Get tested with Superpower

If you’ve been postponing blood testing for years or feel frustrated by doctor appointments and limited lab panels, you are not alone. Standard healthcare is often reactive, focusing on testing only after symptoms appear or leaving patients in the dark.

Superpower flips that approach. We give you full insight into your body with over 100 biomarkers, personalized action plans, long-term tracking, and answers to your questions, so you can stay ahead of any health issues.

With physician-reviewed results, CLIA-certified labs, and the option for at-home blood draws, Superpower is designed for people who want clarity, convenience, and real accountability - all in one place.

Key benefits of Red Cell Distribution Width (RDW) testing

• Measures variation in red blood cell size to flag hidden health issues.
• Spots nutritional deficiencies like iron, B12, or folate before anemia worsens.
• Flags chronic inflammation that may drive fatigue or long-term disease risk.
• Helps explain persistent tiredness when standard blood counts look normal.
• Tracks cardiovascular and metabolic stress linked to heart disease and diabetes.
• Guides treatment by showing whether your body is responding to supplementation.
• Best interpreted with iron studies, B vitamins, and your symptom pattern.

What is Red Cell Distribution Width (RDW)?

Red cell distribution width (RDW) is a laboratory measurement that describes how much your red blood cells vary in size. It's calculated from a routine blood count by analyzing the size spread of all the red cells in your sample.

Not all red blood cells are created equal

Normally, healthy red blood cells are remarkably uniform, like coins minted from the same press. When RDW is elevated, it means your bloodstream contains a mixed population: some cells larger, some smaller, creating greater size variation (anisocytosis).

A window into red blood cell production

RDW reflects the health and consistency of red blood cell manufacturing in your bone marrow. A rising RDW often signals that your body is responding to stress, nutritional deficiency, or disrupted production. It captures the dynamic state of your blood, revealing whether new cells are being made normally or under challenging conditions.

This simple metric has emerged as a sensitive marker of underlying physiological stress and cellular turnover.

Why is Red Cell Distribution Width (RDW) important?

Red Cell Distribution Width measures how much your red blood cells vary in size - a window into how well your bone marrow is producing healthy, uniform cells. Normal RDW sits between roughly 11.5 and 14.5%, and lower values within that range signal more consistent, healthier red cell production. When RDW climbs, it reveals that your bloodstream contains a mix of old and new, large and small cells, often pointing to nutritional deficits, chronic inflammation, or bone marrow stress.

When red cells are uniform in size

Values at the lower end of normal reflect steady, efficient red cell turnover. Your marrow is releasing cells that mature predictably, oxygen delivery stays smooth, and you're less likely to experience fatigue or cognitive fog tied to erratic blood oxygen transport.

When red cell size becomes chaotic

Elevated RDW appears when iron, folate, or B12 run low, or when chronic disease, hemolysis, or recent bleeding forces your marrow into overdrive. You may notice persistent tiredness, shortness of breath, or difficulty concentrating as mismatched cell sizes impair oxygen release. High RDW also tracks with cardiovascular risk, all-cause mortality, and inflammatory conditions, making it a surprisingly powerful predictor beyond anemia alone.

A marker that connects nutrition, inflammation, and longevity

RDW ties together hematologic health, metabolic balance, and systemic inflammation. Monitoring it over time helps detect silent nutrient depletion, chronic disease progression, and cardiovascular vulnerability before symptoms become severe.

What do my Red Cell Distribution Width (RDW) results mean?

Low values

Low values usually reflect a uniform population of red blood cells that are all similar in size. This is generally a normal finding and indicates stable red cell production without recent stress or turnover. It does not typically signal a clinical concern and is seen in healthy individuals with well-regulated iron metabolism and bone marrow function.

Optimal values

Being in range suggests that your red blood cells vary in size within expected limits, reflecting steady and balanced production by the bone marrow. Most healthy adults fall comfortably in the middle to lower portion of the reference range. Stability here supports efficient oxygen delivery and indicates that red cell turnover is proceeding without disruption from nutrient deficiency, inflammation, or hemolysis.

High values

High values usually reflect increased variation in red cell size, a condition called anisocytosis. This often occurs when the bone marrow is producing new cells at different rates or in response to stress, such as iron deficiency, vitamin B12 or folate deficiency, chronic inflammation, or hemolysis. It may also rise during recovery from anemia or in the presence of mixed red cell populations. Elevated RDW is a nonspecific marker but prompts further investigation into underlying causes.

Notes

RDW can be influenced by recent blood loss, nutritional repletion, pregnancy, chronic disease, and certain medications. It is most informative when interpreted alongside hemoglobin, mean corpuscular volume, and iron studies.