INTRODUCTION:Statistical significance indicates whether an observed finding is unlikely to have occurred by chance but does not quantify the magnitude or clinical importance of that finding. Effect size measures and related quantitative measures complement P values by improving the interpretation of laboratory findings. METHODS:This review examines the principal effect size measures and related quantitative measures used in contemporary laboratory medicine. It explains what each measure quantifies, when it is appropriate to use, and how it contributes to data interpretation. The application of these measures is illustrated using 40 published studies representing diverse diseases, laboratory disciplines, patient populations, and study designs. RESULTS:Across the reviewed studies, these measures consistently provided information beyond statistical significance by quantifying differences, associations, agreement, diagnostic performance, and other analytically important characteristics of laboratory tests. They supported a more comprehensive interpretation of biomarkers, analytical methods, diagnostic tests, and clinical interventions. DISCUSSION:Routine reporting and context-specific interpretation of appropriate effect size measures and related quantitative measures alongside P values should become standard practice in laboratory medicine to improve the interpretation, comparability, and clinical relevance of laboratory research.
INTRODUCTION:No evidence-based preanalytical guideline exists for EDTA blood storage before hemoglobin H (HbH) inclusion body detection. We evaluated the stability of rapid (30-minute) brilliant cresyl blue staining across α-globin and β-globin genotypes in blood stored at 4 °C. METHODS:Residual EDTA blood from 322 patients with microcytic hypochromic anemia was stored at 4 °C and tested on days 0, 2, 4, and 7 by 3 blinded medical technologists. Hemoglobin typing and genotyping followed inclusion body counting. Wilcoxon and Mann-Whitney U tests as well as intraclass correlation coefficient(2,1) were applied. RESULTS:Six α-globin genotype groups were identified, including HbH disease (n = 103), by β-globin genotype background. Non-HbH groups showed no meaningful inclusion bodies, confirming stable specificity. In HbH disease with a normal β-globin gene, 100% qualitative concordance was maintained at day 7, with no statistically significant quantitative change from day 0 (P = .28); the intraclass correlation coefficient(2,1) was 0.858. A transient increase at day 2 (P < .001) may have reflected in vitro HbH autoxidation during cold storage. Hemoglobin H disease co-inheriting HbE showed stable but markedly reduced counts throughout storage; a consistent pattern was observed in isolated cases co-inheriting β-thalassemia. DISCUSSION:EDTA blood stored at 4 °C maintains qualitative stability for HbH inclusion body detection for up to 7 days; HbE co-inheritance substantially reduces diagnostic sensitivity, with a similar pattern observed in isolated β-thalassemia co-inheritance.
INTRODUCTION:Priapism is a penile erection that is sustained beyond or is unrelated to sexual stimulation. Depending on the etiology of the priapism, there may be low blood flow to the tissue, causing ischemic priapism, or high blood flow, called nonischemic priapism. Ischemic priapism is assessed in part by corporal blood gas analysis and should be treated emergently to preserve tissue health and function. Ischemic priapism is a common morbidity associated with sickle cell disease (SCD). METHODS:A 16-year-old male individual presented at the emergency department with priapism. His medical history was clinically significant for SCD and prior episodes of priapism. He was not on medications to manage SCD at that time. Corporal blood aspiration was performed to attempt detumescence, and an aliquot of that blood was sent to the laboratory for blood gas analysis. RESULTS:The blood submitted for analysis was deep red, and blood gas results revealed acidosis, hypercarbia, and hypoxemia. These results were consistent with ischemic priapism and prompted more aggressive treatment and patient monitoring. DISCUSSION:This case illustrates the role of blood gas analysis in the evaluation of priapism. Laboratorians should be aware of this rare sample type that may present with extreme values.
