Revista del Laboratorio Clínico最新文献

Alimemazine (Variargil^®) is a non-specific reversible anti-H1 antihistamine that crosses the blood-brain barrier. It acts as anticholinergic drug. It is marketed in drop form (oral suspension). It is used to relieve seasonal allergic rhinitis, angioedema, mild urticaria, allergic conjunctivitis, and for difficulty in falling asleep in children. It has a very variable pharmacokinetic, excessive “heavy hangover drowsiness” and rebound effect after withdrawal. It is not authorised for children under 2 years of age. The case is presented of a patient seen in the emergency room due to drowsiness and lack of response to stimuli after administration of alimemazine due to difficulties in falling asleep.

Background

Despite being the most widely used medical decision-making tool, reference intervals are not usually determined by clinical laboratories, due to the highly demanding activities and costly process it involves. However, scientific societies encourage individual clinical laboratories to establish their own reference values. This is especially important in the cases of folate and vitamin B₁₂, due to strong differences in vitamin status among different populations.

Objective

Our aim is to establish reference intervals for folate and vitamin B₁₂ levels in a healthy blood donor population using an electrochemiluminiscent method (ROCHE DIAGNOSTICS).

Method

Folate and vitamin B₁₂ levels were measured in 141 healthy blood donors aged between 18 and 65 years. Biochemical analyses were performed using a Modular E170 analyzer (ROCHE DIAGNOSTICS) and an electrochemiluminiscent method. Reference intervals were calculated with a non-parametric percentile method following the CLSI guidelines.

Results

There were not significant differences in folate or cobalamin levels between age or sex subgroups. The limits of the reference interval for folate were 2.2 and 18 ng/mL (5–40.7 nmol/L), and 213.8 and 763.3 pg/mL (158.2–564.8 pmol/L) for vitamin B₁₂. These intervals differed from those claimed by the manufacturer.

Conclusions

Our results emphasize the convenience of building reference values based on the population served by the laboratory, in order to unequivocally rule out deficiencies of folate or vitamin B_12.

Introduction

The laboratory must be able to guarantee the stability of stored patient samples for confirmation of results or errors in the interpretation of the medical request. The aim of this study was to evaluate the stability of the blood analytes preserved in tubes sealed with film versus a plastic cap.

Material and methods

A total of 24 blood samples were aliquoted into two tubes; one sealed with film, and the other with a plastic cap. Twenty-six clinical chemistry analytes were measured for 7 consecutive days using a Roche Cobas c 501 autoanalyser. The samples were stored in a refrigerator between 2-8 C. The total error and coefficient of variation were calculated, and the results were compared against the quality requirements of the laboratory.

Conclusions

The variation was higher in the tubes sealed with film than in those with a plastic cap. Enzymes remained within the quality requirements for four days, and ions, apart from iron, were stable for only one day. The metabolites were stable for seven days excluding glucose, uric acid, total proteins, and albumin. It is suggested that each laboratory must evaluate the stability of analytes based on its workflow.

Biochemical studies of the pleural fluid are often a key step in the diagnostic workup. Several parameters (pH, glucose, protein, lactate dehydrogenase, adenosine deaminase) add immediate relevant information, or they can help in the diagnosis of specific causes of pleural effusion (beta-2 transferrin, beta-trace-protein, creatinine, amylase, bilirubin, cholesterol, triglycerides, and C-reactive protein). However, parameters of questionable value may also be requested. The relationship between the attending physician and the clinical laboratory is critical in order to obtain higher diagnostic efficiency. An accurate selection of the biochemical tests to perform achieves the best approach to the study of a pleural effusion.

Introduction

In first trimester combined screening, biochemical and ultrasound markers are used that are modified by different factors such as weight, twins, smoking, etc. The aim of this study is to analyse the influence of foetal gender on these markers, and the repercussion on the result of the screening of trisomy 21.

Material and methods

An observational, descriptive and retrospective study (2013-2015) was conducted. Multiple gestations were excluded. Variables analysed: nuchal translucency, free human chorionic gonadotrophin concentration, pregnancy-associated plasma protein A, and their median corrected multiples. A comparison was made of the medians of the variables in gestations with male and female foetuses, affected and non-affected.

Results

There was a 23.62% increase in the median of the median corrected multiple free human chorionic gonadotrophin and 3.65% in the median of the median corrected multiple pregnancy-associated plasma protein A, in gestations with female foetuses. This increase is observed in gestations with foetuses affected and non-affected by trisomy 21. Male gender: detection rate 86.9%, false positive rate 3.36%. Female gender: detection rate 90.9%, false positive rate 4.10%.

Conclusions

The increase, especially in free human chorionic gonadotrophin levels, leads to an increase in detection rate and false positive rate in gestations with a female foetus. The application of a correction factor by gender requires cost-effectiveness studies.

Introduction

Therapeutic drug monitoring of methotrexate (MTX) is a practice used during acute lymphoblastic leukaemias treatments in order to adjust the leucovorin rescue dose and avoid toxicity. The aim of this work was to evaluate the performance of a bioanalytical method based on liquid chromatography in the control of paediatric acute lymphoblastic leukaemia treatments.

Materials and methods

MTX plasma concentrations were evaluated in a total of 61 patients, divided in 2 groups according to the treatment: 24 h infusion and 36 h infusion. The method used 250 μL aliquots of pre-processed plasma, using a validated analytical method, in an Agilent 1260 chromatograph with a 5 μm Zorbax Eclipse XDB-C18 column (4.6 × 150 mm) and a mobile phase composed of acetonitrile and 0.05 mol/L of a sodium acetate buffer solution at pH 3.5. The detection was performed at 305 nm.

Results

The method did not show interferences by metabolites or other drugs. The lower limit of quantitation was 0.05 μmol/L. Inter- and intra-assay precision and accuracy were acceptable in the working range (0.05-5.0 μmol/L), and linear behaviour was observed. Toxic plasma levels of MTX were observed in 29.4% and 60% of the patients from 24 h infusion and 36 h infusion, respectively. Therefore, leucovorin rescue treatment was either applied earlier or reinforced.

Conclusions

The chromatography method was efficient and accessible for the therapeutic drug monitoring of MTX in paediatric patients, allowing appropriate medical decision making within a short time of analysis.