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Serum/plasma concentration of iron (mass concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of iron present in your blood, typically drawn from a vein. Iron is essential for making hemoglobin, the protein in red blood cells that carries oxygen throughout your body.

Quick summary

["Iron levels help diagnose or monitor conditions affecting iron absorption, anemia, or storage disorders."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
21004-7
Short code
GTT SerPl-Imp
Synonyms
GTT SerPl-Imp
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like fatigue, weakness, pale skin, or shortness of breath, which could indicate low iron levels. They might also order it if you have conditions like anemia, gastrointestinal issues, or if you’re pregnant. Additionally, it could be part of routine check-ups for people at higher risk of iron-related disorders.

What to Expect Before the Test

You can eat and drink normally before the test, but avoid taking iron supplements or certain medications (like antacids) that might interfere with results for 24 hours before your appointment. Bring any medications you’re currently taking to discuss with your provider.

During the Test

A healthcare professional will insert a small needle into a vein in your arm to draw blood. The process usually takes a few minutes, and you may feel a brief pinch. The blood sample will be sent to a lab for analysis.

After the Test

You can return to your normal activities immediately. Apply gentle pressure to the insertion site to stop any bleeding, and check for signs of infection (like redness or swelling) over the next few days. If you experience excessive bruising or pain, contact your provider.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Iron Level

Frequently asked questions

How long will I need to wait for my results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing schedule. Your healthcare provider will discuss the findings with you during your follow-up visit.
What does it mean if my iron level is too low?
A low iron level suggests you may not be absorbing enough iron from your diet or have an increased need for iron (e.g., due to pregnancy, heavy menstrual bleeding, or chronic illness). Your provider may recommend dietary changes, supplements, or further testing to identify the cause.
Can I eat iron-rich foods before the test?
Yes, you can eat a normal meal before the test, but avoid iron supplements or foods high in iron (like red meat, spinach, or fortified cereals) for 24 hours before your appointment to get an accurate result. If you’re unsure, ask your provider for guidance.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy