Chapter 23 Disorders of Red Blood Cells

Question 1

What are the three causes of iron deficiency anemia?

Answer 1

1. Insufficient dietary intake of iron
2. Chronic blood loss
3. Insufficient stores of iron to meet the demand of growth

Question 2

How much iron is needed per day? What is this iron replacing?

Answer 2

Most people require 1-2mg of iron daily to replenish iron lost via feces.

Question 3

What kinds of foods provide iron? Who does this potentially affect? What can be substituted for this special population?

Answer 3

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.

Question 4

What populations are at the highest risk for IDA despite adequate dietary intake? Explain why

Answer 4

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.

Question 5

What is anemia? What is the main issue and what does it cause? What are some symptoms of anemia?

Answer 5

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.

Question 6

Why might severe anemia cause bone pain?

Answer 6

Severe anemia may cause bone pain as the body taxes with bone marrow with increased needs for erythropoiesis production.

Question 7

At what point is iron requirements the highest during life? Why?

Answer 7

Iron requirements are the highest during infancy (3-24 months). Rapid growth.

Question 8

What are the two main causes of IDA in infancy?

Answer 8

1. Maternal iron deficiency
2. Consuming a diet of only cow’s milk (poor source of iron)

Question 9

What are some signs and symptoms that are unique to IDA?

Answer 9

1. Smooth tongue
2. Koilonychia - a deformity of the nails resulting in a spoon or concave appearance.
3. Sores in corner of the mouth
4. Pica - craving of substances that lack nutritional value.

Question 10

What is koilonychia? What causes it?

Answer 10

Spoon nails. Seen with iron deficiency anemia. Caused by decreased oxygen delivery to the peripheral extremities.

Question 11

What are the most common causes of IDA in adults?

Answer 11

Chronic blood loss
- Mensuration
- GI bleeds - PUD, cancer, diverticulosis, hemorrhoids, esophageal varices

Poor dietary intake - vegan, vegetarian

Malabsorption

Question 12

What are megaloblastic anemias? Two common ones?

Answer 12

These are anemias that are associated with impaired DNA synthesis resulting in enlarged RBC.

1. Vitamin B12
2. Folate

Question 13

Cobalamin. What are its two functions?

Answer 13

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.

Question 14

How common is vitamin B12 deficiency? How is vitamin B12 obtained?

Answer 14

Up to 20% of older adults are affected, mainly due to malabsorption. Cobalamin is found in almost all animal products (food).

Question 15

What is pernicious anemia? IF

Answer 15

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.

Question 16

What signs and symptoms would be unique to vitamin B12 deficiency anemia?

Answer 16

Neurologic changes caused by demyelination from inclusion of abnormal lipids in the neuronal chains.

Question 17

Folate-deficiency anemia
How does it differ from vitamin B12?

Answer 17

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.

Question 18

Who is at greatest risk for development of folic acid deficiency?

Answer 18

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

Question 19

What are the pluripotential bone marrow stem cells?

Answer 19

These stem cells are the stem cells that differentiate into all three hematopoietic cell lines - RBC, WBC, and platelets.

Question 20

Aplastic anemia
1. What does it affect?
2. What causes this type of anemia?

Answer 20

1. Aplastic anemia affects the pluripotential bone marrow stem cells. This results in pancytopenia.
2. Aplastic anemia is commonly associated with chemotherapy, radiation treatment, exposure to toxins, and viral infections.

Question 21

What is pancytopenia?

Answer 21

A decrease in RBC, WBC, and platelets.

Question 22

How does CKD results in chronic anemia?

Answer 22

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.

Question 23

How does the RBC appear with
1. Iron deficiency anemia?
2. Megaloblastic anemias?
3. Aplastic anemia?

Answer 23

1. RBC are microcytic (smaller than normal) and hypochromic (less colorful). Poikilocytosis (irregular shape) and anisocytosis (irregular size).
2. Cells are larger than normal.
3. Decreased number of RBCs, WBCs, and platelets

Question 24

What is polycythemia? Why is this a problem? What are some common symtpoms?

Answer 24

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).

Question 25

Polycythemia Vera VS polycythemia secondary

Answer 25

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.

Question 26

What is sickle cell disease? Who is most commonly affected?

Answer 26

A recessive inherited disorder that causes an irregularly shaped hemoglobin. African American individuals are more commonly affected by the disease.

Question 27

What happens to the cells with sickle cell disease? Repeated exposure?

Answer 27

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.

Question 28

How does the sickling affect the body?

Answer 28

1. Chronic hemolytic anemia - the body detects these abnormally shaped, deformed RBC and sends them for destruction in the spleen. This results in anemia. 2. Vessel occlusion - the sickled cells are more likely to clog up blood vessels.

Question 29

What are some common precipitating factors with sickle cell anemia?

Answer 29

Anything that causes a reduction in oxygenation of the tissues. 1. Cold 2. Exercise 3. Stress 4. Infection 5. Dehydration 6. Acidosis

Question 30

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?

Answer 30

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.

Question 31

Thalassemia A- thalassemia B - thalassemia

Answer 31

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.

Question 32

What are RBC main functions?

Answer 32

Carrying of gas throughout the body - oxygen and CO2

Question 33

How long do RBC live in the body?

Answer 33

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

Question 34

Erythropoiesis 1. Where does this occur? 2. What changes between early life and adulthood as far as erythropoiesis?

Answer 34

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.

Question 35

What is bilirubin? Unconjugated vs conjugated. Where is it excreted?

Answer 35

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.

Question 36

What organ breaks down old or damaged RBC?

Answer 36

The spleen breaks down old or damaged RBC

Question 37

Ritculocytes

Answer 37

Immature RBCs

Question 38

What is the normal hemoglobin value for males and females?

Answer 38

Males - 14 to 16.5 Females - 12 to 15

Question 39

Hematocrit - Normal value

Answer 39

This is the percentage of blood that is composed of cells, typically measured in an 100mL sample. Normal values - 37%-50%.

Question 40

Antibodies VS antigens

Answer 40

Antibodies are what the body produces in response to antigens (invaders)

Question 41

Antigen/ Antibodies found in - Type A - Type B - Type AB - Type O

Answer 41

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

Question 42

What determines the Rh factor? When does this determination come about?

Answer 42

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.

Question 43

Signs and symptoms of a transfusion reaction

Answer 43

- 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

Question 44

What are the three causes of hemoglobin?

Answer 44

1. Excessive loss 2. Insufficient production 3. Excessive destruction

Question 45

What are some symptoms unique to aplastic anemia?

Answer 45

Aplastic anemia is caused by dysfunction of the pluripotent stem cells. This results in pancytopenia. Petechiae and purpura are common symptoms due to thrombocytopenia.

Question 46

How does B-thalassemia present?

Answer 46

- 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