Anemia & RBC Disorders Flashcards
1
Q
What is the complete blood count (CBC)?
A
- a basic screening test and is one of the most frequently ordered laboratory procedures
- gives valuable diagnostic information about the hematologic and other body systems, prognosis, response to treatment, and recovery
2
Q
The CBC consists of a series of blood cell tests that determine their: (5)
A
- number
- variety
- percentage
- concentrations
- quality
3
Q
The 3 main components of the CBC
A
- Red Blood Cell Count and Indices
- White Blood Cell Count and Differential
- Platelet Coun
4
Q
“normal” values for a CBC can be affected by several factors including the patient’s: (3)
A
- age
- sex
- race
5
Q
Red blood cells (RBCs) (also called erythrocytes) are the largest cellular component of blood comprising about:
A
- 40 - 45% of total blood volume, and
- 99.9% of formed blood elements.
6
Q
RBCs contains the red, iron-based protein _______ which binds and transports O2 and CO2
A
hemoglobin
7
Q
Hemoglobin contains
A
- 4 molecules of heme:
- Each molecule of heme contains one iron (Fe2+) ion - 4 molecules of globin:
- 2 alpha chains, and 2 beta chains
8
Q
What is the size of each RBC
A
a biconcave disc:
* Diameter: 6.2 - 8.2 µm
* Thickness: 2.0 - 2.5 µm
9
Q
Why are RBC’s a biconcave disc?
A
- It provides an increased surface area for O2 and CO2 transfer.
- It enables them to bend and flex when entering small capillaries
10
Q
Mature RBCs lack a ______ and most cellular organelles.
RBCs normally survive about _____ days in the blood before they are removed primarily by the _______
A
- nucleus
- 120
- spleen
11
Q
a reduction in hemoglobin concentration and/or red blood cell mass
A
anemia
12
Q
What is the RBC count?
A
The total number RBCs per unit volume of whole blood.
13
Q
What physiologic variants effect RBC count?
A
- exercise
- age
- altitude
- pregnancy
- many drugs
14
Q
What is RBC count increased in?
A
- Secondary polycythemia (e.g. secondary to cardiovascular disease, COPD)
- hemoconcentration (dehydration)
- polycythemia vera
- etc
15
Q
What is RBC count decreased in?
A
Anemia, chronic or acute blood loss, fluid overload, bone marrow suppression/disease, etc.
16
Q
What is hematocrit (HCT)?
A
the volume percentage (%) of red blood cells in whole blood
17
Q
How is hematocrit calculated
A
- usually by placing a hematocrit tube in a centrifuge
- or by multiplying the RBC count by the mean corpuscular (cell) volume (MCV)
18
Q
What physiologic variants effect outcomes of hematocrit?
A
Age, pregnancy, many drugs
19
Q
Hematocrit may be increased in:
A
Any condition that increases RBCs including hemoconcentration (as in dehydration, severe burns, vomiting, diarrhea), polycythemia (erythrocytosis), extreme physical exercise, etc.
20
Q
Hematocrit may be decreased in:
A
Many conditions that decrease RBCs including anemia, hemodilution, acute hemorrhage, bone marrow suppression/disease, etc.
21
Q
what is hemoglobin, total, whole blood (Hgb or Hb):
A
the amount of hemoglobin in a given volume of whole blood.
22
Q
Physiologic variants that effect hemoglobin?
A
Age, high altitude, excessive fluid intake, pregnancy, and many drugs.
23
Q
Hemoglobin may be increased in:
A
Hemoconcentration (as in dehydration, severe burns, vomiting), polycythemia (erythrocytosis), extreme physical exercise, hyperlipidemia, etc
24
Q
Hemoglobin may be decreased in:
A
Anemia, acute hemorrhage, hemodilution, bone marrow disease/suppression, etc
25
A hematocrit of < 20% can lead to ________.
A hematocrit > 60% is associated with ________.
- heart failure and death.
- spontaneous clotting of blood.
26
A hemoglobin value < 5.0 g/dL leads to _________
A hemoglobin value > 20.0 g/dL results in __________
heart failure and death.
hemoconcentration and clogging of capillaries
27
What is Mean corpuscular (cell) volume (MCV)? What is the normal range?
