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Test Code FET Iron & Iron Binding Capacity

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Li-Heparin Mint Green Top

Other Acceptable specimens: Serum/Gold Top, Serum/Red Top

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Li-Heparin Plasma and Serum samples must be sent room temperature at 15-25oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours.

Reference Values

 

Test

Age

Sex

Reference Range

IRON

All

All

40 - 160 μg/dL

UIBC

All

All

110 - 367 μg/dL

TIBC

All

All

230 - 430 μg/dL

PSAT

All

All

14 - 50%

 

Note: Reference range based on in-house studies, on the recommendations from  Tietz Textbook of Clinical Chemistry and Roche Diagnostics product literature.

Critical Values

Analyte

Unit

Low

High

Age

N/A

N/A

N/A

N/A

N/A

CPT Codes

N/A, 83550

LOINC Codes

2498-4, 2501-5

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL

Specimen Stability

Storage Temperature

Stability

Room temperature

4 days

Refrigerated

7 days

Frozen

N/A

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Test Components

Iron (FE)

Unsaturated Iron Binding Capacity (UIBC)

Total Iron Binding Capacity (TIBC) is the calculation of FE + UIBC

Percent Iron Saturation (% SAT) is the calculation of (FE/TIBC) X100

Clinical Indications

  • Iron determinations are performed for the diagnosis and monitoring of microcytic anemia (e.g. due to iron metabolism disorders and hemoglobinopathy), macrocytic anemia (e.g. due to vitamin B12-deficiency, folic acid deficiency and drug-induced metabolic disorders of unknown origin) as well as normocytic anemias such as renal anemia (erythropoetin deficiency), hemolytic anemia, hemoglobinopathy, bone marrow disease and toxic bone marrow damage.
  • Iron binding capacity measurements are used in the diagnosis and treatment of anemia.

Methodology

Endpoint Colorimetric (Ferrozine) Method, (Roche Diagnostics)

Direct determination with FerroZine

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • Avoid hemolyzed samples. higher hemoglobin concentrations lead to artifically increased values due to contamination of the sample with hemoglobin-bound iron.
  • The total iron content of the body is about 3 to 3.5 g. Of this amount about 2.5 g is contained in erythrocytes or their precursors in the bone marrow. Plasma contains only about 2.5 mg of iron. Iron  is transported as Fe(III) boung to the plasma protein apotransferrin. The apotransferrin-Fe(III) complex is called transferrin. Normally only about one third of the iron-binding sites of transferring are occupied by Fe(III). The additonal amount of iron that can be bound is the unsaturated (or latent) iron-binding capacity (UIBC). The sum of the serum iron and UIBC represent total iron-binding capacity (TIBC). TIBC is a measurement for the maximum iron concentration that transferring can bind.  
  • The serum TIBC varies in disorders of iron metabolism. In iron-deficiency anemia the TIBC is elevated and the transferrin saturation is lowered to 15% or less. Low serum iron associated with low TIBC is characteristic of the anemia of chronic disorders, malignant tumors, and infections.
  • TIBC and PSAT will not be calculated if iron or UIBC results are less/greater than the reportable range.
  • UIBC will not be reported into EPIC.
  • Pathologically high levels of albumin (7 g/dL) decrease the apparent UIBC value significantly. If the patient's serum iron exceeds the binding capacity of the transferring, a negative UIBC value will result.
  • In patients treated with iron supplements or metal-binding drugs, the drug-bound iron may not properly react in the test, resulting in falsely low values.
  • The physiological function of deferoxamine containing drugs is to bind iron to facilitate its elimination from the body. Therefore, any deferoxamine concentration interferes with the UIBC assay.
  • In the presence of high ferritin concentrations (greater than 1200 μg/L) the assumption that serum iron is almost completely bound to transferrin is not valid anymore. Therefore, such iron results should not be used to calculate Total Iron Binding Capacity (TIBC) or percent transferrin saturation (% SAT).

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour

Routine Turnaround Time: 4 hours

Testing Schedule: 24/7

Synonyms/Keyword Search

Transferring Saturation (% SAT), Total Iron-Binding Capacity (TIBC), Iron (Fe), Unsaturated Iron Binding Capacity (UIBC)

Last Review Date

1/26/23

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