Essential laboratory tests for medical education.

Medical practice requires physicians to have a broad understanding of the basic sciences, have competent clinical skills, and have an ability to practice in evolving health systems in a cost-effective and evidence-based manner. Essential to the practice of medicine is an understanding of the common laboratory tests and the ability to use them effectively. The Essential Laboratory Tests for Medical Education (ELTME) is a concise document explaining the pathophysiology of common laboratory tests and clinical context for each test and was developed in response to an expressed need from medical students, residents and fellows, and medical educators. The ELTME is linked to the Pathology Competencies in Medical Education and its third competency of diagnostic medicine and therapeutic pathology. The ELTME table is a document of common laboratory tests in alphabetical listing. Laboratory tests may be easily queried by name or organ system, and with simple editing tools, new tables may be constructed to fit the needs of individual curricula or learners. Furthermore, the table may be easily expanded by educators who wish to add specific tests to complement their curricula.

The presence of anemia in patients with leg ulcer: laboratory test / La presencia de anemia en pacientes con úlcera de la pierna: prueba de laboratorio / Presença de anemia em pacientes com úlcera da perna: testes laboratoriais

ABSTRACT Objective: To evaluate the presence of anemia in patients with chronic lower limb ulcers based on profile and hematometric indices. Method: This is a cross-sectional study carried out in a university hospital in Rio de Janeiro. The sample was composed of 64 participants with lower limb ulcers and evolution time greater than 12 weeks. Data was collected between May/2016 and December/2017 from hematological analyses, records from medical records, and wound assessment form. Results: 36 (56.2%) were male; 38 (59.4%) between 60 and 80 years old; 56 (87.5%) with chronic diseases and 52 (81.2%) with venous ulcers. 6 years mean of active ulceration. Anemia was detected in 36 (56.2%), 27 (75%) of which were normochromic and normocytic; 14 (38.8%) had deficiency anemia recorded in their medical chart. Conclusion: The low hemoglobin concentration is recurrent among the participants characterizing an anemia condition, whose profile reveals congruence to the anemia of chronic disease.

RESUMEN Objetivo: Evaluar la presencia de anemia en pacientes con úlceras crónicas de miembros inferiores desde el perfil e índices hematimétricos Método: Este estudio seccional transcurrió en un hospital universitario de Río de Janeiro, con una muestra de 64 participantes con úlceras en los miembros inferiores y tiempo de evolución superior a 12 semanas. Los datos se recopilaron entre mayo/2016 y diciembre/2017 investigando los análisis hematológicos, registros en las historias clínicas y formularios de evaluación de la herida. Resultados: 36 (56,2%) eran hombres; 38 (59,4%) tenían entre 60 y 80 años; 56 (87,5%) padecían de enfermedades crónicas y 52 (81,2%), de úlceras venosas. El promedio era de 6 años de úlcera activa. Se detectó anemia en 36 (56,2%), siendo que en 27 (75%) era normocrómica/normocítica; 14 (38,8%) presentaban anemia carencial registrada en la historia clínica. Conclusión: La baja concentración de hemoglobina es recurrente entre los participantes caracterizando un cuadro de anemia que coincide con el de anemia de enfermedad crónica.

RESUMO Objetivo: Avaliar a presença de anemia em pacientes com úlceras crônicas de membros inferiores a partir do perfil e dos índices hematimétricos. Método: Estudo seccional realizado em um hospital universitário do Rio de Janeiro. Amostra composta por 64 participantes com úlceras de membros inferiores e tempo de evolução maior que 12 semanas. Dados coletados entre maio/2016 e dezembro/2017, a partir de análises hematológicas, registros nos prontuários e em formulário de avaliação da ferida. Resultados: 36 (56,2%) eram do sexo masculino; 38 (59,4%) entre 60 e 80 anos; 56 (87,5%) com doenças crônicas e 52 (81,2%) com úlceras venosas. Média de 6 anos de úlcera ativa. Detectou-se anemia em 36 (56,2%), sendo 27 (75%) normocrômica e normocítica; 14 (38,8%) apresentavam anemia carencial registrada em prontuário. Conclusão: A baixa concentração de hemoglobina é recorrente entre os participantes, caracterizando um quadro de anemia cujo perfil revela congruência ao da anemia da doença crônica.

