An Introduction to the Complete Blood Count for Clinical Chemists: Red Blood Cells

BACKGROUND

The most frequently ordered laboratory test worldwide is the complete blood count (CBC).

CONTENT

In this primer, the red blood cell test components of the CBC are introduced, followed by a discussion of the laboratory evaluation of anemia and polycythemia.

SUMMARY

As clinical chemists are increasingly tasked to direct laboratories outside of the traditional clinical chemistry sections such as hematology, expertise must be developed. This review article is a dedication to that effort.

Advances in sepsis biomarkers

Sepsis, a dysregulated host immune response to an infectious agent, significantly increases morbidity and mortality for hospitalized patients worldwide. This chapter reviews (1) the basic principles of infectious diseases, pathophysiology and current definition of sepsis, (2) established sepsis biomarkers such lactate, procalcitonin and C-reactive protein, (3) novel, newly regulatory-cleared/approved biomarkers, such as assays that evaluate white blood cell properties and immune response molecules, and (4) emerging biomarkers and biomarker panels to highlight future directions and opportunities in the diagnosis and management of sepsis.

Dysfibrinogenemia: discrepant results following infusion of purified fibrinogen

Inherited dysfibrinogenemias are molecular disorders of fibrinogen that affect fibrin polymerization. The majority of cases are asymptomatic, but a significant proportion suffer from increased bleeding or thrombosis. We present two unrelated cases of dysfibrinogenemia, both of whom showed a characteristic discrepancy between fibrinogen activity and the immunologic fibrinogen. In one patient, the dysfibrinogenemia was confirmed by molecular analysis; in the other case, the diagnosis was presumptive based upon laboratory studies. Both patients underwent elective surgery. Both received a highly purified fibrinogen concentrate preoperatively and demonstrated a suboptimal laboratory response to the infusion. Three methods for determining fibrinogen concentration (Clauss fibrinogen, prothrombin-derived fibrinogen, and the viscoelastic functional fibrinogen) were utilized in the case of one patient, and these techniques showed discrepant results with the classic Clauss method giving the lowest concentration. Neither patient experienced excessive bleeding during surgery. Although these discrepancies have been previously described in untreated patients, their manifestation after infusion of purified fibrinogen is less well appreciated.

The Utility of PathElective.com as a Curricular Adjunct in Laboratory Medicine Education

Introduction/Objective

PathElective.com was founded as a means of combating stagnating resident and medical student education due to halting of in-person educational activities during the COVID-19 pandemic. The site has since grown to be included in medical student and resident training programs at numerous institutions across the world, serving as a unique means of delivering high-quality and trackable laboratory medicine education.

Methods/Case Report

The PathElective website was developed using Squarespace, video lectures were recorded by each professor or sourced from openly available web resources incorporating virtual slides, reading assignments, or relevant podcasts at the course director’s discretion. Monthly website traffic data were obtained through Squarespace analytics for the first 11 months of the website being available (May 1, 2020, to April 22, 2021). Geographic and source data were obtained through deidentified IP address analysis built-in to Squarespace analytics. Students who registered to take the online courses were assessed before and after interacting with the course materials using a dual form crossover quiz design to prevent memorization of questions and assess comprehension. Quiz data were all anonymous and improvement was determined using a paired t-test. Comparisons between courses were made via percentage improvements.

Results (if a Case Study enter NA)

Over the tracking period, PathElective.com received 352,012 page views, 73,550 visits, 33,225 unique visitors, and accrued 5,815 registered users. Most of the visitors (72.8%) arrived at the site via a direct URL input, 14.9% through a search engine, and 10.6% through social media. Most visitors were from the US (43.8%) or India (11.9%). With a total of 1598 test pairs being analyzed from all clinical pathology modules, the average increase in score was 14.4% (95%, CI=10.3-18.6, p=0.0052). All courses experienced a statistically significant increase in scores except for Clinical Chemistry lesson 3.2 (7%, -1.8-15.9% CI, p=0.12). Courses were well received with a median satisfaction score was very satisfied in all six assessment categories.

Conclusion

PathElective.com is a free and effective means of enhancing clinical pathology training in medical education. Students liked the online format, the quality of the lectures, and course faculty, and felt they could get help if needed. An area of improvement for this platform would be the interaction with students on social media.

Role of von Willebrand Factor in COVID-19 Associated Coagulopathy

Background

COVID-19, the disease caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) can present with symptoms ranging from none to severe. Thrombotic events occur in a significant number of patients with COVID-19, especially in critically ill patients. This apparent novel form of coagulopathy is termed COVID-19 associated coagulopathy and endothelial derived von Willebrand factor (vWF) may play an important role in its pathogenesis.

