|
|
The aspects of laboratory diagnostics of neonatal jaundice, the comparison of two laboratory methods and POCT method of determination of bilirubin.
SLÁMOVÁ, Martina
The topic of my Bachelor Thesis was laboratory diagnostics of newborn jaundice. It consists in determining full blood or plasma bilirubin concentration. I assessed the cross-correlation and the possible interchangeability of two laboratory methods based on different principles of determination, in different types of biological material, by means of statistical evaluation of lab results. I treated the topic of bilirubin determination in newborns from a complex perspective, and I included a comparison of POCT bilirubin level measurements with lab-determined blood bilirubin concentrations in the assessment. The theoretical part contains general facts about types of icterus and about bilirubin metabolism in the organism. It also contains information pertaining of newborns jaundice as such. I have described the causes, the health risks for the newborn implied by their hyperbilirubinemia, and I have also specified the possible therapy. I have collected the backgrounds for the assessment of the methods of bilirubin determination experimentally. The population consisted of normal term and pre-term babies, 37 of whom were treated with phototherapy during the experiment. I determined the bilirubin concentration in a full blood sample by means of direct photometry on a Cobas b221 analyzer. I centrifuged the remaining material in the collecton tube, and I determined the bilirubin concentration in the separated plasma by chemical azo coupling method on the Integra 400 plus analyzer. The POCT measurements were carried out by the pediatric nurses on the department before every blood sampling. They were non-invasive bilirubin measurements in newborns by means of the transcutaneous bilirubinometer JM-103 Konica Minolta Hill-Room Air-Shields. In order to assess the correlation of results, I used the linear regression (Passing-Bablok) statistical method, and the difference chart (Bland-Altman) method. The statistical evaluation implies that the lab methods show very good mutual correlation, which can be expressed with a correlation coefficient of r = 1,025 and a mean difference of -1,41 umol/l. I used direct photometry method as a comparison method to assess the bilirubin measurements done by the POCT method. While the correlation coefficient reached the value 0,803, the average difference between both methods amounted to -45,6 umol/l. This data clearly shows that newborn bilirubin levels measured by transcutaneous bilirubinometer are lower compared to the bilirubin concentration determined by the lab method. Many studies imply that bilirubin measurements in the POCT mode using transcutaneous bilirubinometer often yield rather underestimated results. Measurement results from the discrimination range must be re-checked in the lab. Transcutaneous measurement of newborn bilirubin is a reliable screening method eliminating the numerous blood takings in newborns. Making transcutaneous measurements during phototherapy conditions is not generally recommended, which was confirmed by my experimental results. The only way of how to monitor the effect of this therapy while the therapy is going on, is by means of lab determination of bilirubin concentration. The results of my study imply that full blood bilirubin concentration determination by direct photometry method in newborns correlates excellently with the plasma determination by the chemical method. This method is fully capable to be used as a substitute for the chemical method. I prefer full-blood determination method. The examination requires only a small quantity of the sample, the sample does not require separation before analysis, the result is available quickly, and analyzer operation and maintenance are simple. Analyzers of this type, equipped with modules for direct bilirubin measurement in newborns are often used as POCT instruments near the patient?s bed.
|
guest ::
