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Ferritin, Serum Blood Test

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Ferritin, Serum


Introduction:
Serum ferritin is the ferritin that is in a person’s bloodstream. Ferritin is a protein that stores iron and allows the body to use iron. Many doctors use a blood test to measure the amount of serum ferritin in a patient’s blood in order to assess their health. Several medical conditions can cause an individual to have high or low levels of ferritin in the bloodstream, and a serum ferritin blood test may be used to monitor the progress of a disease.
Ferritin is also known as serum ferritin level, while its formal name is ‘Ferritin, serum'. The ferritin plasma test is done to check the iron stores in the body of the patient. This test is done in conjunction with a TIBC and an iron test to check an overload of iron or deficiency.
Ferritin is a protein found inside cells that stores iron so your body can use it later. A ferritin test indirectly measures the amount of iron in your blood. The amount of ferritin in your blood (serum ferritin level) is directly related to the amount of iron stored in your body.

Ferritin, Serum Blood Test

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Ferritin, Serum

Introduction:
Serum ferritin is the ferritin that is in a person’s bloodstream. Ferritin is a protein that stores iron and allows the body to use iron. Many doctors use a blood test to measure the amount of serum ferritin in a patient’s blood in order to assess their health. Several medical conditions can cause an individual to have high or low levels of ferritin in the bloodstream, and a serum ferritin blood test may be used to monitor the progress of a disease.
Ferritin is also known as serum ferritin level, while its formal name is ‘Ferritin, serum'. The ferritin plasma test is done to check the iron stores in the body of the patient. This test is done in conjunction with a TIBC and an iron test to check an overload of iron or deficiency.
Ferritin is a protein found inside cells that stores iron so your body can use it later. A ferritin test indirectly measures the amount of iron in your blood. The amount of ferritin in your blood (serum ferritin level) is directly related to the amount of iron stored in your body.
Ferritin

This test measures the amount of ferritin in blood. Ferritin is the body's major iron storage protein. This test is used to evaluate iron stores in the body, and monitor the body's response to iron therapy. It may be used for conditions such as iron deficiency (not having enough iron) or iron overload.
A ferritin test can help to confirm an anemia diagnosis and may be used in conjunction with tests that measure the amounts of hemoglobin and hematocrit in an individual’s blood. Some people with certain medical conditions that cause abnormally high amounts of iron in the blood may also undergo periodic ferritin blood tests. Other tests that may be used with a serum ferritin test include a tranferrin test, an iron test and a total iron-binding capacity test. A ferritin blood test checks the amount of ferritin in the blood. Ferritin is a protein in the body that binds to iron; most of the iron stored in the body is bound to ferritin. Ferritin is found in the liver , spleen , skeletal muscles, and bone marrow. Only a small amount of ferritin is found in the blood. The amount of ferritin in the blood shows how much iron is stored in your body.
Ferritin is a ubiquitous intracellular protein that stores iron and releases it in a controlled fashion. The amount of ferritin stored reflects the amount of iron stored. The protein is produced by almost all living organisms, including algae, bacteria, higher plants, and animals. In humans, it acts as a buffer against iron deficiency and iron overload.
Ferritin is a globular protein complex consisting of 24 protein subunits and is the primary intracellular iron-storage protein in both prokaryotes and eukaryotes, keeping iron in a soluble and non-toxic form. Ferritin that is not combined with iron is called apoferritin.
Ferritin is a protein of 450 kDa consisting of 24 subunits that is present in every cell type. In vertebrates, these subunits are both the light (L) and the heavy (H) type with an apparent molecular weight of 19 kDA or 21 kDA respectively; their sequences are about 50% homologous. Amphibians have an additional ("M") type of ferritin; the single ferritin of plants and bacteria most closely resembles the vertebrate H-type. Two types have been recovered in the gastropod Lymnaea, the somatic ferritin being distinct from the yolk ferritin. An additional subunit resembling Lymnaea soma ferritin is associated with shell formation in the pearl oyster. Two types are present in the parasite Schistosoma, one in males, the other in females. All the aforementioned ferritins are similar, in terms of their primary sequence, with the vertebrate H-type. In E. coli, a 20% similarity to human H-ferritin is observed.[5] Inside the ferritin shell, iron ions form crystallites together with phosphate and hydroxide ions. The resulting particle is similar to the mineral ferrihydrite. Each ferritin complex can store about 4500 iron (Fe3+) ions.
Some ferritin complexes in vertebrates are hetero-oligomers of two highly-related gene products with slightly different physiological properties. The ratio of the two homologous proteins in the complex depends on the relative expression levels of the two genes.
Mitochondrial ferritin was recently identified as a protein precursor, and is classified as a metal-binding protein that is located within the mitochondria. After the protein is taken up by the mitochondria it can be processed into a mature protein and assemble to form functional ferritin shells. Its structure was determined at 1.70 angstroms through the use of X-ray diffraction and contains 182 residues. It is 67% helical. The Ramachandran plot  shows that the structure of mitochondrial ferritin is mainly alpha helical with a low prevalence of beta sheets. Unlike other human ferritin, it appears to have no introns in its genetic code.