MCV is the average volume of the red blood cells
28
MCV may be increased in:
Liver disease, alcohol abuse, HIV/AIDS, hemochromatosis, megaloblastic anemias (folate, vitamin B12 deficiencies), myelodysplasia, reticulocytosis, chemotherapy, post-splenectomy, hypothyroidism, newborns, drugs (e.g., methotrexate, phenytoin, zidovudine), etc.
29
MCV may be decreased in:
Iron deficiency, thalassemia, sideroblastic anemia, lead poisoning, hereditary spherocytosis, some anemias of chronic disease, etc.
30
What is Mean Corpuscular (Cell) Hemoglobin (MCH)? What is a normal range?
- the average amount of hemoglobin per red blood cell (RBC) in absolute units
31
How is mean corpuscular hemoglobin (MCH) calculated?
- calculated from measured values of hemoglobin (Hgb) and RBC count by the formula: MCH = (Hgb ÷ RBC count) x 10
32
MCH may be increased in:
Macrocytosis, hemochromatosis, etc
33
MCH may be decreased in:
Microcytosis (iron deficiency, thalassemia), hypochromia (lead poisoning, sideroblastic anemias, anemia of chronic disease), etc.
34
While MCV can indicate if RBCs have a normal ______, it cannot indicate if the RBCs have a normal ______
- mean volume
- shape
35
What are characteristics related to RBC color?
- hypochromia (paler than normal)
- hyperchromia (more red than normal)
- polychromia (variations)
36
What is Mean Corpuscular Hemoglobin Concentration (MCHC)? What is a normal range?
- the average hemoglobin concentration in RBCs.
37
How is mean corpuscular hemoglobin concentration (MCHC) calculated?
- calculated from hemoglobin concentration (Hgb) and the hematocrit (HCT) by the formula: MCHC = (Hgb ÷ HCT) x 100.
38
MCHC may be increased in:
Marked spherocytosis (hereditary spherocytosis) or immune hemolysis), etc. Falsely increased in cellular dehydration syndromes, hyperlipidemia, etc
39
MCHC may be decreased in:
Hypochromic anemias (iron deficiency, thalassemia, lead poisoning), sideroblastic anemia, anemia of chronic disease, etc. Falsely decreased with markedly high white blood cell count.
40
What is Red Cell Distribution Width (RDW)? What is a normal range?
- a measure of the variation of RBC volume.
41
How is red cell distribution width (RDW) calculated?
- calculated with the formula: RDW = (standard deviation of MCV ÷ mean MCV) × 100
42
What is anisocytosis?
An abnormally high (increased) RDW
43
RDW may be increased in:
Certain types of anemia (iron deficiency, pernicious anemia, folic acid deficiency, etc.), sickle cell disease, leukemia, etc
44
What are reticulocytes?
Reticulocytes are immature RBCs that contain cytoplasmic RNA
45
What is reticulocyte count? Why is it important?
- an indication of how rapidly reticulocytes are produced by the bone marrow and then released into the bloodstream.
- The reticulocyte count reflects the erythropoietic activity of the bone marrow and is thus useful in both the diagnosis of anemias and in monitoring bone marrow response to therapy.
46
How is the reticulocyte count expressed? What is a normal range?
- as the percent of the number of reticulocytes per total number of RBCs counted.
(There are normally 25,000 - 85,000 reticulocytes per µL of whole blood in adults)
47
The reticulocyte count may be increased (“reticulocytosis”) in:
Hemolytic anemia, acute blood loss, etc.
48
The reticulocyte count may be decreased (“reticulopenia”) in:
Certain types of anemia, renal disease, bone marrow suppression or infiltration, myelodysplastic syndrome, etc.
49
Normal RBC's have a zone of central pallor about ______ the size of the RBC
The RBC's demonstrate minimal variation in ______
- 1/3 the size
- size and shape
(band neutrophil and segmented neutrophil in middle of image)
50
RBCs are manufactured in the _______ from hematopoietic stem cells.
bone marrow
51
_______ supply to the tissues is the major determinate for RBC production
Oxygen
52
_______ (from kidneys) stimulates RBC production in response to hypoxia
Erythropoietin
53
Maturation of RBC's requires what two things?
vitamin B12 and folic acid.
54
______ is necessary for the formation of hemoglobin.
_______ is the transporter of oxygen
- Iron
- Hemoglobin
55
Normal life span of an RBC is _____ days.
