Hemoglobin is a metalloprotein in red blood cells. It contains iron and is responsible for carrying oxygen from the lungs to the rest of the body. Measuring hemoglobin levels enables healthcare professionals to monitor many other aspects of a person’s health, including finding otherwise hidden conditions.

Measuring Hemoglobin

Healthcare workers can use a few different methods to measure hemoglobin levels. The most common requires taking a blood sample and analyzing the hemoglobin concentration within it.

Recently, a non-invasive method called pulse CO-oximetry has been able to provide continuous hemoglobin counts with similar accuracy to the more invasive options. Hemoglobin tests can also provide an indirect measurement of red blood cell counts, due to hemoglobin being a component of red blood cells.


Reasons for Measuring Hemoglobin Levels

Hemoglobin tests are necessary for a range of reasons. To monitor general health, a healthcare worker may test hemoglobin levels as part of a complete blood count during a routine checkup. A doctor may also use hemoglobin levels to diagnose illness if the patient has other symptoms. Hemoglobin tests can also allow for ongoing monitoring of an existing medical condition.


Typical Hemoglobin Ranges

The World Health Organization identifies the typical hemoglobin ranges for each age group as follows:

  • Six months to four years: At or above 11g/dL
  • Five to 12 years: At or above 11.5g/dL
  • 12 to 15 years: At or above 12 g/dL
  • Adult males: 13.8 to 17.2 g/dL
  • Adult females: 12.1 to 15.1 g/dL
  • Older males: 12.4-14.9 g/dL
  • Older females: 11.7-13.8 g/dL
  • During pregnancy: At or above 11 g/dL

When determining if a patient has a typical hemoglobin level, experts also consider factors like altitude when testing their blood.

digital illustration of red blood cells in vessels


High Hemoglobin Levels

High hemoglobin levels are much rarer than low concentrations and are often asymptomatic. Usually, a doctor only detects high hemoglobin levels by chance or after symptoms of an underlying condition have emerged.

Most of the conditions that cause this symptom lower the level of oxygen in the blood, causing hypoxia. In response, the body produces more hemoglobin.

digital illustration of hemoglobin levels


Causes of High Hemoglobin

A high hemoglobin count may occur due to an underlying condition, a side effect of medicine, or certain lifestyle choices. Some medical conditions that could cause high hemoglobin levels are heart diseases, lung diseases like COPD, dehydration, and carbon monoxide exposure.

Smoking cigarettes or taking anabolic steroids may also drive up hemoglobin levels. People who live at higher altitudes tend to also have high hemoglobin counts.

man who is dehydrated with headache


Low Hemoglobin Levels

Atypically low hemoglobin levels generally indicate a condition called anemia. Generally, anemia means the body is unable to make enough healthy red blood cells or is severely lacking in hemoglobin, preventing the transportation of oxygen. Mild anemia is typical at certain stages of life and during events like pregnancy.

Pregnant Woman in Hospital Room


Low Hemoglobin and Anemia Symptoms

Unlike high hemoglobin levels, low concentrations are far more likely to be symptomatic. These symptoms also indicate the need for physician intervention, as anemia can be a sign of a serious illness.

Symptoms for anemia include weakness, fatigue, pale skin, feeling cold, difficulty breathing, dizziness, headache, and an irregular heartbeat.

elderly woman on park bench can't breathe


Causes of Low Hemoglobin Levels

A person may have a low hemoglobin count if a condition like cancer, cirrhosis, or rheumatoid arthritis prevents the body from producing as many red blood cells as it needs. In some cases, a disease may actively destroy red blood cells. Culprits of this are usually sickle cell anemia or an enlarged spleen.

Hemoglobin levels may also be low if there is notable blood loss, either through an open wound, internal bleeding, or frequent blood donation. In some cases, heavy menstrual bleeding may be responsible for anemia.

close up of person donating blood



To treat high hemoglobin levels, a physician will often prescribe medications. If necessary, they may prescribe phlebotomy, where a health professional regularly drains blood from the body in safe amounts until hemoglobin levels return to a healthy concentration. Treating low hemoglobin levels requires addressing the underlying issue. Some people require only iron supplements, while others need more intricate treatment.

nurse or doctor preparing patient for phlebotomy


Hemoglobin A1c

A physician may test for glycated hemoglobin, also known as hemoglobin A1c or HbA1c. This compound is made when red blood cells join with glucose in the blood. Examining hemoglobin A1c gives health experts a glimpse at their patients’ overall glucose levels over several weeks. High A1c levels can indicate a high risk of developing certain diabetes-related complications, so monitoring is integral to many people’s health.

gloved hand holding blood vial marked for hemoglobin A1C test


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