ferritin mitochondrial

Structure: Ferritin is a large protein shell (MW 450,000) comprised of 24 subunits, covering an iron core containing up to 4000 atoms of iron.
Function: Ferritin acts as the soluble storage form of iron in tissue (hemosiderin is relatively insoluble). It may serve other functions as well although these are controversial. It is found in most cells of the body, especially macrophages, hepatocytes and erythrocytes. Synthesis occurs in the liver and the rate correlates directly with the cellular iron content. Control of ferritin synthesis occurs post-transcriptionally (at the mRNA level). There are iron- and cytokine-responsive elements in ferritin mRNA. Increased iron or cytokines (such as IL-1, IL-6) promotes ferritin translation, resulting in increased iron storage. This is one of the causes of iron "sequestration" that occurs in animals with chronic or inflammatory disease and will reduce serum iron values. The function of serum ferritin is not known, but the concentration correlates well with the amount of stored iron in normal (and most diseased) subjects. Serum ferritin concentrations are quite stable from day-to-day, in contrast to serum iron.
Measurement: Sensitive methods are needed, since serum levels are very low. Immunologic assays requiring species-specific reagents, such as RIA and ELISA, have been employed. Canine and feline-specific ferritin assays are available through Kansas University.

Serum ferritin levels in Shetland Ponies with experimentally-induced acute inflammation (commencing day zero) compared to normal control animals. Reproduced with permission from Smith and Cipriano, Vet Pathol. 24:354-356 (1987)
Variation in disease:
Low serum ferritin: A decrease in the amount of stored iron is the only known cause for a low serum ferritin result. This is the strong point of this test. However, in dogs, serum ferritin values do not appear to correlate with bone marrow iron stores, and normal ferritin values may be seen in dogs with documented iron deficiency. There is no apparent explanation for this. In cats, ferritin appears to be a better indicator of iron stores than in dogs.
High serum ferritin: Increased stored iron (overload) is associated with raised serum ferritin levels (e.g. massive blood transfusions, hemachromatosis). Unfortunately, ferritin is an acute phase reactant protein, so liver disease, infection, inflammation, or malignancy will result in high serum ferritin levels. The concurrent presence of these conditions in an iron-deficient subject may raise serum ferritin concentration to a level not clearly indicative of iron deficiency; or raise the level in a subject with normal iron stores to an extent suggestive of iron overload.
Clinical Information:
Ferritin is a high-molecular-weight protein that contains approximately 20% iron. It occurs normally in almost all tissues of the body but especially in hepatocytes and reticuloendothelial cells, where it serves as an iron reserve. Ferritin is also present in the serum in minute amounts, where it appears to reflect iron stores in normal individuals.
Ferritin plays a significant role in the absorption, storage, and release of iron. As the storage form of iron, ferritin remains in the body tissues until it is needed for erythropoiesis. When needed, the iron molecules are released from the apoferritin shell and bind to transferrin, the circulating plasma protein that transports iron to the erythropoietic cells.
A low serum ferritin value is thought to be the best laboratory indicator of iron depletion. Virtually all patients with low serum iron and low ferritin have iron deficiency. Serum ferritin is clinically useful in distinguishing between iron-deficiency anemia (serum ferritin levels diminished) and "anemia of chronic disease" (serum ferritin levels usually normal or elevated). Serum ferritin is a good screening test in separating erythrocyte microcytosis due to iron deficiency (low values) from microcytosis related to thalassemia minor (normal or high values). An iron-depletion state with a decreased serum ferritin value is quite common among menstruating and reproductively active females and in children.
Ferritin is an acute phase reactant. A normal serum ferritin value, therefore, cannot be used to exclude iron deficiency if a hepatic, malignant, or inflammatory condition is present.
A high serum ferritin value is seen in hemochromatosis and other iron-overload states, as well as acute hepatitis, Gaucher disease, malignancies, and chronic inflammatory disorders.
A normal serum ferritin result varies with gender and age. An abnormally high ferritin will be highlighted on the lab test result as out of range. Ferritin is a non-specific test and can be elevated for reasons other than hemochromatosis. Subsequent tests may be necessary to see if elevations continue over time. A level of more than 200 ng/ml for women and 300 ng/ml for men is considered out of range, but it is rare for organ damage to occur with ferritin levels below 1000 ng/ml.