Predicting Risk of Stroke From Lab Tests Using Machine Learning Algorithms: Development and Evaluation of Prediction Models.

BACKGROUND: Stroke, a cerebrovascular disease, is one of the major causes of death. It causes significant health and financial burdens for both patients and health care systems. One of the important risk factors for stroke is health-related behavior, which is becoming an increasingly important focus of prevention. Many machine learning models have been built to predict the risk of stroke or to automatically diagnose stroke, using predictors such as lifestyle factors or radiological imaging. However, there have been no models built using data from lab tests. OBJECTIVE: The aim of this study was to apply computational methods using machine learning techniques to predict stroke from lab test data. METHODS: We used the National Health and Nutrition Examination Survey data sets with three different data selection methods (ie, without data resampling, with data imputation, and with data resampling) to develop predictive models. We used four machine learning classifiers and six performance measures to evaluate the performance of the models. RESULTS: We found that accurate and sensitive machine learning models can be created to predict stroke from lab test data. Our results show that the data resampling approach performed the best compared to the other two data selection techniques. Prediction with the random forest algorithm, which was the best algorithm tested, achieved an accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve of 0.96, 0.97, 0.96, 0.75, 0.99, and 0.97, respectively, when all of the attributes were used. CONCLUSIONS: The predictive model, built using data from lab tests, was easy to use and had high accuracy. In future studies, we aim to use data that reflect different types of stroke and to explore the data to build a prediction model for each type.

Prognostic Association between Common Laboratory Tests and Overall Survival in Elderly Men with De Novo Metastatic Castration Sensitive Prostate Cancer: A Population-Based Study in Canada.

De novo cases of metastatic prostate cancer (mCSPC) are associated with poorer prognosis. To assist in clinical decision-making, we aimed to determine the prognostic utility of commonly available laboratory-based markers with overall survival (OS). In a retrospective population-based study, a cohort of 3556 men aged ≥66 years diagnosed with de novo mCSPC between 2014 and 2019 was identified in Ontario (Canada) administrative database. OS was assessed by using the Kaplan-Meier method. Multivariate Cox regression analysis was performed to evaluate the association between laboratory markers and OS adjusting for patient and disease characteristics. Laboratory markers that were assessed include neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), albumin, hemoglobin, serum testosterone and PSA kinetics. Among the 3556 older men with de novo mCSPC, their median age was 77 years (IQR: 71-83). The median survival was 18 months (IQR: 10-31). In multivariate analysis, a statistically significant association with OS was observed with all the markers (NLR, PLR, albumin, hemoglobin, PSA decrease, reaching PSA nadir and a 50% PSA decline), except for testosterone levels. Our findings support the use of markers of systemic inflammation (NLR, PLR and albumin), hemoglobin and PSA metrics as prognostic indicators for OS in de novo mCSPC.

The Role of Nuclear Medicine in the Clinical Management of Benign Thyroid Disorders, Part 2: Nodular Goiter, Hypothyroidism, and Subacute Thyroiditis.

