Chapter 23 Disorders of Red Blood Cells Flashcards
What are the three causes of iron deficiency anemia?
- Insufficient dietary intake of iron
- Chronic blood loss
- Insufficient stores of iron to meet the demand of growth
How much iron is needed per day? What is this iron replacing?
Most people require 1-2mg of iron daily to replenish iron lost via feces.
What kinds of foods provide iron? Who does this potentially affect? What can be substituted for this special population?
The largest portions of dietary iron intake come from meats (poultry, fish, red meat). Vegan and vegetarian patients are more easily impacted by IDA due to this. Although most dietary intake of iron is from meats, beans, legumes, tofu, and dark green leafy vegetables have iron in them. Many cereals are also fortified with iron.
What populations are at the highest risk for IDA despite adequate dietary intake? Explain why
Toddlers - toddlers are undergoing massive changes throughout their body as they hit growth spurts that require large amount of iron to maintain.
Adolescents - same reason as toddlers
Women of child bearing age - these women have blood loss via mensuration which can lead to IDA, especially if they have heavier blood loss during their cycles.
What is anemia? What is the main issue and what does it cause? What are some symptoms of anemia?
Anemia is a low circulating red blood cell or hemoglobin count.
Decreased levels of hemoglobin or RBC leads to decreased ability to transport oxygen. Decreased oxygen transportation leads to tissue hypoxia.
Tissue hypoxia can manifest in many ways and are associated with the signs and symptoms of anemia.
Pallor - blood is restricted to more central organs, less is circulating near the skin surface resulting in a pale appearance.
Coldness - decreased circulating blood means cooler temperatures. Blood is warm.
Faintness - brain hypoxia can result in faintness as not enough of the brain is getting oxygen.
Fatigue - less oxygen being transported throughout the body leads to quick and constant fatigue.
Weakness
Headache
Vision changes
Tachycardia - compensatory mechanisms as the heart attempts to make up for the decreased CO from less blood volume.
Why might severe anemia cause bone pain?
Severe anemia may cause bone pain as the body taxes with bone marrow with increased needs for erythropoiesis production.
At what point is iron requirements the highest during life? Why?
Iron requirements are the highest during infancy (3-24 months). Rapid growth.
What are the two main causes of IDA in infancy?
- Maternal iron deficiency
- Consuming a diet of only cow’s milk (poor source of iron)
What are some signs and symptoms that are unique to IDA?
- Smooth tongue
- Koilonychia - a deformity of the nails resulting in a spoon or concave appearance.
- Sores in corner of the mouth
- Pica - craving of substances that lack nutritional value.
What is koilonychia? What causes it?
Spoon nails. Seen with iron deficiency anemia. Caused by decreased oxygen delivery to the peripheral extremities.
What are the most common causes of IDA in adults?
Chronic blood loss
- Mensuration
- GI bleeds - PUD, cancer, diverticulosis, hemorrhoids, esophageal varices
Poor dietary intake - vegan, vegetarian
Malabsorption
What are megaloblastic anemias? Two common ones?
These are anemias that are associated with impaired DNA synthesis resulting in enlarged RBC.
- Vitamin B12
- Folate
Cobalamin. What are its two functions?
Vitamin B12
1. Needed for DNA synthesis and nuclear maturation - affects RBC maturation.
2. Prevents abnormal fatty acids from being added to neuronal lipids. If abnormal lipids are not stopped, myelin breakdown can occur.
How common is vitamin B12 deficiency? How is vitamin B12 obtained?
Up to 20% of older adults are affected, mainly due to malabsorption. Cobalamin is found in almost all animal products (food).
What is pernicious anemia? IF
A specific type of vitamin B12 deficiency caused by lack of intrinsic factor. IF is a protein that is made and secreted into the stomach acid and is essential for B12 absorption.
What signs and symptoms would be unique to vitamin B12 deficiency anemia?
Neurologic changes caused by demyelination from inclusion of abnormal lipids in the neuronal chains.
Folate-deficiency anemia
How does it differ from vitamin B12?
A lack of folic acid in the persons diet can cause this via same mechanisms as vitamin b12 deficiency.
Folate deficiency will not present with the neurologic changes.
Who is at greatest risk for development of folic acid deficiency?
Pregnant women are at a high risk for folic acid deficiency - which can result in neural tube defects (spina bifida, anencephaly). This increased risk stems from an increased need for the vitamin due to fetal development.
Chronic alcohol abusers - alcohol diminished the absorption of folic acid.
Malabsorption syndromes
What are the pluripotential bone marrow stem cells?
These stem cells are the stem cells that differentiate into all three hematopoietic cell lines - RBC, WBC, and platelets.
Aplastic anemia
1. What does it affect?
2. What causes this type of anemia?
- Aplastic anemia affects the pluripotential bone marrow stem cells. This results in pancytopenia.
- Aplastic anemia is commonly associated with chemotherapy, radiation treatment, exposure to toxins, and viral infections.
What is pancytopenia?
A decrease in RBC, WBC, and platelets.
How does CKD results in chronic anemia?
CKD results in chronic anemia because the kidneys are the primary site for erythropoietin - the colony-stimulating factor that stimulates stem cells to differentiate into RBC. Damaged kidney secrete less erythropoietin which results in anemia.
How does the RBC appear with
1. Iron deficiency anemia?
2. Megaloblastic anemias?
3. Aplastic anemia?
- RBC are microcytic (smaller than normal) and hypochromic (less colorful). Poikilocytosis (irregular shape) and anisocytosis (irregular size).
- Cells are larger than normal.
