A free-haemoglobin test tracks the laboratory reference in surgical samples
A small method-comparison study tested stored blood samples from 20 cardiovascular-surgery patients. A latex-based assay followed the laboratory reference closely when measuring unbound free haemoglobin, whereas a bedside device returned higher values. The peer-reviewed analysis also tracked samples after haptoglobin administration. It evaluates measurement agreement within one surgical setting, without testing whether using the assay improves patient outcomes.
Science··Morning
Stored samples put three methods side by side
A latex-based laboratory test measured unbound free haemoglobin close to the reference method in stored surgical blood samples. The peer-reviewed comparison included 119 samples from 20 adults undergoing cardiovascular operations with cardiopulmonary bypass, which uses a machine to support circulation. Samples covered six stages from anaesthesia induction to the following morning. The breakdown of red blood cells releases free haemoglobin. Haptoglobin is the protein that binds it to assist clearance from the bloodstream.[1]
The reference and latex test track each other
The reference used high-performance liquid chromatography, which separates components for measurement. Researchers compared it with latex agglutination immunoturbidimetry, known as LATIA, and a HemoCue bedside device. Accounting for repeated samples from each patient, LATIA’s mean difference from the reference was 2.43 milligrams per decilitre. HemoCue returned higher values, with discrepancies increasing across the concentration range. The researchers suggested that detecting haemoglobin already bound to haptoglobin could be associated with the device’s different readings.[1]
Measurements follow haptoglobin administration
Clinicians chose to administer haptoglobin to eight of the patients. The reference method and LATIA detected a subsequent fall in free haemoglobin, while readings from HemoCue lacked that decline. Reference analysis took about one hour, compared with about 15 minutes for LATIA on an automated analyser and about five minutes for HemoCue. This was a single-centre pilot using stored specimens from an earlier surgical study. It assessed analytical agreement, leaving performance in other clinical settings and effects on patient outcomes untested.[1]
