Análisis clínicos en pediatría: la necesidad de minimizar las horas de ayuno / Clinical analysis in pediatrics: the need to minimize fasting hours

Los informes de laboratorio tienen impacto en las decisiones médicas. El ayuno es un factor preanalítico "controlable" que influye en los distintos parámetros bioquímicos. El objetivo del presente trabajo es poner en discusión la realización en pediatría de análisis clínicos con la indicación de un ayuno fisiológico , analizando resultados obtenidos por diferentes autores y evaluando las diferencias clínicas encontradas según los criterios de calidad establecidos por el laboratorio de Química Clínica. La mayoría de los individuos durante el día se encuentran en estado postprandial. Los resultados del perfil lipídico en ayunas no representan las concentraciones reales promedios de los lípidos plasmáticos de un paciente. El ayuno no sería crítico en la etapa de pesquisa , pero puede ser relevante para establecer un diagnóstico certero o inicio de tratamiento. En el caso de la glucemia si se indica en el control rutinario del paciente, y no hay sospecha de alteraciones en el metabolismo de los hidratos de carbono la glucemia sin ayuno puede ser solicitada comparando la misma con valores de corte adecuado. Las diferentes guías nacionales e internacionales recomiendan que la elección de la métrica para la evaluación, control y seguimiento de pacientes con diagnóstico de diabetes se realicen según el objetivo terapéutico. En los trabajos analizados, observamos que varios parámetros bioquímicos presentaron diferencias estadísticas, aunque las diferencias clínicas no fueron relevantes y permanecieron dentro de los intervalos de referencia. El factor limitante para evaluar parámetros bioquímicos sin ayuno es la falta de valores de referencia adecuados. Hay evidencia suficiente para que tanto el perfil lipídico, la glucemia como el resto de los parámetros bioquímicos del laboratorio de química clínica, sean solicitados con la indicación de un ayuno fisiológico de 2, 4 o 6 horas, dependiendo siempre del motivo de consulta y/o la edad del paciente. Es esencial extender la evaluación a otros analitos en población pediátrica, así como evaluar nuevos puntos de corte para parámetros bioquímicos sin ayuno (AU)

Laboratory reports have an impact on medical decision-making. Fasting is a "controllable" preanalytical factor that influences the different biochemical parameters. The aim of this study is to discuss the performance of clinical analyses in pediatrics with the indication of physiological fasting, analyzing results obtained in different disciplines, and evaluating the clinical differences found according to the quality criteria established by the clinical chemistry laboratory. During the day, most patients are in a postprandial state. Fasting lipid profile results do not represent the actual average plasma lipid concentrations of a patient. Fasting would not be critical in the screening stage, but it may be relevant to establish an accurate diagnosis or initiate treatment. Regarding glycemia, if it is indicated in the routine control of the patient and there is no suspicion of alterations in carbohydrate metabolism, non-fasting glycemia can be requested, comparing it with adequate cut-off values. Different national and international guidelines recommend that the choice of metrics for the evaluation, control, and follow-up of patients with diabetes should be made according to the therapeutic objective. In the studies analyzed, we found that several biochemical parameters presented statistical differences, although the clinical differences were not relevant and remained within the reference range. The limiting factor in the evaluation of biochemical parameters without fasting is the lack of adequate reference values. There is sufficient evidence that the lipid profile, glycemia, and the remaining biochemical parameters of the clinical chemistry laboratory should be requested with the indication of a physiological fast of 2, 4, or 6 hours, always depending on the reason for consultation and/or the patient's age. It is essential to extend the evaluation to other analytes in the pediatric population, as well as to evaluate new cut-off points for biochemical parameters without fasting (AU)

Body fluid matrix effect evaluation on the Hitachi Labospect 008 system.