Why do I need this test?
Laboratory tests may be done for many reasons. Tests are performed for routine health screenings or if a disease or toxicity is suspected. Lab tests may be used to determine if a medical condition is improving or worsening. Lab tests may also be used to measure the success or failure of a medication or treatment plan. Lab tests may be ordered for professional or legal reasons. The following are possible reasons why this test may be done:

  • Adult onset Still's disease
  • Excess-iron disease
  • Iron deficiency anemia
  • Premature labor

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 evaluate the severity of an iron deficiency or overload.
The ferritin tests as well as iron tests are done when a CBC test shows that the hematocrit and hemoglobin of a person are low and the red blood cells are paler and smaller than normal. This often suggests iron deficiency and anemia. Early on, iron efficiency does not cause any physical effects and in healthy people, the symptoms do not show up until the hemoglobin drops to 10 g per deciliter. When the iron-deficiency progresses, the symptoms begin to show up and then a doctor may order a plasma ferritin test.
Purpose is to provide clinicians with a concise reference document describing the appropriate laboratory tests  for assessing patients of all ages suspected of having iron deficiency.
Investigation of the underlying cause of iron deficiency is beyond the scope of this guideline. Iron  overload will be covered in a separate OAML guideline.
Readers are reminded that OAML Guidelines will not apply to every clinical situation, nor can they  serve as a substitute for sound clinical judgment.
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 have not yet developed.
Early iron deficiency usually causes no physical effects at all. 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 may begin to develop and a doctor may order ferritin as wells as other iron-related tests. The most common symptoms of iron deficiency anemia include:

  • Chronic fatigue/tiredness
  • Weakness
  • Dizziness
  • Headaches

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
  • Lack of energy
  • Abdominal pain
  • Loss of sex drive
  • Heart problems

To confirm the presence of iron overload, other iron tests (iron, TIBC) and a genetic test for hereditary hemochromatosis may be ordered as well.
This test measures the amount of iron in the body. Iron is important for red blood cell production. Your doctor may order this test if you have signs or symptoms of anemia.
Causes of Iron Deficiency:

