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Farlex Partner Medical Dictionary © Farlex 2012


A gene on chromosome 5q31.1 that encodes interleukin-5, a cytokine which acts as a  growth and differentiation factor for B cells (inducing the terminal differentiation of late-developing B-cells to immunoglobulin secreting cell) and eosinophils, for the latter of which IL5 is a key regulator of eosinopoiesis, eosinophil maturation and activation.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


Synonym/acronym: Siderophilin, TRF.

Common use

To assess circulating iron levels related to dietary intake to assist in diagnosing disorders such as iron deficiency anemia or hemochromatosis.


Serum (1 mL) collected in a gold-, red-, or red/gray-top tube.

Normal findings

(Method: Nephelometry)
AgeConventional UnitsSI Units (Conventional Units × 0.01)
Newborn130–275 mg/dL1.3–2.75 g/L
1–9 yr180–330 mg/dL1.8–3.3 g/L
10–19 yr195–385 mg/dL1.95–3.85 g/L
 Male215–365 mg/dL2.2–3.6 g/L
 Female250–380 mg/dL2.5–3.8 g/L


Transferrin is a glycoprotein formed in the liver. Its role is the transportation of iron, obtained from dietary intake or RBC breakdown; normally one-third of available transferrin is saturated. Inadequate transferrin levels can lead to impaired hemoglobin synthesis and anemia. Transferrin is subject to diurnal variation, and it is responsible for the variation in levels of serum iron throughout the day. (See monograph titled “Iron-Binding Capacity [Total], Transferrin, and Iron Saturation.”)

This procedure is contraindicated for



  • Determine the iron-binding capacity of the blood
  • Evaluate iron metabolism in iron-deficiency anemia
  • Evaluate nutritional status
  • Screen for hemochromatosis

Potential diagnosis

Increased in

  • Estrogen therapy (estrogen stimulates the liver to produce transferrin)
  • Iron-deficiency anemia (the liver produces transferrin in response to decreased iron levels)
  • Pregnancy (the liver produces transferrin in response to anemia of pregnancy)

Decreased in

    Acute or chronic infection (a negative acute-phase reactant protein whose levels decrease in response to inflammation) Cancer (especially of the gastrointestinal tract) (related to malnutrition) Excessive protein loss from renal disease (related to increased loss from damaged kidney) Hepatic damage (related to decreased synthesis in the liver) Hereditary atransferrinemia Malnutrition (related to a protein-deficient diet that does not provide the nutrients required for synthesis)

Critical findings


Interfering factors

  • Drugs that may increase transferrin levels include carbamazepine, danazol, mestranol, and oral contraceptives.
  • Drugs that may decrease transferrin levels include cortisone and dextran.
  • Transferrin levels are subject to diurnal variation and should be collected in the morning, when levels are highest.
  • Failure to follow dietary restrictions before the procedure may cause the procedure to be canceled or repeated.

Nursing Implications and Procedure


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in evaluating for anemia.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s hematopoietic system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Instruct the patient to fast for at least 12 hr before specimen collection.
  • Note that there are no fluid or medication restrictions unless by medical direction.


  • Potential complications: N/A
  • Ensure that the patient has complied with dietary restrictions; ensure that food has been restricted for at least 12 hr prior to the procedure.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.


  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Instruct the patient to resume usual diet, as directed by the HCP.
  • Nutritional Considerations: Educate the patient with abnormal iron values that numerous factors affect the absorption of iron, enhancing or decreasing absorption regardless of the original content of the iron-containing dietary source. Patients must be educated to either increase or avoid intake of iron and iron-rich foods depending on their specific condition; for example, a patient with hemochromatosis or acute pernicious anemia should be educated to avoid foods rich in iron. Consumption of large amounts of alcohol damages the intestine and allows increased absorption of iron. A high intake of calcium and ascorbic acid also increases iron absorption. Iron absorption after a meal is also increased by factors in meat, fish, and poultry. Iron absorption is decreased by the absence (gastric resection) or diminished presence (use of antacids) of gastric acid. Phytic acids from cereals, tannins from tea and coffee, oxalic acid from vegetables, and minerals such as copper, zinc, and manganese interfere with iron absorption.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family. Educate the patient regarding access to nutritional counseling services. Provide contact information, if desired, for the Institute of Medicine of the National Academies (
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include A/G, cancer antigens, CBC, CBC RBC count, CBC RBC indices, CBC RBC morphology, ferritin, iron/TIBC, prealbumin, and total protein.
  • Refer to the Hematopoietic System table at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners
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She said the Botswana SADC TRF project was also crucial to making a meaningful contribution to exports between Botswana and the two markets.
Ultimately, TRF wants to convey how easy starting an equine-care program in a correctional facility really is.
([section]) 7,441 persons with TRF exposure were identified, and 3,222 unique cases remained after exclusions.
Both TRF and ATF treatments reduced the amount of intracellular ROS in senescent myoblasts, which was indicated by the decline in fluorescence intensity as well as the total number of positively stained cells (Figure 2(c)).
[IC.sub.20] was used to induce minimal injury of the cells; thus prophylactic effects of TRF and [alpha]-TCP treatment can be determined [10].
For example, a monthly report of suppliers could be reviewed and any supplier with a TRF value over 25 would require documented investigation and possible corrective action.
The astrocytes that were exposed to 200 ng/mL of TRF and [alpha]-TCP were subjected to scanning electron microscopy analysis to observe the morphological changes upon glutamate challenge.
Ensuring our submarine crews are well fed and fully stocked is the core function of the folks in the Provisions Branch of Supply Department's Logistics Support Branch at TRF. Their primary duties include receiving all food deliveries on behalf of the submarines, warehousing, delivery, and records keeping for home-ported Trident submarines.
Last week we considered how you can determine a comfortable target annual pension amount and from this sum a Target Retirement Fund (TRF).