Clinical chemistry and laboratory medicine最新文献

Objectives: Vitamin K homologues are essential to human health, and their concentrations in biological samples serve as valuable diagnostic biomarkers. This study was aimed to develop a method for determining vitamins K1 (phylloquinone, VK1) and K2 (menaquinone, MK-4) in human serum. The proposed method was validated and applied to the serum of a cohort of 20 Russian individuals.

Methods: High-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) was used to analyse the content of VK1 and MK-4 in serum. Atmospheric pressure chemical ionisation (APCI) in negative mode was applied to ionise VK1 and MK-4. Protein precipitation and solid-phase extraction (SPE) on polystyrene-divinylbenzene resin were combined to isolate and preconcentrate the analytes from serum.

Results: The HPLC-MSMS method was developed and validated for the determination of vitamins VK1 and MK-4 in human serum. The method demonstrated a lower limit of quantification (LLOQ) of 0.05 μg/L, with more than 71 % recoveries and precision within 17 %. To demonstrate the applicability of the method to real samples, serum from 20 healthy adults was analyzed. VK1 was detected in four individuals (0.094-0.96 μg/L), whereas MK-4 concentrations were below 0.22 μg/L in all cases.

Conclusions: The validated HPLC-MS/MS workflow provides a reliable and sensitive approach for the quantification of VK1 and MK-4 in minimal serum volumes. The method demonstrates robustness, reproducibility, and suitability for large-scale analytical applications. The proposed LC-MS/MS protocol successfully applied to native human serum samples, illustrating its applicability for future clinical and biochemical studies involving vitamin K.

The discovery of circulating tumor DNA (ctDNA) prompted many scientists and companies to apply this new technology for cancer diagnostics. One valuable application of ctDNA is in the screening for cancer. This procedure has been coined "liquid biopsy" and unlike classical biopsy, is minimally invasive. This technology can be used to detect one, a few or several cancers, hopefully at an early, treatable stage. There is considerable debate on the ability of this technology to efficiently detect small, localized tumors since the amount of ctDNA in the circulation is miniscule, potentially leading to many false negatives. Additionally, the false positive rate is concerning, especially for low prevalence tumors. Here, we provide an update and underline important issues that need to be addressed before this technology enters the clinic. Due to substantial financial rewards of successful companies and the prospective large investment of public healthcare resources, scientists have the responsibility to thoroughly validate these technologies and make sure that these tests not only detect cancer, but they also trigger actionable interventions that improve patient survival and/or quality of life.

Objectives: Progesterone regulates reproductive processes and is used clinically to monitor ovarian function in people experiencing fertility problems. Measuring serum progesterone is challenging as it is highly protein-bound and exists at very low physiological levels. An isotope dilution-liquid chromatography-tandem mass spectrometry-based candidate RMP to quantify progesterone in human serum/plasma has been developed.

Methods: To ensure traceability to the SI Units, this RMP utilized primary reference material from the NMIJ. For the determination of progesterone, two-dimensional heart-cut chromatography, in combination with a straightforward protein precipitation protocol, was employed to minimize matrix effects and the coelution of isobaric interferences. Accuracy and precision of the candidate RMP was assessed in a multi-day validation experiment using certified secondary reference materials, spiked serum and plasma samples; measurement uncertainty was evaluated according to the GUM. Equivalence to JCTLM-listed RMPs was determined using leftover samples from the RELA scheme.

Results: The candidate RMP was highly selective for progesterone within a measurement range of 0.0400-72.5 ng/mL (0.127-231 nmol/L) and matrix independent. Intermediate precision was ≤3.3 %, and repeatability ranged from 1.4 to 2.7 % across all concentration levels. The mean bias ranged from 0.1 to 0.7 % for secondary certified reference materials, from -1.6 % to -0.2 % for serum samples, and from -2.3 to 4.0 % for plasma samples. Expanded measurement uncertainty (k=2) for target value assignment (n=6) was found to be ≤3.7 %. Equivalence to JCTLM-listed RMPs demonstrated a relative bias of -2.4 to 2.2 %, all within the measurement uncertainty of the respective RMP.

Conclusions: A candidate RMP based on ID-LC-MS/MS for progesterone quantification is presented, providing metrological traceability, target value assignment, routine test standardization, and the analysis of clinical samples comprising human serum and plasma to ensure the accuracy and traceability of individual patient results.