Hemoglobin: Key Functions, Levels, and Health Impact

Jun 18, 2024 | 4 min read

Question on this topic? Get an instant answer from AI Doctor.Instant answer from AI Doctor.

Hemoglobin, a vital protein in red blood cells, carries oxygen from the lungs to the body and returns carbon dioxide to the lungs. Monitoring hemoglobin levels is crucial for health, as abnormal levels can signal various health problems.

What is Hemoglobin?

Hemoglobin is a complex protein found in red blood cells that plays a crucial role in transporting oxygen throughout your body

Each hemoglobin molecule has four protein parts, each containing an iron atom, which helps it bind to oxygen in your lungs and release it in your tissues, allowing your cells to function properly.

The main functions of hemoglobin are:

  • Oxygen Transport: Hemoglobin grabs oxygen in the lungs and carries it to tissues and organs throughout your body.
  • Carbon Dioxide Removal: It also picks up carbon dioxide, a waste product from your cells, and brings it back to the lungs to be exhaled.
  • Acid-Base Balance: Hemoglobin helps maintain the right balance of acids and bases in your blood, which is crucial for your body's metabolism.

These roles of hemoglobin in delivering oxygen and removing carbon dioxide are essential for keeping your body healthy and functioning properly.

Hemoglobin Test

What is a Hemoglobin Test?

The hemoglobin test is often part of a Complete Blood Count (CBC) test, which is a comprehensive assessment of various components of the blood. 

A hemoglobin test measures the amount of hemoglobin in the blood. This test determines if there are the right number of red blood cells and if the body is getting enough oxygen. 

During the test, a small sample of blood is drawn from a vein, usually in the arm, and analyzed in a laboratory to measure hemoglobin levels. The procedure is quick, minimally invasive, and provides essential information about overall health.

When is it Necessary?

A hemoglobin test is necessary in several scenarios:

  • Routine Health Check-Ups: To screen for conditions such as anemia or polycythemia.
  • Symptoms: Fatigue, weakness, shortness of breath, dizziness, or pale skin, which may indicate abnormal hemoglobin levels.
  • Chronic Conditions: Regular monitoring for individuals with conditions like diabetes or kidney disease to adjust treatment plans accordingly.

Types of Tests

There are two types of hemoglobin tests used to measure various aspects of hemoglobin in the blood:

  • Complete Blood Count (CBC): This common test measures the overall number of red blood cells and hemoglobin concentration in the blood. It provides a comprehensive overview of blood health.
  • Hemoglobin A1c: This test measures the average blood sugar levels over the past three months by evaluating the amount of glucose attached to hemoglobin. It is particularly important for managing diabetes and assessing long-term glucose control.

How to Understand Test Results

You can seek guidance from a healthcare provider to gain a thorough understanding of your hemoglobin levels, including what they indicate about your overall health and any necessary steps to manage your condition.

Also, for a detailed explanation of your hemoglobin levels and personalized health insights, you can upload your test results to our Lab Test Interpretation tool, which provides a quick analysis to help you understand your health condition better, but always consult a professional before taking any action.

Lab Test Interpretation

Lab Test Interpretation

Upload your lab tests, receive detailed interpretations, personalized insights and recommendations.

Hemoglobin Levels

Normal Hemoglobin

Normal hemoglobin levels vary depending on age, gender, and overall health. According to the NCBI publication, normal levels are:

  • Men: 13.5 to 18.0 grams per deciliter (g/dL)
  • Women: 12.0 to 15.0 grams per deciliter (g/dL)
  • Children: 11.0 to 16.0 grams per deciliter (g/dL)

Different labs have slightly different guidelines, so it’s important to refer to the specific reference range provided by the lab conducting the test. 

Low Hemoglobin

Low hemoglobin, also known as anemia, occurs when the hemoglobin level falls below the normal range.


