Alterations Of Hematological Function Flashcards
Clinically, a diagnosis of anemia is now usually made based on the patient’s:
hemoglobin (Hgb) levels.
The clinical diagnosis of anemia is made based on the hemoglobin level only. This lab is a measure of the average amount of hemoglobin in a given volume of blood, therefore is the best measure of the blood’s capacity to transport oxygen to the tissues.
An iron deficiency results in erythrocytes (red blood cells) that are:
microcytic and hypochromic.
Iron is used to make hemoglobin in red blood cells. Therefore, an iron deficiency results in a decrease in hemoglobin formation in the developing red blood cells. Since the hemoglobin takes up approximately 1/3 of the volume of the cytoplasm, a decrease in hemoglobin formations results in smaller (i.e., microcytic) red blood cells. The decrease in hemoglobin results in a decrease in the color or ‘chromicity’ of the red blood cells.
Iron deficiency anemia among adult populations in the United States is most commonly caused by:
chronic gastrointestinal bleeding.
The majority of cases of iron deficiency in adult populations in developed countries is gastrointestinal bleeding. Loss of blood generally means a loss of iron since 65% of the body’s iron is contained in the hemoglobin of RBCs. Common sources include ulcers, inflammatory bowel diseases and cancer of the GI tract. Dietary iron deficiencies are rare in the majority of adults.
Why are young children at risk for iron deficiency anemia?
Growth spurts and possibly a limited diet
Growth spurts cause an increased demand on the bone marrow for iron since body growth involves the production of more red blood cells. If a child is not taking in adequate amounts of iron rich foods or is not taking a multivitamin with iron, then the risk of iron deficiency is high. Approximately 3-5% of young children have an iron deficiency anemia.
Which blood tests is a good measure of iron stores in the body?
Ferritin
Ferritin is the storage form for iron in liver tissues, and when ferritin is formed, a small amount leaks back into the plasma. Plasma levels of ferritin reflect the amount of ferritin stored in the tissues.
Stomach reduction surgery (gastrectomy) commonly leads to vitamin B12 deficiency because:
decreased intrinsic factor production results in decreased vitamin B12 absorption.
Vitamin B12 absorption requires the presence of intrinsic factor secreted by the stomach. Vitamin binds to B12 and the complex is absorbed in the distal ileum (small intestine). A gastrectomy significantly reduces the surface area on the inside of the stomach and therefore the number of cells producing intrinsic factor. Without intrinsic factor there is no B12 absorption.
Which of the group of people are most at risk for developing a B12 deficiency?
Strict vegans
Vitamin B12 is only found in meat, eggs and dairy products, therefore strict vegans (who do not eat any animal products) cannot get B12 from their diet and must take a vitamin B12 supplement.
Which group of people are at highest risk for developing a folate deficiency?
Alcoholics
Alcoholics are at high risk for a folate deficiency because their diets are often limited, however alcohol also interferes with folate storage and metabolism.
Why does a B12 or folate deficiency causes anemia?
Fewer RBCs are produced by the bone marrow.
Production of unusually large stem cells that mature into unusually large erythrocytes.
A vitamin B12 deficiency results in a decrease in DNA synthesis in the RBCs developing in the bone marrow. This results in a decrease in the rate of cell division for these stem cells, which in turn results in fewer RBCs being released from the bone marrow.
Slow development = fewer RBCs formed
Larger RBC lyse more easily in circulation
End result is anemia
A 44-year-old Caucasian woman is seen in the emergency room with sudden onset shortness of breath and extreme fatigue. Her skin, sclera and mucous membranes appear to have a yellowish discoloration. These findings are consistent with which type of anemia?
Autoimmune hemolytic anemia
The sudden onset of shortness of breath and fatigue suggests a rapid onset anemia. Her jaundice suggests hemolysis.
The presence of hemoglobin S in people with sickle cell disease is which type of anemia?
A hemolytic anemia
HgbS reacts to hypoxemia and dehydration, which causes the hemoglobin to take an elongated, rigid shape. This causes a sickling of the RBCs. The rigid, sickled-shaped RBCs get lysed as they pass through narrow capillaries, relating in a hemolytic anemia.
A 25 year old female has a diagnosis of sickle cell disease. Which event will likely stimulate a sickle cell crisis and should absolutely be avoided?
Taking a backpacking trip to Lake Titicaca in Peru which is at 12,507 ft elevation
A primary trigger for sickle cell crisis is hypoxemia, which would result from going to high altitudes.
Aplastic anemia is caused by:
bone marrow failure.
By definition, aplastic anemia is a disorder caused by bone marrow failure and results in the decreased production of RBCs (anemia), WBCs (leukopenia) and platelets (thrombocytopenia).
The term ‘pernicious anemia’ is used as a synonym for which anemia?
Vitamin B12 deficiency anemia
By definition, pernicious anemia is a vitamin B12 deficiency anemia.
Which person are at highest risk for the rapid development of an iron deficiency anemia, a vitamin B12 deficiency anemia, AND a folate deficiency anemia?
A 24 year old pregnant woman in who is not taking pre-natal vitamins
Pregnancy is associated with the three nutrient-deficiency anemia because women will expand their blood volume by 30-40% to support the developing placenta and fetus. It is the only case of a B12 deficiency anemia that can develop within months instead of years.