Some of the signs of iron deficiency and anemia include headaches, dizziness, weakness, and chronic fatigue. As the iron stores begin to deplete, a person can experience drowsiness, tinnitus or ringing in the ears, shortness of breath, and irritability. As the anemia progresses, the symptoms become more severe. Leg pain, headache, chest pain, shock, and heart failure can occur in cases of severe anemia.
Children can develop learning disabilities. Some of the other queer signs of anemia include spoon-shaped toe and finger nails, sores at the corner of the mouth, a smooth tongue or a burning sensation on the tongue, and pica, which means craving for clay, dirt, chalk or licorice. A ferritin level test can also be done when doctors suspect iron overload in a person. The symptoms of iron overload vary and can become worse over time. Hearth problems, loss of sex drive, abdominal pain, lack of energy, weakness, fatigue, and joint pain are some of the signs to look out for. Doctors order iron tests as well as genetic tests to check for hereditary hemochromatosis.
When and how often should I have this test?
When and how often laboratory tests are done may depend on many factors. The timing of laboratory tests may rely on the results or completion of other tests, procedures, or treatments. Lab tests may be performed immediately in an emergency, or tests may be delayed as a condition is treated or monitored. A test may be suggested or become necessary when certain signs or symptoms appear.
Due to changes in the way your body naturally functions through the course of a day, lab tests may need to be performed at a certain time of day. If you have prepared for a test by changing your food or fluid intake, lab tests may be timed in accordance with those changes. Timing of tests may be based on increased and decreased levels of medications, drugs or other substances in the body.
The age or gender of the person being tested may affect when and how often a lab test is required. Chronic or progressive conditions may need ongoing monitoring through the use of lab tests. Conditions that worsen and improve may also need frequent monitoring. Certain tests may be repeated to obtain a series of results, or tests may need to be repeated to confirm or disprove results. Timing and frequency of lab tests may vary if they are performed for professional or legal reasons.
Before having blood collected, tell the person drawing your blood if you are allergic to latex. Tell the healthcare worker if you have a medical condition or are using a medication or supplement that causes excessive bleeding. Also tell the healthcare worker if you have felt nauseated, lightheaded, or have fainted while having blood drawn in the past.

How is the test done?
When a blood sample from a vein is needed, a vein in your arm is usually selected. A tourniquet (large rubber strap) may be secured above the vein. The skin over the vein will be cleaned, and a needle will be inserted. You will be asked to hold very still while your blood is collected. Blood will be collected into one or more tubes, and the tourniquet will be removed. When enough blood has been collected, the healthcare worker will take the needle out.
The amount of discomfort you feel will depend on many factors, including your sensitivity to pain. Communicate how you are feeling with the person doing the test. Inform the person doing the test if you feel that you cannot continue with the test.
During a blood draw, you may feel mild discomfort at the location where the blood sample is being collected.
After a blood sample is collected from your vein, a bandage, cotton ball, or gauze may be placed on the area where the needle was inserted. You may be asked to apply pressure to the area. Avoid strenuous exercise immediately after your blood draw. Contact your healthcare worker if you feel pain or see redness, swelling, or discharge from the puncture site.
During a blood draw, a hematoma (blood-filled bump under the skin) or slight bleeding from the puncture site may occur. After a blood draw, a bruise or infection may occur at the puncture site. The person doing this test may need to perform it more than once. Talk to your healthcare worker if you have any concerns about the risks of this test.
Ask your healthcare worker how you will be informed of the test results. You may be asked to call for results, schedule an appointment to discuss results, or notified of results by mail. Follow up care varies depending on many factors related to your test. Sometimes there is no follow up after you have been notified of test results. At other times follow up may be suggested or necessary. Some examples of follow up care include changes to medication or treatment plans, referral to a specialist, more or less frequent monitoring, and additional tests or procedures. Talk with your healthcare worker about any concerns or questions you have regarding follow up care or instructions.
How do I prepare for this test?

  • For 3 days before the tests avoid iron and vitamin C supplements and juices with vitamin C.
  • You should fast overnight before you have this test. This means you should not eat or drink anything after midnight the night before your test. If you need to take medicines, you may take them with a small amount of water on the morning of your test.
  • Talk to your health care provider if you have any questions.