Old RBCs are removed from the circulation by the spleen
120
spleen
56
What is anemia?
a decrease in numbers of erythrocytes (red blood cells [RBCs]) or hemoglobin (Hgb, Hb).
57
What caueses anemia?
Anemia results from one or more combinations of three basic mechanisms:
58
What causes iron deficiency anemia (IDA)?
Anemia due to decreased iron stores
59
What is the most common form of anemia?
iron deficiency anemia
60
Are men or woman affected more by iron deficiency anemia?
- Female > Male
- affects 20% of women, 50% of pregnant women, and 3% of men
61
What are signs of iron deficiency anemia?
- Skin and conjunctival pallor
- Koilonychia [spooning of the nails]
- Angular cheilitis and atrophic glossitis
- shortness of breath
- weakness
62
What can cause iron deficiency anemia? (3)
- blood loss due to GI bleeding, menstrual loss, or certain types of cancer
- poor iron intake
- poor iron absorption
63
Describe the onset of iron deficiency anemia?
Onset may be acute with rapid blood loss, or chronic with poor diet or slow (chronic) blood loss
64
What are common laboratory measurements of iron status in iron deficiency anemia?
- Serum iron
- Serum transferrin
- Serum ferritin
- Total iron binding capacity (TIBC)
65
How would you describe iron deficiency anemia histologically?
Many of these RBCs are microcytic (smaller than the nucleus of the normal lymphocyte in the field) and hypochromic (with central areas of pallor that exceed half the diameter of the cells)
66
Can Iron deficiency anemia have hypochromia? Microcytosis?
Yes, significant hypochromia and microcytosis is seen in these RBCs, as well as moderate variation in size (anisocytosis) and shape (poikilocytosis) of the RBCs
67
What is the second most prevalent anemia in the USA?
Anemia of Chronic Disease [ACD]
(also known as Anemia of Chronic Inflammation)
68
What is anemia of chronic disease often associated with?
with numerous underlying diseases like:
- neoplasms
- microbial infections
- autoimmune diseases
69
What causes anemia of chronic disease?
caused by inflammatory cytokines (e.g., interleukin 6), which stimulates the hepatic synthesis and release of hepcidin and thereby sequesters iron in macrophages, and also suppresses erythropoietin (EPO) production
70
What does a CBC of anemia of chronic disease reveal?
normocytic, normochromic, mild to moderate anemia, with an abnormally low reticulocyte count
71
What is pernicious anemia?
a megaloblastic, macrocytic anemia resulting from vitamin B12 (cobalamin) deficiency characterized by atrophic gastritis and achlorhydria
72
Describe the etiology of pernicious anemia
caused by an autoimmune-mediated destruction of the gastric mucosa that suppresses the production of intrinsic factor
73
What are signs or pernicious anemia?
- glossitis
- GI symptoms
- Mild jaundice
74
What does a CBC of pernicious anemia show?
- anemia
- MCV is usually elevated
- thrombocytopenia and mild leukopenia are present
75
_______ should not be used during dental treatment in patients with uncontrolled or poorly controlled pernicious anemia
nitrous oxide sedation
76
Serum methylmalonic acid and homocysteine levels are both usually ______ in vitamin B12 deficiency
elevated
77
Folate deficiency develops within months, as body stores are minimal. If intracellular stores of folate fall, DNA replication is blocked, leading to _________
megaloblastic anemia
78
T/F folic acid deficiency results in neurologic abnormalities
false
it does not result in neurologic abnormalities
79
what is aplastic anemia?
It is a bone marrow failure syndrome characterized by immune-mediated bone marrow destruction and peripheral blood pancytopenia
80
What are the most common initial symptoms of aplastic anemia caused by?
anemia and thrombocytopenia
81
Anemia due to acute blood (RBC) loss results in what?
in a posthemorrhagic normochromic normocytic dilutional anemia
82
Anemia due to chronic / slow rate of blood (RBC) loss results in what?
in a deficiency of iron, which, when severe, is characterized by a hypochromic anemia
83
Hemolysis, whether acute or chronic, can be what two types
- Congenital: due to intrinsic RBC defect
- Acquired: due to abnormal marrow or systemic abnormality/disease
84
what causes congenital hemolytic anemias
result from a congenital defect in hemoglobin structure, in RBC metabolism, or in hemoglobin synthesis
85
What are hemoglobinopathies?