BACKGROUND: Non-standard body fluids (NSBFs) can provide essential clinical information otherwise unobtainable with conventional biological specimens. However, as most commercial chemistry reagents are only validated for serum, plasma, and urine by manufacturers, individual laboratories have to validate testing with NSBF to comply with regulatory standards. However, the heightened level of oversight and uncertainty of validation requirements to comply with regulatory standards pose a significant challenge for NSBF testing in clinical laboratories. METHODS: 28 combinations of high-volume chemistry tests requested on NSBF with established clinical utility were selected from retrospective data analysis. Specimens were analyzed with both closed and open channel chemistry reagents on a LABOSPECT 008AS platform (Hitachi High-Tech Co., Tokyo, Japan). Recovery studies were performed using a high concentration serum sample and 5 clinical NSBF samples at varying concentrations for each analyte. Acceptable performance limits were defined as 100 ± 10% of expected recovery. RESULTS: The average percent recovery ranged from 94.5% to 106.6% depending on the analyte/NSBF combination evaluated, and for each of the 28 combinations, the average percent recovery was within the predefined acceptable limits of ± 10%. CONCLUSIONS: The recovery results from this study on the LABOSPECT 008AS platform demonstrates that any systematic matrix interference of high-volume chemistry testing on NSBF samples is well within the defined limits of acceptability. This work also demonstrates recovery studies performed by an individual laboratory are practial and it is feasible to demonstrate compliance with regulatory requirements for accuracy of chemistry testing on NSBF samples.

Evaluation of a flow cytometric test for G6PD-deficient erythrocytes.

OBJECTIVE: Glucose-6-phosphate dehydrogenase (G6PD) deficiency, an X-linked recessive disorder, is the commonest erythrocytic enzymopathy worldwide. Reliable diagnosis and severity prediction in G6PD-deficient/heterozygous females remain challenging. A recently developed flow cytometric test for G6PD deficiency has shown promise in precisely identifying deficient females. This paper presents our experiences with this test in a subtropical setting and presents a modification in flow cytometric data acquisition strategy. METHODS: The methaemoglobin reduction + ferryl Hb generation-based flow cytometric G6PD test was compared with the screening methaemoglobin reduction test (MRT) and confirmatory G6PD enzyme activity assay (EAA) in 20 G6PD-deficient males, 22 G6PD-heterozygous/deficient females and 20 controls. Stained cells were also assessed for bright/dim G6PD activity under a fluorescent microscope. RESULTS: Flow cytometry separated and quantified %bright cells in heterozygous/deficient females, objectively classifying them into 6 normal (>85% bright cells), 14 intermediate (10-85%) and two G6PD-deficient (<10% bright cells). Concordance with MRT was 89% (55/62 cases) and with EAA was 77% (48/62 cases). Fluorometrically predicted violet laser excitation (405-nm) with signal acquisition in the 425-475 nm region was a technical advancement noted for the first time in this paper. CONCLUSION: Flow cytometry/fluorescence microscopy represent technically straightforward methods for the detection and quantification of G6PD-deficient erythrocytes. Based on our results, we recommend their application as a first-line investigation to screen females who are prescribed an oxidant drug like primaquine or dapsone.

A convenient sampling and noninvasive dried spot method of uric acid in human saliva: Comparison of serum uric acid value and salivary uric acid in healthy volunteers and hyperuricemia patients.

Concentration of uric acid (UA) in serum is one of the markers used to diagnose gout and hyperuricemia. However, serum treatment and storage are cumbersome, and wounds are susceptible to infection. Therefore, a new sampling and analysis method using noninvasive biological samples has been developed, called the dried spot method of UA in human saliva (DSM-UHS). Saliva (5 µL) was dropped on filter paper (a spot with a diameter of 5 mm) containing hypoxanthine (IS) (5 µL) and dried at room temperature for 30 min. The filter paper was immersed in 200 µL of lithium carbonate solution and shaken in a block bath shaker for 5 min at 30 °C. Afterward, the extraction was concentrated and reconstituted with 100 µL of lithium carbonate solution analyzed by HPLC-UV. When comparing the concentration of UA in the human saliva of hyperuricemia patients (HPs) and with that of healthy volunteers (HVs), we observed the concentration of UA was higher in the HPs than in the HVs (p < 0.0001). In addition, the results showed a significant linear relationship between the content of UA in saliva and the content of UA in the serum (r = 0.6243). The content of UA in human saliva could indirectly reflect the content of UA in human serum. Then DSM-UHS could be used to determine the content of UA in the saliva of HVs and HPs. This study provides a new research method and strategy for the determination of human UA content and the clinical prewiring of hyperuricemia.

Toxicity profiling of the ethanolic extract of Citrullus lanatus seed in rats: behavioral, biochemical and histopathological aspects.