Results:
The ferritin test measures the amount of ferritin in the blood. Ferritin is a protein found principally in the liver, spleen, skeletal muscles, and bones that stores iron so your body can use it later. As free iron in the blood is toxic to your cells, the majority of iron stored in your body is found in ferritin. Because of this, the ferritin test is the best test to measure the amount of iron in your body.
Low ferritin levels may indicate a lack of iron which can lead to anemia. Low ferritin levels have also been associated with restless leg syndrome, ADHD in children, and hypothyroidism. Elevated Ferritin levels are typically associated with iron overload disorders and periods of disease or acute malnourishment.
Ferritin levels are checked along with other iron tests. The level of ferritin is low in people who have low levels of iron and increase in people who suffer from hemochromatosis as well as extra iron storage disorders. This also happens in people who have had several blood transfusions. An acute phase reactant, ferritin can increase in people with autoimmune disorders, chronic infection, liver disease, inflammation, and few types of cancer.
Laboratory test results may vary depending on your age, gender, health history, the method used for the test, and many other factors. If your results are different from the results suggested below, this may not mean that you have a disease. Contact your healthcare worker if you have any questions. The following are considered to be normal results for this test:

  • Adult males: 30-300 ng/mL (30-300 mcg/L)
  • Adult females: 10-200 ng/mL (10-200 mcg/L)
  • Newborns: 25-200 ng/mL (25-200 mcg/L)
  • Children, 1 month: 200-600 ng/mL (200-600 mcg/L)
  • Children, 2-5 months: 50-200 ng/mL (50-200 mcg/L)
  • Children, 6 months-15 years: 7-140 ng/mL (7-140 mcg/L)

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 have iron deficiency and are elevated in those with hemochromatosis and other excess iron storage disorders and in those who have had multiple blood transfusions.
Ferritin is an acute phase reactant and thus may 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.
Hereditary hemochromatosis or other iron-overload states, acute hepatitis, and Gaucher disease are associated with very high serum ferritin levels. Slight-to-moderate elevation occurs in many malignancies and in chronic inflammatory disorders.

Iron deficiency (uncomplicated)

  • Males: <24 mcg/L
  • Females: <11 mcg/L

Iron overload

  • Males: >336 mcg/L
  • Females: >307 mcg/L

In hemochromatosis, ferritin is often >1,000 mcg/L
For more information about hereditary hemochromatosis testing, see Hereditary Hemochromatosis Algorithm in Special Instructions.
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.
Normal Results

  • Male: 12-300 ng/mL
  • Female: 12-150 ng/mL

Ferritin

Men:

18-270 nanograms per milliliter (ng/mL) or 18-270micrograms per liter (mcg/L)

Women:

18-160 ng/mL or 18-160 mcg/L

Children 6 months to 15 years:

7-140 ng/mL or 7-140 mcg/L

Babies 1 to 5 months:

50-200 ng/mL or 50-200 mcg/L

Newborns:

25-200 ng/mL or 25-200 mcg/L

Note: ng/ml = nanograms per milliliter
The lower the ferritin level, even within the "normal" range, the more likely it is that the patient does not have enough iron.
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
Abnormal Results:
Any inflammatory disorder can raise the ferritin level.
Very high ferritin levels (greater than 1,000 ng/mL) can mean a large buildup of iron in the body (hemochromatosis). One form of this condition is passed on in families (genetic hemochromatosis). Some diseases, including alcoholism, thalassemia, and some types of anemia that cause red blood cells to be destroyed, can also cause hemochromatosis. Also, if you have many blood transfusions, this can sometimes cause the body to store too much iron (acquired hemochromatosis).
High ferritin levels may also be caused by liver disease (cirrhosis or hepatitis), Hodgkin's disease, leukemia, infection, inflammatory conditions (such as arthritis or lupus), or a diet that is too high in iron.
Too much iron in body organs, such as the pancreas or heart, can affect how the organ works.
Higher-than-normal ferritin levels may be due to:

  • Alcoholic liver disease
  • Frequent transfusion of packed red blood cells
  • Hemochromatosis

