RDW
RDW (red cell distribution width) describes how much the red blood cells vary in size.
RDW (red cell distribution width) describes how much the red blood cells vary in size. When the cells are much the same size, RDW is lower; when there is a wider mix of small and large cells, it is higher. It is part of the blood count and is read together with MCV and haemoglobin.
Intake of iron, vitamin B12 and folate shapes how evenly red blood cells are built. Recent blood loss or blood donation, heavy menstruation, alcohol, a recent infection and age also play a part.
Foods that help
Meat, fish, eggs, dairy, legumes, whole grains and dark leafy greens provide the iron, B12 and folate that red blood cells are built from. Vitamin C-rich foods with meals help the body take up iron from plant foods.
Foods to limit
Large amounts of alcohol affect red blood cell production. Coffee and tea with meals reduce how much iron is absorbed.
Track it through the year
One value is a snapshot. Following it up shows whether what you changed is working.
Related markers
Educational information only — not a diagnosis. Every result is checked against safe limits, and anything critical is escalated for follow-up.
See all 84 markers →