Iron Studies, Ferritin, Immunoglobin Flashcards
What are the Iron Studies used for? Normal values?
Used to evaluate iron metabolism in patients when iron deficiency, overload, or poisoning is suspected.
Tests include serum iron level, total iron binding capacity (TIBC), transferrin, and transferrin saturation.
Normal Findings
Iron: Male 80-180 mcg/dL; Female: 60-160 mcg/dL
TIBC: 250-460 mcg/dL
Transferrin: Male 215-365 mg/dL; Female 250-380 mg/dL
Transferrin Saturation: Male 20-50%; Female 15-50%
What does iron deficiency cause?
Iron deficiency causes decreased hemoglobin production leading to microcytic hypochromic RBCs as well as decreases in MCV and MCHC. The serum iron level is decreased, TIBC is elevated, and transferrin saturation is low.
What is Serum Iron measuring?
Serum iron is a measurement of the iron bound to transferrin
What is Iron overload or poisoning?
Iron overload or poisoning is called hemochromatosis or hemosiderosis with excessive iron deposited in the brain, liver, and heart to cause severe dysfunction of these organs.
When should Serum Iron levels be drawn?
Serum iron levels should be drawn in the AM as eating may artificially elevate iron measurements if food had high iron content
What is TIBC?
TIBC is a measurement of all proteins available for binding iron.
TIBC is an indirect measurement of transferrin, but ferritin is not included in TIBC as it binds only stored iron
TIBC is used to monitor patients during hyperalimentation
What is Transferrin?
Transferrin is the largest quantity of iron binding proteins.
Transferrin is a negative acute phase reactant protein so levels decrease with inflammatory reactions.
How do you measure the TIBC?
TIBC is measured by adding excess iron to the patient’s serum - this saturates all the transferrin. Excess iron is removed and the iron that is left is a direct measurement of TIBC and an indirect measurement of transferrin
TIBC varies minimally with iron intake and is more of a reflection of liver function (transferrin is made by the liver) and nutrition than of iron metabolism
What is TIBC and Transferring Saturation?
The percentage of transferrin and other mobile iron-binding proteins saturated with iron is calculated by dividing the serum iron level by the TIBC. Normal is 20-50%.
This is helpful in determining the cause of abnormal iron and TIBC levels. Transferrin saturation is < 15% in iron deficiency anemia and is increased with hemolytic, sideroblastic, or megaloblastic anemias as well as iron overload or iron poisoning.
What are the Interfering Factors of the Iron Studies?
Recent transfusions may increase serum iron.
Recent ingestion of food high in iron may increase serum iron.
Hemolytic diseases may have an artificially high iron content.
Drugs that increase iron levels include estrogens, ethanol, iron preparations, oral contraceptives.
Drugs that decrease iron levels include ACTH, cholestyramine, colchicine, deferoxamine, and testosterone.
Drugs that increase TIBC include fluorides and oral contraceptives.
Drugs that decrease TIBC include ACTH and chloramphenicol
What causes Increased levels of Serum Iron?
Hemosiderosis or hemochromatosis
Iron poisoning.
Hemolytic anemia – iron in hemoglobin of hemolyzed RBCs leaks out.
Massive blood transfusions – 1 mg of iron per ml of packed RBCs.
Hepatitis or hepatic necrosis.
Lead toxicity – lead overload displaces iron stores
What causes Decreased levels of Serum Iron?
Insufficient dietary iron – all body iron is from dietary intake, so a reduced intake will eventually lead to reduced levels.
Chronic blood loss (irregular menses, uterine cancer, GI cancer, inflammatory bowel disease, diverticulosis, urologic tract cancer (hematuria), hemangioma, AVM – chronic blood loss depletes iron because most of iron exists in hemoglobin in RBCs.
Inadequate intestinal absorption of iron (malabsorption, short bowel syndrome) – all iron in body is from dietary intake.
