Do you know that iron tests come in various types, each designed to measure specific aspects of iron in your body? When you're advised to undergo a blood test to check if you're iron deficient, it's beneficial to understand the different types of blood tests for iron studies available.

Iron is a crucial mineral in our bodies, playing a vital role in producing haemoglobin, a protein in red blood cells that carries oxygen from the lungs to the rest of the body. Maintaining proper iron levels is essential for overall health, as both iron deficiency and excess can lead to serious health issues. Various blood tests measure different facets of iron in the body, helping healthcare providers diagnose deficiencies or excesses and guide appropriate treatment.

In this blog post, we'll break down the different types of blood tests that measure iron levels, explaining what they are, how they are conducted, and what the results can tell you about your health.

What are iron study blood tests?

Iron study blood tests are a group of tests that evaluate various aspects of iron in your blood and body. These tests help diagnose and monitor conditions related to iron deficiency or excess. The main components of iron studies include:

• Serum iron
• Total Iron-Binding Capacity (TIBC)
• Transferrin saturation
• Ferritin
• Transferrin
• Complete Blood Count (CBC)

These tests together provide a comprehensive view of your body’s iron levels and help diagnose conditions such as iron deficiency anaemia, hemochromatosis (iron overload), chronic diseases affecting iron metabolism, and other related conditions.

Doctors usually order these tests based on symptoms such as fatigue, weakness, pallor, or abnormal blood results.

1. Serum iron test

What is a serum iron test?

A serum iron test is a blood test that measures the amount of iron currently circulating in your bloodstream. This test provides a snapshot of the iron that is immediately available for your body to use.

The serum iron test serves several important purposes:

• Diagnose iron deficiency or overload - This test helps identify iron deficiency anaemia (but there are is also an instance where you might be having iron deficiency without anaemia) or conditions like hemochromatosis (iron overload).
• Monitor treatment - It is used to monitor the effectiveness of treatments for iron-related conditions, ensuring that interventions are working as intended.
• Assess overall health - The test can be part of a broader health assessment to diagnose various conditions affecting blood and iron metabolism.

How it works

The serum iron test quantifies the iron level in the liquid part of your blood, called serum. Since iron is transported in the blood bound to a protein called transferrin, this test effectively measures the iron bound to transferrin. The results reflect recent iron intake and can help indicate whether you have an iron deficiency or an overload.

Interpreting the results

Interpreting the results of a serum iron test helps in diagnosing and managing iron-related conditions. The normal range for serum iron varies depending on the laboratory and individual factors such as age and gender. Generally, the normal range is:

• Total Iron-Binding Capacity (TIBC): 262–474 micrograms per deciliter (mcg/dL)
• Total Serum Iron: 26–170 mcg/dL in women and 76–198 mcg/dL in men
• Transferrin Saturation: 204–360 milligrams per deciliter (mg/dL)

Abnormal ranges

• Low iron levels: Below the normal range, low iron levels may indicate iron deficiency anaemia, chronic blood loss, or malabsorption issues. Symptoms of low iron levels can include fatigue, weakness, pale skin, and shortness of breath.
• High iron levels: Above the normal range, high iron levels could suggest hemochromatosis, iron poisoning, or conditions causing excessive iron intake or absorption. Specifically, an abnormal range would be above 198 mcg/dL for men and over 170 mcg/dL for women. Symptoms of high iron levels can include joint pain, abdominal pain, fatigue, and liver dysfunction.

Limitations

While the serum iron test provides valuable information about the iron levels in the blood, it has its limitations. The test results can be influenced by various factors, including recent meals, time of day, and menstrual cycles in women, which may cause fluctuations in serum iron levels. Therefore, this test is often used in conjunction with other iron tests to get a comprehensive picture of an individual's iron status.

2. Ferritin test

What is ferritin?

Ferritin is a blood protein that contains iron and is crucial for storing iron in the body. It acts as a reserve, releasing iron when the body needs it for essential functions such as producing red blood cells, ensuring proper oxygen transport, and supporting various metabolic processes.

