Ferritin – What is That?
Why does my doctor test my ferritin level? (What is ferritin, anyway?)
Ferritin is simply a protein that stores extra iron in your body. To understand why your doctor does a blood test to check your ferritin level, you must first understand why you need iron.
Ok, Then, Why Do I Need Iron?
Iron’s main job is to form hemoglobin. Hemoglobin, which is in every red blood cell, carries oxygen from our lungs to the rest of our body. So, without iron, we can’t make hemoglobin. Without hemoglobin, our bodies can’t get oxygen. Without oxygen, the trillions of cells that make up the human body can’t function.
Unfortunately, our bodies don’t make iron. We can only get it from food or supplements.
Why Doesn’t the Doctor Just Test My Iron Level?
Ferritin is normally tested as part of a multi-test iron panel which, of course, includes testing the iron level. It’s not enough to have just the right amount of iron needed to make hemoglobin. You need a back-up supply to replace the iron that is lost in various ways, such as:
- In feces, from cell turnover
- in urine
- in menstrual blood.
- from a bleeding injury (internal or external)
- from shedding skin cells
- from shedding cells in the intestinal lining
As you lose iron, ferritin releases iron. Most of this iron will be used to form hemoglobin. Therefore, your iron level can be normal, but if your ferritin level is low, you might not have enough “refill” iron to replace what you will naturally lose. This can lead to a serious condition called iron deficiency anemia.
What Causes Low Ferritin?
The most common causes of low ferritin are:
1) Low iron intake
This is most common in young, breastfed infants. Babies who are exclusively breastfed should receive an iron supplement.
Low intake is also common in pregnant women and in children having growth spurts. Blood volume increases quickly as a result of a growth spurt or growing fetus. Since there is more blood, there are more red blood cells. As you already know, red blood cells need hemoglobin, and hemoglobin needs iron. Iron intake should increase.
2) Poor iron absorption
Before being absorbed through the small intestine, iron must first be broken down by stomach acid. Intestinal absorption is limited when:
a) The production of stomach acid decreases. This can occur:
- after surgery to remove part of the stomach
- while people are taking anti-acid medications such as proton pump inhibitors.
b) There is a medical condition that affects nutrient absorption, such as celiac disease or Crohn’s disease.
c) Iron is eaten with foods that inhibit its absorption.
3) Blood loss
Blood loss can occur as a result of:
- An illness that causes internal bleeding, such as a bleeding ulcer or colon cancer.
- External bleeding, such as from a cut.
- Parasites such as hookworms, found in developing countries.
What Are Some Symptoms of Low Ferritin?
Symptoms include:
- Weakness
- Pale skin
- Shortness of breath
- Dizziness
- Headaches
Not surprisingly, symptoms of low ferritin are similar to symptoms of iron deficiency anemia. In fact, symptoms of low ferritin are not usually noticed until the hemoglobin level has dropped below normal.
How Is Low Ferritin Treated?
Low ferritin can be treated by consuming iron, either through food or in a supplement. In severe cases, a doctor can infuse iron directly into the body.
Iron in food comes in two different forms: “heme” and “non-heme”.
The body can absorb the heme form of iron more easily. Heme iron is found in meat, fish, and poultry. The highest concentrations are in red meat and liver.
Non-heme iron is the iron found in plants: fruits, vegetables, grains, legumes, beans, tofu, seeds, and nuts. Foods that are fortified with iron are fortified with non-heme iron. Although most of the iron that we eat comes from plant sources, non-heme iron is not absorbed as efficiently as iron from meat, fish, and poultry.
Eating heme-iron foods along with non-heme iron foods can increase the amount of non-heme iron that the body absorbs. Foods with Vitamin C, Vitamin A, and beta carotene can also increase the absorption of non-heme iron.
What Causes High Ferritin?
Once iron is absorbed through the intestine, it stays in the body for quite a while. We don’t have a mechanism to control the amount of excess iron. Extra iron makes its way to our tissues and organs and can stay there for decades.
Having a high ferritin level does not always mean that the iron level is high. Many infectious or inflammatory conditions cause ferritin to ‘leak out’ of cells. Since the leaking is not related to a quantity of iron in the blood, a blood test will show elevated ferritin but often low or normal iron. Conditions which can cause this include:
- HIV
- Some cancers
- Some genetic conditions
- Some types of heart disease
- Some autoimmune disorders, such as rheumatoid arthritis
- Alcoholic liver disease
- Metabolic syndrome/obesity
When or if the inflammation or infection resolves, the ferritin level should return to normal on its own.
Conditions that raise both ferritin and iron levels include:
- Ingesting and absorbing too much iron.
Usually, the body regulates how much iron is absorbed, but it can be an imperfect system. Take iron supplements only upon your doctor’s advice.
- Receiving numerous blood transfusions.
- Certain genetic (inherited) conditions. The most common one, Hereditary Hemochromatosis (HH), affects mainly North Americans and Europeans.
The gene mutation for Hereditary Hemochromatosis is usually harmless. However, in some people it causes the intestines to absorb more iron than the body needs.
Over decades, the excess iron accumulates in the heart, liver, pancreas, pituitary gland, and other tissues. Organ damage begins to cause symptoms at around age 40 in men and after menopause in women.
Because iron studies are now done as a routine part of a physical examination, HH is often caught before significant damage has occurred. (Interestingly, the mutation may have first arisen to provide protection against iron deficiency).
What Are the Symptoms of High Ferritin?
Ferritin that is elevated because of an infection or inflammation does not cause symptoms. Of course, infection and inflammation usually do cause symptoms!
Ferritin that is elevated because of iron overload also does not cause symptoms. Remember that in this case ferritin is elevated as a reflection of excess iron. Therefore, symptoms depend on which body parts are affected by iron buildup.
A few examples of the damage that excess iron causes to organs or tissue include:
- Diabetes, from damage to the pancreas
- Arthritis
- Hyperpigmentation of the skin
- Fibrosis or cirrhosis of the liver
- Heart failure or arrhythmias
The wide variety of symptoms is one reason that iron overload was difficult to diagnose before ferritin and iron testing became routine!
Related reading:
- 8 facts you should know about type 2 diabetes – read here.
- What is cirrhosis and how is it related to non-alcoholic fatty liver disease? Find out here.
How Is High Ferritin Treated?
Ferritin that is high because of an inflammatory or infectious process or disease is not directly treated. Once the infection or inflammation is treated and resolves, the ferritin level should return to normal.
High ferritin due to iron overload is treated by removing some blood from the body. This is a simple procedure, like donating blood, that is done as needed, from only once to every few months or even years.
All Those Tests on My Lab Report Aren’t Just A Waste Of Money?
As you saw, on the surface, ferritin is simple. It stores iron.
Beneath the surface, ferritin levels play a crucial role in helping doctors interpret the meaning of numerous other blood test results. And ferritin itself is often interpreted with the help of other tests.
One day, you will get another lab report with a long list of blood tests you’ve never heard of. And you will know that collectively, those tests really do help your doctor help you to stay healthy!
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Sources: UpToDate – LabTestsOnline – UCSF Health – Medscape – WHO