INTRODUCTION:Hemoglobin A1c has a stringent total allowable error (TEa), making high Six Sigma values difficult to attain. In addition, data from ambulatory accredited laboratories are sparse. METHODS:Internal quality control (QC) data for 2 levels were collected over 8 months on a single-lot Bio-Rad D-10 high-performance liquid chromatography analyzer. Long-term imprecision was the coefficient of variation (s/x¯) × 100 (CV) of all internal QC results combined, capturing between-month variation. Bias was derived from external quality assessment (EQAS) and assigned QC targets, applied as absolute values. The Sigma metric was (TEa ‒ absolute bias) / CV at TEa levels of 6%, 7%, and 8%; the Quality Goal Index distinguished imprecision-driven from bias-driven performance. RESULTS:Long-term CVs were 3.04% (level 1) and 1.34% (level 2); EQASs were satisfactory throughout. At a TEa of 6% with EQAS-derived bias, Sigma metrics were 1.19 and 2.70 and, with a level-specific QC target bias, 1.46 and 4.22. At the Clinical Laboratory Improvement Amendments 2025 criterion of 8%, the Sigma metrics were 2.11 and 5.71. The level 1 Quality Goal Index (0.52) identified imprecision as predominant. DISCUSSION:Despite satisfactory external proficiency, Sigma metrics fell below 3 at both levels against a 6% TEa and below 2 at the clinically pivotal lower concentration, driven by imprecision rather than bias. No control strategy compensates for this; therefore, we proposed a precision-focused corrective plan that targets between-month instability.
INTRODUCTION:Application of College of American Pathologists (CAP) standards for molecular next-generation sequencing assays, typically high-complexity laboratory-developed tests, requires assay-specific, principled translation. We sought to systematically apply CAP laboratory-developed test validation requirements for next-generating sequencing to targeted CFTR gene sequencing on an Illumina iSeq100 Sequencing System and to address assay-specific translational guidance gaps. METHODS:We evaluated the analytic performance (accuracy, precision, analytic sensitivity, and specificity) and other requirements (eg, confirmatory testing, proficiency testing) in a CAP-accredited laboratory, including assessment of logistics (eg, turnaround time, cost), with particular attention to feasibility for smaller laboratories. RESULTS:Variant calls showed complete concordance across analytic parameters but, as the sole outcome measure, obscured subthreshold effects of experimental variables and random variability. Critical site depth analysis was essential to reveal these effects. DISCUSSION:Per-sample costs depend on batch size; smaller laboratories can reduce costs through centralization or sample pooling, although pooling requires longer turnaround (weeks to months), even on a iSeq100 system, potentially causing misalignment of CAP proficiency testing and batch schedules. This issue mandates self-evaluation and code 11 selection for CAP proficiency testing submissions. Real-time sample preparation, however, precludes running negative and internal controls with each processing run, necessitating process controls (eg, minor allele frequency, alternate allele determination) and an individualized quality control plan.
INTRODUCTION:Antibodies of the Kidd blood group system are associated with hemolytic transfusion reactions and, less commonly, hemolytic disease of the fetus and newborn. Naturally occurring antibodies against Kidd antigens are exceedingly rare, with a limited number of cases reported worldwide. We report a case of a naturally occurring anti-Jka antibody detected in a 6-month-old male infant. METHODS:The patient was admitted with a high fever after routine age-appropriate vaccinations. He had no history of blood transfusion, underlying disease, or perinatal complications. Blood, urine, and cerebrospinal fluid cultures were negative, while respiratory viral polymerase chain reaction was positive for human coronavirus 229E. RESULTS:As part of the routine admission protocol, blood grouping and antibody screening were performed, and subsequent antibody identification confirmed the presence of anti-Jka. Serologic testing showed a partial reduction in antibody titer after dithiothreitol treatment, consistent with a predominantly immunoglobulin M antibody, with a possible immunoglobulin G component. The infant and his mother shared the Jk(a - b+) red blood cell phenotype, and maternal antibody screening was negative. In the absence of prior red blood cell exposure or maternal alloimmunization, the antibody was interpreted as naturally occurring. DISCUSSION:This case highlights the importance of recognizing naturally occurring Kidd antibodies in infants to ensure transfusion safety.
INTRODUCTION:As an indicator of coagulation function, the effect of circulating fibrinogen on cardiovascular and cerebrovascular diseases has been well studied, but the association between fibrinogen and poststroke epilepsy (PSE) has not. We explored the relationship between circulating serum fibrinogen levels and PSE events in a large sample of patients who had had an acute ischemic stroke in the past year. METHODS:We obtained from the Dryad database the medical records of 21 459 patients who had experienced an ischemic stroke to analyze the association between circulating fibrinogen level and PSE risk. RESULTS:Smooth curve analysis showed a U-shaped association between circulating fibrinogen level and PSE risk in the patients analyzed. The fold point of the circulating fibrinogen level for the association was 2.9 g/L. When fibrinogen levels were less than 2.9 g/L, an increase in fibrinogen contributed to a statistically significantly reduced risk of PSE events (odds ratio, 0.1 [95% CI, 0.1-0.2]; P < .001). In contrast, when fibrinogen levels were higher than 2.9 g/L, an increase in fibrinogen level was related to a higher risk of PSE events (odds ratio, 1.4 [95% CI, 1.2-1.7]; P < .001). DISCUSSION:Circulating serum fibrinogen level had a potential U-shaped association with PSE risk in a large-scale population of individuals who had had an acute ischemic stroke in the previous year.
