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F15 Lab diagnosis Lect > Week 4 > Flashcards

Week 4 Flashcards

1
Q

RBC’s

A

Red Blood Cells
•RBCs compose 99% of cells in blood
•Each second, 2-3 million RBCs are created and destroyed
•Biconcave disk allows for increased surface area and flexibility
•7 µm in diameter, but can squeeze though capillaries as small as 3 µm wide

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2
Q

RBC function

A

RBC Function
•A flexible “container” for hemoglobin (Hgb)
•Gas exchange involves the transport & release of oxygen & carbon dioxide.
•Contributes to buffering capacity of blood – carbonic anhydrase enzyme catalyzes:

CO2 + H2O  H2CO3  dissociates H+ + HCO3 (bicarbonate).

  • Hgb also acts as a buffer by picking up the H+, to maintain blood pH at 7.35-7.45
  • Clotting mechanism role via formation of a hemostatic plug.
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3
Q

Erythropoietin (EPO)

A

Erythropoietin (EPO)
Bringing it back to the kidneys
•Glycoprotein hormone produced by the kidney.
•Acts on bone marrow stem cells to increase production of RBCs
•In turn, production of EPO is regulated by the oxygen levels detected in the kidney
Can be tested for in serum as a cause of polycythemia

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4
Q

Erythropoietin levels can be increased by natural causes also:

A 
Increased:
high altitude
Chronic obstructive pulmonary dz
Heart dz
Smoking
ANy hypoxic event
Renal Carcinoma or tumors
Hepatic carcinoma or tumors (10% produced in liver)
Adrenal gland tumor
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5
Q

Natural causes of decr. Erythropoietin

A 
Decreased:
Renal Failure
Increased production of Il-1 or TNF
   -AI dz, HIV, Chronic infection
Severe malnutrition
Hypothyroidism
Malignancy
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6
Q

Erythropoiesis

A

Erythropoiesis, or RBC production, is a series of consecutive events where a primitive stem cell matures into a functional erythrocyte. In adults this normally occurs only in the bone marrow of long or flat bones.

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7
Q

Hematopoeisis: Cell maturation

A

Start with large cell with large nucleus -> progressively gets smaller cell with smaller nucleus

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8
Q

Mature RBC life span:

A

120 days

Removed from circulation by the spleen and the liver

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9
Q

Reticulocytes in Circulation

A

Reticular is Latin for “net”
•Easy to identify under the microscope due to their mesh like appearance (ribosomal RNA)
•Lives in circulation for ≈24 hours until becoming a mature RBC
Normal ratio of retics to mature RBC’s is 0.5%-1.5%

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10
Q

Reticulocyte Counts
Size relative to RBC’s?
Color?
Retics mature in peripheral circulation in _____

A

Larger in size than more mature RBCs
•Due to residual RNA, Retics have a bluish appearance, polychromatophilia, with Wright’s stain
In non-anemic individuals, Retics mature in peripheral circulation in ONE day (e.g., they lose the residual RNA). In anemic individuals, Retic maturation time increases in proportion to the severity of the anemia (up to 2.5 days).

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11
Q

Reticulocyte counts

Should expect to see in increase in retics when:

A

Should expect to see an increase when body is responding to an anemia or hemorrhage (reticulocytosis).
•Anemia with low reticulocytes may indicate: Failure of bone marrow –Aplastic anemia
EPO deficiency –Renal failure
Bone marrow malignancy –Leukemia
Anemia of chronic disease
Nutritional deficiencies

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12
Q

Interfereing factors with reticulocyte counts

A

Interfering factors:
•Pregnancy – may see increased count secondary to increased fluid volume, hypoxia
•Howell-Jolly bodies (DNA nuclear remnant) may be miscounted by techs or machines as reticulocytes

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13
Q

Reticulocyte index

A

RI = RET [%] x HCT [L/L] (patient)
0.45 [L/L] (standard HCT)

The relative percentage of reticulocytes may increase if the reticulocytes are increased or the RBCs are decreased. To correct for this the reticulocyte index (RI) is calculated.
•Using the RI is recommended for anemia.
The RI adjusts for the patient’s hematocrit compared to a normal hematocrit of 0.45 (L/L)

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14
Q

Hematocrit

A

The portion of blood composed of erythrocytes.
•Expressed as a percentage of the total blood volume.
•After whole blood is centrifuged, the RBCs will collect at the bottom of the tube.
•The value is determined by dividing the height of the erythrocytes by the total height of the blood in the tube and multiplying by 100.

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15
Q

Hematocrit:
Calculation:
Reference Ranges:

A

It is an indirect measure of the # of RBC’s and their total blood volume.