Citrullus lanatus (Cucurbitaceae) is conventionally used for the treatment of urinary tract infection, renal stones, hypertension, diabetes and diarrhoea. Current study evaluates acute and 28 days repeated toxicity ethanolic extract of C. lanatus seed (EECLS) in Wistar rats to measure its safety profile. The single dose (2000 mg/kg BW) of EECLS was administered while in 28 days repeated study 250, 500 and 1000 mg/kg BW were administered orally in rats. Parameters such as biochemical, haematological and histopathological were analysed in subacute toxicity study. During study, no apparent sign of toxicity, behavioural changes and mortality were detected in acutely exposed animals. In 28 days repeated toxicity study, rats did not show significant changes in behaviour, gross pathology, body weight, biochemical and haematological parameters. Abridged serum glucose and cholesterol levels during the study designate their roles in treatment of hyperglycaemic and hyperlipidaemic conditions. No significant difference was observed in histopathology of liver and kidneys of treated rats. The current investigation demonstrated that EECLS is non-toxic below 1000 mg/kg BW and provides protection to some body organs. The data propose that LD50 of EECLS was greater than 2000 mg/kg BW and the no observed adverse effect level (NOAEL) of EECLS was at the dose of 1000 mg/kg in rats. Taken together, our finding suggests that, EECLS is safe and provides some protection to body organs; also, its extract can be used for further preclinical and clinical evaluation for its therapeutic activity.

Simultaneous determination of 30 neurologically and metabolically important molecules: A sensitive and selective way to measure tyrosine and tryptophan pathway metabolites and other biomarkers in human serum and cerebrospinal fluid.

Concurrent measurement of tyrosine, tryptophan and their metabolites, and other co-factors could help to diagnose and better understand a wide range of metabolic and neurological disorders. The two metabolic pathways are closely related to each other through co-factors, regulator molecules and enzymes. By using high performance liquid chromatography coupled to electrospray ionization triple quadrupole mass spectrometry, we present a robust, selective and comprehensive method to determine 30 molecules within 20 min using a Waters Atlantis dC18. The method was validated according to the guideline of European Medicines Agency on bioanalytical method validation. Analytical performance met all the EMA requirements and the assay covered the relevant clinical concentrations. Linear correlation coefficients were all >0.998. Intra-day and inter-day accuracy were between 80-119% and 81-117%, precision 1-19% respectively. The method was applied to measure TYR, TRP and their metabolites, and other neurologically important molecules in human serum and CSF samples. The assay can facilitate the diagnosis and is suitable for determination of reference values in clinical laboratories.

Clinical and biochemical characteristics of patients admitted to ICU with SARS-CoV-2 / Características clínicas y bioquímicas de pacientes ingresados en UCI con SARS-CoV-2

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Commonly used clinical chemistry tests as mortality predictors: Results from two large cohort studies.

BACKGROUND: The normal ranges for clinical chemistry tests are usually defined by cut-offs given by the distribution in healthy individuals. This approach does however not indicate if individuals outside the normal range are more prone to disease. METHODS: We studied the associations and risk prediction of 11 plasma and serum biomarkers with all-cause mortality in two population-based cohorts: a Swedish cohort (X69) initiated in 1969, and the UK Biobank (UKB) initiated in 2006-2010, with up to 48- and 9-years follow-up, respectively. RESULTS: In X69 and in UKB, 18,529 and 425,264 individuals were investigated, respectively. During the follow-up time, 14,475 deaths occurred in X69 and 17,116 in UKB. All evaluated tests were associated with mortality in X69 (P<0.0001, except bilirubin P<0.005). For calcium, blood urea nitrogen, bilirubin, hematocrit, uric acid, and iron, U-shaped associations were seen (P<0.0001). For leukocyte count, gamma-glutamyl transferase, alkaline phosphatases and lactate dehydrogenase, linear positive associations were seen, while for albumin the association was negative. Similar associations were seen in UKB. Addition of all biomarkers to a model with classical risk factors improved mortality prediction (delta C-statistics: +0.009 in X69 and +0.023 in UKB, P<0.00001 in both cohorts). CONCLUSIONS: Commonly used clinical chemistry tests were associated with all-cause mortality both in the medium- and long-term perspective, and improved mortality prediction beyond classical risk factors. Since both linear and U-shaped relationships were found, we propose to define the normal range of a clinical chemistry test based on its association with mortality, rather than from the distribution.

Sample preparation strategies for the determination of psychoactive substances in biological fluids.

