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Serum/plasma concentration of hemoglobin (hemoglobin level)

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

This test measures the amount of hemoglobin, the protein in red blood cells that carries oxygen throughout your body.

Quick summary

["Helps assess your blood’s ability to carry oxygen and detect anemia or other blood disorders."]

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

Key facts at a glance

LOINC
31768-5
Short code
C trach Ag Bld Ql
Synonyms
C trach Ag Bld Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Is Done

Doctors order hemoglobin tests to check for conditions like anemia (low red blood cells), polycythemia (too many red blood cells), or blood loss. It may also be used during pregnancy, before surgeries, or to monitor chronic illnesses like heart disease or kidney problems.

What to Expect Before the Test

You’ll typically have a small needle inserted into your arm or hand to draw blood. The process takes just a few minutes, and you may feel a slight pinch. No special preparation is needed unless your doctor instructs otherwise.

What the Results Mean

Hemoglobin levels help determine if your blood cells are functioning normally. Very low or very high levels can signal underlying health issues that need further evaluation.

Common Conditions Monitored

Hemoglobin tests are often used to monitor anemia, iron deficiency, blood disorders, or to check for signs of bleeding or blood loss. They may also be part of routine check-ups or pre-surgery evaluations.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Hemoglobin plays a critical role in transporting oxygen from your lungs to tissues across your body. Abnormal levels can indicate conditions affecting red blood cell production, destruction, or blood volume, such as kidney disease, certain cancers, or chronic illnesses like diabetes.

Short name

Hemoglobin (Serum/Plasma)

Frequently asked questions

What causes hemoglobin levels to be too low?
Low hemoglobin levels (anemia) can result from blood loss (e.g., heavy periods, injuries), poor nutrition (e.g., low iron, vitamin B12, or folate), chronic illnesses, or conditions that affect red blood cell production.
What causes hemoglobin levels to be too high?
High hemoglobin levels (polycythemia) may occur due to dehydration, living at high altitudes, certain lung diseases, or blood disorders like polycythemia vera. Rarely, it can be caused by overproduction of red blood cells by the bone marrow.
Can lifestyle changes affect hemoglobin levels?
Yes, diet (e.g., iron-rich foods), hydration, and avoiding smoking can influence hemoglobin levels. If you suspect lifestyle factors are affecting your results, discuss them with your doctor.
  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