  • Nutritional Deficiencies: Inadequate intake of iron, vitamin B12, or folate can lead to low hemoglobin. Iron deficiency anemia is the most common type, often resulting from poor diet or malabsorption issues.
  • Chronic Diseases: Conditions such as chronic kidney disease, cancer, and inflammatory diseases can reduce hemoglobin production. Kidney disease affects erythropoietin production, a hormone crucial for red blood cell production.
  • Blood Loss: Significant blood loss from surgery, injury, or conditions like peptic ulcers and gastrointestinal bleeding can cause anemia. Heavy menstrual bleeding in women is another common cause.
  • Bone Marrow Disorders: Diseases affecting bone marrow, such as leukemia or aplastic anemia, impair the production of red blood cells.
  • Genetic Conditions: Disorders like sickle cell anemia and thalassemia affect the structure and production of hemoglobin, leading to chronic anemia.


Symptoms of low hemoglobin can include:

  • Fatigue and weakness
  • Shortness of breath
  • Dizziness or lightheadedness
  • Pale or yellowish skin
  • Cold hands and feet
  • Rapid or irregular heartbeat

How to Increase:

Boosting hemoglobin levels involves several strategies:

  • Diet: Consume iron-rich foods like lean meats, beans, lentils, and green leafy vegetables.
  • Vitamin C: Enhance iron absorption by including vitamin C-rich foods such as oranges, strawberries, and bell peppers.
  • Supplements: Consider iron supplements if dietary intake is insufficient. However, according to the American Society of Hematology, it is not recommended to take iron supplements for iron deficiency anemia unless instructed by their physicians.
  • Lifestyle Changes: Stay hydrated, avoid excessive alcohol, and engage in regular exercise.

High Hemoglobin

High hemoglobin, or polycythemia, occurs when the hemoglobin level is above the normal range, leading to an increased number of red blood cells.


  • Chronic Lung Disease: Conditions like chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis reduce oxygen levels, prompting the body to produce more red blood cells.
  • Living at High Altitudes: Lower oxygen levels at high altitudes stimulate the production of more red blood cells to compensate for reduced oxygen availability.
  • Smoking: Smoking reduces oxygen supply, leading to increased red blood cell production to carry more oxygen, as mentioned in JAHA.
  • Dehydration: Reduced plasma volume due to dehydration can concentrate red blood cells, increasing hemoglobin levels.
  • Certain Tumors: Some tumors, particularly those affecting the kidneys, can produce excess erythropoietin, leading to increased red blood cell production.
  • Use of Performance-Enhancing Drugs: Athletes sometimes use drugs to boost red blood cell production for better oxygen delivery and performance.


  • Headaches
  • Dizziness
  • Fatigue
  • Blurred vision
  • Itching, especially after a shower or bath
  • Reddened skin, particularly on the face

How to Manage:

  • Hydration: Drink plenty of fluids to maintain blood volume and reduce blood viscosity.
  • Avoid Smoking: Quit smoking to improve lung function and reduce hemoglobin levels.
  • Treat Underlying Conditions: Manage any chronic conditions that may contribute to high hemoglobin levels.
  • Therapeutic Phlebotomy: In some cases, a healthcare provider may recommend removing blood to reduce red blood cell count.
  • Medications: Follow prescribed treatments to manage the underlying causes of high hemoglobin.

Maintaining balanced hemoglobin levels through regular monitoring, a healthy diet, and appropriate medical care is crucial for overall health and well-being.

Frequently Asked Questions

Have more questions?Ask AI Doctor
AI Assistant

Have Questions?

Have a question on this topic? Submit it here and get an instant answer from our AI Doctor.

Please Note!This tool is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always consult a professional before taking any actions.

Make Informed Health Decisions

Talk to Docus AI Doctor, generate health reports, get them validated by Top Doctors from the US and Europe.

Make Informed Health Decisions

You’re only one click away from a life-changing journey

Virtual health assistant powered by AI
350+ world-renowned Doctors