Researchers from Qatar have developed biomarkers for plasma volume and red cell mass, which are used to monitor numerous disease states, such as heart failure, kidney disease or sepsis. The markers provide an applicable method to measure absolute plasma or red cell volumes, via a simple blood test, in a clinical set-up.
In their initial investigation, the scientists observed 33 healthy males over a period of six months. They collected monthly blood samples and concurrently estimated vascular volume.
They then analysed the individual variations of 45 common chemistry markers, such as total protein, cholesterol, calcium, transferrin, and albumin. These observed variations were then matched to the observed plasma volume variability. “We identified two panels of biomarkers, composed of 8 and 15 chemistry variables, which explained approximately 67% of plasma volume variance,” says corresponding author Louisa M. Lobigs, from Aspetar Sports Medicine Hospital, Doha, Qatar.
The scientist explains that, currently, vascular volumes are estimated in hospitals by calculating the change in concentration-based blood markers, such as hemoglobin concentration or hematocrit. This common approach produces relative values and assumes uniform mixing of the blood constituent (often not the case in the critically ill); it is also dependent on factors like the patient’s hydration levels, posture, their fluid intake. Alternatively, absolute vascular volumes can be estimated with radio-active tracers, but it’s a cumbersome and time-consuming approach, according to Lobigs.
The new method measures absolute volumes, and requires only a simple blood test.
“This is extremely promising news for improved volume management in the clinic,” she says. Validation of the model’s stability will be required before it can be streamlined among hospital patients.