A blood test could spot people most at risk of falling seriously ill or dying from Covid-19 by scanning the size of their red blood cells, a study claims.
The 'red cell distribution width' (RDW) test measures the difference in size from a patient's largest to smallest red blood cell.
It is currently used to help diagnose various medical conditions such as anaemia, heart disease, blood disorder and diabetes.
A low reading means a person's red blood cells are all about the same size, while a high score indicates the cells are of varying sizes.
A high RDW normally indicates poor nutrition but US researchers also found it was correlated with Covid-19 death rate.
Shocking data from the peer-reviewed study reveals a person with red blood cells that vary significantly in size is 2.7 times more likely to die from Covid-19.
Regularly monitoring the red blood cells could help determine whether they are responding to treatment or getting worse, the researchers add.
Shocking data from the peer-reviewed study reveals a person with red blood cells that vary significantly in size is 2.7 times more likely to die from Covid-19
The RDW test shows the difference in size between the smallest and largest red blood cells in a sample.
While variation is common, average red blood cells are 6 to 8 micrometers (μm) in diameter.
Higher RDW levels may be associated with adverse outcomes in patients with heart failure .
High RDW may also indicate a nutrient deficiency, anaemia, or other underlying conditions.
Often, RDW is part of a complete blood count - a test that measures all the blood’s components, including white blood cells, platelets, and haemoglobin.
RDW is calculated by measuring the volume of thousands of individual red blood cells (mean cell volume, or MCV).
The rise in RDW thus indicates that the population of red cells have become less uniform in size, less consistent in their physical characteristics.
In mathematical terms, RDW = (standard deviation of MCV)/MCV x 100, to be expressed as a percentage.
Above 14.5 per cent is considered to be elevated.
'We were surprised to find that one standard test that quantifies the variation in size of red blood cells –