Platelet Count: What It Is and What Your Results Mean
Bottom line: Platelets help your blood clot. Normal is 150-400 K/uL. Low platelets increase bleeding risk, high platelets increase clotting risk.
What Is Platelet Count?
Platelets (thrombocytes) are tiny blood cells that help your body form clots to stop bleeding. When a blood vessel is damaged, platelets rush to the site, stick together, and form a plug that seals the wound.
A platelet count is part of a complete blood count (CBC). Low platelets (thrombocytopenia) increase bleeding risk, while high platelets (thrombocytosis) can increase clotting risk. Both conditions can range from mild and incidental to serious and requiring treatment.
Platelet counts can fluctuate temporarily due to infections, inflammation, medications, or recent surgery. Persistent abnormalities should be investigated.
Platelet Count Reference Ranges
| Classification | Range (K/µL) |
|---|---|
| Severely Low (Severe Thrombocytopenia) | Below 50 |
| Low (Thrombocytopenia) | 50 - 99 |
| Mildly Low | 100 - 149 |
| Normal | 150 - 400 |
| Mildly Elevated | 401 - 600 |
| High (Thrombocytosis) | 601+ |
| Very High | 1001+ |
What Affects Your Platelet Count Levels?
- Infections and inflammatory conditions
- Autoimmune disorders
- Bone marrow function
- Medications including blood thinners and chemotherapy
- Liver disease and alcohol consumption
- Vitamin B12 and folate deficiency
When to Get Tested
Platelets are routinely measured as part of a CBC during annual physicals. Additional testing if you have unusual bleeding or bruising, a known blood disorder, or are on medications that affect platelet count.
Look Up Your Platelet Count Result
Select your value below to see a detailed breakdown of what it means:
Severely Low (Severe Thrombocytopenia)
Low (Thrombocytopenia)
Mildly Low
Normal
Mildly Elevated
High (Thrombocytosis)
Read the Full Blood Test Guide
Frequently Asked Questions
150,000 to 400,000 per microliter (150-400 K/uL) is normal. Below 150 K/uL is thrombocytopenia. Above 400 K/uL is thrombocytosis.
Mildly low platelets (100-149 K/uL) are often incidental and not clinically significant. They should be monitored with a repeat test in a few months. Levels below 100 K/uL warrant further investigation.
Reactive thrombocytosis (from infection, inflammation, iron deficiency, or surgery) is the most common cause and usually resolves. Primary thrombocytosis from a bone marrow disorder is less common but requires monitoring.