What Hemoglobin Level Requires A Transfusion

The American Society of Anesthesiologists uses hemoglobin levels of 6 g/dL as the trigger for required transfusion, although more recent data suggest decreased mortality with preanesthetic hemoglobin concentrations of greater than 8 g/dL, particularly in renal transplant patients.

Blood is a living tissue that requires oxygen to live and function properly. The body needs oxygen not only to breathe but also to produce energy through oxidation-reduction reactions that take place within red blood cells (RBCs). Oxygen binds tightly to hemoglobin molecules inside RBCs, which then carry it from our lungs and other tissues back to our hearts. Hemoglobin is an iron-containing protein molecule that has two heme groups at its center. These groups allow hemoglobin to bind with oxygen so that the oxygen can be carried throughout the body by RBCs.
As we age or suffer chronic illnesses like diabetes, heart disease and kidney failure, our bodies become less efficient at producing new healthy erythrocytes. Production rates fall off sharply, causing a condition called anemia. This results in insufficient numbers of RBCs carrying sufficient amounts of hemoglobin and is characterized by weakness, fatigue, shortness of breath on exertion, dizziness, headache, paleness, tingling sensations, irritability, cold hands and feet, feeling sleepy all day, difficulty concentrating, depression, memory problems, frequent infections and rapid heartbeat.
Anemia may result from either increased destruction of RBCs or reduced production of them. One type of anemia known as a pernicious anemia occurs when a person’s immune system attacks their own bone marrow because they have developed a form of autoimmune disorder. Another variety known as megaloblastic anemia is caused by vitamin B12 deficiency. In this case, people are unable to make enough healthy RBCs to meet their daily requirements. Some types of anemia are inherited disorders. Still others occur due to nutritional deficiencies such as low intake of folic acid and iron. Finally, some forms of anemia arise from certain medications used to treat medical conditions like cancer or AIDS.
Hemoglobin is essential for life; however, too much of it can cause health risks. For example, excess amounts of hemoglobin circulating in the bloodstream can damage endothelial lining cell walls found in blood vessels, leading to atherosclerosis and clot formation. Excess hemoglobin can also lead to sickle cell disease, a serious hereditary illness. Sickles are shaped like crescent moons and are formed when the proteins in hemoglobin polymerize into twisted fibers. When sickled RBCs enter small blood vessels, they obstruct the flow of blood and prevent oxygen from getting to nearby tissues. As a result, these areas receive inadequate amounts of oxygen and eventually die. Patients suffering from sickle cell disease require regular blood transfusions to keep their hemoglobin count above 10 g/dL.
In addition to being important for transporting oxygen throughout the body, hemoglobin plays an integral part in protecting us against infection. Our innate immune systems depend upon hemoglobin to fight bacteria and viruses. It does so by releasing free radicals that destroy pathogens. Conversely, if there is too little hemoglobin available, then our immune systems cannot effectively kill invading microorganisms. We often experience this phenomenon during severe anemia episodes. Patients who undergo surgery involving anesthesia or those who are undergoing chemotherapy treatment for cancer are susceptible to bacterial sepsis, a potentially fatal complication. Sepsis is typically caused by bacteria entering the bloodstream and spreading throughout the body. If left unchecked, septic shock develops as a result.
Severe cases of septic shock require immediate treatment with intravenous fluids. To supplement what their bodies don’t get naturally, doctors give patients large doses of antibiotics to control the spread of bacteria. They also administer massive quantities of intravenous fluid containing albumin or plasma — globulins derived from donated human blood — to help maintain normal blood volume and circulation. Albumin is manufactured from pooled donor blood donations. Plasma contains factors needed by the body to regulate coagulation. Both albumin and plasma are routinely given to critically ill patients to restore lost nutrients and combat infectious complications.
Transfusing blood products is another common way to manage severe anemia. Blood transfusions involve replacing deficient amounts of specific blood components with fresh supplies. During the procedure, your doctor will remove some of your blood in the form of a blood donation and replace it with a saline solution. Then she’ll add in additional components including concentrated red blood cells, white blood cells and platelets. Afterward, the blood product will be returned to you via an IV line inserted directly into one of your veins.
