Coffee intake one hour prior to phlebotomy produces no clinically significant changes in routine biochemical test results.

Introduction: Although current guidelines recommend not drinking coffee prior to phlebotomy, our hypothesis is that drinking coffee does not affect the clinical interpretation of biochemical and haematological test results. Materials and methods: Twenty-seven volunteers were studied in basal state (T0) and 1h after (T1) drinking coffee. Routine haematological (Sysmex-XN1000 analyser) and biochemistry parameters (Vitros 4600 analyser) were studied. Results were compared using the Wilcoxon test (P < 0.05). A clinical change was considered when mean percent difference (MD%) was higher than the reference change value (RCV). Results: Coffee intake produced statistically, but not clinically, significant: i) increases in haemoglobin (P = 0.009), mean cell haemoglobin concentration (P = 0.044), neutrophils (P = 0.001), albumin (P = 0.001), total protein (P = 0.000), cholesterol (P = 0.025), high density lipoprotein cholesterol (P = 0.007), uric acid (P = 0.011), calcium (P = 0.001), potassium (P = 0.010), aspartate aminotransferase (P = 0.001), amylase (P = 0.026), and lactate dehydrogenase (P = 0.001), and ii) decreases in mean cell volume (P = 0.002), red cell distribution width (P = 0.001), eosinophils (P = 0.002), and lymphocytes (P = 0.001), creatinine (P = 0.001), total bilirubin (P = 0.012), phosphorus (P = 0.001), magnesium (P = 0.007), and chloride (P = 0.001). Conclusion: Drinking a cup of coffee 1 hour prior to phlebotomy produces no clinically significant changes in routine biochemical and haematological test results.

¿Es necesario el ayuno para la determinación del perfil lipídico? / Is fasting necessary for the determination of the lipid profile?

El propósito de este estudio fue analizar los cambios post prandiales en el perfil lipídico en respuesta a una comida típica argentina. Se extrajo sangre a 33 mujeres voluntarias después de 12 h de ayuno (T0), 1 h después de un desayuno estandarizado (T1) y 1 h después de un almuerzo estandarizado (T2). Se midieron los niveles de: colesterol total, colesterol de lipoproteínas de alta densidad (C-HDL), colesterol de lipoproteínas de baja densidad (C-LDL) y triglicéridos. Los datos se analizaron utilizando la prueba t de Student pareada. Para cada analito se calculó la diferencia porcentual media (DM%) en T1 y T2 respecto de T0 y se comparó con el valor de referencia del cambio (VRC). Las DM% mayores al VRC se consideraron clínicamente significativas. En T1 y T2, los valores de C-HDL fueron más bajos que en T0, mientras que los valores de C-LDL en T1 fueron más bajos que en T0. Los niveles de triglicéridos fueron significativamente más altos en T1 que en T0. En todos los casos, la variabilidad fue estadísticamente significativa, aunque no clínicamente. En este estudio puede observarse que el perfil de lípidos en T1 y T2 no mostró diferencias clínicamente significativas con respecto a los valores basales.

The purpose of the present study was to analyze postprandial lipid profile changes in response to a typical Argentine meal. Blood was collected from 33 female volunteers after a 12 h fasting period (T0), 1 h after a standardized breakfast (T1) and 1 h after a standardized lunch (T2). The levels of total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides were measured. Data were analyzed using paired Student's t-test. Mean difference % (MD %) was calculated for each analyte at T1 and T2 and was further compared with reference change value (RCV). MDs % higher than RCV were considered clinically significant. At T1 and T2, HDL-C values were lower than at T0, whereas LDL-C values at T1 were lower than at T0. Triglycerides levels were significantly higher at T1 than baseline values. In all cases, variability was statistically, though not clinically, significant. This study demonstrates that at T1 and T2 lipid profile showed no clinically significant differences with respect to basal values.