This review focuses on the existing analytical procedures for the determination of new psychoactive substances (NPS) in biological fluids by chromatographic methods. Direct analysis of samples is scarcely employed and most proposed methodologies include a sample pre-treatment in order to remove matrix interferents and, in some cases, pre-concentrate extracts. Current extraction methods for NPS determination in plasma/serum, urine, and oral fluids have been widely discussed, such as liquid-liquid, solid-phase, and micro extraction approaches, highlighting the advantages and drawbacks of the proposed extraction methodologies. Regarding microextraction approaches, techniques like microextraction by packed sorbent, solid-phase microextraction, miniaturized solid phase extraction, and dispersive liquid-liquid extraction have been proposed for NPS determination in biological fluids with reliable analytical results.

La educación con una plataforma multimedia en web mejora los conocimientos y la HbA1c de pacientes mexicanos con diabetes tipo 2. Ensayo clínico abierto / Education with a multimedia web platform improves knowledge and HbA1c of Mexican patients with type 2 diabetes. Open clinical trial

INTRODUCCIÓN: El paciente con diabetes mellitus tipo 2 requiere recibir educación acerca de la enfermedad dirigida a mejorar los conocimientos y habilidades para su control. El objetivo de este estudio fue evaluar la eficacia de la terapia nutricia y de la educación a través de un sitio multimedia, sobre el nivel de conocimientos y control metabólico en pacientes con diabetes tipo 2. MATERIAL Y MÉTODOS: Ensayo clínico abierto de 12 meses de seguimiento en 161 pacientes con diabetes tipo 2. Se asignaron 101 pacientes al grupo de intervención con terapia nutricional (TN) + Nutriluv (sitio multimedia), 80 pacientes al grupo control con TN. Se midió al inicio y al final la hemoglobina glucosilada (HbA1c), glucosa, colesterol, triglicéridos, colesterol LDL y HDL. Se registró el peso, la circunferencia de cintura, el porcentaje de grasa, la presión arterial sistólica y la diastólica. El nivel de conocimientos se midió con el cuestionario de conocimientos en diabetes DKQ24 (por sus siglas en inglés). RESULTADOS: Los conocimientos en diabetes mejoraron en el grupo con TN+Nutriluv comparado con el grupo TN (p < 0,05). La HbA1c, HDL, presión arterial diastólica y circunferencia de cintura mejoraron en el grupo con TN+Nutriluv (p < 0,05). En el grupo con TN mejoró el colesterol HDL, la presión arterial diastólica, la circunferencia de cintura y se incrementó el porcentaje de grasa (p < 0,05). Presentaron mayor riesgo de una HbA1c > 7% quienes tuvieron más años de diagnóstico de la diabetes. CONCLUSIÓN: El uso de un sitio multimedia para proveer educación en diabetes mejora los conocimientos, el HbA1c y otros indicadores de riesgo cardiovascular en pacientes con diabetes tipo 2

INTRODUCTION: The patient with diabetes mellitus type requires to receive education about the disease aimed at improving knowledge and skills for their control. The objective of this study is to evaluate the efficacy of nutritional therapy and education through a multimedia site on the level of knowledge and metabolic control in patients with type 2 diabetes. PATIENTS AND METHODS: Open-label clinical trial of 12 months of follow-up in 161 patients with type 2 diabetes. A total of 101 patients were assigned to the intervention group with nutrition therapy (TN) + Nutriluv (multimedia site in diabetes), 80 patients to the TN control group. The glycosylated hemoglobin (HbA1c), glucose, cholesterol, triglycerides, LDL and HDL cholesterol were measured at the beginning and end. Weight, waist circumference, percentage of fat, systolic blood pressure and diastolic blood pressure were recorded. The level of knowledge was measured with the Diabetes Knowledge Questionnaire (DKQ24). RESULTS: The knowledge in diabetes improved in the group with TN+Nutriluv compared with the TN group (P<0.05). HbA1c, HDL, diastolic blood pressure and waist circumference, improved in the group with TN+Nutriluv (P<0.05). In the group with TN, cholesterol HDL, diastolic blood pressure, waist circumference and the fat percentage was increased (P<0.05). They had a higher risk of having an HbA1c>7% who had more years of diagnosis of diabetes. CONCLUSIONS: The use of a multimedia site with education in diabetes, improves knowledge, HbA1c, and other indicators of cardiovascular risk in diabetes type 2 patients

Comment on: Sensitivity and specificity of cerebrospinal fluid glucose measurement by an amperometric glucometer.

[No Abstract Available].

Erratum: Sensitivity and specificity of cerebrospinal fluid glucose measurement by an amperometric glucometer.

