Saturday, August 18, 2007

 
Subject Title: Clinical Chemistry

Name of Test: Paediatric Bilirubin Measurement

Principle of Test: Using LEICA UNISTAT Biliruninometer

This is a direct spectrophotometer that measures total bilirubin in neonatal serum samples. Light is passed through the sample cuvette. The beam is split by a dichroic mirror and directed towards the 460nm and 550nm filters. The transmittance of the light exiting of the filters is measured by the photodetectors. Total bilirubin is calculated based on the output from the photodetectors.

Procedure:

1. Specimen is collected in a heparinised capillary tube that is sealed at the end and firmly affixed onto a wooden spatula to prevent breakage. As it is light sensitive, it should be protected from light to avoid photolysis of the bilirubin.
2. The capillary tube is place in pre-labeled tube according to the number assigned and spun down to separate serum.
3. The serum is then expelled in the clean cuvette by safepette and measured in bilirubinometer.
4. Result is obtained directly from the display.
5. Results have to be reported immediately by calling up the wards.

- To avoid errors in readings, the outside surface of the cuvette must be free of serum, dust, dirt and smudges; clean if necessary.
- The sample seen in the clear rectangular area of the cuvette must be free of bubbles, tap the cuvette lightly to clear them.

Test results/Reference ranges:

0-1 days : 0-86 umol/L
1-2 days : 0-122 umol/L
3-5 days : 0-175 umol/L
>6 days : 3- 24 umol/L

Clinical Interpretation:

Jaundice is a common, temporary and usually harmless condition in newborn infants. It affects both full-term and premature babies, usually appearing during the first week of the baby's life.

Jaundice occurs when there is a build-up of a naturally bilirubin in the blood. Bilirubin is an orange/red pigment which is produced by the breakdown of haemoglobin. As bilirubin begins to build up, it deposits on the fatty tissue under the skin causing the baby's skin and whites of the baby's eyes to appear yellow.

Severe hyperbilirubinemia is of great concern because it may lead to bilirubin-related brain damage (Kernicterus).

Performing bilurubin test is the first step in making sure that normal degrees of jaundice do not become more severe and can be treated early.

Treatment:

Bilirubin is destroyed by u.v light, phototherapy.


Loh Mun Jo-anne
TG02
0503324F

Comments:
Hi Jo-anne
Why is 460nm & 550nm filters used? Why not other sizes? See u =)

Eugene Wong
TG02
 
hey Joanne

While expelling the serum into the cuvette, what if red cells get in? will the results be affected? what's the significance?

P.S Geoges soon :)

phuiyuen
 
Hi Jo-anne,

You published such interesting post. Here are some of my queries:

Does this Biliruninometer produce false positive results besides false negatives like when the sample is exposed to U.V light?

How does normal room light compared to U.V light affects the viability of bilirubin in sample?

Is the machine able to run EDTA samples instead heparinised samples ( ie use plasma instead of serum) because to my knowledge some machines in the blood bank that I'm attached to are very sensitive to this condition of samples.

Cheero! ^_^

Loh Sharon, Tg 01
 
Hey

Just a simple question here.

You mentioned that the test 'Paediatric Bilirubin Measurement' is done using the 'LEICA UNISTAT Biliruninometer'[or shud it be Bilirubinometer?? :)].

Anyways, is the machine specifically used for just paediatrics or are adult specimens also tested using the same machine?

Thank you

Azhar
TG01
 
To eugene,

er, the analyzer came like that. haha. so.. i guess its just like that.

To Phui Yuen,
actually we will try to expel only the serum. If red cell enter, the results will be high. If the serum is not enough, we will report inadequate vol and another specimen will be requested.

To Sharon,
hmm, it can produce false results, both positive and negative.

it can affect the viability of the sample when exposed to normal light, but not to a great extent. but its advisable to keep it away from light.

i think that plasma can be used as well because what the analyzer is testing is bilirubin and anticoagulants used usually do not contain bilirubin.


To Azhar,

only neonatal samples can be tested. In adults, their serum may contain certain drugs or pigments that affect the results.
 
hi,
will there be any follow uptest for those jaundice positive cases?

thanks,
chenghong
 
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