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Heme I > Section 14 > Flashcards

Section 14 Flashcards

1
Q

What diluent is used for cyanmethemoglobin method of hgb determination

A

Drabkins reagent : potassium ferricyanide & potassium cyanide

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2
Q

What is the oxidizer in the cyanmethemoglobin method and what does it oxidize

A

Potassium ferricyanide
Hgb -> methemoglobin

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3
Q

What is the purpose of potassium cyanide in the oxidizing process

A

Ox methemoglobin to cyanmethemoglobin

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4
Q

How is hgb determined using cyanmethemoglobin method

A

Absorbance of cyanmethemoglobin at 540 nm is directly proportional to concentration of hgb

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5
Q

How is concentration hgb calculated (equation)

A

([unknown])/([known])=(abs unknown)/(abs known)

Concentration* dilution factor
Abs known = 45 standard

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6
Q

What are sources of error using cyanmethemoglobin method

A
  • Drabkins is sensitive to light,
  • high WBC, PLT, or lipemia can interfere with abs measured
  • Intravascular hemolysis (hemoglobin not incorporated in cells -> not desired measurement)
  • abnormal hgb S or C resists lysis
  • abnormal Igs interfere
  • carboxyhemoglobin needs to convert before measured
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7
Q

What is an alternative method to cyanmethemoglobin method

A

Sodium laurel sulphate method

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8
Q

How does SLS differ from cyanmethemoglobin method

A
  • lyses RBCs and WBCs
  • oxidizes iron to ferric state (Fe3)
  • become SLS-hgb hemachrome
  • absorbs light at 555nm
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9
Q

What are the advantages of SLS of cyanmethemoglobin

A
  • lysis of RBC and WBC removes absorbance interference from high WBC count
  • removes excess oils from blood, reduces lipemia interaction
  • not light sensitive
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10
Q

What is hematocrit (hct)

A

% of whole blood occupied by red cells
Varies with: sex, altitude, age, nutrition and smoking

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11
Q

What are the female and male reference ranges for hct

A

Male: 41.0-53.0%
Female: 36.0-46.0%

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12
Q

What is the rule of 3 and when is it used

A

As a general check calculations match NOT to calculate real values
RBC3= hgb
Hgb3= hct

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13
Q

What is mean cell volume (MCV)

A

Average size of red cells (micro/macro indicator)
MCV=(hct*10)/RBC
RBC= in millions, drop scientific notation

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14
Q

MCV reference ranges for females and males

A

M&F: 80-96 fL

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15
Q

What is mean cell hemoglobin (MCH)

A

Average weight of hgb per RBC (NOT an indicator of chromia, no size correlation)
MCH= (hgb*10)/RBC in millions

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16
Q

What is the reference range for females and males for MCH

A

M&F: 29.0-32.0 pg

17
Q

What is mean cell hemoglobin concentration (MCHC)

A

Avg amount of red cell vol occupied by hgb (indicator of chromia)
MCHC%= (hgb/hct)*100

18
Q

What is the reference ranges for MCHC

A

M&F: 33.4-35.5%

19
Q

When can MCHC % be considered lab error (cannot occur)

A

> 36(except for Sphreocytes)
<30

20
Q

What can cause MCHC to be >36

A

Cold agglutination
Lipemia
Hemolysis
Icterus

21
Q

Define RDW

A

Red cell distribution width, amount of red cell size variation
Quantifies anisocytosis

22
Q

What is the RDW reference range

A

11.5-15 g/L or %

23
Q

How long does it take for reticulocytes to mature

A

3 total: 2 days in bone marrow, 1 in peripheral blood

24
Q

Why are reticulocyte counts done

A

To measure the erythropoietic activity of the bone marrow

25
Q

What method is used to count retics

A

Miller disk
Count only retincs in A square
Count all cells in B square
Count until B=111
A/10 = %retics

26
Q

What stain is used to count retics

A

Supravital stain with new methylene blue
Precipitates RNA from cell to highlight retics

27
Q

What are sources of error in retic counting

A

Mixing of blood and stain
Moisture (refractile cells are NOT retics)
Other RBC inclusions

28
Q

When and how to correct retic count for abnormal hct

A

Correct if hct<45
Corrected= raw retic% *(pt hct/normal hct)
Normal = 45

29
Q

What is RPI

A

Retic production index - retics produced on a daily basis

30
Q

RPI equation

A

RPI= (corrected retic)/(# days to mature)

31
Q

How to calculate increased # days to mature for retics

A

Days increase =((pt hct- normal hct)/2)*0.1
1+Days increase= total days to mature in blood

32
Q

Reference range for all retics

A

Raw, corrected and RPI= 0.5-1%

33
Q

What is a normal bone marrow response for anemia

A

3% increase

34
Q

What does ESR represent

A

Erythrocyte sedimentation rate (mm/hr)
Amount of rbcs settling in 1 hour
Directly proportional to RBC mass
Monitor for inflammation

35
Q

List 6 abnormal clinical conditions that increase ESR

A
  • MM
  • inflammatory disease
  • RA and collagen diseases
  • chronic infections
  • tissue damage or necrosis
  • autoimmune diseases
36
Q

What are the ESR reference ranges

A

Male: 0-20 mm/hr
Female: 0-30 mm/hr

37
Q

What is the hgb reference range for male and female

A

Male: 13.5-17.5 g/dL
Female: 12-16 g/dL

38
Q

What is the male and female reference range for RBC

A

Male: 4.5-5.9
Female: 4.0-5.2

39
Q

lipemia affects which red cell indice

A

MCHC

Heme I (15 decks)

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