red cell width high

4 min read 08-03-2025

Meta Description: Discover the significance of a high red cell distribution width (RDW) blood test. Learn about the underlying causes, associated symptoms, and available treatment options for this common hematological finding. This comprehensive guide explores various conditions linked to elevated RDW, including anemia, nutritional deficiencies, and bone marrow disorders. Understand how your doctor diagnoses and manages high RDW to maintain optimal red blood cell health.

High red cell distribution width (RDW) is a blood test result that indicates variability in the size of your red blood cells. Red blood cells, or erythrocytes, are crucial for carrying oxygen throughout your body. When the RDW is high, it suggests that the red blood cells are not all the same size. Some are larger than normal (macrocytic), and some are smaller than normal (microcytic). This variation can be a sign of underlying health issues.

What is Red Cell Distribution Width (RDW)?

RDW is a measurement that reflects the variation in the size of your red blood cells. It's expressed as a percentage or coefficient of variation (CV). A normal RDW range typically falls between 11.5% and 14.5%, although this can vary slightly depending on the laboratory. A high RDW, exceeding the upper limit of this range, signifies anisocytosis – a condition characterized by red blood cells of unequal size.

Understanding the Significance of RDW

The size of red blood cells is important because it directly affects their function. Larger or smaller than normal red blood cells may not function as efficiently in carrying oxygen. Therefore, a high RDW often points towards an underlying medical condition impacting red blood cell production or maturation.

Causes of High Red Cell Distribution Width (RDW)

Several factors can contribute to an elevated RDW. These can be broadly categorized as:

1. Anemia

Many types of anemia are associated with high RDW. This includes:

Iron deficiency anemia: This is the most common cause. Lack of iron impairs hemoglobin production, resulting in smaller red blood cells (microcytic) and an increased RDW.
Vitamin B12 deficiency anemia (pernicious anemia): A deficiency in vitamin B12 leads to the production of larger, immature red blood cells (macrocytic), contributing to a high RDW.
Folate deficiency anemia: Similar to B12 deficiency, folate deficiency results in macrocytic anemia and elevated RDW.
Thalassemia: This inherited blood disorder affects hemoglobin production, resulting in microcytic and hypochromic (pale) red blood cells, often with a high RDW.
Sickle cell anemia: This genetic disorder causes abnormally shaped red blood cells, leading to varied sizes and a potentially elevated RDW.

2. Nutritional Deficiencies

Besides iron, vitamin B12, and folate, other nutritional deficiencies can also influence red blood cell size and contribute to a high RDW. These deficiencies often interact with and exacerbate anemias.

3. Bone Marrow Disorders

Diseases affecting the bone marrow, the site of red blood cell production, can lead to irregularities in red blood cell size and shape, resulting in a high RDW. Examples include:

Myelodysplastic syndromes (MDS): A group of cancers affecting the bone marrow's ability to produce healthy blood cells.
Aplastic anemia: A rare condition where the bone marrow doesn't produce enough blood cells.
Leukemia: Cancer of the blood-forming tissues.

4. Other Conditions

Other factors that can cause a high RDW include:

Chronic inflammation: Conditions such as rheumatoid arthritis or inflammatory bowel disease.
Hypothyroidism: Underactive thyroid gland.
Alcohol abuse: Excessive alcohol consumption can negatively impact red blood cell production.
Kidney disease: Kidney dysfunction can affect the production of erythropoietin, a hormone necessary for red blood cell production.
Certain medications: Some medications can affect red blood cell production.

Symptoms of High RDW

A high RDW itself doesn't typically cause noticeable symptoms. Instead, the symptoms are related to the underlying condition causing the elevated RDW. These symptoms can include:

Fatigue: Feeling unusually tired or weak.
Shortness of breath: Difficulty breathing, especially during exertion.
Paleness: Pale skin, lips, and nail beds.
Headache: Frequent or severe headaches.
Dizziness: Feeling lightheaded or faint.

Diagnosing High RDW

Diagnosing the cause of a high RDW involves a combination of tests:

Complete blood count (CBC): This is the initial test that reveals the elevated RDW.
Peripheral blood smear: A microscopic examination of a blood sample to assess the size and shape of red blood cells.
Iron studies: Measures iron levels in the blood to diagnose iron deficiency.
Vitamin B12 and folate levels: Measures levels of these essential vitamins.
Bone marrow biopsy: In some cases, a bone marrow sample is taken to examine for abnormalities.

Treating High RDW

Treatment for high RDW focuses on addressing the underlying cause. This might involve:

Iron supplements: For iron deficiency anemia.
Vitamin B12 or folate supplements: For deficiencies in these vitamins.
Medication: For conditions like hypothyroidism or chronic inflammation.
Chemotherapy or other cancer treatments: For bone marrow disorders.
Lifestyle changes: Such as dietary modifications, alcohol cessation, and improved nutrition.

Note: This information is for educational purposes only and should not be considered medical advice. Always consult with a healthcare professional for any health concerns or before making any decisions related to your health or treatment. They can accurately diagnose the underlying cause of your elevated RDW and recommend the appropriate course of action. Early diagnosis and treatment are crucial in managing the condition and preventing potential complications.