The RDW test is a blood analysis that measures the distribution of red blood cell volume and size. This test assists in the diagnosis of various conditions, notably anemia, as well as thalassemia (Mediterranean anemia), diabetes, heart disease, liver disease, and cancer. It also provides crucial information for evaluating general health status and identifying infections and other health issues.

Your doctor may recommend checking the RDW value in a complete blood count if you experience one or more of the following symptoms:
* Dizziness and fatigue
* Pale skin
* Headache
* Shortness of breath
* Symptoms indicative of anemia
* Blood loss due to surgery or trauma
* Chronic conditions such as Crohn's disease, diabetes, HIV, or AIDS