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Transferrin Saturation (Calculated)

Test ID: A886

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Transferrin is the main protein that binds to and transports iron around the body. Transferrin saturation is an estimate of how many of the transferrin iron-binding sites are occupied by iron. Average transferrin saturation is 25%. Below 10% indicates iron deficiency, and above 50% indicates iron overload, which can result in organ damage due to toxic non-transferrin bound iron.



How to order a test


  • Transferrin Saturation Index (TSI)
  • Transferrin Saturation Percentage (TS%)

What is Included?

Calculation of transferrin saturation, using measured values for serum iron and serum transferrin. Iron levels are measured by colorimetric (ferene) methodology, and transferrin levels are measured by immunoturbidimetric methodology.

Turnaround Time

1 – 3 business days
The turnaround time is not guaranteed. The average turnaround time is 1 – 3 business days from the date that the sample arrives at the laboratory. Shipping time for the sample is not included. Additional time is required if the case requires confirmatory or reflex testing, or if the sample is insufficient, or if a recollection is required.

Related Documents

Additional Information and Resources


Preparation Before Specimen Collection

Collect blood sample for this test after fasting overnight (for 8–12 hours). Fasting means that no food or drink (aside from water) is to be consumed.

Avoid the consumption of any iron-containing supplements for 24 hours prior to collecting blood sample.

Specimen Type



50 μL in a microtainer


Microtainer (regular blood tube)

Collection Method

This test requires a blood sample from a finger prick. All supplies for sample collection are provided in the kit.

  1. First wash and dry hands. Warm hands aid in blood collection.
  2. Clean the finger prick site with the alcohol swab and allow to air dry.
  3. Use the provided lancet to puncture the skin in one quick, continuous and deliberate stroke.
  4. Wipe away the first drop of blood.
  5. Massage hand and finger to increase blood flow to the puncture site. Angle arm and hand downwards to facilitate blood collection on the fingertip.
  6. Drip blood into the microtainer tube.
  7. Dispose of all sharps safely and return sample to the laboratory in the provided prepaid return shipping envelope.

NOTES: Avoid squeezing or ‘milking’ the finger excessively. If more blood is required and blood flow stops, perform a second skin puncture on another finger. Do not touch the fingertip.

Specimen Storage

Maintain specimen at temperatures between 2°C and 30°C during storage and transport.

Specimen Stability

Blood samples can be refrigerated or kept at room temperature for up to 7 days.

Causes for Rejection

  • Incorrect or incomplete patient identification
  • Incorrect specimen collection
  • Inappropriate storage and transport conditions
  • Incorrect specimen volume
  • Severe hemolysis



To determine transferrin saturation for the evaluation of iron status.

Low transferrin saturation occurs in iron deficiency anemia, while high transferrin saturation is indicative of iron overload or hemochromatosis.


  • This report is not intended for use in medico-legal applications. 
  • These results should be interpreted in conjunction with other laboratory and clinical information.
  • Correct specimen collection and handling is required for optimal assay performance. 
  • Interferences from medication or endogenous substances may affect results.


  • Colorimetric (ferene) (Alinity c Iron assay)
  • Immunoturbidimetric (Alinity c Transferrin assay)

Reference Intervals

Average transferrin saturation is 25%, with a normal range of 14 – 50%.

This reference range was obtained from “Laboratory Reference Ranges” from the Endocrine Society.