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Precision medicine, employing genome-guided biomarkers and therapeutic strategies, has changed clinical trial recruitment and reporting. An increasing number of clinical trials have an eligibility component requiring the absence or presence of a specific molecular variant to validate predictive biomarkers that inform or recommend therapeutic action.

This is the April 2016 issue of Clinical Chemistry, Volume 62, Issue 4.

Clostridium difficile is the most common cause of healthcare associated infections in the United States and is increasingly recognized as a pathogen in the community. This organism is considered to be one of the most urgent antibiotic resistant threats to public health, and can cause a variety of clinical manifestations ranging from asymptomatic to mild diarrhea, to toxic megacolon, and even death.

This is the March 2016 issue of Clinical Chemistry, Volume 62, Issue 3.

Gestational diabetes mellitus (GDM) is associated with adverse pregnancy outcomes, but risk is reduced with identification and early treatment. Glucose measurements are affected by preanalytical sample handling, such as temperature of storage, phlebotomy–analysis interval, and use of a glycolysis inhibitor. We evaluated glucose concentrations and the incidence of GDM after strict implementation of the American Diabetes Association (ADA) preanalytical guidelines, compared with usual hospital conditions.

Evidence is accumulating that circulating 1,25-dihydroxyvitamin D [1,25(OH)2D] concentrations are inversely related to overall mortality.

Limited information is available about testosterone concentrations representative of the general US population, especially children, women, and non-Hispanic Asians.

This is the February 2016 issue of Clinical Chemistry, Volume 62, Issue 2.

There are now numerous epidemiological studies that have demonstrated that low plasma concentrations of vitamin D are associated with not only bone related disorders, but with a wide variety of adverse health outcomes.

Mass spectrometry–based in vitro diagnostic devices that measure proteins and peptides are underutilized in clinical practice, and none has been cleared or approved by the Food and Drug Administration (FDA) for marketing or for use in clinical trials. One way to increase their utilization is through enhanced interactions between the FDA and the clinical mass spectrometry community to improve the validation and regulatory review of these devices.

A driving force in the development of point-of-care diagnostics is to conveniently provide information without delay so that healthcare decisions can be made while the patient is on-site. Most point-of-care devices are based on immunochemical, electrochemicalor colorimetric techniques that can be miniaturized and made portable.

"A mass spectrometer is a sensitive and specific instrument." In some form or another, this is often the label applied to the platform by all manner of professions (chemists, physicists, biologists, physicians, clinicians, and laboratorians, novice and expert alike). This is a view of mass spectrometry (MS) through rose-colored glasses. It should be properly said that MS can be sensitive and specific, but not without due consideration for the measurement to be performed. In clinical laboratories, this measurement is the extraction, detection, and often, quantification of a compound of interest from a biological matrix.

Protein glycosylation is increasingly recognized as a crucial modulator of protein function, offering a third layer of biological information over genomics and proteomics. Modern tools for analyzing released N-glycans from cells and body fluids, i.e., the glycome, have shown abnormal protein glycosylation in numerous human diseases. These include both genetic and acquired diseases, ranging from diabetes, cancer, and inflammatory disease to neurodegenerative and neuromuscular disease. Insights from this novel field in human medicine provide exciting perspectives toward understanding disease processes, identifying therapeutic targets, and designing individualized diagnostics based on protein concentrations and glycosylation status. However, the main question is how we can translate this information into concrete biomarkers in a clinical diagnostic setting, with high demands on technical robustness and the ability to interpret results within specific patient groups.

Analytically sensitive techniques for measuring minimal residual disease (MRD) in multiple myeloma (MM) currently require invasive and costly bone marrow aspiration. These methods include immunohistochemistry (IHC), flow cytometry, quantitative PCR, and next-generation sequencing. An ideal MM MRD test would be a serum-based test sensitive enough to detect low concentrations of Ig secreted from multifocal lesions.

Despite increasing prevalence of novel psychoactive substances, no human metabolism data are currently available, complicating laboratory documentation of intake in urine samples and assessment of the drugs' pharmacodynamic, pharmacokinetic, and toxicological properties. In 2014, THJ-018 and THJ-2201, synthetic cannabinoid indazole analogs of JWH-018 and AM-2201, were identified, with the National Forensic Laboratory Information System containing 220 THJ-2201 reports. Because of numerous adverse events, the Drug Enforcement Administration listed THJ-2201 as Schedule I in January 2015.