Back Blood-tests Explained

Ferritin

At a Glance

Why Get Tested?

To determine your body's total iron storage capacity

When to Get Tested?

When your doctor suspects that you may have too little or too much iron in your system

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

You may be instructed to fast for 12 hours before the test;in this case, only water is permitted.

The Test Sample

What is being tested?

Ferritin is an iron-containing protein and is the primary form of iron stored inside of cells. The small quantity of ferritin that is released into the blood is a reflection of the amount of total iron stored in the body. This test measures the amount of ferritin in the blood.

In healthy people, about 70% of the iron absorbed by the body is incorporated into the hemoglobin of red blood cells.Most of the remaining 30% is stored as ferritin or as hemosiderin, a complex of iron, proteins, and other materials. Ferritin and hemosiderin are present primarily in the liver but also in the bone marrow, spleen, and skeletal muscles.

When available iron is insufficient to meet the body's needs, iron stores are depleted and ferritin levels decrease.This may occur because of insufficient iron intake, inadequate absorption, or increased need for iron such as during pregnancy or due to a condition that causes chronic blood loss.Significant depletion of iron stores may occur before any signs of iron deficiency develop.

Iron storage and ferritin levels increase when more iron is absorbed than the body needs. Chronic absorption of excess iron will lead to the progressive buildup of iron compounds in organs and may eventually cause their dysfunction and failure.This happens in hemochromatosis, a genetic disease in which the body absorbs too much iron, even on a normal diet.

How is the sample collected for testing?

A blood sample is drawn by needle from a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

A 12-hour fast may be required. In this case, only water is permitted. Morning specimens are preferred.

The Test

How is it used?
When is it ordered?
What does the test result mean?
Is there anything else I should know?

How is it used?

The ferritin test is ordered to assess a person's iron stores in the body. The test is sometimes ordered along with an iron test and a TIBC to detect the presence and severity of iron deficiency or iron overload.

When is it ordered?

The ferritin test may be ordered, along with other iron tests, when a routine CBC shows that a person's hemoglobin and hematocrit are low and their red blood cells are smaller and paler than normal (microcytic and hypochromic), suggesting iron deficiency anemia even though other clinical symptoms may not have developed yet.

In the early stage of iron deficiency, no physical effects are usually seen. If a person is otherwise healthy, symptoms seldom appear before the hemoglobin in the blood drops below a certain level (10 g per deciliter). However, as the iron-deficiency progresses, symptoms eventually begin to develop and a doctor may order ferritin as well as other iron-related tests.The most common symptoms of iron deficiency anemia include:

Chronic fatigue/tiredness
Weakness
Dizziness
Headaches
Pale skin (pallor)

As iron stores continue to be depleted, there may be shortness of breath, ringing in the ears (tinnitus), drowsiness, and irritability. If the anemia progresses in severity, chest pain, headaches, leg pains, shock, and even heart failure may occur. Children may develop learning (cognitive) disabilities. Besides the general symptoms of anemia, there are certain symptoms that are characteristic of iron deficiency. These include pica (cravings for specific substances, such as licorice, chalk, dirt, or clay), a burning sensation in the tongue or a smooth tongue, sores at the corners of the mouth, and spoon-shaped finger- and toe-nails.

A ferritin level may also be ordered when iron overload is suspected. Symptoms of iron overload will vary from person to person and tend to worsen over time.They are due to iron accumulation in the blood and tissues.Symptoms may include:

Joint pain
Fatigue, weakness
Weight loss
Lack of energy
Abdominal pain
Loss of sex drive
Loss of body hair
Heart problems such as congestive heart failure (CHF)

To confirm the presence of iron overload, other iron tests (iron, TIBC) and a genetic test for hereditary hemochromatosis may be ordered as well.

What does the test result mean?

Ferritin levels are often evaluated in conjunction with other iron tests. A summary of the changes in iron tests seen in various diseases of iron status is shown in the table below.

Disease	Iron	TIBC/Transferrin	UIBC	%Transferrin Saturation	Ferritin
Iron Deficiency	Low	High	High	Low	Low
Hemochromatosis	High	Low	Low	High	High
Chronic Illness	Low	Low	Low/Normal	Low	Normal/High
Hemolytic Anemia	High	Normal/Low	Low/Normal	High	High
Sideroblastic Anemia	Normal/High	Normal/Low	Low/Normal	High	High
Iron Poisoning	High	Normal	Low	High	Normal

Ferritin levels are low in people who are iron deficient and are elevated in those with hemochromatosis or who have had multiple blood transfusions.

Ferritin is an acute phase reactant and can be increased in people with inflammation, liver disease, chronic infection, autoimmune disorders, and some types of cancer.Ferritin is not typically used to detect or monitor these conditions.

Is there anything else I should know?

Normally, most ferritin is found inside of cells with only a small amount in the blood. When there is damage to organs that contain ferritin, such as the liver, spleen, and bone marrow, ferritin levels can become elevated even though the total amount of iron in the body is normal.

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