Pregnancy (late) – fetal requirements deplete mother’s store of iron.
Iron deficiency anemia
Neoplasm
What causes Increased levels of TIBC or Transferrin ?
Estrogen therapy
Pregnancy (late)
Polycythemia vera
Iron deficiency anemia
What causes Decreased levels of TIBC or Transferrin ?
Malnutrition, hypoproteinemia – transferrin is a protein and will decrease as protein is depleted.
Inflammatory diseases, cirrhosis – transferrin is a negative acute phase reactant protein so will decrease with acute inflammatory reactions.
Hemolytic anemia, pernicious anemia, sickle cell anemia – have elevated iron levels and decreased TIBC
What causes Increased levels Transferrin Saturation?
Hemochromatosis or hemosiderosis, increased iron intake – increased iron saturates transferrin.
Hemolytic anemias – iron is increased and saturates transferrin
What causes Decreased levels Transferrin Saturation?
Iron deficiency anemia, chronic illnesses (malignancy, other chronic illnesses) – iron levels are low so transferrin levels are increased.
What is Ferritin mainly used for? Normal values?
Most sensitive test to determine iron deficiency anemia.
Normal Ranges: Male 12-300 ng/mL; Female 10-150 ng/mL
What can Ferritin also be used for?
Ferritin test also used in patients with chronic renal failure to monitor iron stores
Ferritin can act as an acute phase reactant protein so may be elevated in non-iron related conditions (acute inflammatory diseases, infections, metastatic cancer, lymphomas). Elevations occur 1-2 days after onset of acute illness and peaks at 3-5 days. If iron deficiency also exists in these patients, it may not be recognized with a factitious elevation by the concurrent disease
What is Ferritin?
Ferritin is the major iron storage protein and is present in serum in concentrations directly related to iron storage. In normal patients, 1 ng/mL of serum ferritin corresponds to 8 mg of stored iron.
Decreases in ferritin levels indicate a decrease in iron storage (iron deficiency anemia) with a level less than 10 being diagnostic.
Decrease in ferritin will often occur before other signs such as decreased iron levels or change in RBC count or indices.
What are the Interfering Factors of Ferritin?
Recent transfusions or recent ingestion of a meal high in iron can cause elevated ferritin – ingested iron stimulates ferritin production.
Recent administration of radionuclide can cause abnormal levels.
Hemolytic diseases may have artificially high iron content due to hemolyzed RBCs – ferritin synthesis increased to store the iron.
Acute and chronic inflammatory diseases can falsely increase levels.
Disorders of excess iron storage (hemochromatosis, hemosiderosis) have high ferritin levels.
Iron deficient menstruating women may have decreased ferritin levels.
Iron preparations may increase ferritin levels
What causes increased levels of Ferritin?
Hemochromatosis, hemosiderosis – increased iron stores.
Megaloblastic anemia, hemolytic anemia – RBCs lyse to release iron.
Alcoholic/inflammatory hepatocellular disease, inflammatory disease, advanced cancers – ferritin is an acute phase reactant protein.
Chronic illnesses like leukemia, cirrhosis, chronic hepatitis, or collagen vascular diseases.
What causes decreased levels of Ferritin?
Iron deficiency anemia – iron stores are decreased so less ferritin is required.
Severe protein deficiency – ferritin synthesis is reduced.
Hemodialysis – iron stores are reduced by dialysis
What is Immunoglobin Electrophoresis used for? Normal values?
Used to assist in diagnosis and monitoring of therapeutic response in many diseases – ordered if serum protein electrophoresis indicates a spike at the immunoglobulin level.
Normal ranges: IgG: 565-1765 mg/dL IgA: 85-385 mg/dL IgM: 55-375 mg/dL IgD and IgE: minimal
What are the proteins in the blood made of?
Proteins in the blood are made up of albumin and globulin. One type of globulin is gamma globulins.
Antibodies are made of gamma globulins and are called immunoglobulins.