Calculation:
Hct = (MCV X RBC)/10

Reference Ranges:
37-47% for females
42-52% for males

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16
Q

Exmaple of anemic and how it influences hematocrit

A

The RI in patients with good marrow responses to anemia should be 2-3% indicating increased RBC production.
RI

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17
Q

Increased Reticulocytes will occur when:

A 
Increased levels
Reticulocytosis
•Hemolytic anemia
•Hemorrhage
•HDN (hemolytic disease of the newborn)
•Treated deficiency anemias
When your body is responding to deficits
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18
Q

Reticulocyte levels will decrease when:

A 
Decreased levels
Reticulocytopenia
•Pernicious anemia
•Nutrient deficiencies
•Aplastic anemia
•Radiation therapy
•Marrow failure
•Chronic diseases
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19
Q

Peripheral Smear Evaluation

A

Peripheral Smear Evaluation
•Inexpensive and powerful diagnostic tool.
•Used to determine if cells appear normal in size, shape, and count
•Not required in all patients. However helpful in diagnosing a range of deficiencies, diseases and disorders involving production, function and destruction when the CBC gives an incomplete picture.

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20
Q

How do we count RBC’s?

A
  • Coulter Counter
  • 1st commercially-available machine built to automate the procedure
  • 10 times more accurate than manual counting
  • Takes 1/3rd the time
21
Q

RBC count reference ranges:

A

Women
3.6-5.0 x 106/mm3
Children

    birth to 8 weeks
4.0-6.1 x 106/m m3
    2-6 months
3.8-5.6 x 106/mm3
    6 months to 1 year
3.8-5.2 x 106/mm3
    1-6 years
3.9-5.3 x 106/mm3
    6-16 years
4.0-5.2 x 106/mm3
    16-18 years
4.2-5.4 x 106/mm3
22
Q

Erythrocytosis

A

Increased RBCs due to:

Primary polycythemia (genetic disorder)
Secondary polycythemia (high altitude or pulmonary disorder)
Dehydration (reduced plasma to RBC ratio)
Bone marrow proliferative disorder (leukemia)
Renal Proliferative Disorder

23
Q

Anemia:

caused by:

A

Anemia: decrease in RBC’s = erythrocytopenia =anemia

Due to many factors:
–Malnutrition
–Malabsorption
–Inflammation
–Hemorrhage
–Hemolytic
–BM failure
–Renal disease
–Etc.
24
Q

Anisocytosis

A 
Anisocytosis
•Any significant variation in size of RBC
•Found in most anemias and leukemias
•Results from abnormal cell development
Often due to deficiency in raw material
   (i.e. iron, B12, folic acid)
•Graded on a scale of 1+ to 4+
•Variation corresponds with RDW
25
Q

Macrtocytes
What are they?
Round Macrocytes caused by:
Oval Macrocytes caused by:

A 
Macrocytes
–Round macrocytes
•Liver disease
–Oval macrocytes
•B12/folic acid deficiency
•Pernicious Anemia
Increase size (macrocytic)
Greater than 8um
26
Q

Microcyte

smaller than:

A 
Microcyte
•Decreased size  (microcytic)
–Smaller than 6 um
–Often has an increased central pallor due to decreased hemogobin concentraions
•Iron deficiency
•Blood loss
•Sideroblastic
27
Q

Red Blood Cell Distribution Width

A

RBC variation in size
•Red blood cell Distribution Width (RDW) (measurement in the difference in size of RBC’s)
•Statistical measure of variation in RBC size
•Calculated from MCV & RBC
•An indicator of the degree of anisocytosis
•RDW histogram (essentially a distribution graph) allows visualization of differing RBC populations

28
Q

Increases in RDW have clinical significance: could indicate:

A

Increases in RDW have clinical significance:
•Iron deficiency anemia
•B12 or folic acid deficiency anemia
•Hemoglobinopathies
Decreases in RDW are NOT clinically significant
Normal Adult Values: 11.5-14.5

29
Q

Poikilocytosis

A

Poikilocytosis = RBC variation in shape
•Recall that normal
RBCs have the shape of a doughnut
•Pathologies can cause distortions in normal RBC shape, which may affect proper RBC function
•Poikilocytosis: Excessive variation in normal RBC shape

30
Q

Target Cells
What are they?
They can indicate:

A 
Target cells
Dark center & periphery separated by pale area.  
•Thalassemia
•Splenectomy
•Liver disease! (not processing cholesterol correctly)
•Iron deficiency
•Hemoglobinopathies
•Decreased osmotic fragility

Test to follow up with: CBC with differential, iron studies, liver profile testing

31
Q

Spherocytes

A

Sphere or globe” with dense appearance (no central pallor), increased hemoglobin content, increased thickness of the cell and often a decrease in diameter = spherocytes

–Autoimmune hemolytic anemia
–Hereditary spherocytosis

Burst more readily when exposed to osmotic pressure due to increased osmotic fragility
Patients present with anemia,

32
Q

Schistocytes

A

Schistocytes
•Fragmented cells RBC’s
–Resulting from some form of trauma to the membrane
–Artificial heart valve
–Hemolytic uremic syndrome (HUS)
–Disseminated intravascular coagulation (DIC)
–Thrombotic thrombocytopenic purpura (TTP)

33
Q

Echinocytes

A

Echinocytes
Multiple tiny spicules (10-30) evenly distributed over the cell surface. Result from exposure of certain substances to the cell surface. Also known as burr cells. Characteristically seen in uremia.

34
Q

Acanthocytes

A

Acanthocytes (spur cells)
Spheroid RBCs with a few large thorny projections. Usually 5-10 spicules per cell. Hard to differentiate from echinocytes (shorter and more regular spicules).

