Charles Patrick Davis, MD, PhD
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- What is hemoglobin?
- How is hemoglobin measured?
- What are normal hemoglobin values?
- What does a low hemoglobin level mean?
- What does a high hemoglobin level mean?
- What is sickle cell disease?
- What is thalassemia?
- What is the hemoglobin A1c test?
What does a high hemoglobin level mean?
Higher than normal hemoglobin levels can be seen in people living at high altitudes and in people who smoke. Dehydration produces a falsely high hemoglobin measurement which disappears when proper fluid balance is restored.
Some other infrequent causes are high hemoglobin levels are:
- Advanced lung disease (for example, emphysema)
- Certain tumors
- A disorder of the bone marrow known as polycythemia rubra vera, and
- Abuse of the drug erythropoietin (Epogen) by athletes for blood doping purposes (increasing the amount of oxygen available to the body by chemically raising the production of red blood cells).
What is sickle cell disease?
Sickle cell disease is a genetic condition in which the quality of hemoglobin is defective. This condition can cause abnormal hemoglobin which, in turn, can result in abnormally shaped (sickled) red blood cells (see illustration). These abnormal red blood cells cannot easily pass through small blood vessels and, therefore, could deprive the body organs of adequate oxygen. Occasionally, sickle cells may block a blood vessel resulting in significant oxygen deprivation to the area depending on the blood supply.
Sickle cells also have a shorter life span than normal red blood cells (10 to 20 days compared to 120 days). This rapid turnover may result in inadequate time to replace the red blood cells and may result in anemia.
In order for a person to have sickle cell anemia, one defective hemoglobin gene must be inherited from each parent. If only one gene is inherited from one parent, then the condition is much milder and it is referred to as sickle cell trait.
Symptoms of sickle cell anemia vary depending on its severity. Patients with sickle cell trait may experience mild, if any, symptoms at all. In sickle cell disease, symptoms are more significant, especially in episodes of acute crisis. These symptoms can include:
- generalized body aches and pain,
- chest pain,
- bone pain,
- shortness of breath,
- ulceration of skin,
- blindness, and
- delayed growth and puberty.
Next: What is thalassemia?
Viewers share their comments
Find out what women really need.