Platelets, also called thrombocytes, are blood cells that circulate through the blood and play an important role in blood clotting. When you get bloodwork done, your doctor will routinely check your platelet count as part of a complete blood count (CBC). There are a few key reasons why platelet counts are monitored closely.
To screen for potential bleeding or clotting disorders
A normal platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. If your platelet count falls outside this normal range, it could indicate an underlying medical condition:
- Low platelet count (thrombocytopenia): Less than 150,000 platelets. Can increase risk of excessive or prolonged bleeding.
- High platelet count (thrombocytosis): More than 450,000 platelets. Can increase risk of blood clots.
Some examples of conditions associated with abnormal platelet counts include:
| Low Platelet Count | High Platelet Count |
|---|---|
| Immune thrombocytopenia | Essential thrombocytosis |
| Viral infections like mononucleosis or hepatitis | Iron deficiency anemia |
| Leukemia | After surgery |
| Side effect of medication | Tissue damage or inflammation |
| Enlarged spleen | Cancer like leukemia or lymphoma |
Checking the platelet count as part of routine bloodwork can help identify these disorders early on.
To monitor medical conditions and treatments that affect platelets
In some chronic diseases, regular monitoring of the platelet count is important to help guide treatment decisions and prevent complications.
- Cancer: Chemotherapy and radiation can cause low platelet counts. The platelet count is tracked closely to avoid excessive bleeding.
- Chronic liver disease: Platelet production may be impaired. A declining platelet count signals worsening liver function.
- HIV: HIV and medications used to treat it can sometimes lead to low platelet counts. The platelet count helps monitor disease progression and medication side effects.
- Autoimmune disorders: Such as lupus or rheumatoid arthritis may be associated with abnormally low or high platelet counts.
By frequently checking the platelet count, doctors can assess if treatments need to be adjusted to address any changes.
To evaluate platelet function
The platelet count provides useful but limited information. A normal platelet count does not necessarily mean your platelets are functioning properly. Additional platelet function testing may sometimes be warranted, such as:
- Platelet aggregation testing: Evaluates how well platelets clump together and form clots when exposed to certain stimulants.
- Platelet adhesion testing: Assesses how well platelets stick to simulated areas of blood vessel damage.
- Genetic testing: To look for mutations linked to inherited platelet disorders.
Platelet function testing provides a more complete picture and may pick up defects in platelet activity even when the platelet count is normal. It can be useful in investigating unexplained bleeding or clotting episodes.
To establish a baseline
Getting a baseline platelet count is useful for future comparison whenever you are faced with:
- A new disease diagnosis
- Starting a new medication
- Undergoing a surgical procedure
Having an initial platelet count in your medical record gives your doctor a point of reference that they can use to interpret future test results and monitor your health status over time.
To screen prior to medical procedures
Platelet counts are commonly checked before surgeries and other invasive procedures when there is a risk of significant blood loss, such as:
- Major surgery
- Dental extractions
- Biopsies
- Endoscopies
- Childbirth
This allows the medical team to identify any bleeding risks beforehand and take appropriate precautions as needed.
Typical requirements for procedures:
| Platelet Count | Procedure Restriction? |
|---|---|
| >50,000/microliter | None |
| 30,000-50,000/microliter | Procedures as clinically stable |
| <30,000/microliter | Avoid nonessential procedures |
To identify any drug effects on platelets
Some medications can influence the platelet count. Monitoring platelets provides a way to detect and manage any complications related to lowered platelet counts such as:
- Heparin: Used as a blood thinner. Can cause a condition called heparin-induced thrombocytopenia (HIT).
- Quinine: Found in tonic water. Can trigger immune thrombocytopenia.
- Sulfonamide antibiotics: Adverse reaction may include thrombocytopenia.
- Chemotherapy drugs: Bone marrow suppression can lead to reduced platelet production.
When starting a new medication known to potentially affect platelets, your doctor may order more frequent testing to confirm the platelet count remains at a safe level.
To assess your overall health
While the platelet count provides specific information about your blood’s clotting ability, it also offers general insights about your health status:
- Can reflect adequacy of platelet production by the bone marrow.
- May indicate the presence of inflammation, infection or other stresses on the body.
- Low platelet counts can be a sign of nutritional deficiencies.
In this way, the platelet count offers one snapshot of overall body function. Trends over time may provide clues to guide further medical evaluation and prevent complications.
Conclusion
Platelet counts are such a routine blood test because platelets play an essential role in hemostasis and thrombosis. Monitoring your platelet count helps screen for bleeding or clotting disorders, guides treatment approaches for many medical conditions, and assesses readiness for procedures and surgeries. It also provides one indicator of your general health status. By understanding why your doctor orders this simple blood test, you can better appreciate how it contributes to your good health.