Content

vWF is a multimeric glycoprotein molecule that is involved in inflammation, primary and secondary hemostasis. Studies have shown that patients with COVID-19 have significantly elevated levels of vWF antigen and activity, likely contributing to an increased risk of thrombosis seen in CAC. The high levels of both vWF antigen and activity have been clinically correlated with worse outcomes. Furthermore, the severity of a COVID-19 infection appears to reduce molecules that regulate vWF level and activity such as ADAMT-13 and high density lipoproteins (HDL). Finally, studies have suggested that patients with blood group O (a blood group with lower than baseline levels of vWF) have a lower risk of infection and disease severity compared to other blood groups; however, more studies are needed to elucidate the role of vWF

Summary

CAC is a significant contributor to morbidity and mortality. Endothelial dysfunction with the release of pro-thrombotic factors, such as vWF, needs further examination as a possible important component in the pathogenesis CAC.

Sky High or Undetectable? A Patient with Discordant Hemoglobin A1c

A female patient aged 47 years presented with a hemoglobin A1c (HbA1c) level of 54.6%, as measured by ion-exchange high-performance liquid chromatography (HPLC), and a glucose level of 106 mg/dL. The HbA1c was re-evaluated using a turbidimetric inhibition immunoassay and found below the level of detection. Hemoglobinopathy testing led to the identification of a hemoglobin variant consistent with Hb Raleigh, in which a valine → alanine substitution on the beta chain effects a charge difference, resulting in coelution with HbA1c on HPLC and a spuriously high reading. Many Hb variants may interfere with HbA1c measurement and generate misleading results. The unique properties of Hb Raleigh may give rise to analytical errors when evaluating HbA1c using 2 different methods-molecular charge-based (eg, HPLC) and molecular structure-based (eg, immunoassay)-yielding diametrically opposed results. Consequently, recognition and diagnosis of this entity are essential in patients with Hb Raleigh, especially when monitoring long-term glucose control.

Laboratory Assay Evaluation Demystified: A Review of Key Factors Influencing Interpretation of Test Results Using Different Assays for SARS-CoV-2 Infection Diagnosis

Laboratory tests are an integral part of the diagnosis and management of patients; however, these tests are far from perfect. Their imperfections can be due to patient health condition, specimen collection, and/or technological difficulty with performing the assay and/or interpretation. To be useful clinically, testing requires calculation of positive predictive values (PPVs) and negative predictive values (NPVs). During the current global pandemic of COVID-19 (coronavirus disease 2019), multiple assays with unknown clinical sensitivity and specificity have been rapidly developed to aid in the diagnosis of the disease. Due to a lack of surveillance testing, the prevalence of COVID-19 remains unknown. Hence, using this situation as an clinical example, the goal of this article is to clarify the key factors that influence the PPV and NPV yielded by diagnostic testing, By doing so, we hope to offer health-care providers information that will help them better understand the potential implications of utilizing these test results in clinical patient management.

Validation of a multiplex qPCR assay for the identification and quantification of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis: In vitro and subgingival plaque samples

OBJECTIVE

To validate a multiplex qPCR (m-qPCR) assay for the simultaneous identification and quantification of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis in subgingival samples.

MATERIAL AND METHODS

In vitro samples: DNA combinations of A. actinomycetemcomitans and P. gingivalis in similar or different concentrations were prepared. qPCR and m-qPCR were performed using the same primers and hydrolysis probes specific for 16SrRNA genes. Results were analyzed using intra-class (ICCs) and Lin's correlation coefficients (r) based on quantification cycle (Cq) values. Subgingival plaque samples: a cross-sectional study analyzing subgingival plaque samples harvested from periodontally-healthy and chronic periodontitis patients. Samples were processed by either qPCR or m-qPCR targeting both bacteria. Sensitivity, specificity, predictive values and Lińs correlation coefficients (r) were calculated using CFU/mL as primary outcome.

RESULTS

In vitro samples: m-qPCR yielded a good reproducibility (coefficients of variation around 1% and ICCs > 0.99) for both bacterial species. m-qPCR achieved detection limits and specificity similar to qPCR. An excellent concordance (r = 0.99) was observed between m-qPCR and qPCR for A. actinomycetemcomitans and P. gingivalis without statistical significant differences between both methods Subgingival plaque samples: a high sensitivity (above 80%) and specificity (100%) was obtained with the m-qPCR for both bacteria. The m-qPCR yielded a good concordance in Cq values, showing a good level of agreement between qPCR and m-qPCR.

CONCLUSION

The tested m-qPCR method was successful in the simultaneous quantification of A. actinomycetemcomitans and P. gingivalis, with a high degree of sensitivity and specificity on subgingival plaque samples.