INTRODUCTION:Complex structural variants in thalassemia are rare and often undetectable or misdiagnosed by conventional genetic testing methods. We report a case initially misclassified by multiplex ligation-dependent probe amplification (MLPA) as a heterozygous ‒α3.7 deletion that was subsequently correctly identified by third-generation sequencing (TGS) as the Hong Kongαα (HKαα)/‒α4.2 genotype. METHODS:Gap polymerase chain reaction (PCR) was used to screen for 4 common deletional α-thalassemia variants (-SEA, -THAI, ‒α3.7, and ‒α4.2). A PCR-reverse dot blot detected 3 nondeletional mutations. We used MLPA to analyze copy number variations in the α-globin gene cluster; TGS characterized large deletions, cis/trans phasing, and complex structural rearrangements. RESULTS:Gap PCR identified the female patient as a heterozygous -SEA carrier. In the male patient, gap PCR showed 3 bands (‒α3.7, wild type, and ‒α4.2), making genotyping uncertain. The MLPA findings suggested a heterozygous ‒α3.7 deletion; TGS revealed coexisting deletion and duplication fragments, leading to the final diagnosis of HKαα/‒α4.2. DISCUSSION:For HKαα and ‒α4.2 coinheritance, gap PCR cannot provide an accurate genotype, and MLPA may erroneously report a heterozygous ‒α3.7 deletion. Third-generation sequencing accurately identified this complex variant, demonstrating its suitability for detecting such structural variants in clinical diagnostics.
INTRODUCTION:This study retrospectively characterized the laboratory features of direct antiglobulin test (DAT)-positive anemia in newly diagnosed multiple myeloma (MM) and explored associated immunologic alterations to better understand MM-related immune dysregulation. METHODS:We enrolled 77 patients with newly diagnosed MM admitted to our hospital between 2021 and 2025. Based on DAT results, patients were assigned to a DAT-positive group (n = 52) or a DAT-negative group (n = 25). Clinical characteristics, laboratory parameters, and peripheral blood T-cell subsets were compared between groups. RESULTS:Monoclonal immunoglobulin (M protein) isotype distribution was statistically significantly different between groups (P < .001), with immunoglobulin G predominating in the DAT-positive group (88.46%). Compared with the DAT-negative group, DAT-positive patients had lower albumin, sodium, and potassium levels as well as a lower albumin to globulin ratio but higher levels of globulin and ferritin as well as higher absolute lymphocyte counts (all P < .05). Flow cytometric analysis showed increased T-cell-related parameters, particularly CD8-positive T cells, in the DAT-positive group, whereas reduced natural killer-cell and B-cell counts were more common in the DAT-negative group. DISCUSSION:The observed laboratory profile suggested a more pronounced state of inflammatory or immune activation and electrolyte disturbances, highlighting the need for improved clinical recognition and detection of potential immune-mediated red blood cell injury, hemolytic predisposition, and related immune abnormalities.
INTRODUCTION:Automated blood cell separators are commonly used for autologous platelet-rich plasma (PRP) preparation. Although these devices ensure stable platelet concentrations, low contamination, and high reproducibility, unified protocols remain lacking. This study explored a collection protocol that uses real-time visual feedback and dynamic parameter adjustment. METHODS:In this single-center retrospective study, we analyzed 35 autologous PRP collections. Visual criteria (pale lemon-yellow appearance, uniform turbidity, absence of macroscopically visible particles) and adjustment rules were developed. Platelet concentration, enrichment factor, and residual red blood cell (RBC) and white blood cell levels were assessed. RESULTS:Median platelet concentration was 1500 × 109/L (IQR, 1031-1618 × 109/L), and the mean (SD) enrichment factor was 6.33 (2.76); 71.43% (25/35) of products fell within a range of 1000 to 1800 × 109/L, consistent with reported 3-fold to 8-fold enrichment. Red blood cell counts ranged from 0 to 0.20 × 1012/L. No macroscopic RBCs were detected, but 37.1% (13/35) of RBCs exceeded a threshold of 0.05 × 1012/L. White blood cell counts ranged from 0 to 1.69 × 109/L, below the leukocyte-poor threshold proposed by Kikuchi et al. DISCUSSION:This study presented a protocol capable of producing PRP within the therapeutic range and achieving effective leukocyte control. Our findings provide a practical strategy for translating subjective experience into objective, trainable procedures. Given the limitations of small sample size and subjective visual criteria, further prospective machine vision validation is warranted.
