Free thyroid hormone: Methods and standardization.

Free thyroid hormone (FTH) serves as the preferred indicator for the clinical assessment of thyroid function, mainly encompassing free thyroxine and free triiodothyronine. The immunoassay commonly employed in the clinical setting exhibits certain unresolvable deficiencies. The results of over 5,500 clinical laboratories for FTH from China in 2024 demonstrated that the outcomes of immunoassay were not comparable, with robust CVs calculated in accordance with ISO 13528 ranging from 13.82% to 21.42%. Establishing reference methods is an important tool to achieve accurate and comparable results of free hormones. Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) holds a distinct advantage in the precise detection of small molecules, and two reference methods for free thyroxine based on LC-MS/MS are included in the JCTLM list. This article conducts a comprehensive review of the detection methods and standardization of FTH. It presents the metabolism of thyroid hormones, the significance of detection, the techniques, and application examples of free thyroid hormone assays, and deliberates on the current status, prospects, and recommendations for the standardization of FTH assays. Immunoassay and LC-MS/MS, as significant techniques for FTH detection, are predominantly emphasized in the case references. Ultrafiltration and equilibrium dialysis, which are utilized to separate FTH, are also addressed. This article aims to discuss the status quo of FTH detection and clarify the advantages of LC-MS/MS in FTH detection, propose that LC-MS/MS can be utilized as an auxiliary validation method or alternative method in clinical applications, and offer suggestions for the standardization of testing results.

The endogenous factors affecting the detection of serum SARS-CoV-2 IgG/IgM antibodies by ELISA.

To investigate endogenous interference factors of the detection results of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgM/IgG. Enzyme-linked immunosorbent assay (ELISA) was used to detect SARS-CoV-2 IgM/IgG in sera of 200 patients without COVID-19 infection, including rheumatoid factor (RF) positive group, antinuclear antibody (ANA) positive group, pregnant women group, and normal senior group, with 50 in each group and 100 normal controls. The level of SARS-CoV-2 IgG in pregnant women was significantly higher than that in the normal control group (p = 0.000), but there was no significant difference between other groups. The levels of SARS-CoV-2 IgM in the pregnant women group, normal senior group, ANA positive group, and RF positive group were significantly higher than that in the normal control group (p < 0.05), with significant higher false-positive rates in these groups (p = 0.036, p = 0.004, p = 0.000, vs. normal control group). Serum RF caused SARS-CoV-2 IgM false-positive in a concentration-dependent manner, especially when its concentration was higher than 110.25 IU/L, and the urea dissociation test can turn the false positive to negative. ANA, normal seniors, pregnant women, and RF can lead to false-positive reactivity of SARS-CoV-2 IgM and/or IgG detected using ELISA. These factors should be considered when SARS-CoV-2 IgM or IgG detection is positive, false positive samples caused by RF positive can be used for urea dissociation test.

Research progress of radiation carcinogenic effect and its interference factors for survivors of the atomic bomb disaster in Japan / 中国辐射卫生

Based on the study of solid cancer incidence in survivors of the atomic bomb disaster (atomic bomb survivors) from 1958 to 1998, the Radiation Effects Research Foundation (RERF) performed an additional 11-year follow-up (1999—2009) to further investigate the 50-year solid cancer incidence of atomic bomb survivors from 1958 to 2009. Considering influencing factors such as gender, smoking, drinking, body mass index, and medical exposure, we updated the radiation risk estimate for solid cancer and found a new problem of the relationship between gender-specific dose response, exposure age and cancer incidence during the study, which provides guidance for future research.

A Validation Study of the Limulus Amebocyte Lysate Test as an End-Product Endotoxin Test for Polyvalent Horse Snake Antivenom.