Antihypertensive Efficacy of Amlodipine and Losartan after Two ‘Missed’ Doses in Patients with Mild to Moderate Essential Hypertension

We compared the effects of amlodipine (5 − 10 mg, n = 94) and losartan (50 − 100 mg, n = 94) on the lowering of blood pressure (BP) at steady state and after two missed doses, as well as on tolerability. This was a randomized, double-blind study of 12 weeks of active treatment followed by 2 days of placebo treatment. Twenty-four-hour ambulatory blood pressure monitoring and office BP measurements were performed at baseline, week 12 and after the 2-day drug holiday. After 12 weeks, amlodipine was significantly more effective than losartan in reducing both 24-h systolic blood pressure (SBP) (−18.0 versus −10.8 mmHg) and diastolic blood pressure (DBP) (−10.6 versus −8.0 mmHg). While mean SBP and DBP for both treatments increased comparably during the drug holiday, BP values remained significantly lower than baseline for both treatments. The superior BP-lowering effect of amlodipine compared with losartan was maintained during the drug holiday.

Comfort zone-design free stalls: do they influence the stall use behavior of lame cows?

The behavior of 59 cows in 4 herds, each with Comfort Zone-design free stalls with dimensions suitable for 700-kg, mature Holstein dairy cows, was filmed for a 48-h period. Comparison was made between nonlame, slightly lame, and moderately lame cows on either rubber-crumb-filled mattress stall surfaces bedded with a small amount of sawdust (2 herds) or a Pack Mat design, which consisted of a rubber-crumb-filled mattress pad installed 5 cm below a raised rear curb, bedded with 5 to 8 cm of sand bedding (2 herds). All other stall design components were similar. Despite adequate resting space and freedom to perform normal rising and lying movements, lame cows on mattresses stood in the stall for >2 h longer than nonlame cows. Although a significant increase in stall standing behavior was observed in lame cows on Pack Mat stalls, the mean (95% confidence interval) standing time in the stall was only 0.7 (0 to 3.0) h/d for nonlame cows and 1.6 (0 to 4.2) h/d for moderately lame cows, which was less than the 2.1 (0 to 4.4), 4.3 (1.6 to 6.9), and 4.9 (2.5 to 7.3) h/d spent standing in the stall for nonlame, slightly lame, and moderately lame cows on mattresses, respectively. This observation supports the hypothesis that it is the nature of the stall surface that dictates changes in stall standing behavior observed in lame cows, rather than other components of stall design. The finding that only 5 to 8 cm of sand over a mattress pad provides most of the benefits of deep sand-bedded stalls, along with other advantages related to stall maintenance and manure handling, gives farmers another useful housing alternative with which to improve cow comfort and well-being.

[Most frequent nursing diagnoses in elderly women hospitalized at the medical and surgical unit]

Due to the high incidence of elderly people which are presently hospitalized and the countless needs presented by them, this study aimed at describing the most common nursing diagnoses among fifty elderly hospitalized women, who were evaluated considering their need for home care. The authors concluded that the subjects studied presented diagnoses which involved all types of human response patterns, with particular emphasis on the diagnosis of knowledge deficit.

[Assessment of satisfaction of a group of elderly women and caretakers with a discharge planning]

Independently of the type of quality assistance improvement model chosen in a health institution, the implementation of ways of assessing it is also necessary. This study analyze the degree of satisfaction among a group of 50 hospitalized elderly women and/or caretakers after the implementation of a discharge planning in a Emergency Medical Clinic Unit. The present paper also investigates the need for continued assistance and points out which information is considered the most important by the patient. Results show that both the elderly and caretakers were highly satisfied with the assistance provide, most of which felt confident about their ability to continue it and that the most important information was that related the main health problem of elderly patient. It is inferred from this study that a discharge planning should be adapted by the health professionals in the hospital.

Twin gestation: fetal presentation as a function of gestational age

OBJECTIVE

Our objective in this study was to evaluate the rate of spontaneous version in twin gestation throughout the third trimester.

STUDY DESIGN

Serial ultrasonographic examinations were performed on 119 consecutive patients with twin gestation. The incidence of spontaneous version as a function of gestational age was calculated.

RESULTS

The mean birth weight and gestational age at delivery were 2640 gm and 37 weeks, respectively. Nineteen percent had birth weight discordancy, and 37% were delivered by cesarean section. The incidence of spontaneous version decreased from 60% at 28 to 30 weeks' gestation to 25% to 30% at term. The lowest incidence of spontaneous version was observed in pregnancies with a cephalic-cephalic presentation (7%). All other presentations were relatively unstable. Neither the patients' parity nor the presence of birth weight discordancy, the placental location, or the amniotic fluid volume had a significant association with the incidence of spontaneous version.

CONCLUSION

These data should be incorporated into the routine antepartum counseling of patients with twin gestation. Their use in this capacity may result in a decreased cesarean delivery rate if clinicians realize that malpresentations may spontaneously resolve before the onset of labor.