[No Abstract Available].

Application and optimization of reference change values for Delta Checks in clinical laboratory.

BACKGROUND: Delta check is a patient-based QC tool for detecting errors by comparing current and previous test results of patient. Reference change value (RCV) is adopted in guidelines as method for delta check, but the performance is not verified. We applied RCV-based delta check method to patients' data and modified for application. MATERIALS AND METHODS: Reference change value were calculated using results of internal QC materials and biological variation data. Test results of 17 analytes in inpatients, outpatients, and health examination recipients were collected. The detection rates of currently used delta check method and those of RCV-based method were compared, and the methods were modified. RESULTS: Reference change value-based method had higher detection rates compared to conventional method. Applied modifications reduced detection rates. Removing the pairs of results within reference interval reduced detection rates (0.42% ~ 10.92%). When RCV was divided by time interval, the detection rates were similar to prior rates in outpatients (0.19% ~ 1.34%). Using RCV multiplied by twice the upper limit of reference value as cutoff reduced the detection rate (0.07% ~ 1.58%). CONCLUSIONS: Reference change value is a robust criterion for delta check and included in clinical laboratory practice guideline. However, RCV-based method generates high detection rates which increase workload. It needs modification for use in clinical laboratories.

A blood-based biomarker panel (NIS4) for non-invasive diagnosis of non-alcoholic steatohepatitis and liver fibrosis: a prospective derivation and global validation study.

BACKGROUND: Non-invasive tests that can identify patients with non-alcoholic steatohepatitis (NASH) at higher risk of disease progression are lacking. We report the development and validation of a blood-based diagnostic test to non-invasively rule in and rule out at-risk NASH (defined as non-alcoholic fatty liver disease [NAFLD] activity score [NAS] ≥4 and fibrosis stage ≥2). METHODS: In this prospective derivation and global validation study, blood samples, clinical data, and liver biopsy results from three independent cohorts with suspected NAFLD were used to develop and validate a non-invasive blood-based diagnostic test, called NIS4. Derivation was done in the discovery cohort, which comprised 239 prospectively recruited patients with biopsy-confirmed NASH (NAFLD NAS ≥3; fibrosis stage 0-3) from the international GOLDEN-505 phase 2b clinical trial. A complete matrix based on 23 variables selected for univariate association with the presence of at-risk NASH and avoiding high multi-collinearity was used to derive the model in a bootstrap-based process that minimised the Akaike information criterion. The overall diagnostic performance of NIS4 was externally validated in two independent cohorts: RESOLVE-IT diag and Angers. The RESOLVE-IT diag cohort comprised the first 475 patients screened for potential inclusion into the RESOLVE-IT phase 3 clinical trial. Angers was a retrospective cohort of 227 prospectively recruited patients with suspected NAFLD and clinical risk factors for NASH or fibrosis stage 2 or more according to abnormal elastography results or abnormal liver biochemistry. Both external validation cohorts were independently analysed and were combined into a pooled validation cohort (n=702) to assess clinical performance of NIS4 and other non-invasive tests. FINDINGS: The derived NIS4 algorithm comprised four independent NASH-associated biomarkers (miR-34a-5p, alpha-2 macroglobulin, YKL-40, and glycated haemoglobin; area under the receiver operating characteristics curve [AUROC] 0·80, 95% CI 0·73-0·85), and did not require adjustment for age, sex, body-mass index (BMI), or aminotransferase concentrations. Clinical cutoffs were established within the discovery cohort to optimise both rule out and rule in clinical performance while minimising indeterminate results. NIS4 was validated in the RESOLVE-IT diag cohort (AUROC 0·83, 95% CI 0·79-0·86) and the Angers cohort (0·76, 0·69-0·82). In the pooled validation cohort, patients with a NIS4 value less than 0·36 were classified as not having at-risk NASH (ruled out) with 81·5% (95% CI 76·9-85·3) sensitivity, 63·0% (57·8-68·0) specificity, and a negative predictive value of 77·9% (72·5-82·4), whereas those with a NIS4 value of more than 0·63 were classified as having at-risk NASH (ruled in) with 87·1% (83·1-90·3) specificity, 50·7% (45·3-56·1) sensitivity, and a positive predictive value of 79·2% (73·1-84·2). The diagnostic performance of NIS4 within the external validation cohorts was not influenced by age, sex, BMI, or aminotransferase concentrations. INTERPRETATION: NIS4 is a novel blood-based diagnostic that provides an effective way to non-invasively rule in or rule out at-risk NASH in patients with metabolic risk factors and suspected disease. Use of NIS4 in clinical trials or in the clinic has the potential to greatly reduce unnecessary liver biopsies in patients with lower risk of disease progression. FUNDING: Genfit.

