Platelets (PLT)

Clotting cells — chemotherapy often drives these dangerously low.

What it is

Platelets are small cell fragments that initiate blood clotting. They are produced in the bone marrow and have a lifespan of about 10 days. When damaged, the body responds by forming a platelet plug at the injury site.

Why it matters

Thrombocytopenia (low platelets) is a common and serious chemotherapy side effect. Below 50 ×10⁹/L, bleeding risk is significant. Below 20, spontaneous bleeding can occur. Platelet counts determine whether treatment can proceed and whether prophylactic transfusions are needed.

How to test

Full blood count.

This information is for educational purposes only. Always discuss testing and interpretation of results with your care team.

Optimal range

Below 50 ×10⁹/L

significant bleeding risk

150–400 ×10⁹/L

normal

Above 400 ×10⁹/L

thrombocytosis — may indicate inflammation or iron deficiency

How often

Each chemotherapy cycle.