Terezinha P. Munhoz

Lamellar Body Count and Stable Microbubble Test on Gastric Aspirates from Preterm Infants for the Diagnosis of Respiratory Distress Syndrome

Background: Lamellar body count (LBC) in amniotic fluid is being used to identify infants at risk of respiratory distress syndrome (RDS) who would benefit from surfactant prophylaxis or very early therapy. The test in gastric aspirates of newborns has not been properly explored. Objective: The main objective of this research was to evaluate the performance of LBC alone or in combination with the stable microbubble test (SMT), done on gastric aspirates from preterm babies to predict RDS. Methods: A total of 34 preterm infants with RDS and 29 without RDS, with a gestational age between 24 and 34 weeks, were included in the study. Gastric fluid was collected in the delivery room. A diluent (dithiothreitol) allowed all samples to be processed, even the thickest and non-homogeneous ones, without centrifugation. The SMT was done for comparison. Results: The best cut-off value was <42,000 lamellar bodies/µl to predict RDS, with a sensitivity of 92% (95% CI 73–100%) and specificity of 86% (95% CI 77–95%). The area under the receiver-operating characteristic curve was 0.928 (95% CI 0.86–0.99). SMT showed similar results. LBC and SMT together in series (positive result if both tests were positive) showed a sensitivity of 100% and a specificity of 86%. Conclusion: LBC on gastric aspirates diluted in a solution of dithiothreitol can be rapidly and easily performed, and may be used alone or in combination with SMT as a predictor of RDS, allowing selective prophylaxis or very early treatment only in surfactant-deficient newborns.

Lamellar body count and stable microbubble test on tracheal aspirates from infants for the diagnosis of respiratory distress syndrome.

Objectives: To evaluate the performance of lamellar body count in tracheal aspirates from intubated preterm babies to predict respiratory distress syndrome. Design: Case-control study. Setting: Three neonatal intensive care units. Patients: Seventy-two patients not older than 3 days were included in the study, 38 preterm infants with respiratory distress syndrome, 16 preterms without respiratory distress syndrome, and 18 term infants. All required mechanical ventilation. Interventions: Lamellar body count was performed in an automated cell counter. Tracheal samples were diluted in dithiothreitol without centrifugation and kept frozen at −20°C until use. Samples were placed in a dithiothreitol-containing test tube at a ratio of one part tracheal aspirate to six parts dithiothreitol solution, vortexed for 10 secs, and aspirated by the cell counter. Lamellar body count was performed using the platelet channel. All results were multiplied by seven. The stable microbubble test was done for comparison. Measurements: Lamellar body count and stable microbubble test. Main Results: Lamellar body count was significantly lower in the respiratory distress syndrome group compared with the non respiratory distress syndrome preterm group and also with the term group. The median and interquartile range obtained for lamellar body count were 38,500/&mgr;L (14,000–112,000) for the respiratory distress syndrome group, 822,500/&mgr;L (442,000–962,500) for the non respiratory distress syndrome preterm group, and 633,000/&mgr;L (322,000–1,608,000) for the term group (p < .001). The sensitivity and specificity of lamellar body count and stable microbubble test for the diagnosis of respiratory distress syndrome were calculated, taking into consideration the respiratory distress syndrome and the non respiratory distress syndrome preterm groups. Considering a cutoff point of 200,000 lamellar bodies/&mgr;L, lamellar body count sensitivity was 92.1% (95% confidence interval 78.6–98.3) and lamellar body count specificity was 93.8% (95% confidence interval 69.8–99.8). The area under the curve was 0.94 (95% confidence interval 0.84–1.00). Conclusions: Lamellar body count and stable microbubble test can be rapidly and easily performed on tracheal aspirates and they seem to have very good performance for diagnosing respiratory distress syndrome in intubated patients.