O objetivo do presente estudo foi analisar as alterações do perfil lipídico pós-prandial em resposta a uma refeição típica argentina. O sangue foi coletado de 33 mulheres voluntárias após um período de jejum de 12 horas (T0),1 h após um café da manhã padronizado (T1) e 1 h após um almoço padronizado (T2). Foram medidos os níveis de: colesterol total (CT), colesterol HDL (C-HDL), colesterol LDL (C-LDL) e triglicérides. Os dados foram analisados utilizando o teste t de Student pareado. A diferença média% (DM%) foi calculada para cada analito em T1 e T2 e foi comparada com o valor de mudança de referência (VRC). Os MDs% maiores que o VRC foram considerados clinicamente significativos. Em T1 e T2, os valores de C-HDL foram menores que em T0, enquanto os valores de C-LDL em T1 foram menores que em T0. Os níveis de triglicérides foram significativamente maiores em T1 do que os valores basais. Em todos os casos, a variabilidade foi estatisticamente, embora não clinicamente, significativa. Este estudo demonstra que no perfil lipídico em T1 e T2 não houve diferenças clinicamente significativas em relação aos valores basais.

Tomar mate previo a la flebotomía no interfiere en las pruebas bioquímicas de rutina / Drinking mate prior to phlebotomy does not interfere with routine biochemical tests

En este estudio se evaluó el efecto de tomar mate en las pruebas bioquímicas de rutina. Se extrajo sangre a 32 mujeres voluntarias luego de 12 horas de ayuno y a la hora (T1), dos horas (T2) y tres horas (T3) posteriores a la toma de 5 mates. Se estudiaron parámetros hematológicos y analitos de química clínica. Los resultados se analizaron empleando pruebas estadísticas para muestras relacionadas. Se calculó la diferencia porcentual media (DM%) de cada analito en cada hora respecto del valor basal y se comparó con el valor de referencia del cambio (VRC). Una DM% mayor que el VRC se consideró clínicamente significativa. En T1, T2 y T3 los recuentos de neutrófilos, eosinófilos y linfocitos fueron más bajos que en T0, también los niveles de glucosa, urea, creatinina y cistatina C fueron más bajos que en T0, mientras que los valores de proteínas totales, colesterol transportado por lipoproteínas de baja densidad y la actividad enzimática de lactato deshidrogenasa fueron más altos que en T0. En todos los casos los cambios fueron estadísticamente significativos, aunque no lo fueron desde el punto de vista clínico. Tomar 5 mates antes de la flebotomía no interfiere en los resultados de las pruebas bioquímicas de rutina.

In the present study the effect of drinking mate in routine biochemical tests was evaluated. Blood was collected from 32 female volunteers after a 12 h fasting period. In addition, 1 hour (T1), 2 hours (T2), and 3 hours (T3) after drinking 5 mates, blood was collected again. Hematological parameters and clinical chemistry analytes were studied. The results were analyzed using statistical tests for related samples. Mean difference % (MD%) was calculated for each analyte and was further compared with reference change value (RCV). The MDs% higher than RCV were considered clinically significant. At T1, T2, and T3 the count neutrophils, eosinophils and lymphocytes were lower than at T0. Also glucose, urea, creatinine, and cystatin C values were lower than at T0 whereas total proteins, LDL-C, and LD enzymatic activity values were higher than at T0. In all cases, variability was statistically significant but not clinically significant. Drinking 5 mates prior to phlebotomy does not interfere with the results of routine biochemical tests.

Neste trabalho, o efeito de beber chimarrão foi avaliado em testes bioquímicos de rotina. O sangue foi extraído de 32 mulheres voluntárias após 12 horas de jejum, e uma hora (T1), duas horas (T2) e três horas (T3) após a tomada de 5 chimarrões. Parâmetros hematológicos e analitos de química clínica foram estudados. Os resultados foram analisados utilizando testes estatísticos para amostras relacionadas. A diferença percentual média% (DM%) de cada analito em cada hora foi calculada em relação ao valor basal e comparada com o valor de referência da modificação (VRM). Uma DM% maior que o VRM foi considerada clinicamente significativa. Em T1, T2 e T3 as contagens de neutrófilos, eosinófilos e linfócitos foram mais baixas que em T0, Também os níveis de glicose, ureia, creatinina e cistatina C foram mais baixos que em T0, ao passo que os valores de proteínas totais, colesterol transportado por lipoproteínas de baixa densidade e a atividade enzimática de lactato desidrogenase foram mais altos que em T0. Em todos os casos as alterações foram estatisticamente significativas, embora do ponto de vista clínico não o tenham sido. Tomar 5 chimarrões antes da flebotomia não interfere nos resultados dos testes bioquímicos de rotina.