Low ferritin levels often mean an iron deficiency is present. This can be caused by long-term (chronic) blood loss from heavy menstrual bleeding, pregnancy, not enough iron in the diet, or bleeding inside the intestinal tract (from ulcers, colon polyps, colon cancer, hemorrhoids, or other conditions). In rare cases, too much iron may be lost through the skin (because of a disease such as psoriasis) or in the urine.
Lower-than-normal levels may be due to:

  • Heavy menstrual bleeding
  • Intestinal conditions that cause poor absorption of iron
  • Iron deficiency anemia
  • Long-term digestive tract bleeding

A serum ferritin result below the normal range for the patient’s age is diagnostic of iron deficiency and should prompt investigation and treatment. Serum ferritin typically has a wide reference range and will vary with age and gender, consult your laboratory’s report for the established reference ranges.  Inflammation is common and in its presence ferritin may be elevated and give seemingly normal results, even in the presence of iron deficiency.  Therefore, a serum ferritin result within the normal range for the patient’s age, but less than 100 ug/L, does not exclude depleted or reduced iron stores. In this situation it is recommended that the patient’s response to iron replacement be assessed or other causes of microcytic anemia be excluded.
Results of these iron studies tests may mean the following:

  • A low serum iron level and low serum ferritin level may be caused by iron deficiency anemia.
  • A high TIBC and low serum iron level may be caused by iron deficiency anemia, pregnancy, and chronic blood loss.
  • A high serum iron level may be caused by too much iron in your diet, vitamin B6 therapy, or some anemias caused by an inability to use iron.
  • A high ferritin level and a normal serum iron level might indicate liver disease from infection or alcoholism, chronic inflammatory disease (such as arthritis or asthma), hypothyroidism, and type 2 diabetes.
  • A high ferritin level combined with a high serum iron level may be a sign of hemosiderosis (an accumulation of iron in some of your tissues).
  • A low TIBC and high serum iron may be a sign of sideroblastic anemia (a condition that prevents your red blood cells from using iron).
  • A high serum ferritin level, high serum iron, and low TIBC may be caused by hemochromatosis.

The interpretation of an elevated serum ferritin requires consideration of several separate disease categories. These come under the broad headings of:

  • Iron overload
  • Acute inflammatory conditions
  • Liver disease
  • Alcohol excess

Causes of iron overload
Primary

  • Hereditary haemochromatosis
  • Hereditary aceruloplasminemia

(Wilson’s disease)
Secondary

  • Transfusion overload
  • Excess dietary iron
  • Porphyria cutanea tarda
  • Ineffective erythropoiesis (Sideroblastic anaemia, Thalassemia)

Causes of high serum ferritin without iron overload
• Liver disease – non-alcoholic hepatitic steatosis (NASH)* or viral hepatitis (B/C?G)
• Alcohol excess*
• Chronic inflammatory conditions
– Rheumatoid arthritis, inflammatory bowel disease
– Bacterial infections
• Malignancy especially haematological
• Thyrotoxicosis
• Familial hyperferritinemia and cataract syndrome
* Can have iron overload in certain settings
The most sensitive method for predicting whether the elevated serum ferritin represents iron overload due to haemochromatosis is the transferrin saturation. A transferrin saturation of >60% in males and >50% in females has a sensitivity of >90% for iron overload.
If the transferrin saturation is elevated on more than one occasion then testing for the common mutations of the HFE gene is indicated in Caucasian patients. Try to test patients when they are otherwise well and avoid screening tests for haemochromatosis if a patient is acutely unwell. If the patient is sick, the serum ferritin may be misleadingly high as it is an acute phase reactant. Conversely the serum transferrin saturation falls during acute illness and therefore may mask the presence of iron overload. If a high transferrin saturation is unexplained a fasting sample may be useful as iron saturation can be affected by a high iron meal.
Hereditary haemochromatosis
The most common cause of iron overload is mutation of the HFE gene, by the substitution of tyrosine for cysteine at amino acid 282. Homozygosity for the C282Y mutation is found in 85–90% of patients of Northern European origin who have typical hereditary haemochromatosis and results in absence of the HFE gene on the cell surface. There is high prevalence of this mutation with 10–14% C282Y heterozygosity rates and 0.5% homozygosity amongst Caucasians. Homozygous patients have a 50–75% chance of developing iron overload. Heterozygotes are unlikely to develop the disease in the absence of other risk factors for iron overload but can transmit the gene mutation to their children. Fifteen to 20 per cent of the patient population is heterozygous for a different mutation resulting in the substitution of aspartate for histidine at amino acid 63 termed H63D. This mutation alters the binding affinity for the transferrin receptor and does not usually contribute to increased iron overload in the absence of the C282Y mutation. Patients heterozygous for both C282Y and H63D mutations are termed heterozygotes and can develop haemochromatosis.

