Use of Heterophilic Blocking Tubes in Suspected Heterophile Antibody Interference Among Pubertal Patients

Background and Objectives: Today, immunoassay methods are still widely used in the analysis of hormone tests. Due to the properties of the reagents used in immunoassay analyses and components other than the measured analyte, deviations in clinical results may occur. There are many factors that cause this condition called interference, and one of the most common of these is heterophile antibody (Ab). Puberty is a process that begins between the ages of 8 and 13 in girls and 9 and 14 in boys. Pulsatile luteinizing hormone (LH) release during sleep is the first hormonal change that indicates the approach of puberty. The reliability of the laboratory analysis result is important. In order to determine whether there is a risk of interference in the LH tests we analyzed in our laboratory, 48 serum samples of pediatric patients belonging to the pubertal age group were included in the study. Materials and Methods: In order to evaluate the suspicion of heterophile Ab interference, we measured the samples again by binding the antibodies and removing them from the matrix, as recommended in the Clinical and Laboratory Standards Institute (CLSI) I/LA30 guideline. For this, we used a heterophile blocking tube (HBT). We analyzed the samples with Beckman Coulter UniCel DxI 800 and Roche Cobas e601 immunoassay systems. We aliquoted the supernatants of the samples processed according to the HBT application protocol and measured them on both autoanalyzers. Results: We found a significant difference between the results of the samples measured before and after HBT pretreatment on the Beckman Coulter UniCel DxI 800 autoanalyzer (p = 0.01). LH values after HBT were higher than those before HBT: very high LH values were obtained in 4 patients, while the values showed increases ranging from 2 to 4.64-fold in 5 patients. There was no significant difference between the results evaluated before and after HBT pretreatment on the Roche Cobas e601 autoanalyzer (p = 0.27). Although there was a significant difference between the LH results of the HBT-untreated sera obtained in two different autoanalyzers (p < 0.001), we found that the LH measurements after HBT pretreatment did not create a statistically significant difference between the two devices (p = 0.76). Conclusions: We concluded that while HBTs were ineffective in detecting heterophile antibody interference in LH testing, the study underscores the complexity of interference in pediatric hormone assays and highlights the need for further investigation into alternative methods to ensure reliable test results in this age group.