Part 2 of this series of Continuing Education articles on benign thyroid disorders deals with nodular goiter, hypothyroidism, and subacute thyroiditis. Together with Part 1 (which dealt with various forms of hyperthyroidism), this article is intended to provide relevant information for specialists in nuclear medicine dealing with the clinical management of patients with benign thyroid disorders, the primary audience for this series. Goiter, an enlargement of the thyroid gland, is a common endocrine abnormality. Constitutional factors, genetic abnormalities, or dietary and environmental factors may contribute to the development of nodular goiter. Most patients with nontoxic nodular goiter are asymptomatic or have only mild mechanical symptoms (globus pharyngis). Work-up of these patients includes measurement of thyroid-stimulating hormone, free triiodothyronine, free thyroxine, thyroid autoantibodies, ultrasound imaging, thyroid scintigraphy, and fine-needle aspiration biopsy of nodules with certain ultrasound and scintigraphic features. Treatment for multinodular goiter includes dietary iodine supplementation, surgery, radioiodine therapy (to decrease thyroid size), and minimally invasive ablation techniques. Hypothyroidism ranges from rare cases of myxedema to more common mild forms (subclinical hypothyroidism). Primary hypothyroidism often has an autoimmune etiology. Clinical presentations differ in neonates, children, adults, and elderly patients. Work-up includes thyroid function tests and ultrasound imaging. Nuclear medicine is primarily used to locate ectopic thyroid tissue in congenital hypothyroidism or to detect defects in iodine organification with the perchlorate discharge test. Treatment consists of thyroid replacement therapy with l-thyroxine, adjusting the daily dose to the individual patient's metabolic and hormonal requirements. Subacute thyroiditis is a self-limited inflammatory disorder of the thyroid gland, often associated with painless or painful swelling of the gland and somatic signs or symptoms. Inflammation disrupts thyroid follicles resulting in a rapid release of stored thyroxine and triiodothyronine causing an initial thyrotoxic phase, often followed by transient or permanent hypothyroidism. Although subacute thyroiditis is often related to a viral infection, no infective agent has been identified. Subacute thyroiditis may be caused by a viral infection in genetically predisposed individuals. Work-up includes lab tests, ultrasound imaging, and radionuclide imaging. Thyroid scintigraphy demonstrates different findings depending on the phase of the illness, ranging from very low or absent tracer uptake in the thyroid gland in the hyperthyroid phase to a normal appearance in the late recovery phase. Since subacute thyroiditis is self-limited, treatment is directed toward relief of pain. High-dose nonsteroidal antiinflammatory drugs are usually the first-line treatment. If severe pain persists, a course of corticosteroids may be necessary. Permanent hypothyroidism develops in up to 15% of patients with subacute thyroiditis, even more than 1 y after presentation.

Immunological and Hematological Response in COVID-19.

INTRODUCTION: Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has recently and rapidly emerged and developed into a global pandemic. Through the renin-angiotensin system, the virus may impact the lung circulation, but the expression on endothelium may conduct to its activation and further systemic damage. While precise mechanisms underlying these phenomena remain to be further clarified, the understanding of the disease, its clinical course, as well as its immunological and hematological implications is of paramount importance in this phase of the pandemic. METHODS: This review summarizes the evidence gathered until 12 June; electronic databases were screened for pertinent reports on coronavirus and inflammatory and hematological changes. Search was conducted by two independent investigators; keywords used were "SARS-CoV-2," "COVID-19," "inflammation," "immunological," and "therapy." RESULTS: The viral infection is able to trigger an excessive immune response in predisposed individuals, which can result in a "cytokine storm" that presents an hyperinflammation state able to determine tissue damage and vascular damage. An explosive production of proinflammatory cytokines such as TNF-α IL-1ß and others occurs, greatly exaggerating the generation of molecule-damaging reactive oxygen species. These changes are often followed by alterations in hematological parameters. Elucidating those changes in SARS-CoV-2-infected patients could help to understand the pathophysiology of disease and may provide early clues to diagnosis. Several studies have shown that hematological parameters are markers of disease severity and suggest that they mediate disease progression. According to the available literature, the primary hematological symptoms-associated COVID-19, and which distinguish patients with severe disease from patients with nonsevere disease, are lymphocytopenia, thrombocytopenia, and a significant increase in D-dimer levels. CONCLUSIONS: SARS-CoV-2 infection triggers a complex response altering inflammatory, hematological, and coagulation parameters. Measuring these alterations at certain time points may help identify patients at high risk of disease progression and monitor the disease severity.

Prognostic value of labs ordered on patients hospitalized with COVID-19.