Patients heterozygous for either C282Y or H63D mutations can develop iron overload in the setting of alcohol excess, non-alcoholic hepatic steatosis or porphyria cutanea tarda. Other mutations involving the transferrin 2 receptor and ferroportin are termed HFE 3 and HFE 4 respectively. Juvenile haemochromatosis (HFE2) is an autosomal recessive disorder also and involves mutation of chromosome 1q. Affected children have a profound defect in regulation of intestinal iron absorption, and develop symptomatic haemochromatosis in their early 20s.
Clinical manifestations of hereditary haemochromatosis can be grouped as early or late.
Early

  • Asthenia
  • Arthralgia
  • Elevation of serum transaminses

Late

  • Hepatomegaly
  • Cirrhosis and hepatoma
  • Diabetes
  • Arthritis of the 2nd and 3rd MC P joints ‘painful handshake’
  • Cardiomyopathy
  • Pigmentation
  • Impotence

Patients with a diagnosis of hereditary haemochromatosis genotype must therefore have serum glucose and liver enzymes checked on a regular basis. If there is hepatomegaly, elevation of the liver enzymes or the serum ferritin is greater than 1 000 ug/L then a liver biopsy to exclude liver cirrhosis is indicated.   If cirrhosis is present the patient requires screening for hepatocellular carcinoma at regular intervals. Liver biopsy A liver biopsy should be considered if the patient has an unexplained high ferritin especially in the setting of high transferrin saturation. The pattern of iron distribution in HH is periportal and hepatocytic rather than predominantly in the Kuppfer cells. Liver biopsy provides the hepatic iron concentration – a semiquantitative evaluation of iron excess. A value greater than 1.9 is very suggestive of HH. Liver biopsy frequently detects associated lesions such as steatosis

