Hemoglobin is a protein rich in iron, located within your red blood cells. Its primary role is to transport oxygen from the lungs to all the tissues and muscles throughout the body. In addition to delivering oxygen, hemoglobin also picks up carbon dioxide from the tissues and carries it back to the lungs to be exhaled. The iron component within hemoglobin is what binds to oxygen and gives blood its characteristic red color.
Defining High Hemoglobin Levels
Healthcare providers measure hemoglobin in grams per deciliter (g/dL) of blood. There are accepted values for what constitutes a normal level. For adult males, the range is between 13.5 and 18.0 g/dL. For adult females who are not pregnant, the normal range is 12.0 to 15.0 g/dL.
A hemoglobin level above 18.0 g/dL in men and 15.0 g/dL in women is considered high. These thresholds are important markers that may prompt a healthcare provider to investigate the underlying reason for the increase. Children have different ranges that change with age, and levels also vary during pregnancy.
Potential Causes of Elevated Hemoglobin
The reasons for elevated hemoglobin can be separated into two main categories: factors related to your environment and lifestyle, and underlying medical conditions. Dehydration is a common cause, as insufficient fluid decreases blood plasma volume, making hemoglobin more concentrated and leading to a temporarily high reading. Living at high altitudes where oxygen levels are lower can also cause hemoglobin to rise, as the body compensates by producing more red blood cells to maximize oxygen capture. Smoking is another factor, as the carbon monoxide from smoke reduces the oxygen-carrying capacity of blood, signaling the body to produce more hemoglobin.
Certain medical conditions can lead to a sustained increase in hemoglobin production, often as a response to chronic low oxygen levels in the body, a state known as tissue hypoxia. For example, chronic obstructive pulmonary disease (COPD) and other lung diseases impair the body’s ability to take in oxygen, prompting the bone marrow to produce more red blood cells to compensate. Similarly, some congenital heart conditions can result in a higher red blood cell count. In rarer cases, tumors, particularly those on the kidneys, can release hormones that stimulate red blood cell production.
A specific bone marrow disorder called polycythemia vera directly causes the overproduction of red blood cells. In this condition, the bone marrow produces too many red blood cells independent of the body’s actual oxygen needs. This results in an absolute increase in red cell mass and is a primary, rather than a secondary, cause of elevated hemoglobin.
Associated Symptoms and Health Implications
Individuals with high hemoglobin may experience frequent headaches, dizziness, or a general sense of fatigue. Some people report blurred or double vision and may notice a ruddy, reddish complexion, particularly on the face, hands, and feet. This flushed appearance is due to the increased volume of red blood cells visible through the skin.
The primary health concern associated with persistently high hemoglobin is increased blood viscosity. This thickness can impede blood flow through smaller vessels and increases the risk of developing blood clots. These clots can travel to the brain, heart, or lungs, leading to serious events such as a stroke or heart attack.
This change in blood consistency forces the cardiovascular system to work harder to circulate blood throughout the body. Over time, this can put a strain on the heart and blood vessels. Managing high hemoglobin is therefore focused on addressing the underlying cause to reduce blood viscosity and mitigate these associated risks.
When to Consult a Healthcare Provider
Discovering you have a high hemoglobin level from a blood test is a finding that requires professional medical interpretation. It is not something that should be self-diagnosed, as the range of potential causes is broad, spanning from simple dehydration to more complex medical conditions.
During a consultation, a doctor will likely conduct a thorough review of your medical history, including any existing conditions, medications, and lifestyle factors like smoking or living at a high altitude. A physical examination may also be performed to check for signs related to the potential causes. Depending on these initial findings, further diagnostic tests may be ordered to identify the specific reason for the high hemoglobin.
These follow-up tests can help differentiate between a relative increase due to factors like dehydration and a true increase in red blood cell mass. The goal is to accurately diagnose the underlying issue so that an appropriate management plan can be developed.