- Decreased number of RBCs, WBCs, and platelets
What is polycythemia? Why is this a problem? What are some common symtpoms?
Abnormally high total red blood cell mass with a hematocrit greater than 49% in males and 48% in females.
Polycythemia increases the blood’s viscosity . This abnormally thick blood increases the risk for stroke, heart disease, blood clots.
Common symptoms include HTN, headaches, dizziness, trouble with hearing and sight (due to decreased cerebral blood flow).
Polycythemia Vera VS polycythemia secondary
Polycythemia Vera is primary. Neoplastic disease affecting the pluripotent cells of the bone marrow which causes an absolute increase in RBC, WBC, and platelets counts.
Secondary is caused by increased levels of erythropoietin, commonly in response to tissue hypoxia.
What is sickle cell disease? Who is most commonly affected?
A recessive inherited disorder that causes an irregularly shaped hemoglobin. African American individuals are more commonly affected by the disease.
What happens to the cells with sickle cell disease? Repeated exposure?
RBC affected by sickle cell disease are normal when oxygenation conditions are normal. When oxygenation conditions decrease, this can cause the shape of the RBC to become sickled. At first, these cells can return to their normal form with reoxygenation, but overtime the affected cells become less likely to revert and more likely to remain sickled.
How does the sickling affect the body?
- Chronic hemolytic anemia - the body detects these abnormally shaped, deformed RBC and sends them for destruction in the spleen. This results in anemia.
- Vessel occlusion - the sickled cells are more likely to clog up blood vessels.
What are some common precipitating factors with sickle cell anemia?
Anything that causes a reduction in oxygenation of the tissues.
1. Cold
2. Exercise
3. Stress
4. Infection
5. Dehydration
6. Acidosis
What complications can arise from the increased chance of blood vessel occlusion seen with sickle cell disease? What organ is in particular danger and why?
Acute - acute infarcts can occur anywhere throughout the body and can occur in multiple areas at once.
- MI, stroke, retinal infarct leading to blindness, lung infarcts.
Chronic - chronic damage can be done to any organ system. Reduction in blood flow to organ can cause slow damage.
The spleen is in particular danger due to slow blood flow and low oxygen tension.
Thalassemia
A- thalassemia
B - thalassemia
Group of inherited disorders of hemoglobin synthesis leading to decreased synthesis of either alpha or beta globin chains in adult hemoglobin.
B - thalassemia - severe anemia that affects adults. Bone marrow attempts to compensate, enlarging and becoming hyperactive.
A - thalassemia - affect both fetus, infants, and adults. Can cause microcytic RBC. If all four genes inherited mark for A-thalassemia then the fetus dies before being born due to inability to carry oxygen.
What are RBC main functions?
Carrying of gas throughout the body - oxygen and CO2
How long do RBC live in the body?
RBC live 120 days in the body. Older RBC are broken down in the spleen. It is broken down into iron and amino acids which are recycled.
Heme - iron
globin - amino acids
Erythropoiesis
1. Where does this occur?
2. What changes between early life and adulthood as far as erythropoiesis?
Formation of RBC
1. Erythropoiesis occurs in the bone marrow.
2. Erythropoiesis occurs in all the bones during early childhood. As we age this switches to mainly occurring just in the vertebrae, sternum, ribs, and pelvis.
What is bilirubin? Unconjugated vs conjugated. Where is it excreted?
Bilirubin is a waste product created when old RBC are broken down. Old RBC are broken down in the spleen. After breakdown in the spleen unconjugated bilirubin is left over, this is transported to the liver where it is conjugated and made water-soluble. This form of bilirubin is excretable via feces.
What organ breaks down old or damaged RBC?
The spleen breaks down old or damaged RBC
Ritculocytes
Immature RBCs
What is the normal hemoglobin value for males and females?
Males - 14 to 16.5
Females - 12 to 15
Hematocrit
- Normal value
This is the percentage of blood that is composed of cells, typically measured in an 100mL sample.
Normal values - 37%-50%.
Antibodies VS antigens
Antibodies are what the body produces in response to antigens (invaders)
Antigen/ Antibodies found in
- Type A
- Type B
- Type AB
- Type O
Type A - has antibodies for type B. Will attack cells with type B.
Type B - has antibodies for type A.
Type AB - has no antibodies, can take any type of blood.
Type O - has antibodies for both type A and B
What determines the Rh factor? When does this determination come about?
The Rh factor is determined by the absence of the D antigen. If the D antigen is present then there is Rh (+). Rh (+) people can receive either Rh(+) or Rh (-) blood.
Signs and symptoms of a transfusion reaction
- Heat along vein being transfused
- Flushing of the face
- Urticaria/rash, headache, pain in the lumbar region
- Chills, fever, constricting pain in the chest
- Cramping in the abdomen
- N/V
- Tachycardia, hypotension, dyspnea
What are the three causes of hemoglobin?
- Excessive loss
- Insufficient production
- Excessive destruction
What are some symptoms unique to aplastic anemia?
Aplastic anemia is caused by dysfunction of the pluripotent stem cells. This results in pancytopenia. Petechiae and purpura are common symptoms due to thrombocytopenia.
How does B-thalassemia present?
- Chipmunk face, prone to bone fractures, retarded growth. These are caused by bone marrow hyperactivity to attempt to increase RBC production.
- Increased iron absorption in the GI tract. This can worsen with repeated blood transfusions. Increased iron in the body can result in iron deposits throughout which can affect HF, liver cirrhosis, and endocrine problems
Enlarged spleen - from frequent RBC breakdown
