PDW Blood Test: Understanding Its Purpose and Results

Introduction

The PDW blood test is a medical test that checks for size differences in blood platelets. The main function of platelets includes clotting and ensuring smooth blood flow in the body³.  

In this article, we will cover the basics of a PDW blood test. We’ll discuss why it’s done, how it’s done, and what the results mean. We will also touch on the connection between PDW and blood disorders tied to platelets. Lastly, we’ll share ways to get ready for a doctor’s visit for a PDW test. 

Overview of PDW Blood Test

The role of a PDW (platelet distribution width) blood test is to assess how well a person’s platelets are working whose main function is to create clots and aid in wound repair and stop blood loss³. 

What is PDW?

PDW test measures the size differences in platelets in a person’s blood. High PDW means that there is a range of platelet sizes, and low PDW suggests more similar sized platelets³. Knowing these variations helps doctors understand how a person’s platelets are functioning. 

Importance of PDW Blood Test

The purpose of doing a PDW blood test is as follows.  

• Evaluating Platelet Function: Examining how well platelets work helps decide if a person can form blood clots and maintain smooth blood flow. Abnormal platelet activity can hint at health problems that might need further investigation and management².  
• Diagnosing Blood Disorders: A PDW blood test is useful for spotting blood disorders. For example, it sheds light on platelet distribution and activity. This means we may spot issues such as thrombocytopenia (low platelet count) or thrombocytosis (high platelet count)¹. 

How is the PDW Blood Test Performed?

A PDW blood test needs a blood sample from a vein in your arm or hand. Below we have described how to get ready for the test and what happens during the process.  

Preparing for the Test 

Typically, no unique preparations are needed for a PDW blood test. But if you’re also doing other tests on the same day, your healthcare provider may suggest some things. Always let your provider know about any drugs, vitamins, supplements, or herbal products you’re taking. This avoids an unexpected impact on test results.  

The Blood Test Procedure 

During the test, a medic places a small needle into a vein in your arm or hand to take blood. Once they get the sample, it’s sent to a laboratory for study. Though the test is quick and mostly painless, some people might feel dizzy or sick. Deep, slow breaths help lessen these feelings. Also, some people may feel slight pain or see bruises where the needle went in⁴. 

Understanding PDW Blood Test Results

1. Normal PDW Levels 

Normal PDW levels fall between 8 to 12 femtoliters. This indicates that your platelets are at peak performance and no medical action is needed³. 

2. Low PDW Levels 

Low PDW levels (below 8 femtoliters) could mean that a majority of your platelets are old or that your bone marrow is making fewer platelets than usual³. 

• Possible Causes: Low PDW could be due to bone marrow failure, lupus, some medications such as chemotherapeutic agents, hypothyroidism, lack of iron, or HIV/AIDS. 
• Risks and Complications: With a low PDW level, your blood may have trouble clotting. The risk of heavy bleeding is higher. You might then need more tests to know the cause and work out a management plan with your doctor. 

3. High PDW Levels 

High PDW levels (above 12 femtoliters) show higher levels of young platelets in the blood³.  

• Possible Causes: Elevated PDW levels could be due to a recent wound or surgery, blood loss, or too much alcohol/vitamin B12  deficiency. Chronic health problems, infections, or even birth control pills may also affect PDW levels. 
• Risks and Complications: High PDW levels are linked to an increased risk of forming blood clots. Clots in the arms or legs can be risky if they break loose and travel to other body parts, clogging the blood supply to those parts. 

Platelet-Related Blood Disorders

With PDW blood tests, doctors can check for blood disorders tied to platelets. Two common types include thrombocytopenia (low platelet count) and essential thrombocythaemia (high platelet count). 

Thrombocytopenia (Low Platelet Count) 

Thrombocytopenia means you have too few platelets in your blood, which raises the risk of bleeding and bruising. Likely causes include problems with the immune system, some medications, and inherited diseases⁵. Doctors can diagnose it through blood tests, physical exams, and by looking at your medical history. 

Essential Thrombocythaemia (High Platelet Count) 

In essential thrombocythaemia, the bone marrow makes too many platelets. This overproduction could be due to gene changes or conditions like cancer. With too many platelets, your risk of forming blood clots increases. This could lead to serious issues like strokes or heart attacks⁶. 

Diagnosis and Management

After finding a blood disorder through PDW blood tests or other ways, it’s time to look at management choices. These help control symptoms and avoid likely issues. 

Diagnosing Blood Disorders

Diagnosing blood disorders often involves several steps. It starts with looking at your medical past, physical examination findings, and laboratory test results that matter. Depending on the suspected disease, you may need more blood or imaging tests. 

