PRELIMS POST-LAB Flashcards by Arriane Camacho

 [?]is recommended; not shaking.

Inversion

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 Specimens are transported in an [?] to ensure complete clot formation and reduce agitation.

upright position

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 Samples of patients with known [?] shown be pre-warmed before testing.

Cold Agglutinin Antibodies

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 Specimens for routine testing should be delivered to the laboratory within [?] of collection.

45 minutes to 1 hour

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Requirements of a Quality Specimen

 Patient properly (?)
 Patient properly (?) for draw
 Specimen collected in the correct (?) and labelled correctly
 Correct (?) used
 Specimen properly mixed by (?) if required
 Specimens not (?)
 Specimens requiring (?) collected in a timely manner
 Timed specimen drawn at the (?)

identified
prepared
order
anticoagulants and preservatives
inversion
hemolyzed
patient fasting
correct time

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REASONS for SPECIMEN REJECTION

 The test order (?) and the (?) identification do not match.
 The (?) is unlabelled, or the labelling, including patient ID number, is incorrect.
 The specimen is (?).
 The specimen was collected at the (?).
 The specimen is collected at the (?).
 The specimen was (?), and the test requires whole blood.
 The specimen was contaminated with (?).
 The specimen is (?).

requisition; tube
tube
hemolyzed
wrong time
wrong tube
clotted
intravenous fluid
lipemic

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Basic Hematologic Methods of Examination

QUALITATIVE Analysis
QUANTITATIVE Analysis

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establishing morphological characteristics of cells in the blood, and blood – forming organs; and the presence of foreign elements in cells.

QUALITATIVE Analysis

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giving the number of blood cells; concentration of hemoglobin, hematocrit, so as erythrocytic and thrombocytic indices.

QUANTITATIVE Analysis

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The oxygen – binding capacity of blood is directly proportional to the [?] rather than the red blood cell count.

hemoglobin concentration

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is the most important screening test for diseases associated with anemia and for following the response of these diseases to treatment.

HEMOGLOBINOMETRY

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Makes use of whole blood or plasma

Methodologies

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Difficult to crystallize and accurately weigh hb

Indirect methods

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Gasometric Method Device

Van Slyke Apparatus

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blood = oxygen

(standard conditions of temperature and pressure)

Gasometric Method

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Gasometric Method

Oxygen:
Hemoglobin:

Oxygen: 1.34 ml
Hemoglobin: 1 gram

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Measures only active hemoglobin

Gasometric Method

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iron (blood) +hb

measurement of the iron content reflects the amount of hemoglobin in the blood

CHEMICAL METHOD

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Iron - hb (sulfuric acid +potassium persulfate)

WONG TEST

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Proteins are precipitated by (?), and the iron in the proteinfree filtrates is made to form

tungstic acid
ferric thiocyanate

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measured spectrophotometrically for the amount of iron and thus hemoglobin

ferric thiocyanate

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WONG TEST

iron: (?) gram per (?) gram hemoglobin or per ml of blood

0.347
100
100

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WONG TEST American standard

0.338 gram per 100 gram hb/100 ml blood

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The iron content of whole blood is determined

ASSENDELFT TEST

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Iron - hb ( acid or ashing) =✓ titrated (TiCl3) =✓ complexed (developer) =✓ measured photometrically

ASSENDELFT TEST

Hemoglobin concentration is determined by assessment of blood specific gravity.

GRAVIMETRIC METHOD (Copper Sulfate Method)

GRAVIMETRIC METHOD uses CuSO4 solution made to a specific gravity of

1.053 or 1.055

drop sinks = SG...

equals or exceeds that of the CuSO4 solution

drop rises = SG...

is less

GRAVIMETRIC METHOD Drops of blood are made to fall into a series of (?) having SG from (?) at an interval of

40 CuSO4 solutions 1.035 to 1.075 0.001

16 solutions may be used (?) with an interval of (?)

1.015 to 1.075 0.004

If the SG is the same as that of the solution, it will remain (?) for (?) before it sinks.

stationary 10 – 15 secs

VALUES : (?) for women (corresponds approximately to (?) (?) for men (corresponding to (?) o Normal range : (?)

1.053; 12.5 g/dL 1.055; 13.5 g/dL 1.048 – 1.066

This is used for mass screening.

GRAVIMETRIC METHOD

Based on the use of colour standards with which the red colour of the whole blood is matched.

