential for iron transportation. Copper status is tightly linked to iron mobility, red blood cell production, and mitochondrial energy output. One of copper’s main roles in iron transport is through the activity of the copper-dependent protein called ceruloplasmin. 

Ceruloplasmin transforms iron, converting it into a form that can bind to transferrin, the iron transportation protein that moves iron throughout the body. By helping regulate and enable iron transportation, ceruloplasmin helps prevent oxidative damage that can result from excess free iron buildup. Without adequate copper or ceruloplasmin, iron isn’t able to bind to transport proteins, and is left circulating in the blood, but unavailable to cells. Low copper is common in individuals with a history of zinc supplementation, as zinc and copper have antagonistic roles and compete for absorption and utilization in the body.

Vitamin A also plays a major role in iron transportation, helping release iron from its storage form. It does this by regulating hepcidin, the hormone that determines whether iron is absorbed or held in storage (along with iron regulatory protein-2). Vitamin A also supports hemoglobin production, which is the protein in red blood cells that transports oxygen throughout the body.

When iron transport is impaired, iron accumulates as total serum iron rather than being stored appropriately as ferritin or delivered to tissues where it’s needed. The result? Iron deficiency symptoms with seemingly “normal” iron labs, especially if ferritin isn’t tested.

Step 3: Iron Storage

Iron is stored as a protein within our cells called ferritin. Think of ferritin as your body’s iron reservoir and the most accurate marker of iron reserves, although it still must be interpreted alongside other iron markers.

If there are issues with iron transportation, such as insufficient copper or vitamin A, iron cannot be effectively delivered into cells and therefore cannot be properly stored. In these cases, iron may appear normal in the bloodstream but remain functionally unavailable.

Iron storage is also heavily influenced by hepcidin. Inflammation increases hepcidin activity, causing more iron to be shuttled into storage. This raises ferritin levels, and is a common cause of ferritin levels over 100 ng/mL for women.

In many cases, elevated ferritin is a protective response, and the body’s way of locking excess iron away to reduce oxidative stress. However, excess stored iron or iron overload can impair liver detoxification, feed gut microbiome imbalances and slow hormone clearance over time.

This is where we often see an intersection between iron overload and estrogen dominance, contributing to high estrogen symptoms such as heavy or painful menstrual cycles, breast tenderness, mood changes, headaches, and heightened symptoms mid-cycle around ovulation. 

Vitamin D has the opposite effect on hepcidin, decreasing its activity and allowing more iron to be released from ferritin into circulation. This becomes especially important when ferritin levels are low and needs to be restored, or when ferritin is high but iron availability remains low and symptoms of anemia arise. In both scenarios, vitamin D status and proper supplementation can significantly influence iron balance and symptom presentation.

Comprehensive Iron Testing: What to Test and Why

As you can see, there’s a lot of nuance when it comes to the conversation of iron levels, because of the different factors involved in iron recycling. To truly assess iron status, we cannot rely on a single marker. We primarily look at total serum iron and ferritin to assess iron balance. However, including markers related to iron transportation can help tell a more complete story. Here are our recommendations for comprehensive iron testing:

1. Total Iron

• Measures circulating iron in the blood
• Not enough information on its own, and must be considered alongside other markers to understand the full picture
• Can be either high or low, opposite of ferritin, in the case of iron recycling or utilization issues
• Functional optimal range: 85-130 ug/mL

2. Ferritin

• Reflects iron storage 
• Low ferritin = depleted reserves
• High = inflammation or iron overload
• Functional optimal range: 70-90 ng/mL for women

3. Transferrin and Transferrin Saturation (%)

• Measures the protein that transports iron throughout the body, as well as the percentage of iron bound to transferrin 
• Low saturation often signals poor absorption, inflammation, or impaired mobilization
• Functional optimal range: transferrin 300-400 ug/dL and 25-35% saturation

Highly valuable add-ons:

• CBC (Complete Blood Count): This evaluates red blood cell health and can hint at iron deficiency anemia, as well as folate or B12 deficiencies
  
• hs-CRP (high-sensitivity C-Reactive Protein): An inflammation marker that influences iron storage and hepcidin activity
  
• Cellular micronutrient testing: Provides insight into cellular copper and vitamin A levels, which are far more informative than serum levels

Ready to Cut Through the Confusion?

When iron can’t be properly absorbed, transported, or stored, lab values can be confusing. Taking a deeper look at iron utilization can uncover hidden disruptions in gut health, micronutrient status, and inflammation. It can also help clarify whether iron supplementation is truly appropriate or potentially counterproductive.

Could iron recycling or micronutrient support be the missing piece in your current treatment plan? A comprehensive assessment combined with deeper evaluation of gut health and micronutrient balance can help reveal what’s really driving your symptoms, and guide more effective, personalized support.

If you’re ready to address your unanswered questions and walk through targeted strategies to restore energy, hormone balance, and vitality, consider booking a Functional Clarity Session. Together let’s uncover what your body is truly telling you. You’ll walk away with a clear, personalized roadmap and next steps for your healing journey. But don’t wait, we only have a few spots left – book your session today!

Written by Romana Brennan, MS, RDN