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PDW

Blood clotting Biomarker

Sample Needed

Collection Type: Blood, Urine

Body System

Related System: Blood clotting

Overview

Platelet Distribution Width (PDW) is a measure of the variation in platelet size (anisocytosis) reported as part of a complete blood count or platelet profile. It quantifies how uniform or heterogeneous platelets are; larger variation often indicates increased platelet production or activation. PDW is used alongside platelet count and mean platelet volume (MPV) to evaluate bleeding or clotting disorders, bone marrow activity, inflammatory states, and risk of thrombotic disease. Testing is indicated for unexplained bruising, bleeding, petechiae, thrombosis, or monitoring known hematologic or inflammatory conditions. PDW can vary with age, pregnancy, acute illness, and certain medications; small gender differences exist but are usually clinically minor.

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Test Preparation

Overnight fasting (8-12 hrs) is required
Do not eat or drink anything except water before the test
Avoid iron supplements for at least 24 hours prior to sample collection
The urine sample must preferably be the first morning midstream urine (part of urine that comes after the first and before the last stream)
Collect the urine sample in a sealed and sterile screw-capped container provided by our sample collection professional
Ensure that the urethral area (from where the urine is passed) is clean & container doesn't come in contact with your skin
Women are advised not to give the sample during the menstrual period unless prescribed
You should submit all the required samples for this package at once during the scheduled sample collection
Do not stop taking your thyroid medications on the day of the test unless otherwise advised by the doctor

Why Do I Need This Test

Profile: included in platelet/haematology panels or “blood clotting” profiles - Symptoms: unexplained bleeding, easy bruising, petechiae, recurrent clots, fatigue - Conditions: detects/monitors thrombocytopenia/thrombocytosis, ITP, myeloproliferative disorders, inflammation, sepsis - Reasons for abnormal: altered platelet production, activation, destruction, or laboratory artifact - Biological meaning: high PDW = variable (activated/immature) platelets; low PDW = uniform platelet population - Lifestyle: smoking, alcohol, certain drugs (antiplatelet/chemotherapy), acute infection - Family history: inherited platelet disorders or familial thrombophilia may prompt testing

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Symptom Checker

Understanding Test Results

<9% (low): Platelets are unusually uniform.
May reflect reduced marrow variability (e.g., some marrow failure states) or pre-analytical/sample issues; rarely clinically significant alone.
Correlate with low platelet count and clinical context.
9–17% (normal): Expected variation in platelet size; no isolated abnormality suggested when platelet count and MPV are normal.
17–20% (mildly high): Suggests increased platelet size variability early platelet activation, inflammation, or increased release of immature platelets.
Investigate infection, inflammatory disease, or recent platelet-destructive process.
>20% (markedly high): Stronger indicator of platelet activation or a reactive/primary marrow process (immune thrombocytopenia, myeloproliferative neoplasm, sepsis, DIC).
Associated with higher thrombotic risk in some settings.
Always interpret with platelet count, MPV, clinical signs, and repeat testing or further hematology evaluation as needed.

Normal Range

9-17%

FAQs

Q: What happens if PDW is high?

A: High PDW means increased variation in platelet size (anisocytosis), often reflecting platelet activation or production of unusually large young platelets. It can accompany inflammation, infections, immune thrombocytopenia or bone marrow disorders such as myeloproliferative disease, and is linked to altered clotting risk. It is not diagnostic alone—doctors interpret it with platelet count, MPV and clinical context and may order further tests.

Q: What does a PDW mean?

A: PDW stands for platelet distribution width, a measure of variation in platelet size on a complete blood count. It reflects platelet heterogeneity and activation; increased PDW indicates greater size variability (seen with inflammation, thrombocytopenia, myeloproliferative disorders or active platelet destruction), while normal/low PDW suggests uniform platelets. It’s interpreted with platelet count and mean platelet volume; abnormalities need further evaluation.

Q: What deficiency causes high PDW?

A: High platelet distribution width (PDW) is commonly seen with vitamin B12 (cobalamin) deficiency and, less commonly, folate deficiency; megaloblastic ineffective hematopoiesis produces larger, immature platelets that increase size variability. Treating the deficiency often normalizes platelet indices. Other causes—acute inflammation, infection, immune or myeloproliferative disorders—should also be considered and correlated with clinical findings and blood counts.

Q: What diseases are PDW high in?

A: Elevated PDW is seen in conditions with platelet activation or heterogenous platelet size, including immune thrombocytopenia and other thrombocytopenias, myeloproliferative neoplasms (e.g., essential thrombocythemia), acute coronary syndromes and stroke, sepsis and systemic inflammatory states, diabetes, preeclampsia, disseminated intravascular coagulation, and various malignancies. It’s an adjunct marker of platelet activation and disease severity.

Q: Which cancers cause high PDW?

A: Elevated PDW has been reported in several malignancies, commonly including lung, colorectal, gastric, breast, ovarian and pancreatic cancers, as well as hepatocellular and renal cell carcinomas. Increased PDW likely reflects tumour-driven inflammation and altered platelet production/activation; it may correlate with advanced stage or poorer prognosis in some studies, but findings vary and PDW is not diagnostic alone.

Q: How to reduce high PDW in blood?

A: High PDW reflects platelet activation or underlying conditions. Reduce it by treating the root cause: manage infections, inflammation, and chronic diseases (diabetes, hypertension, dyslipidaemia); stop smoking and limit alcohol; eat a balanced diet, maintain healthy weight, stay active and hydrated. Review medications with your doctor (some drugs affect platelets) and follow prescribed treatments. Repeat testing and specialist evaluation if PDW stays high.