I am posted to the biochemistry/clinical chemistry section of my lab for 2 weeks. For this 2 weeks, I have been doing 2 kinds of major test on EDTA-coagulated blood specimens. One is G6PD and the other is HbA1c Quantitation. I will be putting up a post regarding HbA1c Quantitation.
At the end of my first week, I have learnt a new constituent in the blood, which can be tested. It is HbA1c or Glycosylated (or glycated) hemoglobin. Glucose in the blood stream will normally be attracted to the haemoglobin part at the lysine molecule of the RBC to form glcosylated haemoglobin. Thus the amount of HbA1c is directly proportional to amount of glucose, meaning that if there are more glucose present in the blood, the more HbA1c will be present in the blood. It’s a known fact htat RBC has a half-life of about 3 months before they are replaced by the spleen. Hence by measuring the percentage of HbA1c in the blood, we can determine how high the patient’s blood glucose has been on average over the last 3 months.
Currently HbA1c is the best suitable way to monitor the progress of medication for patients suffering from diabetes mellitus. It is also able to determine the appropriate dosage quantity of anti-diabetic drugs do administer to patients so as to effectively reduce glucose blood level and reduce possible side-effects.
I am now working in a company who uses a machine manufactured in Japan to quantitate in percentage the amount of HbA1c in the blood specimen. Me as a lab technician,I am required to load the blood specimen manually. However before loading the blood specimen, I am instructed to shake and mix well every blood specimen and it is important to remove any air bubbles present using a disposalable plastic pipette. This is becase the machine has a laser to detect the level of blood in the tube,it will not go all the way to the bottom to aspirate blood. Thus presence of air bubbles will give false level of blood detection, causing inaccurate amount of blood aspirated, in the end causing false results.
The principle of my company’s machines is as follows; the concentration of HbA1c and the concentration of total haemoglobin in the blood sample are measured separately, and then the ratio is reported as percentage of HbA1c. A latex agglutination inhibition method is used for measurement of specific HbA1c. The total haemoglobin is then measured using the toral haemoglobin reagent where all derivatives are converted into alkaline hematin in an alkaline solution of a non-ionic detergent.
By Ivan Ng
TG01
0605070B
11.40pm
4 July 2008 (Friday)
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8 comments:
heys,
hope that you are enjoying your SIP over there!:D
i'm just curious, why do you all have to measure HbA1c to find out the glucose level when you can directly measure the amount of glucose?
Isit to find out the average amount of glucose over 3 months? Is there more advantages of measuring HbA1c?
Thanksss!:D
Neela
TG02
Group 9
hello bro,
how does the latex agglutination inhibition method works? and how do u calibrate your machines? within runs or between runs?
yuxuan
Reply to Neela:
HbA1c is usually used for patients who are already diagnosed as diabetic. Normally it is to determine the effectivity of the anti-diabetic drug. In addition, the doctor would have normally assigned a controlled diet to the patient to control his/her diabetic condition. However, some patients may not follow. For example, henry is a diabetic patient, he did not follow the strict diet and the instructed medication, if u test his blood for glucose directly,obvioulsy its high. However on the day before he go to the doctor for a check-up blood test, he took the medication, this will naturally reduce the glucose level in the blood. thus shows a reduce in glucose level. This will be a false indication that the drug is effective. HbA1c is to determine if the drug dosage used is appropriate and most importantly to see if the patient is following the strict diet and instructed medication for the past 3 months. This is becase the red blood cells have a half-life of 3 months and glucose is bounded to the haemoglobin part of the lysine molecule.
By:Ivan
heyyyss...
Thanks for ur explanation.It was clear and i understood well.
thx huh!
enjoy ur SIP!
Neela:D
hello!
i've got a dumb question but i really need to know that.
what is HbA1c?
Thanks!
Chew Yu Mei
TG01
Reply to Yu Mei,
HbA1c is just a term or short termed formed to refer to Glycosylated (or glycated) hemoglobin, whereby glucose is attracted to the haemoglobin part at the lysine molecule of the RBC.
From Ivan.
Reply to Yu Xuan,
Calibration is not done according to schedulled. It is done when it is appropriate and when the need arises. Normally, calibration is done when there is a change in the control reagent lot/batch or test reagent lot. Calibration is also done when the L/J chart shows deviation according to westgurad rule.Latex agglutination inhibition is the methodology used by the machine to quantitate HbA1c. The principle of the machine and latex agglutination inhibition is the same. The total haemoglobin is measured using the total haemoglobin reagent where all derivatives are converted into alkaline hematin in an alkaline solution of a non-ionic detergent.
From Ivan.
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