How the ferritin test works

The ferritin test measures the amount of ferritin in the blood, providing an estimate of the body's iron stores. Unlike the serum iron test, which reflects the iron currently circulating in the blood, the ferritin test gives a more comprehensive picture of the iron stored in tissues and available for future use.

Ferritin tests can now be conducted in the comfort of your own home. Try our new Ferritin Tests from Aussie Pharma Direct here.

Normal ferritin levels

Ferritin levels can vary based on age and gender. Here are the typical reference ranges:

Men: 12-300 nanograms per millilitre (ng/mL)

Women: 10-150 nanograms per millilitre (ng/mL)

Children:

• Newborn: 25-200 ng/mL
• ≤1 month: 200-600 ng/mL
• 2-5 months: 50-200 ng/mL
• 6 months-15 years: 7-142 ng/mL

Significance of ferritin levels

Low ferritin levels

Low ferritin levels are a strong indicator of iron deficiency, often preceding a drop in serum iron levels. When ferritin levels are low, it suggests that the body's iron stores are depleted, which can lead to iron deficiency anaemia if not addressed.

Low ferritin levels can be caused by various factors, including poor dietary intake of iron, chronic blood loss (such as from heavy menstrual periods or gastrointestinal bleeding), and conditions that impair iron absorption.

High ferritin levels

High ferritin levels can indicate iron overload, a condition where too much iron accumulates in the body, potentially leading to organ damage. One common cause of high ferritin levels is hemochromatosis, a genetic disorder that affects iron metabolism. 

In addition to iron overload, high ferritin levels can also be a sign of inflammation or chronic diseases. Inflammatory conditions such as infections, liver disease, and certain cancers can cause ferritin levels to rise, as ferritin is also an acute-phase reactant, meaning it increases in response to inflammation.

Total Iron-Binding Capacity (TIBC)

What is TIBC?

Total Iron-Binding Capacity (TIBC) is a blood test that measures the blood's capacity to bind iron with transferrin, the main protein in the blood that binds to iron and transports it throughout the body. TIBC is significant in assessing the body's ability to transport iron, providing insight into iron status and availability.

How the TIBC test works

The TIBC test determines how well iron can bind to transferrin and other proteins in the blood. Transferrin levels increase when the body senses low iron levels, making more binding sites available to capture iron. Conversely, transferrin levels decrease when iron levels are high, reducing the need for additional binding sites.

Significance of TIBC levels

High TIBC levels

High TIBC levels generally indicate iron deficiency. When the body's iron stores are low, the liver produces more transferrin to maximise the amount of iron that can be transported. Elevated TIBC can suggest conditions such as:

• Iron deficiency anaemia
• Chronic blood loss

Low TIBC levels

Low TIBC levels may suggest iron overload or chronic disease. When iron levels are high, the liver reduces the production of transferrin since there is sufficient iron available for transport. Conditions associated with low TIBC include:

• Hemochromatosis
• Chronic diseases

4. Transferrin test

What is Transferrin?

Transferrin is a glycoprotein produced by the liver that plays a crucial role in the transport of iron throughout the body. It binds to iron ions absorbed from the digestive tract and carries them to various tissues, including the bone marrow, where iron is used for red blood cell production. Transferrin ensures that iron is delivered efficiently to where it is needed and helps maintain iron homeostasis.

How the transferrin test works

The transferrin test measures the amount of the protein transferrin in your blood. To understand how this test works, it's essential to know the role of transferrin in the body:

1. Production - Your liver produces transferrin. The production rate of transferrin is regulated by the body's iron levels. When iron stores are low, the liver increases transferrin production to enhance iron absorption and transport.
2. Function - Transferrin binds to iron ions in the bloodstream and carries them to various tissues where iron is required, such as the bone marrow for red blood cell production.
3. Response to iron levels - When your body's iron stores are low, the liver makes more transferrin to increase the amount of iron that can be transported in the blood. Conversely, when iron levels are high, transferrin production decreases.

