Difference Between Iron and Ferritin Blood Tests

The main difference between iron and ferritin blood tests is that the iron blood test measures the iron levels in the blood along with some proteins related to iron while the ferritin blood test measures the stored iron in the body. 

Iron and ferritin tests are two types of tests used to diagnose the iron deficiency or anemia. Iron is the cation that binds with oxygen while iron is stored inside ferritin, a protein.  

Key Areas Covered 

1. What is Iron Blood Test
     – Definition, Facts, Types
2. What is Ferritin Blood Test
    – Definition, Facts, Importance
3. What are the Similarities Between Iron and Ferritin Blood Tests
     – Outline of Common Features
4. What is the Difference Between Iron and Ferritin Blood Tests
     – Comparison of Key Differences

Key Terms 

Ferritin Test, Iron Deficiency, Iron Test, Serum Ferritin, Serum Iron, TIBC, Transferrin Saturation, UIBC

What is Iron Blood Test

Iron blood tests are a set of tests that measure the concentration of iron in the body. They help to diagnose low iron or iron deficiency. Iron is an essential nutrient, which is required in small quantities to form red blood cells. It is a vital component in hemoglobin, the oxygen-transport metalloprotein. Iron comes to body from diet and supplements. It is absorbed by the duodenum of the small intestine and is transported throughout the body by a protein produced in the liver called transferrin. Most of the iron is incorporated into hemoglobin and the remainder is stored in tissue in the form of ferritin or hemosiderin. A small amount of iron is used in the production of myoglobin and some enzymes.

Figure 1: Transferrin Bound to Free Iron

When the body meets insufficient amounts of iron, there is a depletion in the iron stores and the level of iron in the blood decreases. The most common symptoms of iron deficiency include weakness, dizziness, fatigue, headaches, and pale skin. Moreover, absorbing too much iron progressively builds up iron compounds inside organs, causing dysfunction and failure of those organs.  

Types of Iron Blood Tests

There are several types of iron blood tests:

• Serum Iron Test – It measures the level of iron in the serum, the liquid portion of the blood. The reference ranges of iron in the serum should be 60-170 mcg/dL. 
• Transferrin Test – It directly measures the level of transferrin in the blood. Transferrin is one-third saturated (20-50%) with iron under normal conditions.
   
• TIBC (total iron binding capacity) – It measures the total amount of iron bound by proteins in the blood. The test is an indirect measurement of transferrin availability. The reference ranges of TIBC are 250-370 mcg/dL.
• UIBC (unsaturated iron-binding capacity)- It measures the reserve capacity of transferrin, which should be two-thirds of the ferritin. The reference ranges of UIBC are 120-470 mcg/dL. 
• Transferrin Saturation – It reflects the percentage of transferrin that is saturated with iron (100 x serum iron/TIBC).  
• Serum Ferritin – It measures the amount of stored iron in the body. 

What is Ferritin Blood Test

The serum ferritin test measures the stored iron levels in the body. Ferritin is the main iron-storage protein in the body. It releases iron when required. Most of the ferritin occur inside the cells and a fewer amount can be found in the blood. The highest concentration of ferritin can be found in hepatocytes and reticuloendothelial cells. Ferritin binds to transferrin in order to be transported throughout the body.

Figure 2: Ferritin with Iron

The reference ranges of ferritin in the blood are 20-500 ng/mL in men and 20-200 ng/mL in women. High levels of ferritin indicate iron storage disorders such as hemochromatosis. Low levels of ferritin indicate iron deficiency. Generally, ferritin test is performed simultaneously with the serum iron test in order to determine the iron deficiency conditions.  

Similarities Between Iron and Ferritin Blood Tests 

• Iron and ferritin blood tests are two types of tests performed to measure iron levels in the body. 
• Blood is the specimen for both types of tests. 
• Both types of tests are performed simultaneously. 

Difference Between Iron and Ferritin Blood Tests 

Definition 

Iron blood tests refer to blood tests that evaluate the amount of iron in the body by measuring several substances in the blood while ferritin blood tests refer to blood tests that measure the amount of ferritin in a person’s bloodstream.   

Significance 

There are several types of iron blood tests and ferritin blood test is one of the iron blood tests. 

Types of Measurement 

Iron blood tests measure the concentration of iron, iron storage and transport proteins while ferritin blood tests measure the concentration of ferritin in the blood. 

Conclusion 

Iron blood tests measure the iron, ferritin, and transferrin concentrations in the blood while the ferritin test measures the serum ferritin concentration. Both types of tests are required for the diagnosis of iron deficiency. The main difference between iron and ferritin blood tests is the parameters measured in each type of blood test.   

Reference:

1. “Iron Tests.” LAB TESTS ONLINE, Available Here
2. “Ferritin Test.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 10 Feb. 2017, Available Here

Image Courtesy:

1. “PBB Protein TF image” By www.pdb.org (Public Domain) via Commons Wikimedia
2. “Ferritin 3foldchannel” By Acms116 – Own work (CC BY-SA 4.0) via Commons Wikimedia