56
Seen in:
Post splenectomy
Alcoholic cirrhosis
Various hemo
35
Q

Dacrocytes

A 
Dacrocytes
•Teardrop shaped cells can be seen in meylofibrosis with myeloid metaplasia.  The are pathologic and usually indicate significant bone marrow failure.
•Also seen in moderate numbers with:
–Megaloblastic anemia
–Renal failure
–Severe iron deficiency
–Thalassemia major
36
Q

Elliptocytes

A

Elliptocytes
•Also known as ovalocytes, normally comprise less than 1% of total RBCs. Numbers can increase up to 10% in cases of thalassemia or deficiencies of iron or folate. In cases of hereditary elliptocytosis, nearly all of the cells may be ovoid

37
Q

Sickle cells

A

Sickle cells
•Abnormal hemoglobin SS is prone to crystallization when oxygen tension is low, RBCs change shape into long thin sickle forms that get stuck in capillaries, further decreasing blood flow and oxygen tension.
•Patients may start out with splenic enlargement, but eventually (by early adolescence) the spleen size has been tremendously reduced in size due to continual stasis and infarctions.

38
Q

Howell-Jolly Bodies

A

Howell-Jolly bodies
•Small (1mm) inclusions of nuclear chromatin remnants or fragments. Most often present post splenectomy, because the spleen would naturally remove these RBCs from circulation.

Also seen during increased production of RBCs, following cell destruction, such as in hemolytic anemia

39
Q

Heinz bodies

A 
Heinz bodies
Formed by damage to hemoglobin through oxidative stress leading to irreversible hemichrome oxidation and precipitation.
Seen in:
       Alpha thalassemia
Congenital hemolytic anemia
       G6PD deficiency
40
Q

Basophilic Stippling

A

Basophilic stippling
Indicates toxic injury to the bone marrow. May also appear with severe anemia, such as megaloblastic anemia
!Lead poisoning! (test blood for lead levels!)
Myelofibrosis

41
Q

Erythrocyte sedimentation Rate

Is it a good screening test? Diagnostic test? Monitoring test?

A

Erythrocyte Sedimentation Rate = the rate at which RBC’s settle in an hour

•Commonly performed, simple and inexpensive lab test to assess overall inflammation.
•Used to track the progress of a disease or to monitor treatment. “sickness index”
•Not used diagnostically
•Results directly correlate with the amount of fibrinogen in anticoagulated blood.
-Not a good test, not good specificity or sensitivity (not a good test for screening or diagnosing)
-Only useful if you have a baseline sed rate and you’re monitoring treatment

42
Q

Why does ESR increase?

A 
The normal negative
   cellular surface charge of the
  “Zeta potential” repels RBC’s
•Inflammatory proteins,
   collectively known as acute
   phase reactants, mainly fibrinogen, neutralize the normal negative charge
•RBCs overcome Zeta potential & stack up on one another = Rouleaux formation
•Larger mass of cells settles faster
43
Q

ESR
Utility:
Limitations:

A

Utility:
•Follow the course of a disease – in general, as the disease worsens the ESR increases and as the disease resolves the ESR decreases
•Can be used to monitor therapy – especially for inflammatory autoimmune diseases

Limitations:
•Nonspecific, nonsensitive
•May NOT be elevated in active disease
•Many factors can alter the test results

44
Q

ESR interfering Factors:

A

Interfering factors
•Low results if test not set up within 3 hours of sample collection
•Pregnancy (2nd & 3rd tri) may elevate
•Menstruation may elevate
•Sedimentation tube must be vertical
•Some anemia’s falsely increase – correction nomograms are available
•Polycythemia & sickle cell disease decreases
•Protein-producing malignancies falsely  ESR
•Any bubble in column invalidates the test

45
Q

What can increase the ESR?

good for assisting diagnosis in what two conditions:

A

Increased rate
•Chronic renal failure
•Malignant diseases
•Bacterial infections
•Inflammatory diseases / Autoimmune Disease
•Necrotic diseases, MI
•Diseases assoc. with increased plasma proteins
•Assists in the diagnosis for: !!polymyalgia rheumatica and temporal arteritis!! (may be > 100 mm/hr)

46
Q

What can falsely decr. ESR?

A

Falsely decreased levels
•Sickle cell disease – cells severely distorted & can not form rouleaux
•Hereditary spherocytosis – cells are too spherical, do not stack in rouleaux
•Hypofibrinogenemia – decreased protein inhibits aggregation & settling of RBCs
•Polycythemia vera – increased RBC counts inhibit settling due to simple concentration interference

47
Q

Good summarizing chart on Pg 82!

A

Good summarizing char on Pg 82!

48
Q

Complete blood count

A 
Complete Blood Count
•The Complete Blood count (CBC) is the most routinely run panel in the health care system.  
•It is inexpensive and often included as part of a routine health screening.
–Includes information about
•RBCs
•WBCs
•Platelets
•Nutritional status
•Inflammation
•Many specific disease states
•Hydration
•Occult blood loss
•And many more…

F15 Lab diagnosis Lect (6 decks)

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