INTRODUCTION:Hemoglobinopathies are a heterogeneous group of inherited disorders whose prevalence and phenotypic spectrum are influenced by population dynamics and diagnostic strategies. Longitudinal data from nonendemic European regions remain scarce. METHODS:We conducted a retrospective longitudinal analysis of hemoglobinopathies diagnosed at a regional hospital in southern Spain over a 30-year period (1996-2025). Diagnoses were classified as thalassemia syndromes or structural hemoglobin variants and analyzed according to the native or migrant origin of the patient. Temporal trends were assessed in relation to demographic changes and evolving laboratory methods. RESULTS:A total of 5340 hemoglobinopathies were identified: 1716 (32.1%) thalassemias and 3624 (67.9%) structural variants. Migrant patients accounted for 83.8% of diagnoses. Thalassemias predominated among native patients (88.1%), whereas structural variants, particularly hemoglobin S, predominated in migrant patients (78.6%). Annual diagnoses increased more than 5-fold during the study period, particularly after systematic high-performance liquid chromatography screening was introduced in 2008, with cases among migrant patients showing a strong linear trend (R2 = 0.86). DISCUSSION:This 30-year experience demonstrates a major shift in the epidemiology and diagnosis of hemoglobinopathies in southern Spain. Migration and advances in laboratory diagnostics have increased the detection of structural variants and complex genotypes, highlighting the need for continuously updated diagnostic algorithms in increasingly diverse populations.
INTRODUCTION:ABO discrepancies caused by weak A subgroups are uncommon but clinically important because they can lead to mistyping and inappropriate transfusion management. METHODS:We present the cases of 2 patients at an academic medical center who were historically typed as group O but were found to harbor weak A subgroups upon detailed investigation. RESULTS:In case 1, the patient's red blood cells demonstrated weak reactivity with anti-A reagent on forward typing, with anti-A1 and anti-B identified on reverse typing. In case 2, the patient's red blood cells were nonreactive with anti-A reagent on forward typing but did agglutinate with anti-A,B reagent. Reverse typing showed weak reactivity against A1 and A2 cells, with strong reactivity against B cells, consistent with an anti-A antibody. In both cases, molecular genotyping performed at a reference laboratory returned results consistent with an Aw or Ael allele. DISCUSSION:These cases illustrate the serologic spectrum of weak A phenotypes, highlight the variable sensitivity of ABO reagents in detecting minimal antigen expression, and underscore the possible utility of molecular characterization when serologic results are ambiguous.
INTRODUCTION:Acute leukemias of ambiguous lineage, not otherwise specified (ALAL, NOS), represent a rare but clinically significant subset of leukemias characterized by immunophenotypic heterogeneity and an absence of lineage-defining markers. METHODS:We report a diagnostically challenging case of ALAL, NOS, in a 59-year-old man who presented with constitutional symptoms and was found to have marked leukocytosis, anemia, thrombocytopenia, and 96% circulating blasts. RESULTS:Flow cytometry revealed expression of progenitor markers (CD34, HLA-DR, terminal deoxynucleotidyl transferase) with weak and variable expression of B-cell (CD19, CD22), T-cell (CD5, CD7), and myeloid (CD13, CD33) markers. Immunohistochemistry confirmed CD79a expression but lacked the lineage-defining markers myeloperoxidase, CD3, strong CD19, and PAX5. RESULTS:Cytogenetic and molecular testing revealed a constitutional Robertsonian 13;14 translocation and SH2B3 mutations without diagnostic alterations characteristic of acute myeloid leukemia or acute lymphoblastic lymphoma. The case met diagnostic criteria for ALAL, NOS, per the 2022 International Consensus Classification and World Health Organization 5th edition classifications. Treatment was initiated with hyperfractionated cyclophosphamide, vincristine, adriamycin, and dexamethasone chemotherapy, and the patient ultimately achieved minimal residual disease negativity. The patient subsequently underwent allogeneic stem cell transplantation approximately 7 months after diagnosis. DISCUSSION:This case underscores the diagnostic challenges and therapeutic considerations in managing ALAL, NOS.