Step-by-Step Process:

A typical way to diagnose blood disorders might include the following steps.  

• Looking into your full medical past. 
• Doing a physical check-up. 
• Running laboratory tests, imaging tests, or both. 
• Refer you to a specialist if needed. 
• Finding a diagnosis from the information collected. 

Additional Blood Tests:  

Doctors may recommend extra blood tests. These tests could be coagulation tests, complete blood count (CBC), or specialised tests like peripheral blood smear or quantitative immunoglobulins. 

Management Options 

The type of blood disorder, how severe it is, and its causes shape the management choices. Possible options could include the ones below. 

• Medications: A doctor may give drugs to boost platelet count, suppress the immune system, or improve overall platelet function. 
• Blood Transfusions: People with very low platelets or a high risk of bleeding might need blood or platelet transfusions. These replace lost platelets and bring clotting back to normal. 
• Lifestyle and Home Remedies: In some cases, changing your lifestyle or home remedies may help improve overall blood health. Such changes could include eating a balanced diet full of vitamins and minerals, doing physical activities, or avoiding some drugs known to affect platelet function. 

Complications of Platelet Disorders

Platelet disorders may bring forth different complications. These depend on the person and the exact disorder.  

• Haemorrhages or Clotting Issues: As described above, the first concern with platelet issues is the high chance of uncontrolled bleeding (haemorrhages) or risky blood clots forming. These problems can be life-threatening and may need urgent help. 
• Enlarged Spleens:The main function of the spleen is to filter out unwanted substances from the blood and help fight disease. Some diseases or medical issues can make the spleen grow larger, which can reduce platelet circulation⁷. It may also raise the risk of other health issues. 

Preparing for your Doctor’s Appointment

If your PDW blood test results are not normal, or you have symptoms that hint at a bleeding or clotting issue, it’s vital to book an appointment with your healthcare provider.  

What to Bring?

Here’s what to take to your doctor’s visit. 

• A written list of symptoms you’re dealing with, however small they may seem. 
• A detailed list of all drugs, supplements, and vitamins you’re taking now, plus their doses. 
• Any important medical records or past test results. 
• A list of questions or concerns you wish to discuss with your doctor. 

Questions to Ask?

Try to ask these questions during your visit.  

• What could be causing my symptoms or abnormal PDW levels? 
• Will I need more tests or a referral to experts? 
• What are the possible risks or issues tied to my PDW levels or symptoms? 
• What management options may help manage my symptoms or the basic condition? 
• Are there lifestyle changes or home remedies that may make my overall blood health better? 

Conclusion

Knowing why PDW blood tests are done and what their results mean provides information on how a person’s platelets are working and the overall health of their blood. Noticing abnormal PDW levels is the key to finding possible blood disorders and their management options.  

Frequently Asked Questions (FAQs)

References

1. National Center for Biotechnology Information (NCBI). Thrombocytopenia [Internet]. [cited 2024 Feb 13]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542208 
2. National Center for Biotechnology Information (NCBI). Platelet function and ageing – PMC [Internet]. [cited 2024 Feb 13]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4935731 
3. Tzur I, Barchel D, Izhakian S, Swarka M, Garach-Jehoshua O, Krutkina E, Plotnikov G, Gorelik O. Platelet distribution width: a novel prognostic marker in an internal medicine ward. J Community Hosp Intern Med Perspect. 2019 Dec 14;9(6):464-470. Doi: 10.1080/20009666.2019.1688095. PMID: 32002150; PMCID: PMC6968671 Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6968671/
4. WHO Guidelines on Drawing Blood: Best Practices in Phlebotomy. Geneva: World Health Organization; 2010. Annex F, Explaining the procedure to a patient. Available from: https://www.ncbi.nlm.nih.gov/books/NBK138658/
5. National Heart, Lung, and Blood Institute. Platelet Disorders – Thrombocytopenia. NHLBI, NIH. [Internet]. Available from: https://www.nhlbi.nih.gov/health/thrombocytopenia
6. Ashorobi D, Gohari P. Essential Thrombocytosis. [Updated 2023 Aug 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539709/
7. Armitage JO. Spleen. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 150. Available from: https://www.ncbi.nlm.nih.gov/books/NBK258/

Disclaimer: The information provided here is for educational/awareness purposes only and is not intended to be a substitute for medical treatment by a healthcare professional and should not be relied upon to diagnose or treat any medical condition. The reader should consult a registered medical practitioner to determine the appropriateness of the information and before consuming any medication. PharmEasy does not provide any guarantee or warranty (express or implied) regarding the accuracy, adequacy, completeness, legality, reliability or usefulness of the information; and disclaims any liability arising thereof.

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