Evaluierung des hCG-Immunoassays am Immulite 2500

This dissertation describes an evaluation of Immulite 2500 hCG Assay. Multiple hCG-related molecules (ßhCG, HhCG, nhCG) are present in serum and urine samples. There is a high degree of structure similarity with luteinizing hormone (LH). This is the source of potential problems with detecting hCG. Recognition of hCG is a sure method to detect pregnancy, because it is produced by trophoblast tissue of placenta. In patients with gestational trophoblastic diseases, testicular tumours and extragonadal carcinoma, hCG is elevated. Within-run imprecision (n=20) was determined with patient samples of 4 different concentrations and for the specified control materials (3 different levels). Betweenrun imprecision was done with control material (3 different levels) and patient samples of 3 different concentrations. In addition carry over and linearity studies were done. The Advia Centaur (Bayer) was used for Method comparison (n=182) and calculations were done according to Bablock/Passing and Bland/Altman. We examined the stability about 2 days and we tested 20 serum of patients with testicular cancer. The coefficients of variation (CVs) for the intra-asssay imprecisions were between 3.7%, and 5.6% for the control samples and between 3.0% and 8.5% for the patient samples. The coefficients of variation (CVs) for the inter-asssay imprecisions ranged from 5,56% until 9,57% for the control samples and from 5.9% until 15.1% for the patient samples. Linearity was tested up to 83 424mlU/ml, with r = 0.9996 (1st approach) and r=0,9968 (2nd approach). High concentrated (mean of 9364mlU/ml and 70 174,55mlU/ml), and low concentrated samples (mean of 7.2mIU/ml and 7,76mlU/ml) were measured alternately. The low concentrated sample didn’t increase, so there wasn’t any carry over detected. Method comparison with the Advia Centaur (Bayer) for 182 patients with sample concentrations between 1.18mlU/ml and 102379 mIU/ml showed a good correlation coefficient of r=0.9896 (for the range <1mlU/ml until 5000mlU/ml). For the range <1mlU/ml until >100 000mlU/ml there was measured a good correlation of r=0,9997. According to Bland/Altman the Immulite 2500 measured lower than ADIVIA Centaur over the whole analytical range. In regard to the good analytical performance, the short time-to-first-result of 15 minutes, the easy fast operation, qualifies the immunoassay analyzer as a practicable routine diagnostic for pregnancy tests.