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Red Blood Cell (RBC) Hemoglobin Concentration (Serum/Plasma)

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, using a sample of your blood drawn from a vein.

Quick summary

["Hemoglobin levels help assess your body’s ability to deliver oxygen efficiently and identify potential blood disorders."]

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

Key facts at a glance

LOINC
43547-9
Short code
Deprecated Finger.3rd-R XR GE 3V
Synonyms
Deprecated Finger.3rd-R XR GE 3V
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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 Is Done

Your healthcare provider may order this test to check for anemia (low hemoglobin), polycythemia (high hemoglobin), or other blood-related conditions. It’s also used to monitor chronic diseases like heart failure or kidney disease that can affect hemoglobin levels.

What to Expect Before the Test

No special preparation is needed, but avoid vigorous exercise or eating a heavy meal 2 hours before your blood draw. Wear a loose shirt for easy access.

During the Test

A healthcare professional will insert a small needle into your arm to draw blood. You may feel a brief pinch, but it’s usually over quickly. The blood sample is then sent to a lab for analysis.

After the Test

You can resume normal activities immediately. Apply gentle pressure to the site to stop any bleeding, and check for signs of infection (redness, swelling, or fever) in the next few days.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Hemoglobin (Hb) in Serum/Plasma

Frequently asked questions

What causes abnormal hemoglobin levels?
Common causes of low hemoglobin include iron deficiency, vitamin B12 or folate deficiencies, chronic diseases (e.g., kidney disease), or blood loss from injuries or heavy periods. High hemoglobin levels may result from dehydration, lung disease, or overproduction of red blood cells (e.g., polycythemia vera).
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the results with you during your follow-up visit.
Can lifestyle changes affect hemoglobin levels?
Yes! Eating iron-rich foods (like lean meats, spinach, or lentils), staying hydrated, and avoiding excessive alcohol can help maintain stable hemoglobin levels. If you suspect a deficiency, talk to your provider about supplements or dietary adjustments.
  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