BloodTestEasy

RDW 22.0 %

Very high

Consider discussing this with your doctor in the coming weeks.

1011.514.516203022.0
  • Below typical range
  • Normal
  • Borderline high
  • High
  • Very high
Your band
Very high · 20–30 %
Distance from typical range
7.5 % above 14.5

What 22.0 % means

An RDW of 22.0 % is markedly above the typical adult range of about 11.5–14.5%. Values this high usually accompany a significant, identifiable blood problem and deserve timely follow-up.

An RDW this high means your bloodstream contains red cells of dramatically different sizes — typically a sign of severe or combined nutrient deficiencies, active red cell destruction, a recent transfusion given for significant anemia, or, less commonly, a bone marrow disorder such as myelodysplastic syndrome in older adults. Very high values almost never appear with an otherwise completely normal CBC, so the accompanying hemoglobin and MCV usually make the story much clearer. Occasionally an extreme value is a lab artifact (for example, from cold agglutinins), which a repeat test can sort out.

Most US labs consider an adult RDW-CV of roughly 11.5% to 14.5% normal (some labs extend the upper limit to about 15%, and MedlinePlus cites slightly different figures for men and women); this ladder follows the widely used 11.5–14.5% convention.

Common causes

  • Severe iron deficiency anemia
  • Severe vitamin B12 or folate deficiency (including pernicious anemia)
  • Combined deficiencies affecting cell size in both directions at once
  • Hemolytic anemia — active destruction of red cells
  • Recent blood transfusion, especially after significant anemia
  • Myelodysplastic syndrome or another bone marrow disorder, mainly in older adults
  • Sickle cell disease and some other inherited blood disorders
  • Lab artifact, such as cold agglutinins clumping cells in the sample

Symptoms that can go with it

  • Marked fatigue or weakness
  • Shortness of breath, even with light activity
  • Noticeably pale skin
  • Dizziness or feeling faint
  • Rapid heartbeat or palpitations
  • Yellowing of skin or eyes (jaundice) if red cells are breaking down
  • Dark urine with hemolysis
  • Chest discomfort with exertion in severe anemia — this specific symptom needs urgent care

Sensible next steps

  1. Contact your clinician within the next few days to review this result together with your hemoglobin — do not wait for a routine annual visit
  2. If you also have chest pain, severe shortness of breath, or fainting, seek emergency care now — those symptoms, not the RDW itself, are the emergency
  3. Expect blood work such as ferritin, B12, folate, a reticulocyte count, and possibly hemolysis markers or a blood smear review
  4. Mention any recent transfusion — it can raise RDW for weeks and may fully explain the number
  5. Ask whether the result should be repeated to rule out a lab artifact
  6. Work with your clinician on the underlying cause; RDW falls on its own once that is treated

Frequently asked questions

Is 22.0 % a normal RDW level?

No — 22.0 % is well above the typical adult range of about 11.5–14.5%. Values this high usually accompany a significant blood problem such as severe deficiency or red cell breakdown, so contact your clinician soon to review the full CBC.

What does a high RDW mean?

At 22.0 %, the variation is marked, and values this high nearly always come with other CBC abnormalities such as low hemoglobin. Severe deficiencies, active red cell destruction, recent transfusion, or (less commonly, in older adults) a bone marrow disorder are the main explanations. This deserves follow-up within days, not months.

Can RDW be high when hemoglobin is normal?

Yes. RDW often rises before hemoglobin falls, so a high RDW with normal hemoglobin can be an early warning that iron, vitamin B12, or folate stores are running low. It can also follow recent blood donation or blood loss that your body is already correcting. A simple set of follow-up tests — usually ferritin, B12, and folate — can check for a developing deficiency before it becomes anemia.

Is a low RDW something to worry about?

No. A low RDW simply means your red blood cells are very uniform in size, and no disease is diagnosed from a low RDW alone. If your hemoglobin, MCV, and the rest of your CBC are normal, a low RDW needs no follow-up beyond mentioning it at your next visit.

How can I lower a high RDW?

At 22.0 %, the priority is diagnosis, not home remedies. A value this high usually reflects a significant deficiency, red cell breakdown, or another condition your clinician needs to identify and treat directly. Once the cause is treated, RDW falls on its own over the following months.

What is the difference between RDW-CV and RDW-SD?

Both measure the same thing — variation in red cell size — but on different scales. RDW-CV is a percentage (typical adult range about 11.5–14.5%) and is what most US labs report as 'RDW.' RDW-SD is reported in femtoliters (fL), with a typical range of roughly 39–46 fL, and is less affected by the average cell size. If your report shows a number in the 40s with 'fL' next to it, you are looking at RDW-SD, and percentage-based ranges do not apply to it.

Does a high RDW mean cancer?

Almost never. The overwhelming majority of high RDW results are explained by iron, B12, or folate deficiency, blood loss, or chronic illness — not cancer. Research has linked higher RDW to worse outcomes in various diseases, but that makes it a general, non-specific marker of illness and inflammation, not a cancer test. In older adults with a persistently high RDW and other unexplained CBC abnormalities, clinicians may check for bone marrow disorders, which is one reason follow-up matters — but a high RDW by itself is not a reason to fear cancer.

Check a different RDW value

Related values on your lab report

Sources

Educational information, not medical advice. Reference ranges vary between labs — always compare with the range printed on your own report and discuss results with your doctor. Full disclaimer