How to interpret results from transferrin test

The total iron-binding capacity (TIBC) test assesses the amount of iron that transferrin can bind to. This essentially tells us how much iron transferrin can carry at any given time. TIBC is typically measured in micrograms per deciliter (mcg/dL), with a normal range falling between 250 and 450 mcg/dL.

Another test, transferrin saturation, provides a more precise indication of iron status. It calculates the percentage of transferrin that's actually bound to iron. Normal values typically fall between 15% and 50%. Low transferrin saturation (below 10%) can be a sign of iron deficiency anaemia, indicating insufficient iron is being transported. High transferrin saturation (above 50%) might suggest iron overload, signifying an excess of iron being transported.

Complete Blood Count (CBC)

A Complete Blood Count (CBC) is not specifically part of an iron study blood test, but it is often ordered alongside iron studies to provide a comprehensive view of a patient's overall health and to help diagnose or monitor conditions related to iron levels.

A CBC measures various components of the blood, including red blood cells (RBCs), white blood cells (WBCs), haemoglobin, hematocrit, and platelets.

Indicators:

• Haemoglobin (Hb) - Low levels can indicate anaemia, which may be caused by iron deficiency.
• Hematocrit (Hct) - Measures the proportion of blood volume that is occupied by red blood cells. Low levels can also indicate anaemia.
• Red Blood Cell Count (RBC) - Low RBC counts can be a sign of anaemia.
• Mean Corpuscular Volume (MCV) - Measures the average size of red blood cells. Low MCV can indicate microcytic anaemia, often due to iron deficiency.

The limitation of haemoglobin in detecting iron deficiency

Screening for iron deficiency using haemoglobin will only identify the most severe cases, where iron deficiency has progressed to anaemia. Haemoglobin alone is not specific for iron deficiency or iron deficiency anaemia because:

• Late indicator - Haemoglobin levels only decrease after iron stores are significantly depleted and iron-deficient erythropoiesis has occurred.
• Non-specific - Low haemoglobin can be caused by various types of anaemia and other health conditions, not just iron deficiency.

Ferritin is a much more reliable marker for assessing iron status as it specifically indicates iron stores, making it a more accurate test for diagnosing iron deficiency.

It is important to avoid relying solely on haemoglobin to evaluate for iron deficiency. Instead, a more comprehensive blood test specifically designed to assess iron levels, such as the ferritin test or any of the iron study blood tests, should be used. Of course, all of these will require the recommendation from your healthcare provider.

What type of iron study blood test should I go for?

The specific type of iron study blood test you need depends on your individual situation and the reasons for your concern. If you're experiencing symptoms that might be related to iron deficiency, such as fatigue, pale skin, or shortness of breath, your doctor will likely recommend a comprehensive blood panel that includes tests like:

• Serum iron - Measures the amount of iron circulating in your blood.
• Total Iron Binding Capacity (TIBC) - Assesses the transferrin available for iron transport (as discussed earlier).
• Transferrin saturation - Indicates the percentage of transferrin carrying iron.
• Ferritin - Evaluates your iron stores in the body.

There are also at-home iron test kits available in the market, like the TouchBio Ferritin Rapid Test. This specific test is a fingertip blood test that uses a rapid technology to detect ferritin levels in whole blood. It provides a qualitative result (positive or negative) at a cut-off concentration of 30ng/ml.  A positive result suggests your iron stores are likely sufficient, while a negative result might indicate lower iron stores.

Despite the convenience and immediate results offered by at-home test kits like the TouchBio Ferritin Rapid Test, it is crucial to follow up with a general practitioner regardless of the results. Your doctor can provide a more comprehensive assessment and may recommend further testing to confirm whether you are iron deficient, experiencing iron overload, or maintaining healthy iron levels.

Disclaimer

The information presented in this article by Aussie Pharma Direct is intended for general educational purposes only. The content is based on research by our team from various reputable medical sources, however, it is not a substitute for professional medical advice. If you have any concerns about your iron levels or experience symptoms that might be related to iron deficiency or overload, it is always best to consult a qualified healthcare professional. They can perform a thorough evaluation, order the appropriate blood tests, and recommend the most suitable treatment plan for your individual needs.

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