Hemolytic anemias caused by a congenital, hereditary abnormality in the hemoglobin molecule
86
What is sickle cell anemia?
a congenital hemoglobin synthesis disorder characterized by the production of a variant hemoglobin molecule (hemoglobin S [HbS]) and a resulting chronic hemolytic anemia.
87
What is the most common hereditary hemolytic anemia?
Sickle cell anemia
88
Who is most commonly affected with sickle cell anemia
predominantly affects persons of African descent
89
What causes Hemoglobin S (HbS or sickle cell disease)
- Arises from a mutation substituting thymine for adenine in the sixth codon of the beta-chain gene, GAG to GTG.
- This causes coding of valine instead of glutamic acid in position 6 of the hemoglobin beta chain.
90
Why does HbS change shape?
HbS is unstable and polymerizes into long strands when exposed to various stressors, including hypoxemia (deoxygenation) and acidosis. This results is affected RBCs to deform into a characteristic sickle shape
91
Is sickle cell disease dangerous? Why or why not?
Sickle cell disease (SCD) (the homozygous HbS state), is a severe, life threatening condition with over 85 to 95% of normal hemoglobin being replaced by HbS
92
What is the heterozygous HbS state?
In patients with sickle cell trait each RBC contains only ~ 30 to 45% HbS
93
What is the most common clinical manifestation of sickle cell disease
Vaso-occlusive events (crises)
94
Vaso-occlusive events (crises) are caused by what?
tissue ischemia resulting when blood flow in the microvasculature is disrupted and blocked by sickled RBCs
(often occur spontaneously or can be precipitated by hypoxia, dehydration, infection)
95
What are vaso-occlusive events (crises) characterized by?
- acute, intermittent episodes of unremitting pain and tenderness
- fever, tachycardia, and anxiety
96
What does a CBC for sickle cell disease usually show?
shows moderate to severe anemia usually with marked reticulocytosis
97
Though in early childhood the spleen may be enlarged (splenomegaly) with sickle cell disease, continual stasis and trapping of abnormal RBC's leads to what?
infarctions that eventually reduce the size of the spleen tremendously by adolescence.
(This is sometimes called "autosplenectomy")
98
What are thalassemias?
inherited disorders of hemoglobin caused by genetic mutations leading to decreased synthesis of either the alpha or beta globin chain of hemoglobin A.
99
Who does ß-thalassemia effect most
It occurs predominantly in patients from the Mediterranean region
100
What causes beta-thalassemia?
caused by more than 200 point mutations that lead to defects in the transcription, splicing, or translation of ß-globin mRNA resulting in defective ß-globin chain synthesis.
101
What are the classification of beta thalassemia?
- Beta thalassemia minor (beta-thalassemia trait): heterozygous form
- Beta thalassemia major (Cooley's anemia or Mediterranean fever): homozygous form
- Beta thalassemia intermedia: disease in between both states
102
Beta-Thalassemia characteristic deformities include:
"chipmunk facies" craniofacial deformities include:
* Skeletal Class II malocclusion with anterior open bite
* Maxillary hypertrophy
* Frontal bossing
* Depression of the nasal bridge
103
Who most often has oral manifestations of beta-thalassemia?
in patients with β-thalassemia major and are reflective of the underlying extramedullary hematopoiesis.
104
What are dental arch morphologic changes in β-thalassemia major:
1. Mandibular arch is telescoped within the (hypertrophic) maxillary arch (aka: Brodie syndrome or Brodie crossbite or scissor crossbite):
- Palatal cusps of the maxillary molars lie outside the buccal cusps of opposing mandibular molars.
105
Reported clinical findings in β-thalassemia major include what?
- growth retardation
- skeletal deformities
- bone marrow expansion and hyperplasia
- splenomegaly and hepatomegaly
106
Who is most affected by Glucose-6-phosphate Dehydrogenase (G6PD) Deficiency
a recessive X-linked trait:
affected persons are primarily men who are susceptible to drugs or other compounds with oxidative activity
107
What is hereditary spherocytosis caused by?
by mutations that affect the RBC cytoskeleton-membrane tethering proteins, leading to loss of membrane and eventual conversion of RBCs to round spherocytes.