The only definitive management of snake envenoming is the use of snake antivenom. Endotoxin contamination is a serious threat to the safe use of parenteral drugs. A greater understanding of the nature of limulus amebocyte lysate (LAL) test interference and use of permissible dilutions has minimized enhancement problems. Common interference issues include suboptimal pH, enzyme or protein modification, and nonspecific LAL activation. This study aimed at determining the interference factors associated with validating the antivenom sera preparations to avoid false-positive results when testing snake antivenom serum samples by the LAL method. Phase I (preliminary screening/interference assay) was performed to determine a compatible test dilution, which was then used in Phase II (inhibition-enhancement/validation study). The best approach to resolve interference issues was dilution by 1:80 (maximum valid dilution) plus a specific treatment as heat-activation at 70°C-80°C for 10 min with rehydration of LAL reagent with endotoxin-specific buffer solution.LAY ABSTRACT: Snake antivenom sera are produced by immunizing horses with repeated nonlethal doses of snake venom. Bacterial endotoxins constitute one of the major problems in the formulation of pharmaceutical products. One such method for detecting endotoxin levels is the bacterial endotoxin test (BET). However, some substances show strong interfering action with the BET that cannot be avoided by simply diluting the sample solution. In this work, the test for interfering factors was performed as two identical series of product dilutions-one spiked with 2λ and one left unspiked. The result of the interference test revealed the noninterfering dilution (NID) of the product, which was used for the actual validation. Our results showed that after treating the samples using different procedures, such as heat activation at 70-80°C for 10 min followed by centrifugation at 2000 rpm for 10 min and dilution of samples in BD100 (biodispersing agent), inhibition and enhancement up to 1:100 maximum valid dilution (MVD) were observed. Finally, to resolve this inhibition/enhancement problem, the activated sample was heated at 70-80°C for 10 min with rehydration of the Endosafe LAL reagent in an endotoxin-specific buffer solution (BG120) to block ß-d-glucans and limulus amebocyte lysate (LAL) reactive material (LAL-RM).

Problems analysis and new fabrication strategies of mediated electrochemical biosensors for wastewater toxicity assessment.

Conventional mediated electrochemical biosensors for toxicity assessment were almost based on 'one-pot' principle, i.e., mediators and the under-test chemicals were mixed together in the same vessel. In this process, the electron mediator is assumed to be merely an electron acceptor and cannot react with under-test toxicants. Actually，some under-test pollutants (such as metal ions) could react with the electron mediators, thus affecting the detection accuracy and sensitivity of the sensors. It was also found that at least two other interference factors have been ignored in present'one-pot' mediated electrochemical biosensor systems, i.e., (1) the electrochemical sensitivity of mediators to pH; and (2) the potential reactions between under-test chemicals and buffers and the consequent pH changes. In this study, the three ignored interference factors have been investigated systematically and demonstrated by significance tests. Moreover, a solving strategy, an isolation method, is proposed for fabrication of novel mediated electrochemical biosensor to avoid the interference factors existing at present mediated electrochemical biosensor. According to the testing results obtained from the isolation method, IC50 values of Cu2+, Cd2+, Zn2+, Fe3+, Ni2+ and Cr3+ were 21.3 mg/L, 3.7 mg/L, 26.7 mg/L, 4.4 mg/L and 10.7 mg/L, respectively. The detection results of four real water samples also suggested this method could be applied for the practical and complex samples.

Analysis of influencing factors of intra-laboratory turnaround time in emergency biochemistry tests / 国际检验医学杂志

Objective To investigate the intra-laboratory turnaround time(ILTAT) of the emergency biochemistry tests and to analyze the factors influencing ILTAT in order to adopt the corresponding improvement measures for perfecting the service quality and ensuring the patient medical safety.Methods ILTAT of the emergency biochemical specimens in our hospital from June to November 2015 was performed the retrospective statistics for comparing the determination timely rate between ILTAT≤60 min and ILTAT2 ≤120 min.ILTAT at different time periods in laboratory was emphatically analyzed.Results The determination timely rate of ILTAT ≤120min(ILTAT 1) was 98.8%(8638/8743),and which of ILTAT ≤60min(ILTAT 2) was 83.7%(7317/8743).The determination timely rate of ILTAT1 had no statistical difference among different time periods (χ2=3.36,P>0.05).The determination timely rate of ILTAT2 had statistical difference among different time periods(χ2=134.5,P<0.01).The determination timely rate of T 2(10:01-12:00) was highest (88.1%),which of T1 (8:01-10:00) was lowest(76.8%),which of T3(12:01-14:00) and T7 (6:01-8:00) was lower (79.4% and 80.2% respectively).Conclusion At present,ILTAT in our laboratory meets the requirements of the current regulations.Analyzing the ILTAT influencing factors in the emergency biochemistry,optimizing the workflow,improving the equipments and staffing allocation and improving the degree of information processing can further shorten the emergency biochemical ILTAT,and better meet the clinical and patient′s needs.