DIRECT MATCHING METHODS

- utilizes a printed colour scale graded from 10 to 100%

Tallqvist Hemoglobin Scale

- this is matched with the colour of a drop of the patient’s blood on absorbent paper.

Tallqvist Hemoglobin Scale

- highly erroneous because of subjectivity

Tallqvist Hemoglobin Scale

- the percentages on the scale are not accurate

Tallqvist Hemoglobin Scale

- Blood is drawn by capillary attraction between two glass plates, one transparent and the other white and translucent.

Dare Hemoglobinometer

- The colour is matched with a rotating disk on tinted glass varying in thickness and red color intensity

Dare Hemoglobinometer

- Comparison of the transmission of light through a layer of hemolyzed blood (oxyhemoglobin) of constant depth with that of a standardized glass wedge with a transmission of 540 nm (green colour)

Spencer Hemoglobinometer

- The intensity of light is measured rather than the colour.

Spencer Hemoglobinometer

The red cells are laked in dilute HCl, converting hemoglobin into acid hematin (brownish yellow color).

ACID HEMATIN

The preparation id diluted with distilled water until the color of the solution matches that of the comparator block.

ACID HEMATIN

The concentration of Hb is read directly from the gram scale etched on the tube

ACID HEMATIN

produce more homogenous lipid and protein moiety than does the acid hematin method, producing a more accurate solution.

Fairly strong alkali solutions

(COHb, SHb, Hi) are converted to hematin solution.

Inactive hemoglobin components

NaOH: 5 ml of 0.1 N Blood: 0.05 ml of blood -heated in a boiling water bath for 4 - 5 mins -cooled -read against a standard

ALKALI HEMATIN METHOD

(?) of blood + (?) Copper-free – glass – distilled aqueous NH4OH solution in a stoppered cuvette measured with a green filter at (?) nm with (?) as blank

0.02 ml 5 ml 540 0.007 N NH4OH

is measured as oxyhb at 415 nm, the SORET band of maximal absorbance for oxyhemoglobin.

Plasma hb

(absorbance band in the 400-430 nm region of the spectrum – which is actually the region of peak absorbance of heme compounds)

SORET band

Plasma hb is measured as oxyhb at 415 nm, the SORET band (absorbance band in the 400-430 nm region of the spectrum – which is actually the region of peak absorbance of heme compounds) of maximal absorbance for oxyhemoglobin.

HARBOE Method : ALTERNATIVE METHOD

 Uses benzidine derivatives in which hb catalyzes the rapid oxidation of benzidine by hydrogen peroxide

METHOD of NAUMANN

 More sensitive but it is inaccurate because normal plasma contains hydrogen peroxide inhibitor, and benzidine is carcinogenic

METHOD of NAUMANN

 Blood is diluted in a solution of K(FeCN)6 and KCN.

CYANMETHEMOGLOBIN (HiCN) Method

 The K(FeCN)6 oxidizes hb to Hi and KCN provides cyanide ions to form HEMIGLOBINCYANIDE (HiCN), which has a broad absorption maximum at a wavelength of 540 nm.

CYANMETHEMOGLOBIN (HiCN) Method

DRABKIN’S REAGENT  K(FeCN)6 = 0.200 g  KCN = 0.050 g  KH2PO4 = 0.140 g  Non – ionic detergent = 1 or 0.5 ml Dilute to 1L with distilled water

 20 ul of whole blood + 5.0 ml of DRABKIN’s Reagent  Incubate for atleast 3 mins at room temperature Absorbance read at 540 nm

DRABKIN’S METHOD

 Corrected by adding 20 ul of patient’s plasma to Drabkins reagent to be used as blank

Lipemia

 Corrected by centrifuging test mixture and determining the hb in the supernatant fluid

Extremely high WBC counts (>30 x 109/L)

 These provide resistance of cells to hemolysis causing now turbidity.

Hb S and Hb C

 Correction is done by diluting Hb mixture 1:2 by taking 1 part and adding one part of distilled water.

Hb S and Hb C

 The absorbance reading must be multiplied by the dilution factor which is 2.

Hb S and Hb C

 Corrected by replacing NaHCO3 with KH2PO4

Easily precipitated globulins (WM, MM)

(?) in heavy smokers prolongs formation of HiCN to 1 hour. Readings taken at the normal pace cause erroneous results

Carboxyhemoglobin

 Denotes the percentage of erythrocytes in a known volume of whole blood centrifuged at a constant speed for a constant period of time.