Background: Hospitalists at our institution have taken on most non-intensive care unit (ICU) coronavirus disease 2019 (COVID-19) care. Based on sparse research, our institution developed a protocol for ordering labs for this patient population, including routine admission labs in addition to eight COVID-19-specific daily labs. The study goal is to determine if COVID-19-specific admission labs have any prognostic value beyond that provided by routine admission labs and vitals, and costs of labs with no prognostic value.Methods: We retrospectively reviewed adult patients admitted with COVID-19 from 3/2020 to 7/2020. Outcomes were mortality, ICU stay, and length of hospitalization. Multivariable logistic and linear regression were used to determine if COVID-19-specific admission labs have any prognostic value beyond that provided by vitals and routine admission labs. COVID-19-specific labs were d-Dimer, fibrinogen, ferritin, LDH, CK, pro-BNP, troponin, and CRP. Multivariable models included all routine admission labs and vitals. COVID-19-specific admission labs were included in the multivariable models if the p-value was <0.05 in the univariable analysis.Results: 331 patients met study criteria, inpatient mortality was 13.0%, 52.4% of patients required ICU stays and the average length of hospitalization was 8.9 days. COVID-19-specific labs showed no additional prognostic value for mortality. CRP, LDH, and d-Dimer provided additional prognostic information for ICU stay. CRP≥100 mg/dL and LDH≥900 U/L were associated with increased length of hospitalization.Conclusion: Only 3 of 8 admission COVID-19-specific labs recommended by our institution's protocol had additional prognostic value beyond that provided by routine labs and vitals. The total cost of non-prognostic COVID-19-specific labs during the study period was $75,874.

Why do they do it? A grounded theory study of the use of low-value care among primary health care physicians.

BACKGROUND: The use of low-value care (LVC) is widespread and has an impact on both the use of resources and the quality of care. However, few studies have thus far studied the factors influencing the use of LVC from the perspective of the practitioners themselves. The aim of this study is to understand why physicians within primary care use LVC. METHODS: Six primary health care centers in the Stockholm Region were purposively selected. Focus group discussions were conducted with physicians (n = 31) working in the centers. The discussions were coded inductively using a grounded theory approach. RESULTS: Three main reasons for performing LVC were identified. Uncertainty and disagreement about what not to do was related to being unaware of the LVC status of a practice, guidelines perceived as conflicting, guidelines perceived to be irrelevant for the target patient population, or a lack of trust in the guidelines. Perceived pressure from others concerned patient pressure, pressure from other physicians, or pressure from the health care system. A desire to do something for the patients was associated with the fact that the visit in itself prompts action, symptoms to relieve, or that patients' emotions need to be reassured. The three reasons are interdependent. Uncertainty and disagreement about what not to do have made it more difficult to handle the pressure from others and to refrain from doing something for the patients. The pressure from others and the desire to do something for the patients enhanced the uncertainty and disagreement about what not to do. Furthermore, the pressure from others influenced the desire to do something for the patients. CONCLUSIONS: Three reasons work together to explain primary care physicians' use of LVC: uncertainty and disagreement about what not to do, perceived pressure from others, and the desire to do something for the patients. The reasons may, in turn, be influenced by the health care system, but the decision nevertheless seemed to be up to the individual physician. The findings suggest that the de-implementation of LVC needs to address the three reasons from a systems perspective.

Larvicidal Action of Cannabidiol Oil and Neem Oil against Three Stored Product Insect Pests: Effect on Survival Time and in Progeny.

SStored product pests can be detrimental to agricultural produce. As much as chemical pesticides are effective control agents, they involve several environmental and health risks. Within the framework of studies on alternative pest management methods, interest has focused on a plethora of plants whose extracts have demonstrated promising action as insecticides. Azadirachta indica and the derived neem oil have been extensively tested against many harmful insect species. In contrast, Cannabis sativa L. and its main compound, CBD, a highly concentrated cannabinoid, have not been investigated much. The present study examined the potential insecticidal activity of CBD and neem oils against 4th instar larvae of Tribolium confusum, Oryzaephilus surinamensis and Plodia interpunctella on wheat, rice and corn seeds. Treatment efficacy was expressed in terms of larval mortality. Mortality was observed in relation to dosage, time exposure intervals and product types. The results showed clear pesticidal activity for both oils, which at high doses induced significant mortality. The treatments produced significantly fewer offspring in the insect species tested than the control. The efficacy of treatment in progeny suppression was, as expected, dose dependent.