Validation of the Sysmex sp-1000i automated slide preparer-stainer in a clinical laboratory

Background The speed and quality of information have become essential items in the release of laboratory reports. The Sysmex®SP1000-I device has been developed to prepare and stain smear slides. However, for a device to be cleared for use in the laboratory routine it must pass through a validation process. Objective To evaluate the performance and reliability of the Sysmex® SP-1000i slide preparer-stainer incorporated into the routine of a hospital laboratory in Porto Alegre. Methods Peripheral blood samples of patients attending the laboratory for ambulatory exams with leukocyte counts between 7000/°L and 12,000/°L were evaluated, independent of gender and age. Two slides were prepared for each sample using the Sysmex® SP-1000i equipment; one of the slides was used to perform quality control tests using the CellaVision® DM96 device, and the other slide was used to compare pre-classification by the same device and the classification performed by a pharmacist-biochemist. Results The results of all the slides used as controls were acceptable according to the quality control test as established by the manufacturer of the device. In the comparison between the automated pre-classification and the classification made by the professional, there was an acceptable variation in the differential counts of leukocytes for 90% of the analyzed slides. Pearson correlation coefficient showed a strong correlation for band neutrophils (r = 0.802; p-value < 0.001), segmented neutrophils (r = 0.963; p-value < 0.001), eosinophils (r = 0.958; p-value < 0.001), lymphocytes (r = 0.985; p-value < 0.001) and atypical lymphocytes (r = 0.866; p-value < 0.001) using both methods. The red blood cell analysis was adequate for all slides analyzed by the equipment and by the professional. Conclusion The new Sysmex®SP1000-i methodology was found to be reliable, fast and safe for the routines of medium and large laboratories, improving the quality of microscopic analysis in complete blood counts.

New red blood cell and reticulocyte parameters and reference values for healthy individuals and in chronic kidney disease

Introduction: The importance of local references values has been well described in the literature; this is because the characteristics of the population may influence the laboratory tests. Objective: To establish the reference range for traditional and extended red blood cell parameters and reticulocyte indices in order to investigate its application in patients with chronic kidney disease (CKD). Materials and methods: 249 blood donors (125 males and 124 females) were selected to establish the reference values. The hemodialysis sample consisted of 62 patients with terminal CKD (48 male and 14 female). All analyzes were performed using the Sysmex XE-5000 automated hematology analyzer. Results: Differences between reference values was observed in relation to gender: red blood cells (RBC), hemoglobin (HGB), hematocrit (HCT), mean corpuscular hemoglobin concentration (MCHC), percentage of hyperchromic red blood cells (%HYPER), percentage of microcytosis (%MICRO), percentage of macrocytosis (%MACRO), absolute reticulocyte count (RET), reticulocyte hemoglobin content (RET-He), immature reticulocyte fraction (IFR), low fluorescence reticulocytes (LFR), medium fluorescence reticulocytes (MFR), and high fluorescence reticulocytes (HFR). Individuals with CKD presented RBC, HGB, HCT, MCHC, red cell distribution width expressed as coefficient of variation (RDW-CV), percentage of hypochromic red blood cells (%HYPO), percentage of reticulocytes (RET%), RET (female group), IFR, LFR, MFR, and HFR results compatible with the anemic state, which can be observed in 91.8% of patients. All studied parameters were in the area under the curve (AUC) > 0.4. In male group, %HYPO (AUC: 0.806) and IFR (AUC: 0.762) presented higher AUC values, while female group presented %HYPO (AUC: 0.806), %HYPER (AUC: 0.815), and IFR (AUC: 0.660). Conclusion: The medical advancement, the development of new techniques and hematological parameters have revealed important information about functional integrity of bone marrow, diagnosis of anemia and recombinant human erythropoietin monitoring therapy used in hemodialysis patients.

Mean Platelet Volume and Immature Platelet Fraction in Autoimmune Disorders

Mean platelet volume (MPV), measured using automated blood analysers, has been appraised as a potential biomarker in cardiovascular disease, diabetes mellitus, and cancer. The test, a useful tool in differentiation of thrombocytopenic states, has now been carried out for autoimmune disorders, but data are yet scarce. Controversial results have been obtained in systemic and organ-specific autoimmune disorders. Another test, the immature platelet fraction (IPF) reflects the amount of young, reticulated platelets. IPF is calculated by automated hematology analysis or flow cytometry, and it is usually high in patients with rapid platelet destruction. For both MPV and IPF, standardization of cutoff is a major need. In this review, we focus the current applicability of MPV and IPF as biomarkers in patients with autoimmune diseases.