What Is Platelet Count in a Blood Test?

Platelets (thrombocytes) are cell fragments that form blood clots to stop bleeding. The platelet count measures how many are in a microliter of blood.

Normal Range

• 150,000–450,000/µL
• Below 50,000: increased bleeding risk
• Below 20,000: spontaneous bleeding risk
• Above 450,000: increased clotting risk

Low Platelets (Thrombocytopenia)

• Immune thrombocytopenia (ITP)
• Bone marrow suppression — chemotherapy, leukemia
• Medications — heparin, certain antibiotics
• Liver disease with enlarged spleen
• Viral infection — HIV, hepatitis C
• Pregnancy — usually mild
• Alcohol use

High Platelets (Thrombocytosis)

• Reactive — infection, inflammation, iron deficiency, surgery
• Essential thrombocythemia — bone marrow disorder
• Post-splenectomy

Symptoms

• Low: easy bruising, petechiae, nosebleeds, prolonged bleeding
• High: headaches, dizziness, clotting symptoms