Okie, time to blog again. I am attached to the biochemistry lab for this two weeks. During the campus discussion week, i've shared about G6PD deficiency testing. Now, i am going to blog on another test done in the biochem lab.
Except G6PD, most of the things done here make use of machines for testing. Neonatal Total Bilirubin is one of them that uses machine to analyse the results.
Background infor
We've learned how bilirubin is formed in school already. In case some of us forget, here is brief explanation of the process. Haemoglobin in the body is broken down into heme (iron and porphyrin) and globin (protein). Iron and protein are then re-utilized by the body while heme goes through a metabolic degradation where the porphyrin ring opened up to form biliverdin. Biliverdin is then further reduced to bilirubin, where it is transported to the liver via the plasma. It is in the liver where it conjugates with glucuronic acid to form bilirubin diglucuronide and excreted into the bile and then goes into the intestine. It will then reduced to form urobiliogen by the action of intestinal bacteria.
So, in this test, the sample that is collected is blood. The blood has to be spin down such that the plasma could be obtained to test for the bilirubin level.
Clinical Significance
When blood contains excessive bilirubin, it gets deposited in the tissues and cause the shade of yellow. It is also referred as jaundice or icterus. This condition may be due to 3 reason. 1) The bilirubin produced is more than the kidney can process and excrete. ( Hemolytic disease) 2) Having liver damage which resulted in inability to excrete normal amount of bilirubin produced. 3) The liver’s excretory ducts are obstructed and blocked.
Jaundice in the infants are quite common as their liver are immature or inefficient. Due to the deficient liver enzymes, the liver could not conjugate the bilirubin. The condition gets better when the liver is more matured and the enzymes are more functional. Possible treatment for the babies are phototherapy.
The bilirubinometer is used to measure the total bilirubin in the plasma of newborns. By measuring the absorbance of the plasma at 460nm, the concentration of bilirubin can be determined.
Methods
1) A heel prick is done and blood is collected via the capillary tube through capillary action.
2) A capillary tube is used to collect the blood of the newborn. When it is received in the lab, make sure that one end of the tube is properly sealed.
3) The capillary is placed in a plastic tube in the centrifuge in spin down at 3000rpm for 3 minutes. (make sure that one end of the tube is sealed and sealed end placed facing down)
4) Plasma should be visible at the top of the tube.
5) Spring-lock the capillary into a dispenser and slowly inject the plasma into a clean cuvette. ( Make sure there is no air-bubbles)
6) The capillary tube is then discarded and the cuvette is loaded into the bilirubinometer.
7) The measuring chamber will rotate downward to align the plasma of the patient to the optical path and results will be shown.
8) The results are to be recorded on the request form for entering into the system later on.
* If the reading exceeds the critical value of more than 300µMol/L, the test have to be repeated.