Some common Questions:
1.  My iron level is normal, but my ferritin level is low. Why is that?
The development of iron-deficiency anemia is a gradual process. If your body is not taking in enough iron, your body first uses the iron that is stored in tissues (i.e., ferritin) and blood levels of ferritin will begin to decrease. If not corrected, the stored iron begins to be depleted as it is used in the production of red blood cells. In the early stages of iron-deficiency, blood levels of iron can be normal while stored iron, and therefore ferritin levels, will begin to decrease.
2.  I know eating foods high in iron or taking iron supplements will increase my iron level but will it also increase my ferritin level?
Yes. Taking in more iron will increase the level of iron in your body. If the level of iron in your body increases and is more than your body requires, then your body will begin to store more iron in the form of ferritin.
3.  What other conditions may alter ferritin levels?
Increased levels may be seen in alcohol abuse, acute hepatitis, and infections.
4.  Who should take iron supplements?
The people who typically need iron supplements are pregnant women and patients with documented iron deficiency. Young women who become anemic due to poor dietary intake and chronic and/or excessive loss of blood during the menstrual cycle may require iron supplements. People should not take iron supplements before talking to their doctor as excess iron can cause chronic iron overload. An
5.  Is there any way to cure iron overload?
If it is due to a temporary condition or ingestion of iron supplements, then it will likely resolve on its own once the condition or supplement ingestion is resolved. If it is due to hemochromatosis or to a chronic disease, then it cannot be cured; careful management by your physician is required. In severe cases, periodic removal of a prescribed amount of blood, also known as therapeutic phlebotomy, may be necessary.
Limitations of Serum Ferritin:
That serum ferritin is an acute-phase reactant and that there are gender differences (normally lower in women) make ferritin somewhat less than an ideal test for determining iron deficiency. TSAT also has some acute-phase reactivity insofar as transferrin may be elevated in the setting of inflammation, which would lower the TSAT if circulating iron is constant. Transferrin may be low because of decreased transferrin synthesis in the setting of malnutrition and chronic disease, which would raise TSAT if circulating iron is constant. There also are significant (17 to 70%) diurnal fluctuations in TSAT that make it difficult to interpret its value if the time of day at which the test is obtained varies from test to test.
The situation in which the TSAT is low and the serum ferritin is high often is encountered among hemodialysis patients. The serum ferritin may be elevated in this setting because of functional iron deficiency or RE blockade. The therapeutic dilemma is to decide whether additional iron supplements are indicated to bring the TSAT up into the K/DOQI target range, especially in patients who are not achieving the target Hb in the setting of ESA treatment. This is a risk versus benefit analysis: What is the risk to the patient's safety by giving him or her additional intravenous iron versus the benefit of providing additional iron for RBC production so that the patient can enjoy the physiologic and quality of life rewards of a higher Hb level?
Ultimately, the diagnosis of iron deficiency should not be made in a clinical vacuum. It needs to be made by examining the entire patient, looking for the presence of inflammation or infection, especially if a dialysis catheter is present. Every catheter has a biofilm that can provoke an inflammatory response even in the absence of fever, leukocytosis, or positive blood cultures. In most of the patients with the dilemma of elevated serum ferritin and low TSAT, removal of the catheter should be considered a high priority. That issue notwithstanding, the question boils down to whether the patient needs more iron to support higher levels of Hb. An increase in the ESA dosage may seem to be the path of least resistance, because ESAs are perceived as more benign than intravenous iron. However, most of the patients with high serum ferritin and low TSAT levels already are demonstrating evidence of ESA resistance, so they already are on very high dosages of an ESA and still below the Hb target. That is the situation in which the clinician must come to terms with whether the patient should receive more iron and whether the serum ferritin and TSAT are providing the information that is needed to make that decision.
The accuracy of serum ferritin and TSAT is determined by their sensitivity and specificity. Sensitivity is the probability that a positive test will accurately identify iron status as deficient. Specificity is the probability that a negative test will accurately identify iron status as not deficient. The sensitivity and the specificity of these tests, as determined by three authors using different criteria. The conclusion is that a TSAT of 20% seems to be relatively good in terms of sensitivity, meaning that few patients are truly iron deficient with a TSAT much higher than 20%, but a ferritin cutoff of 100 or even 200 ng/ml tends to miss close to a majority of patients who ultimately may respond to intravenous iron.

References:
http://www.muschealth.com/lab/content.aspx?id=150038
http://labtestsonline.org/understanding/analytes/ferritin/tab/faq
http://www.nlm.nih.gov/medlineplus/ency/article/003490.htm
http://www.webmd.com/a-to-z-guides/ferritin?page=3
http://en.wikipedia.org/wiki/Ferritin
http://www.mayomedicallaboratories.com/test-catalog/Overview/8689
http://www.cdnhemochromatosis.ca/disorder/diagnosis.php
http://www.healthtestingcenters.com/ferritin-serum.aspx
http://www.privatemdlabs.com/lp/ferritin_info.php
http://www.oaml.com/documents/IronDeficiencyFinalMarch2012.pdf
http://www.ehow.com/about_5594320_serum-ferritin-vs_-serum-iron.html
http://www.wisegeek.com/what-is-serum-ferritin.htm
http://www.rnzcgp.org.nz/assets/documents/Publications/Archive-NZFP/Feb-2002-NZFP-Vol-29-No-1/berkhan.pdf
http://cjasn.asnjournals.org/content/1/Supplement_1/S4.full
http://www.medicalhealthtests.com/pathology-test/ferritin-test-plasma-or-serum.html

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