Cyanmethemoglobin Flashcards
The cyanmethemoglobin is said to be the method of choice for hemoglobin determination because:
- Cyanmethemoglobin is stable in dilutions.
- Cyanmethemoglobin standard are readily available.
- All hemoglobin derivatives except sulfhemoglobin are measured with their conversion to cyanmethemoglobin.
Principle of Cyanmethemoglobin Method:
- Hemoglobin iron is converted from ferrous to ferric state to form methemoglobin by the action of ferricyanide.
- Methemoglobin then combines with potassium cyanide to produce the stable cyanmethemoglobin which is measured spectrophotometrically.
Complete the statement:
Hemoglobin iron is converted from _____ to _____ state to form methemoglobin by the action of ferricyanide.
Ferrous
Ferric
Complete the Statement:
Hemoglobin iron is converted from ferrous to ferric state to form _____ by the action of _____.
Methemoglobin
Ferricyanide
Complete the statement:
_____ then combines with potassium cyanide to produce the stable cyanmethemoglobin which is measured spectrophotometrically.
Methomoglobin
Complete the statement:
Methemoglobin then combines with _____ to produce the stable cyanmethemoglobin which is measured spectrophotometrically.
Potassium cyanide
Complete the statement:
Methemoglobin then combines with potassium cyanide to produce the stable _____ which is measured spectrophotometrically.
Cyanmethemoglobin
Patient Preparation:
- Explain the test purpose.
- If your blood sample is being tested only for hemoglobin, you can eat and drink normally before the test.
Materials needed:
Anticoagulated blood
Test tubes
Pipette
Spectrophotometer
Drabkin’s reagent
Cuvette
Write down the step-by-step procedure in the Cyanmethemoglobin Determination:
- Place 5 ml of Drabkin’s reagent into a test tube.
- Using Sahli pipette, draw blood to 0.02 cc mark. Make sure to wipe the outer wall of the pipette, and then dispense the blood to the test tube.
- Gently draw up and down to rinse the pipette and also to mix the resulting colloidal suspension.
- Cover and mix well by inversion. Let it stand for 5 minutes.
- Transfer the mixture to a cuvette.
- Set the spectro to 100% transmittance at the wavelength of 540 nm. Using a cyanmethemoglobin reagent blank.
- Continue reading the patient’s sample and record the percentage transmittance.
How many ml of Drabkin’s reagent is transferred into the test tube?
5ml of Drabkin’s reagent
How many cc of blood is needed to be transferred to the test tube with Drabkin’s reagent?
0.02cc of blood
After we cover and mix the solution of Drabkin’s reagent and blood into the test tube, we let the solution stand for how many minutes?
5 minutes
Complete the statement:
We set the spectrophotometer into _____ transmittance at the wavelength of _____.
100%
540 nm
Formula to get the Abs:
Abs = 2-log (%T)
Formula for the Conc of Unknown:
Conc of Unknown: (abs of unknown/abs of std) x value of std
Reference value for Male:
13.5 - 18.0 g/L
Reference value for Female:
12 - 15 g/L
Clinical Implications:
- Decreased Hgb levels are found in
Anemia. - Increased Hgb levels are found in: Polycythemia vera, congestive heart failure, and chronic obstructive pulmonary disease.
Complete the Statement:
Decreased Hgb levels are found in _____.
Anemia
Complete the Statement:
Increased Hgb levels are found in _____, _____, and _____
PV
CHF
COPD
Sources of Errors:
- Errors inherent in the sample:
a. Blood sample collected through improper venipuncture
b. Blood sample collected through improper skin or capillary puncture technique. - Errors inherent in the method.
- Errors inherent in the equipment:
a. The accuracy of the equipment is not uniform
b. Unmatched cuvettes
c. Improper standardization of the photometer or colorimeter - Operator’s error – human errors
Human errors can be reduced by:
- Understanding the clinical significance of the test and the necessity for a dependable method
- Adherence to oral and written instructions
- Familiarity with the equipment and with the sources of error
Identify what Step Number:
Place 5 ml of Drabkin’s reagent into a test tube.
Step 1
Identify what Step Number:
Using Sahli pipette, draw blood to 0.02 cc mark. Make sure to wipe the outer wall of the pipette, and then dispense the blood to the test tube.
Step 2
Identify what Step Number:
Gently draw up and down to rinse the pipette and also to mix the resulting colloidal suspension.
Step 3
Identify what Step Number:
Cover and mix well by inversion. Let it stand for 5 minutes.
Step 4
Identify what Step Number:
Transfer the mixture to a cuvette.
Step 5
Identify what Step Number:
Set the spectro to 100% transmittance at the wavelength of 540 nm. Using a cyanmethemoglobin reagent blank.
Step 6
Identify what Step Number:
Continue reading the patient’s sample and record the percentage transmittance.
Step 7
