Hemoglobin Test
Also known as: Hgb, Hb
What is Hemoglobin?
Hemoglobin is a protein in red blood cells that carries oxygen from your lungs to the rest of your body and returns carbon dioxide from the body to the lungs.[MedlinePlus (NIH)]
What This Test Measures
This test measures the amount of hemoglobin in your blood, typically as part of a complete blood count (CBC). It indicates how well your blood can carry oxygen.[Mayo Clinic]
Why It's Important
Hemoglobin levels help diagnose and monitor anemia, polycythemia, and other conditions that affect red blood cells.[MedlinePlus (NIH)]
Low hemoglobin means your tissues may not get enough oxygen, causing fatigue and weakness. High hemoglobin may indicate dehydration or other conditions.[Cleveland Clinic]
Who Should Get This Test?
Hemoglobin is measured as part of a CBC. Testing is recommended for:
Risk Factors
- People with symptoms of anemia (fatigue, weakness, pale skin)
- Women with heavy menstrual periods
- Pregnant women (routine screening)
- People with chronic diseases (kidney disease, cancer, rheumatoid arthritis)
- Those with a family history of anemia or blood disorders
- Vegetarians and vegans (at risk for B12/iron deficiency)
- People who have had surgery or significant blood loss
- Those taking medications that can affect blood cells
- Endurance athletes
- People with gastrointestinal conditions affecting absorption
- Elderly adults (higher risk of anemia)
Screening Schedule
As part of routine physical exams; more frequent monitoring if anemia is present or at risk
What Happens During the Test
A healthcare provider draws blood from a vein in your arm. Hemoglobin is measured as part of a complete blood count (CBC), one of the most common blood tests.
Duration
5 minutes or less
Discomfort Level
Minimal - brief pinch when needle is inserted
Risks & Side Effects
This is a routine blood test with very low risks.
- •Slight pain or bruising at needle site
- •Brief lightheadedness (rare)
- •Small risk of infection (very rare)
Normal Range
For men: 13.5 to 17.5 g/dL. For women: 12.0 to 15.5 g/dL.
Note: Normal ranges may vary slightly between laboratories and differ for children and pregnant women.
Source: MedlinePlus (NIH)Unit Conversion
Convert between g/dL and g/L
| g/dL | g/L |
|---|---|
| 10 | 100 |
| 12 | 120 |
| 14 | 140 |
| 16 | 160 |
| 18 | 180 |
High Values
High hemoglobin may be caused by dehydration, smoking, living at high altitude, lung disease, or polycythemia vera (a blood cancer). It can increase the risk of blood clots.[Mayo Clinic]
Low Values
Low hemoglobin (anemia) can cause fatigue, weakness, shortness of breath, and pale skin. Causes include iron deficiency, vitamin deficiencies, chronic diseases, and blood loss.[Mayo Clinic]
Test Limitations & Accuracy
Several factors can affect hemoglobin test results:
- ⚠Dehydration can falsely elevate hemoglobin
- ⚠Overhydration can falsely lower hemoglobin
- ⚠Living at high altitude naturally increases hemoglobin
- ⚠Recent blood transfusion affects results
- ⚠Pregnancy normally lowers hemoglobin due to increased blood volume
- ⚠Time of day may cause slight variations
- ⚠Smoking increases hemoglobin levels
- ⚠Certain medications affect hemoglobin production
Alternative & Complementary Tests
Related tests to evaluate hemoglobin and anemia:
Measures percentage of blood that is red blood cells
Evaluates iron stores; helps identify iron deficiency
Complete iron panel for anemia workup
To check for B12 deficiency anemia
To check for folate deficiency anemia
Measures new red blood cell production
Frequently Asked Questions
How can I increase my hemoglobin levels?
You can increase hemoglobin by eating iron-rich foods (red meat, beans, spinach), vitamin C to improve iron absorption, foods with B12 and folate, and avoiding iron blockers like coffee and tea with meals. Supplements may be needed for deficiencies.
Source: Cleveland ClinicWhat causes low hemoglobin?
Common causes include iron deficiency (most common), vitamin B12 or folate deficiency, chronic diseases, blood loss (including heavy menstruation), bone marrow problems, and certain genetic conditions like sickle cell disease.
Source: Mayo ClinicWhat are the symptoms of low hemoglobin?
Symptoms include fatigue, weakness, pale skin, shortness of breath, dizziness, cold hands and feet, brittle nails, and headaches. Severe anemia can cause chest pain and irregular heartbeat.
Source: MedlinePlus (NIH)Is low hemoglobin serious?
Mild anemia may cause few symptoms, but severe anemia can strain the heart and other organs. Left untreated, it can lead to serious complications. The underlying cause should always be identified and treated.
Source: Mayo ClinicReferences
Related Condition Guides
Medical Disclaimer
This information is for educational purposes only and is not intended as medical advice. Always consult with a qualified healthcare provider for interpretation of test results and medical decisions.
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