INTRODUCTION:Bias in analytes due to EDTA contamination is easy to miss and represents a common and clinically relevant preanalytical error. We designed a study to determine the in vitro effects of rising rates of EDTA contamination in blood samples and to evaluate how these findings could inform the development of multianalyte thresholds for detecting such errors automatically. METHODS:We incrementally spiked blood samples with increasing volumes of EDTA‑contaminated specimen and measured the resulting changes in alkaline phosphatase, calcium, magnesium, potassium, and iron levels. Using these observations, we developed a series of multianalyte thresholds and evaluated their performance against 1 year of retrospective clinical data (n = 2407). RESULTS:Our experiments demonstrated that increasing rates of EDTA contamination produced changes in several analytes. Accordingly, we applied multianalyte thresholds using potassium and calcium to retrospective samples. Across all samples, smaller magnitudes of analyte deviation resulted in higher detection rates of subtle EDTA contamination but poorer specificity. We selected a rule of a potassium level of 6.5 mmol/L or higher and a calcium level below 6.5 mg/dL (1.63 mmol/L), which identified 14 samples with a contamination rate of 42.8%. DISCUSSION:Multianalyte thresholds show promise as an effective approach for automatically identifying clinically significant EDTA contamination in clinical specimens.
INTRODUCTION:Hemolysis is a physiologic condition that results from the lysis of red blood cells and the release of their contents into the plasma. This condition may occur in the setting of a genetic, infectious, mechanical, or immune-mediated process. Classically, hemolysis results in a primarily indirect hyperbilirubinemia as free hemoglobin is metabolized to bilirubin, which is then conjugated and excreted; however, in rare instances, severe and chronic hemolysis may saturate the biliary excretion system and result in a direct hyperbilirubinemia. METHODS:In this report, we present a 73-year-old man who presented with severe jaundice and was found to have warm autoimmune hemolytic anemia. RESULTS:The patient's total bilirubin level was 72.4 mg/dL, with a direct bilirubin level of 43.6 mg/dL and elevated liver enzymes. Imaging was consistent with an obstructive process, and hilar thickening on magnetic resonance cholangiopancreatography raised concern for a superimposed cholangiocarcinoma. Endoscopic retrograde cholangiopancreatography, however, removed several black pigment stones, known to be associated with chronic hemolysis, and cytology brushings were negative for malignancy. DISCUSSION:This case is an excellent illustration of how sustained extravascular hemolysis can overwhelm hepatic excretory capacity and produce secondary cholestasis that mimics malignancy.
INTRODUCTION:Routine repeat testing of critical laboratory values delays reporting, and its effectiveness lacks empirical evidence. This study investigated the impact of automated repeat testing on report accuracy and timeliness. METHODS:This retrospective study of data from a large accredited medical center in Taiwan analyzed the occurrence rate, relative frequency, differences in repeat testing, and reporting delays of critical and dangerous values. Acceptable difference criteria were based on measurement uncertainty or College of American Pathologists criteria. Differences greater than the acceptable difference criteria were defined as "large differences." RESULTS:The occurrence rates of critical and dangerous values were 0.15% and 0.23%, respectively, with an acceptable difference rate of 99.57%. Large differences occurred at 0.39% (within the analytical measurement range [AMR]), 7.69% (above the AMR), and 0% (below the AMR). Repeated testing caused a median reporting delay of 10 to 33 minutes. DISCUSSION:Repeat testing within the AMR is unnecessary. Values above the AMR require repeat testing, whereas values below the AMR warrant investigation of preanalytical errors. Targeted repeat testing policies can reduce reporting times, minimize reagent waste, and enhance patient safety.
