What Is Ferritin? Understanding Low Iron, Symptoms and Treatment Options

Feeling constantly tired, struggling with your energy levels, or finding it harder to concentrate than usual? While there are many possible causes of fatigue, low iron stores are one of the most common and often overlooked reasons. Measuring your ferritin level can provide valuable insight into your iron status, sometimes before anaemia develops.

In this article, we'll explain what ferritin is, what low ferritin means, the symptoms to watch for, common causes of iron deficiency, and the treatment options available.

What Is Ferritin?

Ferritin is a protein that stores iron within the body's cells. A ferritin blood test measures how much stored iron you have available in reserve.

Iron plays an essential role in producing haemoglobin, the protein found in red blood cells that carries oxygen throughout the body. Without sufficient iron stores, your body's ability to deliver oxygen efficiently can be affected, leading to a range of symptoms.

Because ferritin reflects your body's iron reserves, it is often one of the most useful tests for identifying iron deficiency.

What Does Low Ferritin Mean?

A low ferritin level typically indicates that your iron stores are becoming depleted.

Importantly, ferritin can fall before anaemia develops, meaning you may experience symptoms of iron deficiency even when your haemoglobin level remains within the normal range. This is why some individuals with "normal" blood counts can still feel significantly affected by low iron stores.

As a general guide:

• Ferritin below 30 µg/L usually suggests low iron stores.

• Ferritin below 12 µg/L often indicates severely depleted or absent iron stores.

• Ferritin levels between 30-50 µg/L may still be associated with iron deficiency symptoms in some individuals.

  
  

Laboratory reference ranges can vary slightly, so results should always be interpreted alongside your medical history and symptoms.

Common Symptoms of Low Iron

Low iron can affect many systems within the body. Symptoms often develop gradually and may be mistaken for stress, poor sleep, or a busy lifestyle.

Common symptoms include:

✔ Persistent tiredness or fatigue that does not improve with rest

✔ Shortness of breath during everyday activities

✔ Dizziness or light-headedness

✔ Pale skin

✔ Feeling cold more frequently than usual

✔ Hair thinning or increased hair shedding

✔ Brittle or weak nails

✔ Restless legs, particularly in the evening or at night

✔ Frequent headaches

✔ Poor concentration and reduced mental clarity ("brain fog")

If these symptoms sound familiar, a ferritin blood test may help identify whether low iron is contributing to how you feel.

What Causes Low Iron?

Iron deficiency can occur for a variety of reasons, including increased iron requirements, reduced dietary intake, or blood loss.

1. Heavy Menstrual Periods

Heavy menstrual bleeding is one of the most common causes of iron deficiency in women of reproductive age.

2. Pregnancy

During pregnancy, the body's iron requirements increase significantly to support both maternal health and the developing baby.

3. Inadequate Dietary Iron Intake

Individuals following vegetarian or vegan diets may be at greater risk if their iron intake is insufficient or not carefully planned.

4. Regular Blood Donation

Frequent blood donation can gradually reduce iron stores, particularly if adequate replacement does not occur.

5. Reduced Iron Absorption

Conditions that affect the digestive system, such as coeliac disease, may reduce the body's ability to absorb iron effectively.

6. Blood Loss from the Gastrointestinal Tract

Bleeding from the stomach or bowel can cause iron deficiency, sometimes with few obvious symptoms.

If you are a man or a postmenopausal woman with low iron levels, it is important to investigate the underlying cause. Your GP may recommend further assessment to rule out gastrointestinal bleeding or other medical conditions.

Can Ferritin Be Too High?

Yes. While low ferritin often indicates depleted iron stores, ferritin levels can also become elevated.

High ferritin levels may occur due to:

• Inflammation

• Acute or chronic infections

• Liver disease

• Excessive alcohol intake

• Haemochromatosis (an inherited condition causing excess iron accumulation)

  
  

Because ferritin is also an inflammatory marker, it can rise even when iron stores are low. This means a "normal" ferritin result does not always completely exclude iron deficiency.

For this reason, ferritin should be interpreted alongside other blood results, symptoms and clinical history to gain a complete picture of your health.

How Is Low Iron Treated?

Oral Iron Supplements

For many people, iron tablets are the first-line treatment for iron deficiency. When taken correctly, they can effectively replenish iron stores over time.

However, treatment often requires several months, and some individuals experience side effects including:

• Nausea

• Constipation

• Stomach discomfort

• Bloating

  
  

Iron Infusions

For people who cannot tolerate iron tablets, do not absorb iron effectively, or need their iron levels corrected more rapidly, an iron infusion may be considered.

Iron infusions deliver iron directly into the bloodstream, allowing iron stores to be replenished more quickly under clinical supervision.

When Should You Consider Testing Your Ferritin?

You may benefit from ferritin testing if you experience:

• Unexplained fatigue

• Hair loss or hair thinning

• Persistent brain fog

• Restless legs

• Breathlessness

• Heavy periods

• Ongoing symptoms despite a normal full blood count

Early identification of low iron can help prevent symptoms from worsening and guide appropriate treatment.

Assessing Iron, Thyroid Function and Vitamin B12 Together

Fatigue does not always have a single cause. Low iron, thyroid disorders and vitamin B12 deficiency are among the most common contributors to low energy levels and reduced wellbeing.

Our Advanced Thyroid, Iron and B12 Blood Test assesses:

• Ferritin (iron stores)

• Thyroid function

• Vitamin B12 levels

Every result is reviewed by a clinician, ensuring your results are interpreted in the context of your symptoms and overall health.

Take Control of Your Energy Levels

Persistent tiredness should never be ignored. Understanding your ferritin level can be an important first step towards identifying and addressing the underlying cause of fatigue.

If you're experiencing symptoms of low iron, a comprehensive blood test can help provide clarity and guide the most appropriate next steps for your health.