Some experts believe that the best way to determine whether to order a blood transfusion is based on a patient’s hemoglobin level. Others disagree. What determines the need for transfusion? Read on to find out.
What Hemoglobin Level Requires A Transfusion
If you’ve ever been diagnosed with anemia, you know how difficult it is to pinpoint exactly why you’re experiencing symptoms such as weakness, tiredness and poor concentration. Even though anemia is a complex disorder, there are some simple ways to check yourself for anemia. Your physician will perform a complete blood count (CBC) test to measure your hemoglobin content.
A CBC involves drawing a sample of your blood using a needle attached to a long tube. Next, a technician performs a series of tests on your blood, looking for different parameters. She checks your hemoglobin content, white cell counts, platelet counts, reticulocyte percentages, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and red blood cell distribution width (RDW). Based on her findings, she might recommend further testing to determine any underlying causes.
The average adult male produces about 12 ounces (340 grams) of blood every 24 hours. Women produce slightly less blood. Each unit is composed of approximately 4 million RBCs, 2 million platelets, 100,000 white blood cells and 50,000 smaller fragments called microparticles. Donors must go through extensive screenings before donating their blood. Donor eligibility depends on many factors such as height, weight, allergies, previous surgeries, diseases, etc. Screenings include taking a detailed questionnaire, checking vital signs, performing routine lab work and having a physical examination.
Donated blood is tested extensively before transfusion. Each component of a donated unit is individually inspected for the presence of bacteria, viruses, parasites and prions. Before any individual receives a blood transfusion, his or her blood is screened for hepatitis C, hepatitis B, HIV, HTLV I & II, syphilis, West Nile virus and Chlamydia trachomatis. All donors are asked to wait 48 hours after giving birth before donating again. You should never donate unless you feel up to it, even if you’ve just had a stressful event. Also, avoid consuming alcohol, smoking cigarettes or doing drugs.
Many hospitals use a standard transfusion trigger based on hemoglobin levels. But what is considered “normal” varies among individuals. According to the American Society of Anesthesiology (ASA), a safe hemoglobin range for most adults is between 7.0 to 9.5 g/dL. However, recent studies show that lower hemoglobin thresholds may actually improve outcomes. In fact, the ASA recommends maintaining hemoglobin levels over 8.0 g/dL in patients scheduled for major surgical procedures involving general anesthesia. Here’s what an ASA study showed :
In 2001, researchers studied nearly 1,500 patients undergoing coronary bypass grafting under general anesthesia. At various stages, half of the patients were randomly assigned to receive an infusion of packed red blood cells (PRBCs) beginning at hemoglobin levels of 7 g/dL. The rest received no transfusion until their postoperative recovery room course began. Study results indicated that PRBC recipients experienced significantly fewer complications than did nonrecipients. Specifically, patients receiving transfusions early had higher incidences of organ dysfunction, deep vein thrombosis (DVT) and pulmonary embolism (PE). Additionally, death occurred earlier in the group receiving transfusions later.
Researchers followed up on this study five years later. Results revealed that early transfusion was associated with improved survival in both men and women. In the original trial, the mortality rate was 23 percent among patients receiving transfusions soon after surgery but dropped to 16 percent in the followup study. This suggests that early transfusion reduces hospital stays and lowers overall costs.
Although the evidence seems conclusive, the exact hemoglobin threshold still remains controversial. Many physicians argue that lowering the transfusion trigger would increase costs without improving clinical outcomes. Other specialists claim that the benefits outweigh potential risks. Ultimately, each patient’s personal situation must weigh heavily in the decision-making process.
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For decades, the transfusion medicine community has relied upon outdated methods to calculate transfusion triggers. Most centers rely solely upon the amount of hemoglobin present in the blood recipient. But according to the International Committee of Medical Journal Editors, recent research indicates that this method is unreliable. For instance, hemoglobin values vary widely from patient to patient. Moreover, laboratory accuracy can differ greatly depending on the operator. So, some experts propose basing decisions on physiologic variables rather than fixed hemoglobin levels. Such measurements include pulse oximetry and central venous pressure.

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