Calidad en la etapa preanalítica: evaluación de dos estrategias para verificar la correcta recogida de orina de 24 horas / Quality in the pre-analytical phase: assessment of two strategies to verify the correct collection of 24-hour urines

Introducción. Evaluar la calidad de la muestra de orina de 24 horas (orina-24h) es un desafío en el laboratorio de análisis clínicos. Para la detección de las muestras mal recogidas se han propuesto diferentes estrategias basadas en la excreción urinaria de creatinina. El objetivo de este estudio fue evaluar el desempeño de 2 de ellas: una basada en el intervalo de referencia de la excreción urinaria de creatinina (estrategia-IR) y otra propuesta por el Swiss Survey on Salt Group (estrategia-S). Materiales y métodos. El estudio se realizó en el año 2016 en una población de Argentina. Participaron 69 sujetos adultos. Se obtuvieron muestras de orina-24h mal recogidas (N=69) y bien recogidas (N=69) que a su vez se clasificaron como mal y bien recogidas según las 2 estrategias evaluadas. Se calculó el coeficiente kappa, la proporción de muestras clasificadas incorrectamente y el cociente de probabilidad (CP) positivo y negativo. Se consideró la diferencia como estadísticamente significativa para un valor de p<0,05. El estudio fue aprobado por un Comité de Bioética local y se obtuvo el consentimiento informado de cada participante. Resultados. Estrategia-IR vs. estrategia-S: coeficiente kappa: 0,26 (IC-95%: 0,10-0,42; p=0,020) vs. 0,51 (IC-95%: 0,37-0,64; p=0,000); muestras clasificadas incorrectamente: 37 vs. 25% (p=0,000); CP positivo: 1,7 (IC-95%: 1,2-2,4) vs. 9,8 (IC-95%: 3,7-25,8); CP negativo: 0,6 ((IC-95%: 0,4-0,8) vs. 0,5 ((IC-95%: 0,4-0,6). Conclusión. La estrategia-S presentó mejor desempeño que la estrategia-IR para detectar las muestras de orina-24h mal recogidas

Introduction. Assessment of the quality of the 24-hour urine sample (urine-24h) is a challenge in the clinical laboratory. Different strategies based on urinary creatinine excretion have been proposed for the detection of poorly collected samples. The objective of this study was to evaluate the performance of two of these strategies: one based on the reference interval of urinary creatinine excretion (IR-Strategy), and the other one proposed by the Swiss Survey on Salt Group (S-Strategy). Materials and methods. The study was carried out in the year 2016 with a population from Argentina. A total of 69 adult subjects were included in the study. Complete urine samples (N=69) and incomplete samples (N=69) were obtained. These were classified as poor, and well collected, according to the two strategies evaluated. Kappa coefficient, proportion of incorrectly classified samples, and positive and negative likelihood ratios (LR) were calculated. The difference was considered statistically significant for a P<.05. The study was approved by a local Bioethics Committee, and the informed consent was obtained from each participant. Results. Strategy-IR vs. Strategy-S: Kappa coefficient: 0.26 (95% CI; 0.10-0.42; P=.020) vs. 0.51 (95% CI; 0.37-0.64; P=.000); incorrectly classified samples: 37% vs. 25% (P=.000); positive LR: 1.7 (95% CI; 1.2-2.4) vs. 9.8 (95% CI; 3.7-25.8); negative LR: 0.6 (95% CI; 0.4-0.8) vs. 0.5 (95% CI; 0.4-0.6). Conclusion. The S-Strategy showed a better performance than the IR-Strategy in the detection of poorly collected urine samples

Fasting conditions: Influence of water intake on clinical chemistry analytes.

