Iron Tests

Iron Tests

 

Definition

Iron tests are a group of blood tests that are done to evaluate the iron level in blood serum, the body's capacity to absorb iron, and the amount of iron actually stored in the body. Iron is an essential trace element; it is necessary for the formation of red blood cells and certain enzymes. At the other extreme, high levels of iron can be poisonous.

Purpose

There are four different types of tests that measure the body's iron levels and storage. They are called iron level tests, total iron-binding capacity (TIBC) tests, ferritin tests, and transferrin tests. These tests are given for several reasons:
  • To help in the differential diagnosis of different types of anemia.
  • To assess the severity of anemia and monitor the treatment of patients with chronic anemia.
  • To evaluate protein depletion and other forms of malnutrition.
  • To check for certain liver disorders.
  • To evaluate the possibility of chronic gastrointestinal bleeding. Blood loss from the digestive tract is a common cause of iron deficiency anemia.
  • To help diagnose certain unusual disorders, including iron poisoning, thalassemia, hemosiderosis, and hemochromatosis.
A serum iron test can be used without the others to evaluate cases of iron poisoning.

Precautions

Patients should not have their blood tested for iron within four days of a blood transfusion or tests and treatments that use radioactive materials. Recent high stress levels or sleep deprivation are additional reasons for postponing iron tests.
Blood samples for iron tests should be taken early in the morning because serum iron levels vary during the day. This precaution is especially important in evaluating the results of iron replacement therapy.

Description

Iron tests are performed on samples of the patient's blood, withdrawn from a vein into a vacuum tube. The amount of blood taken is between 6 mL and 10 mL (1/3 of a fluid ounce). The procedure, which is called a venipuncture, takes about five minutes.

Iron level test

The iron level test measures the amount of iron in the blood serum that is being carried by a protein (transferrin) in the blood plasma.
Medications and substances that can cause increased iron levels include chloramphenicol, estrogen preparations, dietary iron supplements, alcoholic beverages, methyldopa, and birth control pills.
Medications that can cause decreased iron levels include ACTH, colchicine, deferoxamine, methicillin, and testosterone.

Total iron-binding capacity (tibc) test

The TIBC test measures the amount of iron that the blood would carry if the transferrin were fully saturated. Since transferrin is produced by the liver, the TIBC can be used to monitor liver function and nutrition.
Medications that can cause increased TIBC levels include fluorides and birth control pills.
Medications that can cause decreased TIBC levels include chloramphenicol and ACTH.

Transferrin test

The transferrin test is a direct measurement of transferrin—which is also called siderophilin—levels in the blood. Some laboratories prefer this measurement to the TIBC. The saturation level of the transferrin can be calculated by dividing the serum iron level by the TIBC.

Ferritin test

The ferritin test measures the level of a protein in the blood that stores iron for later use by the body.
Medications that can cause increased ferritin levels include dietary iron supplements. In addition, some diseases that do not directly affect the body's iron storage can cause artificially high ferritin levels. These disorders include infections, late-stage cancers, lymphomas, and severe inflammations. Alcoholics often have high ferritin levels.

Preparation

Patient history

Before patients are tested for iron, they should be checked for any of the following factors:
  • Prescription medications that affect iron levels, absorption, or storage
  • Blood transfusion or radioactive medications within the last four days
  • Recent extreme stress or sleep deprivation
  • Recent eating habits. Test results can be affected by eating large amounts of iron-rich foods shortly before the blood test.

Fasting

Patients scheduled for an iron level, TIBC, or transferrin test should fast for 12 hours before the blood is drawn. They are allowed to drink water. Patients scheduled for a ferritin test do not need to fast but they should not have any alcoholic beverages before the test.

Aftercare

Aftercare consists of routine care of the area around the venipuncture.

Risks

The primary risk is the possibility of a bruise or swelling in the area of the venipuncture. The patient can apply moist warm compresses if there is any discomfort.

Normal results

Iron level test

Normal serum iron values are as follows:
  • Adult males: 75-175 micrograms/dL
  • Adult females: 65-165 micrograms/dL
  • Children: 50-120 micrograms/dL
  • Newborns: 100-250 micrograms/dL.

Tibc test

Normal TIBC values are as follows:
  • Adult males: 300-400 micrograms/dL
  • Adult females: 300-450 micrograms/dL.

Transferrin test

Normal transferrin values are as follows:
  • Adult males: 200-400 mg/dL
  • Adult females: 200-400 mg/dL
  • Children: 203-360 mg/dL
  • Newborns: 130-275 mg/dL.
Normal transferrin saturation values are between 30-40%.

Ferritin test

Normal ferritin values are as follows:
  • Adult males: 20-300 ng/mL
  • Adult females: 20-120 ng/mL
  • Children (one month): 200-600 ng/mL
  • Children (two to five months): 50-200 ng/mL
  • Children (six months to 15 years): 7-140 ng/mL
  • Newborns: 25-200 ng/mL.

Abnormal results

Iron level test

Serum iron level is increased in thalassemia, hemochromatosis, severe hepatitis, liver disease, lead poisoning, acute leukemia, and kidney disease. It is also increased by multiple blood transfusions and intramuscular iron injections.
Iron levels above 350-500 micrograms/dL are considered toxic; levels over 1000 micrograms/dL indicate severe iron poisoning.
Serum iron level is decreased in iron deficiency anemia, chronic blood loss, chronic diseases (lupus, rheumatoid arthritis), late pregnancy, chronically heavy menstrual periods, and thyroid deficiency.

