This first of two articles on method comparison studies gives some key concepts related to the design of the method comparison study, data analysis and graphical presentation, stressing the importance of a well-designed and carefully planned experiment using adequate statistical procedures for data analysis when...

When a new D-dimer method is evaluated, it’s typically compared to an established D-dimer method using both an analytical and a clinical comparison. Analytical comparisons should be discouraged, as they do not give any useful information about the potential clinical usability of the assay. D-dimer assay comparisons...

The measurement of the parameters pH, pCO₂ and pO₂ is vulnerable to a number of preanalytical errors and this article shares practical tips to help avoid these errors, ensuring that the results of analysis accurately reflect the patient’s acid-base and oxygenation status. The tips include the removal of air bubbles, ...

The process of blood gas and pH measurement involves preheating the arterial blood sample to normal body temperature (37 °C) prior to measurement of pH, partial pressure of oxygen (pO₂) and partial pressure of carbon dioxide (pCO₂). This ensures that results reflect in vivo temperature condition. A minority of...

The significance of good practice during the preanalytical phase of clinical laboratory investigation cannot be overemphasized. One aspect of the preanalytical phase – the transport of samples – is considered here; in particular the transport of samples via pneumatic tube systems. This is an update of a previous...

Clinical sensitivity, clinical specificity and predictive values are frequently used as performance measure for a biochemistry assay. When D-dimer assay performance is presented, emphasis is often on the negative predictive value (NPV). However, predictive values are greatly influenced by the prevalence of the...

Plasma sodium concentration is measured with an ion-specific electrode (ISE) using either an undiluted sample (direct ISE) or diluted sample (indirect ISE).  This is the second of two linked articles highlighting the spurious sodium values that can occur if an indirect ISE method is used to analyze plasma samples with ...

Reprinted from Ann Lab Med 2014 Sep; 34(4):263-73. Procalcitonin (PCT) is used as a biomarker for the diagnosis of sepsis, severe sepsis and septic shock. At the same time, PCT has also been used to guide antibiotic therapy. This review outlines the main indications for PCT measurement and points out possible...

This article first appeared in Pathology in Practice (Hobba H, Silver L. Evolution of POC testing. Pathology in Practice 2013; 14 [2]: 63) and is reproduced here by kind permission (www.pathologyinpractice.com). © 2013 kdm communications limited Point-of-care (POC) testing has allowed the pathology department in...

Disturbance of sodium balance is a common occurrence among hospitalized patients that can, if not identified and treated, cause significant morbidity; severe disturbance is potentially lethal. So estimation of plasma sodium concentration is one of the most frequently requested blood tests.  Historically, plasma sodium ...