INTRODUCTION: Currently available recommendations regarding fasting requirements before phlebotomy do not specify any maximum water intake volume permitted during the fasting period. The aim was to study the effects of 300 mL water intake 1 h before phlebotomy on specific analytes. MATERIALS AND METHODS: Blood was collected from 20 women (median age (min-max): 24 (22 - 50) years) in basal state (T0) and 1 h after 300 mL water intake (T1). Glucose, total proteins (TP), urea, creatinine, cystatin C, total bilirubin (BT), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides (Tg), uric acid (UA), high-sensitivity C-reactive protein, gamma-glutamyl transferase (GGT), aspartate-aminotransferase (AST), alanine-aminotransferase and lactate-dehydrogenase (LD) were studied. Results were analyzed using Wilcoxon test. Mean difference (%) was calculated for each analyte and was further compared with reference change value (RCV). Only mean differences (%) higher than RCV were considered clinically significant. RESULTS: Significant differences (median T0vs median T1, P) were observed for TP (73 vs 74 g/L, 0.001); urea (4.08 vs 4.16 mmol/L, 0.010); BT (12 vs 13 µmol/L, 0.021); total cholesterol (4.9 vs 4.9 mmol/L, 0.042); Tg (1.05 vs 1.06 mmol/L, 0.002); UA (260 vs 270 µmol/L, 0.006); GGT (12 vs 12 U/L, 0.046); AST (22 vs 24 U/L, 0.001); and LD (364 vs 386 U/L, 0.001). Although the differences observed were statistically significant, they were not indicative of clinically significant changes. CONCLUSIONS: A water intake of 300 mL 1 h prior to phlebotomy does not interfere with the analytes studied in the present work.

Utilidad clínica del valor de referencia del cambio en la medición de creatinina plasmática / Clinical utility of the reference change value in the measurement of plasma creatinine

Introducción. La enfermedad renal crónica constituye un desafío global que exige el fortalecimiento de estrategias para su detección precoz. Asesorar adecuadamente al médico sobre la interpretación de resultados de creatinina plasmática (Cr) respecto de su intervalo de referencia (IR) y variabilidad biológica contribuye a mejorar su interpretación clínica. El objetivo de este estudio fue evaluar la utilidad del valor de referencia del cambio (VRC) para interpretar resultados consecutivos de Cr. Materiales y métodos. Se incluyeron 205 individuos adultos que concurrieron al laboratorio con solicitud de Cr y que, dentro del año previo, tenían otra medición de este analito. Se calculó el VRC para Cr considerando: Z=2,33, CVI=5,95% y CVA=1,9% (método enzimático). Para cada individuo se determinó la diferencia porcentual entre los dos valores de Cr y se confrontó con el VRC; se analizaron datos clínicos de cada paciente. Resultados. El 10% (20/205) de la población total mostró un aumento de Cr, respecto del valor previo superior al VRC, aunque dentro del IR. De ellos, el 50% presentaba factores de riesgo de enfermedad renal crónica (hipertensión, diabetes, enfermedad cardiaca, tratamiento con antiinflamatorios no esteroides). Conclusión. Una proporción significativa de los individuos estudiados presentó un aumento de Cr superior al VRC, aunque dentro del IR, y muchos de ellos tenían factores de riesgo de enfermedad renal crónica. Esto indica que el VRC es un parámetro útil para la interpretación correcta de resultados dado que permite identificar aumentos de Cr, aún dentro del IR, que podrían tener significación clínica (AU)

Introduction. The chronic renal disease constitutes a global challenge which demands the strengthening of strategies for its early detection. An adequate advising to physicians about the result interpretation of plasma creatinine (Cr) with respect to the reference interval (RI) and its biological variation contributes to improve clinical interpretation. The aim of this study is to evaluate the utility of the reference change value (RCV) to interpret Cr values. Materials and methods. Total of 205 adult outpatients who attended the laboratory with a medical request for Cr and who had another measurement of this analyte within the previous year were included. The RCV for Cr was calculated considering Z=2.33, CVI=5.95% y CVA=1.9% (enzymatic method). The percentage difference between the last two Cr values was determined for each individual; if this value reflected an increase>VRC, clinical data were evaluated as well. Results. Out of total population, 10% (20/205) showed a Cr increase taking in account the previous value, greater than the RCV but within the RI. Out of them, 50% presented risk factors for renal disease (hypertension, diabetes, heart disease, non steroidal anti-inflammatory drugs treatment). Conclusion. A significant proportion of the involved adults showed a Cr increase superior to the RCV but within the RI. Many of them presented risk factors for renal disease. This indicates that the RCV is a parameter of great utility for the correct interpretation of results, since it allows identifying increases of Cr which may have clinical significance, even within the RI (AU)