Biochemistry/ Immunology

Hey guys, this is Sally. I'm sorry for this late posting but I'm sure it's worth the wait because I have lots to share. But before I start, let me give you a brieg introduction on what I'm doing. The hospital I'm working in has only one lab and it is divided into different sections such as Admin, Haematology, Biochemistry/Immunology, Microbiology and Cytology/Histology. Needless to say, I'm posted to the Biochemistry/Immunology section and will be staying there for the next few months.

Basically, I get to work with all analysers and machines almost everyday. 95% of my work are automated and so what I simply have to do is to learn on the theory of the tests and the procedures involved in the operating and maintenance of these big machines. Everyday, we receive as many as 500 blood samples from patients and they will request for tests such as renal screen (K, Cl, Na...), lipid profile (glucose, HDL, LDH, triglycerides...), liver test (AST, ALP, creatinine...), HIV and many more. Then, we have to centrifuge the samples (which comes in gel tubes) at 3000rpm for 10 min before loading into the main analysers called Modular P & E. These Modulars will then test for the quantity of the requested analytes using the serum in the tubes. We do not have to order the test manually. This is because the Modulars are linked to the PSM (Personal Security Manager) and the PSM is further linked to the LIS. So when the Modulars scan the barcode label on the tube, the PSM will transmit the requested tests for the particular tube from the LIS to the Modulars and they will straightaway know what tests to do.

After reading this, you may think that my work is much relaxed but it is not like what you think because we have to be extremely careful about this machines. We have to do daily checks and maintenance to make sure that there is sufficient reagents and we run controls many times a day. Furthermore, we always have to check results generated to ensure that they are correct and making sense and even before loading, we have to be able to think quick, because sometimes doctor may send in only a plain tube for many tests and these tests are performed using different machines. If the sample is an urgent one, we still have to remember to load the tube at another machine after it finished processing at the previous one. Sometimes, when the workload is heavy, we may forget about it. So, my supervior will contantly remind us to make sure we did not leave out on any tubes.

The other tests are either manually performed or the preparation procedures are more tedious and they are microalbumin (qualitative) dip stick test, blood gases test, homocysteine, anti-nuclear antibody, rubella, anti-dsDNA test, G6PD test and anti-thyroglobulin test. A few of them are scheduled tests because there are less frequently requested.

Today, I chose to focus on G6PD test because this is a test that I get to perform everyday and I have found alot of information on it.

What is G6PD and what is the purpose of the test?

G6PD is glucose-6-phosphate dehydrogenase and it is an enzyme involved in the metabolic pathway of RBCs. G6PD test is usually performed on newborns and it is to test for any G6PD deficiency. It is an inherited condition which means that unless one of your parents have this condition, if not you will not have this deficiency at all. This condition is mostly seen in males than females.

Procedures of the G6PD test

1. Take two small cups and label one of them "Neg" and the other with the baby's lab request no. Note: Neg means negative control


2. Then take 100ul of G6PD reagent into both cups.


3. For the Neg control, add 2.5ul of the negative control "blood" and mix thoroughly by pipetting up and down.


4. Same for the patient's cup, add 2.5ul of baby's blood into the cup and mix thoroughly.


5. Then on a piece of absorbent paper, label with the word Neg and patient's lab request no.


6. Add one drop of each mixture on the piece of absorbent paper.


7. Repeat step 7 every 5 min for two times.


8. Finally, incubate in the oven at 35 degree celsius for 5 min and observe under long wave UV light.

Pls refer to the above drawing. I will try to take the pic of the real test. But for now, you just have to understand what i'm drawing.

Results

For the Neg control, there should not be any fluorescence seen. However, if you see flourescence on the test using the baby's blood, it indicates that the baby is having the enzyme, G6PD and so he/she is not suffering from G6PD deficiency.

This test is very simple and easy to perform but we must always ensure that before reading the results under the UV light, the absorbent paper must be dry. If not, this may result in false positive result. Simply, you won't see any fluorescence on the patient's test even when he/she is not suffering from this deficiency and you may mistaken the patient as suffering from G6PD deficiency and this can be serious. Therefore, adequate drying is important!

Hope that by now, you have learnt something.

If you have read carefully, I have left out on a few points for you to ask me so please feel free to ask if you are not clear.

Sally, TG02

0503315D