Tibc test

The TIBC is increased in iron deficiency anemia, polycythemia vera, pregnancy, blood loss, severe hepatitis, and the use of birth control pills.
The TIBC is decreased in malnutrition, severe burns, hemochromatosis, anemia caused by infections and chronic diseases, cirrhosis of the liver, and kidney disease.

Transferrin test

Transferrin is increased in iron deficiency anemia, pregnancy, hormone replacement therapy (HRT), and the use of birth control pills.
Transferrin is decreased in protein deficiency, liver damage, malnutrition, severe burns, kidney disease, chronic infections, and certain genetic disorders.

Ferritin test

Ferritin is increased in liver disease, iron overload from hemochromatosis, certain types of anemia, acute leukemia, Hodgkin's disease, breast cancer, thalassemia, infections, inflammatory diseases, and hemosiderosis. Ferritin levels may be normal or slightly above normal in patients with kidney disease.
Ferritin is decreased in chronic iron deficiency and severe protein depletion.

Resources

Books

Pagana, Kathleen Deska. Mosby's Manual of Diagnostic and Laboratory Tests. St. Louis: Mosby, Inc., 1998.

Key terms

Anemia — A disorder marked by low hemoglobin levels in red blood cells, which leads to a deficiency of oxygen in the blood.
Ferritin — A protein found in the liver, spleen, and bone marrow that stores iron.
Hemochromatosis — A disorder of iron absorption characterized by bronze-colored skin. It can cause painful joints, diabetes, and liver damage if the iron concentration is not lowered.
Hemosiderosis — An overload of iron in the body resulting from repeated blood transfusions. Hemosiderosis occurs most often in patients with thalassemia.
Iron poisoning — A potentially fatal condition caused by swallowing large amounts of iron dietary supplements. Most cases occur in children who have taken adult- strength iron formulas. The symptoms of iron poisoning include vomiting, bloody diarrhea, convulsions, low blood pressure, and turning blue.
Plasma — The liquid part of blood.
Siderophilin — Another name for transferrin.
Thalassemia — A hereditary form of anemia that occurs most frequently in people of Mediterranean origin.
Transferrin — A protein in blood plasma that carries iron derived from food intake to the liver, spleen, and bone marrow.

Patient discussion about Iron Tests

Q. My Iron/TIBC tests normal, Ferritin,Serum = 22. Range 22-322. What is the problem? Iron Bind. Cap. ug/dL 324 range 250 - 450 UIBC ug/dL 206 range 150 - 375 Iron, Serum ug/dL 118 range 40 - 155 Iron Saturation % 36 range 15 - 55 Biopsy = Prostate Cancer....PCA high = 10.2 PSA now 8.3 PSA Ultra W/Serial Monitor ...Ultrasenitive = 8.26

A. What makes you think something is not normal? Ferritin values may be low in some people, and iron deficiency is usually defined as ferritin 15. Do you have anemia? Currently, it doesn't seem you have any problem with the iron levels.

Take care,

More discussions about Iron Tests
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Samples from 1500 renal dialysis patients being treated with erythropoietin also were studied for comparisons of the diagnostic power of Ret He results with traditional iron tests including SI (<40 ug/dL), TS (<20%), SF (< 100 ng/ml), and hemoglobin (< 110 g/L).
Based on the laboratory results, ductile iron tests were organized in an industrial metalcasting facility.
The effects of the additives were monitored by comparison with the initial state of the ductile iron test samples taken before and after addition for each experiment.
In addition, screening for iron overload instead of performing DNA-based testing may reduce the risks of potential genetic discrimination that some authors suggest is associated with identification of a C282Y homozygote with normal serum iron tests (9-11).
She worked with the same eight men who participated in the iron tests.
The bundled tests included serum ferritin tests (a test that measures iron storage) and serum iron tests, which Damon bundled with a basic blood chemistry panel, and tests for apolipoproteins (a test that measures blood lipid proteins), which Damon bundled with a coronary risk profile.
The number of ferritin and serum iron tests billed by DAMON to Medicare on an annual basis skyrocketed; according to AUSA Loucks, Medicare paid more than $16,000,000 for unnecessary ferritin tests.
As it had with the bundling of the ferritin and iron tests, Damon made it difficult for physicians to order the coronary risk profile without the apolipoprotein tests, and did not disclose to physicians that, while they were being charged a nominal fee for the new tests, Medicare and other government health programs were going to be billed at the full fee schedule rates.
The number of ferritin and serum iron tests billed by DAMON to Medicare on an annual basis skyrocketed, and DAMON received millions more from government programs for the addition of these medically unnecessary tests.
The number of serum iron tests billed by Bioran to Medicare on an annual basis skyrocketed from a few hundred in 1988 to more than 100,000 in 1991.
The government also alleged that the pricing practices of Bioran led many doctors to believe they had no choice but to receive the serum iron tests whenever a SMAC was ordered, and to order tests they would not otherwise have ordered if they had been meaningfully informed of the billing practice by Bioran.