INTRODUCTION:The use of virtual crossmatch for HLA antigen compatibility assessment before transplantation has become common practice in transplantation medicine. The accuracy of virtual crossmatch relies on accurate and complete donor HLA antigen typing and up-to-date patient HLA antigen antibody characterization. Here, we report a case in which anti-HLA-DP antibodies were detected in the patient, and the donor HLA-DPB1*29:01 was not included in the bead panel of Luminex-based single antigen bead assay (LSA). METHODS:The deceased donor HLA antigen typing results were downloaded from the United Network for Organ Sharing. Serum samples were tested for HLA antibodies using LSA. Epitope analysis was performed manually based on alignment of HLA-DP using the Sequence Alignment Tool from the IPD-IMGT/HLA database (https://www.ebi.ac.uk/ipd/imgt/hla/). RESULTS:The LSA showed that anti-HLA-DP3, DP6, DP9, DP11, DP14, DP15, DP17, and DP20 were positive. HLA antigen typing with real-time polymerase chain reaction showed that the donor carried HLA-DPB1*29:01. Epitope analysis showed that the anti-HLA-DPB1*29:01 donor-specific antibody was present in this patient. DISCUSSION:The LSA can miss antibodies against HLA antigens not represented by the beads, leading to false-negative results for donor-specific antibodies. Failure to consider the possibility of unrepresented HLA proteins may potentially lead to incorrect clinical decision. Epitope analysis may help predict reactivity to HLA antigens not present on LSA beads.
INTRODUCTION:Symptomatic hypocalcemia and hypomagnesemia are life-threatening emergencies. Acute diagnostic and therapeutic maneuvers are well known, but underlying etiologies and the long-term therapeutic choices are not. METHODS:A 38-year-old woman who was found to have metastatic malignant melanoma during post-iodide 131 treatment uptake and whole-body scanning for treatment of differentiated thyroid cancer presented to an emergency department after the third round of platinum-based chemotherapy with severe muscle cramping. She was found to have profound hypocalcemia that was treated. The next day, her symptoms returned, and severe hypomagnesemia was found in a visit with her oncologist. RESULTS:Blood and urine tests revealed severe renal magnesium wasting and inappropriately normal intact parathyroid hormone given her severe hypocalcemia. All electrolyte abnormalities resolved with intravenous magnesium administration over 2 days. DISCUSSION:Severe renal magnesium wasting can cause concurrent functional hypoparathyroidism. Recognition of concurrent hypomagnesemia is essential in the laboratory workup of hypocalcemia.
INTRODUCTION:This study evaluated 5 methods for identifying intravenous fluid contamination in basic metabolic panel specimens. METHODS:Results for blood urea nitrogen, calcium, chloride, carbon dioxide, creatinine, glucose, potassium, and sodium were retrieved from metabolic panels tested in August 2025. All 5 methods were applied to 11 862 result sets with both preceding and subsequent results available within 48 hours. Chart review was conducted for all flagged specimens. RESULTS:The 5 methods collectively flagged 333 specimens, including 94 confirmed contaminations and 239 reflecting pathophysiologic changes or treatment effects. Alert rates ranged from 0.16% to 1.62%, and positive predictive values ranged from 23% to 100%. Among the 94 contaminated specimens, contaminants included 63 saline, 11 dextrose, 4 potassium, 5 PlasmaLyte A (Baxter) or lactated Ringer's solution, and 11 other fluids. The methods showed differing sensitivities across contaminant types. False alerts were associated with diverse clinical conditions or therapeutic interventions, including kidney impairment, diabetes, hypokalemia, substantial infusion volumes, and recent calcium injections. The methods differed in the likelihood of false alerts. DISCUSSION:All 5 methods showed low alert rates with variable positive predictive values. Their performance is influenced by patient population characteristics. Local verification is essential before adopting externally developed methods for detecting specimen contaminations.
INTRODUCTION:Pertussis is an acute respiratory infectious disease caused by Bordetella pertussis. Hyperleukocytosis in pertussis contributes to a drastically worsened prognosis by promoting pulmonary hypertension and multiorgan failure, leading to accelerated disease progression and elevated mortality. Exchange transfusion can improve the prognosis of in children with pertussis and increase the success rate of treatment. METHODS:We retrospectively analyzed 2 infants with severe pertussis treated with modified exchange transfusion. Reconstituted whole blood was prepared using O-type leukoreduced concentrated red blood cells and AB-type leukocyte-reduced, virus-inactivated fresh frozen plasma, with a red blood cell to plasma ratio of 1:1 to 2:1 and a hematocrit of 40% to 50%. The total exchange volume was 150 to 180 mL/kg (approximately twice the blood volume). RESULTS:After exchange transfusion, both infants showed marked reduction in white blood cell count and clinically significant improvement in dyspnea. No severe adverse reactions occurred, and both children were discharged. DISCUSSION:Modified double-volume exchange transfusion is a safe and effective treatment for infants with severe pertussis and hyperleukocytosis.