Diagnostic Laboratory Tests for COVID-19 in US: Methodology and Performance.

Background: COVID-19 is a global pandemic caused by a new coronavirus strain. Innovative tests have been developed to diagnose and characterize the spread of COVID-19. Only a few studies have reported the diagnostic value of currently available tests. The diagnostic performance of the tests is a major concern after the recent resurgence in COVID-19. Methods: Published papers and FDA data on the currently available tests were used for analysis. Likelihood ratios, and predictive values of tests were computed. Only FDA approved tests were included. RT-PCR performance among different specimen types were also explored. Main results: All the published reports on the COVID-19 tests reported RT-PCR as the validation tool for their results. Not all available COVID-19 tests reported their sensitivity and specificity. Among the publications which reported, the positive likelihood ratio ranged between 0.15 to 0.88 and tests had high negative likelihood ratio (0.99). Conclusion: Although most recent publications showed high positive and negative likelihood ratios and high predictive values, the publications on test accuracy and validity have limited scope primarily due to their small sample size and insufficiencies in methodology and published data. Although most lab tests reported high sensitivity and specificity, false omission and false discovery rates were found notable in several COVID-19 lab tests. These results suggest need for caution on test results' interpretation. Practitioners also need to integrate evidence that is evolving rapidly.

Utility of Perioperative Laboratory Tests in Pediatric Patients Undergoing Spinal Fusion for Scoliosis.

STUDY DESIGN: Retrospective comparative study. OBJECTIVES: We aimed to characterize the frequency of perioperative laboratory tests for posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) and to assess whether test results affected clinical management. SUMMARY OF BACKGROUND DATA: Perioperative laboratory tests for PSF including complete blood count, coagulation laboratory tests, basic metabolic panels (BMPs), and type and screen, are commonly ordered based on providers' discretion or existing order sets. Studies have shown unnecessary laboratory tests as financially and physically costly in adults; however, no studies have examined the necessity of common perioperative laboratory tests in pediatric spinal deformity surgery. METHODS: Retrospective review of patients aged 10-18 years who underwent PSF for AIS at our center in the past three years. The clinical utility of perioperative laboratory tests was assessed based on detected incidence of anemia, blood transfusions, hematology/endocrinology/nephrology consultations, insulin administration, and postponed/canceled surgeries. RESULTS: A total of 234 patients were included (mean age 14.4 ± 1.8 years, 75% female). Of 105 (44.9%) patients with preoperative coagulation laboratory tests, 21 (20%) had abnormal results; however, none had subsequent hematology consultations or canceled/postponed surgeries. Postoperatively, only 5 (2.1%) patients and 30 (12.8%) patients had hemoglobin values less than 8 g/dL on postoperative day (POD) 1 and 2, respectively. Multivariate analysis identified POD1 hemoglobin ≤9.35 g/dL as the only predictor of hemoglobin <8 g/dL on POD2. Overall, there were 8 (3.4%) indicated blood transfusions postoperatively. Costs of unnecessary laboratory tests averaged $95.27 (range $49.72 to $240.27) per patient. CONCLUSIONS: Many perioperative laboratory orders may be unnecessary in pediatric spinal deformity surgery, subjecting patients to extraneous costs and needlesticks. In particular, preoperative coagulation laboratory tests, perioperative BMPs, and additional postoperative CBCs for those with hemoglobin >9.35 on POD1 may not be warranted. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Effect of beef ingestion by humans on plasma concentrations of creatinine, urea, and cystatin C.

