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Hemoglobin concentration (whole blood)

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

This test measures the amount of hemoglobin in your red blood cells, which carries oxygen throughout your body. Hemoglobin levels help assess your blood’s ability to transport oxygen effectively.

Quick summary

["Hemoglobin levels indicate your body’s oxygen-carrying capacity and can signal potential blood disorders."]

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

Key facts at a glance

LOINC
4600-3
Short code
Hgb Kansas Bld Ql
Synonyms
Hgb Kansas Bld Ql
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
12
Ref high
17.5
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85018
SNOMED
900000000000003004
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 Is This Test Done?

Doctors may order this test to check for anemia (low hemoglobin), polycythemia (high hemoglobin), or other blood-related conditions. It’s also used during pregnancy, before surgeries, or if you have symptoms like fatigue, pale skin, or shortness of breath.

What to Expect Before the Test

You’ll typically have a small needle inserted into your arm or hand to draw a blood sample. The process takes 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 results help determine whether your blood is carrying enough oxygen. Abnormally low or high levels may require further evaluation by your healthcare provider.

Common Conditions Linked to Hemoglobin Levels

Low hemoglobin (anemia) can cause fatigue, weakness, or dizziness. High hemoglobin (polycythemia) may lead to increased blood viscosity, which can strain your heart or blood vessels. Your doctor will discuss findings with you.

Reference range

Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A

Specimen: whole-blood

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Hemoglobin (Hgb) Blood Test

Frequently asked questions

What causes hemoglobin levels to be too low?
Hemoglobin levels can drop due to blood loss (e.g., from injuries or heavy periods), poor nutrition (e.g., low iron or vitamin B12), chronic illnesses (e.g., kidney disease), or certain medications. Lifestyle factors like excessive alcohol use or smoking may also contribute.
What causes hemoglobin levels to be too high?
High hemoglobin can result from conditions like polycythemia vera (a blood disorder), dehydration, living at high altitudes, or certain lung diseases. Rarely, it may be linked to genetic factors or overproduction of red blood cells by the bone marrow.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status, symptoms, or medical history. Regular checks may be recommended if you have a chronic condition, are pregnant, or take medications that affect blood production.
  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