Measurement of cystatin C levels in the cerebrospinal fluid of patients with amyotrophic lateral sclerosis.

The diagnosis of amyotrophic lateral sclerosis (ALS) is mainly based on clinical and electrophysiological features. It is yet to be confirmed if cystatin C (Cys-C) can be a candidate diagnostic biomarker for ALS. This retrospective study aimed at investigating the changes in the level of Cys-C levels in the cerebrospinal fluid (CSF) of Chinese patients with ALS. CSF and serum samples obtained from patients with ALS, healthy controls (HC) and neurodegenerative disease controls from March 2012 to May 2014 were analyzed for levels of Cys-C using an immunoturbidimetric assay. The results were checked for the presence of meaningful correlations between Cys-C levels and variables such as the age of onset, site of symptoms onset, disease duration, and amyotrophic lateral sclerosis functional rating scale revised (ALSFRS-R) score, forced vital capacity (FVC) and rate of ALS disease progression. There was no difference in the Cys-C levels in CSF and serum between patients with ALS and controls. However, the serum Cys-C levels correlated with the ALSFRS-R score and the site of symptoms onset. The statistical analysis exhibited reduced levels of serum Cys-C in Upper limb-onset ALS (U-ALS) compared to Lower limb-onset ALS (L-ALS). The present data demonstrate that the level of Cys-C in CSF should not be considered as a biomarker of ALS. Cys-C in serum may be useful as an indicator of the severity of disease and site of symptoms onset although the specificity of serum Cys-C levels in ALS was not significant.

History of the preanalytical phase: a personal view.

In the 70ies of the last century, ther term "preanalytical phase" was introduced in the literature. This term describes all actions and aspects of the "brain to brain circle" of the medical laboratory diagnostic procedure happening before the analytical phase. The author describes his personal experiences in the early seventies and the following history of increasing awareness of this phase as the main cause of "laboratory errors". This includes the definitions of influence and interference factors as well as the first publications in book, internet, CD-Rom and recent App form over the past 40 years. In addition, a short summary of previous developments as prerequesits of laboratory diagnostic actions is described from the middle age matula for urine collection to the blood collection tubes, anticoagulants and centrifuges. The short review gives a personal view on the possible causes of missing awareness of preanalytical causes of error and future aspects of new techniques in regulation of requests to introduction of quality assurance programs for preanalytical factors.

Analysis of the interference factors of indwelling gastric tube and nursing countermeasure for patients undergoing laryngeal cancer surgery / 中国实用护理杂志

Objective To investigate the interference causes of indwelling gastric tube for patients undergoing laryngeal tumor surgery,and explore the appropriate clinical nursing countermeasures.Methods 60 cases of laryngeal cancer patients with indwelling gastric tube were divided into the control group and the observation group with 30 cases in each group.The control group used indwelling gastric tube with routine nursing,while in the observation group,the influencing factors for indwelling gastric tube were analyzed and per-tinent neasures were adopted timely.The satisfaction degree of patients,incidence of postoperative compli-cations,hospitalization time and effective rate of treatment were compared.Results The factors influ-encing use of indwelling gastric tube were tracheal extubation by patients,trachea cannula exodus,pipe blockage and postoperative complications.After timely expectant treatment and positive nursing,the nutri-tion intake and postoperative recovery were not affected.The related indexes of the observation group were better than those of the control group.Conclusions Patients after laryngeal cancer surgery need longtime indwelling gastric tube.Measures such as strengthening of education and propaganda,close observation of patients′ condition and timely expectant treatment should be given in order to ensure the normal use of gastric tube and reach desirable treatment effect.