PURPOSE: The effect of eating meat on serum concentrations of creatinine has varied among previous reports, with some finding no effect and others finding 50-100% increases, which appears related to how the beef is cooked. For other analytes related to kidney function, urea is well known to increase following a protein meal, and the effect of eating meat on cystatin C concentrations has been studied once. METHODS: We had 32 participants eat a measured amount of cooked beef (5-6 or 10-12 oz; 142-170 or 284-340 g) and collected blood for measurements at 1 h before and immediately before eating beef, then at 1, 2, and 4 h after eating the beef. We measured creatinine using both alkaline picrate and enzymatic methods, cystatin C using a nephelometric immunoassay, and urea using an enzymatic method. RESULTS: For creatinine, both the picrate and enzymatic methods showed similar responses, with a peak average increases of 5.9 µmol/L (0.07 mg/dL) and 4.6 µmol/L (0.05 mg/dL), respectively, at 2 h. Cystatin C had a very slightly maximal decrease of -0.037 mg/L at 2 h. Urea had the largest change, increasing by 0.30 and 0.77 mmol/L at 2 and 4 h respectively. CONCLUSIONS: Healthy individuals were found to have minor increases in serum creatinine (~5 µmol/L) following the ingestion of 5/6 or 10/12 oz of fried beef. Cystatin C appears to decrease very slightly in some people after beef ingestion, possibly due either to circadian variation or to a hormonal effect of eating. We conclude that ingesting these amounts of fried beef has a small effect on plasma creatinine concentrations. Although these increases would likely not affect the diagnosis of a kidney impairment in this population or in those with kidney disease, eating meat before collecting blood for creatinine measurement should be avoided.

Interventions to Educate Family Physicians to Change Test Ordering: Systematic Review of Randomized Controlled Trials.

The purpose is to systematically review randomised controlled trials (RCTs) to change family physicians' laboratory test-ordering. We searched 15 electronic databases (no language/date limitations). We identified 29 RCTs (4,111 physicians, 175,563 patients). Six studies specifically focused on reducing unnecessary tests, 23 on increasing screening tests. Using Cochrane methodology 48.5% of studies were low risk-of-bias for randomisation, 7% concealment of randomisation, 17% blinding of participants/personnel, 21% blinding outcome assessors, 27.5% attrition, 93% selective reporting. Only six studies were low risk for both randomisation and attrition. Twelve studies performed a power computation, three an intention-to-treat analysis and 13 statistically controlled clustering. Unweighted averages were computed to compare intervention/control groups for tests assessed by >5 studies. The results were that fourteen studies assessed lipids (average 10% more tests than control), 14 diabetes (average 8% > control), 5 cervical smears, 2 INR, one each thyroid, fecal occult-blood, cotinine, throat-swabs, testing after prescribing, and urine-cultures. Six studies aimed to decrease test groups (average decrease 18%), and two to increase test groups. Intervention strategies: one study used education (no change): two feedback (one 5% increase, one 27% desired decrease); eight education + feedback (average increase in desired direction >control 4.9%), ten system change (average increase 14.9%), one system change + feedback (increases 5-44%), three education + system change (average increase 6%), three education + system change + feedback (average 7.7% increase), one delayed testing. The conclusions are that only six RCTs were assessed at low risk of bias from both randomisation and attrition. Nevertheless, despite methodological shortcomings studies that found large changes (e.g. >20%) probably obtained real change.

Laboratory blood tests useful in monitoring renal function in neonates.

It is important to monitor renal function in the neonate, especially in premature infants where nephrogenesis is still in process upon birth. The kidneys are responsible for maintaining homeostasis in the extracellular environment by preventing overaccumulation of waste products and electrolytes. This review describes developmental physiology of the renal system as well as laboratory testing to monitor renal function and glomerular filtration in neonates. Drugs that may affect renal function in infants are also discussed.

Lab Tests Online and consumer understanding of laboratory testing.

Lab Tests Online is a "peer-reviewed, non-commercial, patient-centered" resource where patients and their relatives and caregivers can learn about the tests used to screen for, diagnose, and manage disease. Consumers are becoming increasingly involved in the management of their own health care and increasingly have access to their laboratory results through electronic health records. Research has shown that consumers have difficulty with health literacy in general and with numerical data in particular. The Lab Tests Online global websites are an important step toward helping consumers understand the complexity of the pathology process, the expertise of the people involved and the meaning of the results provided to them and their healthcare professionals.