Hematocrit

A small amount of whole blood is centrifuged to determine maximum packing of erythrocytes, expressed as PCV or Hct.

MICROHEMATOCRIT METHOD

MICROHEMATOCRIT METHOD SPECIMEN REQUIREMENTS

 Anticoagulated Whole Blood (EDTA)  Capillary blood collected in Heparinized Capillary Tubes  Specimens should be stored at room temperature and be processed within 6 hours after blood collection.

MICROHEMATOCRIT METHOD REAGENTS and EQUIPMENTS

 Capillary hematocrit tubes (with red band or plain)  Non-absorbent sealing clay  Microhematocrit reader device  Microfuge with an RCF of 10,000 to 15,000 g

PROCEDURE 1. Fill atleast two capillary tubes approximately (?) full. 2. (?) the unfilled end. 3. (?). 4. Determine microhematocrit value using the (?) 5. Results should agree within (?) for duplicates.

2/3 Seal Centrifuge microhematocrit reader 0.02L/L

MICROHEMATOCRIT METHOD NORMAL VALUES  VARIATION dependent on age and gender of the population o Birth : o Age 1 : o Adult Female : o Adult Male :

o Birth : 45%-60% o Age 1 : 27%-44% o Adult Female : 37%-47% o Adult Male : 40%-55%

MICROHEMATOCRIT METHOD Significant Correlations: Increased

 Polycythemia  Hemoconcentration due to shock  Dehydration

MICROHEMATOCRIT METHOD Significant Correlations: Decreased

 Anemia  Physiologic hydremias of pregnancy

MACROHEMATOCRIT METHOD: Specimen

 Anticoagulated whole blood o EDTA o Ammonium Potassium Oxalate

MACROHEMATOCRIT METHOD PROCEDURE  Fill the (?) to 0 mark using a disposable pipette. The column should be bubble free  Place tube in the rack and set timer for  After 60 minutes, read using the (?) on the right. (10 – 0)

wintrobe tube 60 minutes scale

 1 hematocrit point =  1 hematocrit point =

0.34 gram hb/100 ml of blood 107,000 red blood cells/cumm of blood

 applicable only to normocytic, normochromic red cells  Used as a random check

Rule of Three

MACROHEMATOCRIT METHOD BASIC EQUATIONS

 3 x RBC = Hb  3 x Hb = Hct (+/- 3%)

decreases Hct values because of shrinkage of rbcs

 Excess anticoagulant

may increase of decrease Hct depending on which part of the specimen (plasma or cells) is principally drawn into the microhct tube

 Insufficient mixing of blood prior to obtaining Hct sample

decreases Hct because of leakage of specimen; erythrocyte loss is greater than plasma loss

 Improper sealing of capillary tube

increases Hct. Results should be read within 10 mins after centrifugation.

 Inadequate centrifugation or allowing tubes to stand too long after the centrifugation

increases the Hct.

 Including a large buffy coat in the reading

increases or decreases the reading

 Improper use of the microhematocrit reader

may damage the blood sample.

 Heat sealing of capillary tubes

may cause the Hct to be falsely increased by as much as 0.02 L/L.

 Trapped plasma

is the small amount of plasma that remains in the rbc portion of the spun. (sickle cell anemia, hypochromic anemia, spherocytosis, macrocytosis, and thalassemia)

Trapped plasma

(spherocytes and sickle cells interfere with rbc packing)

 Certain abnormal rbc shapes

Hct and Hb appear normal; therefore, unreliable for evaluation of anemia immediately following acute blood loss.

 During the first few hours of acute blood loss

which decreases plasma volume  Specimen collection errors may alter the results

 Dehydration increased Hct because of fluid loss

introduction of interstitial fluid to the sample causes falsely decreased Hct.

Hemoconcentration increases Hct

blood: 1:251 dilution NH4OH: 0.007 N

OXYHEMOGLOBIN METHOD

The water used in the preparation of ammonia solution must be glass distilled because minute amounts of copper in distilled water or other diluents employed will allow HbO2 to be converted to Hi and lower the values

OXYHEMOGLOBIN METHOD

ensures mixing and oxygenation of hemoglobin

Shaking

PRELIMS POST-LAB Flashcards

(95 cards)