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Test ID: FEC Iron and Total Iron-Binding Capacity, Serum

Reporting Name

Iron and Total Fe Binding Cap, S

Useful For

Screening for chronic iron overload diseases, particularly hereditary hemochromatosis

Specimen Type

Serum


Necessary Information


Patient's age and sex are required.



Specimen Required


Patient Preparation:

1. Fasting (12 hours)

2. Iron-containing supplements should be avoided for 24 hours prior to draw.

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1 mL

Collection Instructions:

1. Draw blood before 12 noon (preferred).

2. Serum gel tubes should be centrifuged within 2 hours of collection.

3. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 7 days
  Frozen  180 days

Reference Values

IRON

Males: 50-150 mcg/dL

Females: 35-145 mcg/dL

 

TOTAL BINDING CAPACITY

250-400 mcg/dL

 

PERCENT SATURATION

14-50%

Day(s) and Time(s) Performed

Monday through Saturday; Continuously

Test Classification

This test has been cleared, approved or is exempt by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

83540-Iron

83550-Iron-binding capacity

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FEC Iron and Total Fe Binding Cap, S 50190-8

 

Result ID Test Result Name Result LOINC Value
IRON Iron 2498-4
TIBC Total Iron Binding Capacity 2500-7
SAT Percent Saturation 2502-3

Testing Algorithm

See Hereditary Hemochromatosis Algorithm in Special Instructions.

Clinical Information

Ingested iron is absorbed primarily from the intestinal tract and is temporarily stored in the mucosal cells as ferritin (Fe[III]). Ferritin provides a soluble protein shell to encapsulate a complex of insoluble ferric hydroxide-ferric phosphate. On demand, iron is released into the blood by mechanisms that are not clearly understood, to be transported as Fe(III)-transferrin.

 

Transferrin is the primary plasma iron transport protein, which binds iron strongly at physiological pH. Transferrin is generally only 25% to 30% saturated with iron. The additional amount of iron that can be bound is the unsaturated iron-binding capacity (UIBC). The total iron-binding capacity (TIBC) can be indirectly determined using the sum of the serum iron and UIBC. Knowing the molecular weight of the transferrin and that each molecule of transferrin can bind 2 atoms of iron, TIBC and transferrin concentration is interconvertible.

 

Percent saturation (100 x serum iron/TIBC) is usually normal or decreased in persons who are iron deficient, pregnant, or are taking oral contraceptive medications. Persons with chronic inflammatory processes, hemochromatosis, or malignancies generally display low transferrin.

 

Serum iron, total iron-binding capacity, and percent saturation are widely used for the diagnosis of iron deficiency. However, serum ferritin is a much more sensitive and reliable test for demonstration of iron deficiency.

Interpretation

In hereditary hemochromatosis, serum iron is usually above 150 mcg/dL and percent saturation is above 60%. In advanced iron overload states, the percent saturation often is above 90%.

 

For more information about hereditary hemochromatosis testing, see Hereditary Hemochromatosis Algorithm in Special Instructions.

Clinical Reference

1. Tietz Textbook of Clinical Chemistry. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company. 1999

2. Fairbanks VF, Baldus WP: Iron overload. In Hematology. Fourth edition. Edited by WJ Williams, AJ Erslev, MA Lichtman. New York, McGraw-Hill Book Company, 1990, pp 482-505

Analytic Time

Same day/1 day

Method Name

Immunoturbidimetric Assay

Forms

If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen.

Mayo Clinic Laboratories | Hematology Catalog Additional Information:

mml-benign-hematology-disorders