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Test Code SFEC Iron and Total Iron-Binding Capacity, Serum


Ordering Guidance


The recommended primary test for assessment of iron deficiency is serum ferritin. Order FERR1 / Ferritin, Serum.



Additional Testing Requirements


Although measurement of serum iron, total iron-binding capacity, and percent saturation should not be used as primary testing for iron deficiency, they may be helpful when used in conjunction with ferritin and soluble transferrin receptor, especially in patients with inflammation. Order both FERR1 / Ferritin, Serum; and STFR / Soluble Transferrin Receptor (sTfR), Serum with this test.



Specimen Required


Patient Preparation:

1. Fasting (12 hours)

2. For 24 hours before collection, patient should not take iron-containing supplements.

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Draw blood before noon (preferred).

2. Within 2 hours of collection, serum gel tubes should be centrifuged.

3. Within 2 hours of collection, red-top tubes should be centrifuged, and the serum aliquoted into a plastic vial.


Secondary ID

621385

Useful For

Screening for chronic iron overload diseases, particularly hereditary hemochromatosis

 

Screening for iron deficiency as the cause of anemia

 

Monitoring treatment for iron deficiency anemia

 

This test should not be used as the primary test for iron deficiency.

Profile Information

Test ID Reporting Name Available Separately Always Performed
IRON Iron No Yes
TIBC Total Iron Binding Capacity No Yes
SAT Percent Saturation No Yes

Testing Algorithm

For more information see Hereditary Hemochromatosis Algorithm.

Method Name

IRON: Colorimetric Assay

TIBC: Turbidity/Calculation

SAT: Calculation

Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

Reference Values

IRON

Males: 50-150 mcg/dL

Females: 35-145 mcg/dL

 

TOTAL IRON-BINDING CAPACITY

250-400 mcg/dL

 

PERCENT SATURATION

14-50%

Interpretation

Serum iron concentration is elevated in iron overload conditions including hemochromatosis.(1)

 

Serum iron concentration is decreased in iron deficiency, iron deficiency anemia, and anemia of chronic disease.(1)

 

Total iron-binding capacity values are elevated in anemia of chronic disease and iron overload conditions.(1)

 

Total iron-binding capacity values are decreased in iron deficiency, iron deficiency anemia, and iron-refractory iron deficiency anemia.(1)

 

Percent saturation often exceeds 45% in hereditary hemochromatosis and 90% in advanced iron overload states.(2)

 

Percent saturation less than 16% is generally used to screen for iron deficiency, but a threshold of 20% is used in the presence of inflammation.(3)

 

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

Method Description

Iron:

Under acidic conditions, iron is liberated from transferrin. Lipemic samples are clarified by the detergent. Ascorbate reduces the released Fe(3+) ions to Fe(2+) ions which then react with FerroZine to form a colored complex. The color intensity is directly proportional to the iron concentration and can be measured photometrically.(Package insert: IRON2. Roche Diagnostics; V9, 09/2019)

 

Transferrin:

Human transferrin forms a precipitate with a specific antiserum, which is determined turbidimetrically.(Package insert:TRSF2 reagent. Roche Diagnostics; v10.0, 04/2022)

 

Calculations:

Total iron-binding capacity (TIBC) = Transferrin x 1.18

Percent saturation = (Iron/TIBC) x 100

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 to 2 days

Specimen Retention Time

7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

83540-Iron

83550-Iron-binding capacity

LOINC Code Information

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

 

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