COVID-19 y tratamiento guiado con tests de diagnóstico bioquímicos y moleculares para reducir el daño cardiaco y la cardiotoxicidad / COVID-19 and treatment guided by biochemical and molecular diagnostic tests to reduce myocardial damage and cardiotoxicity

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Implementation of patient-based real-time quality control.

The quest to use patient results as quality control for routine clinical chemistry testing has long been driven by issues of the unavailability and cost of suitable quality control material and the matrix effects of synthetic material. Hematology laboratories were early adopters of average of normals techniques, primarily because of the difficulty in acquiring appropriate, stable quality control material, while in the chemistry laboratories, the perceived advantages and availability of synthetic material outweighed the disadvantages. However, the increasing volume of testing in clinical chemistry plus the capability of computer systems to deal with large and complex calculations has now made the use of patient-based quality control algorithms feasible. The desire to use patient-based quality control is also driven by increasing awareness that common quality control rules and frequency of analysis may fail to detect clinically significant assay biases. The non-commutability of quality control material has also become a problem as laboratories seek to harmonize results across regions and indeed globally. This review describes the history of patient-based quality control in clinical chemistry, summarizes the various approaches that can be implemented by laboratory professionals, and discusses how patient-based quality control can be integrated with traditional quality control techniques.

Sensitivity and specificity of cerebrospinal fluid glucose measurement by an amperometric glucometer.

OBJECTIVES: To provide more data regarding the role of an amperometric glucometer in diagnosing meningitis. Methods: This is a prospective study conducted at the Pediatric and Neonatology Department, Qatif Central Hospital, Qatif, Saudi Arabia between March 2017 and September 2018. We measured glucose concentrations in cerebrospinal fluid (CSF) and blood using a central laboratory and amperometric glucometer (AG). We compared CSF/blood glucose ratios obtained in a central laboratory from clinical bedside examination with a glucometer, and calculated the sensitivity and specificity for detecting cases of meningitis. Results: A total of 101 patients with clinical suspicion of meningitis were recruited for CSF sampling. Of 101 CSF samples, 61 (60%) were suggestive of meningitis. Of 101 samples, 47 had hypoglycorrhachia identified by a standard laboratory, and 17% of them were also detected by AG. The correlation between CSF/blood glucose by AG and laboratory ratios was substantial (r=0.894, p  less than 0.01, 95% CI: 0.805-0.983). The AG sensitivity was 100% and specificity was 55% in pediatric cases, while in neonates the sensitivity was 86% and the specificity was 26%. Conclusion: Amperometric glucometers  can be used to detect hypoglycorrhachia accurately. This  point-of-care testing tool is easily accessible and can be used by health care providers for cases suspected of meningitis.

Preparation of In-House Quality Control Human Serum for Urea and its Use in Clinical Chemistry.

BACKGROUND: Quality control materials play a vital role in the laboratory internal and external quality assessment program. However, Ethiopia and other developing countries are challenged by the unavailability and high cost of commercial control material. Therefore, preparing in-house quality control human serum will be a cost-effective way to obtain QC material for use in poor settings in a country like Ethiopia. To prepare urea in-house control human serum and scientifically evaluate it with commercially available sera already in use in the clinical chemistry laboratory of the Ethiopian Public Health Institute. METHODS: The urea in-house quality control human serum was prepared as per ISO Guide 80, a guideline document protocol from 57 participants' normal serum specimens at the Ethiopian Public Health Institute clinical chemistry laboratory. The quality control material was analyzed on a fully automated chemistry analyzer (Cobas 6000). The initial 20 values were used for calculation of means, standard deviation (SD) and coefficient of variation (CV). Results were compared with those of commercially available lyophilized human sera. RESULTS: The average concentrations of urea were found to be near the middle of the physiological range of healthy subjects and the in-house serum could be a good substitute for the commercial serum of normal range. The prepared in-house quality control human serum is stable for about three months without any alterations in the concentration of urea. CONCLUSIONS: Well prepared in-house quality control human serum is a good substitute for commercially available control serum of normal range, especially in a developing country like Ethiopia.