High or low platelet count: what it can mean and when to get checked
Platelets help blood clot. Learn the many reasons a platelet count can be high or low, which signs need prompt attention and what a doctor looks at next.
What platelets do
Platelets are tiny blood cells that gather at the site of an injury and help form a clot. A normal count varies between laboratories, so compare your result with the range printed on your own report.
Why platelets can be low
- Viral infections, including dengue, which can lower counts for a short time.
- Some medicines.
- Immune causes, where the body clears platelets too quickly.
- Liver disease or an enlarged spleen.
- Low vitamin B12 or folate.
- Bone marrow problems.
- Pregnancy-related changes, which are often mild.
- A false low reading from clumping in the sample.
Why platelets can be high
- Reaction to infection, inflammation or surgery.
- Iron deficiency, which is a common reason for a mildly high count.
- After the spleen is removed.
- Rarely, a condition of the bone marrow that makes too many platelets.
Signs that need prompt attention
Please seek medical care quickly for any of the following:
- bleeding from the nose or gums that does not stop,
- blood in urine or stool, or black stools,
- many tiny red or purple spots on the skin, or large unexplained bruises,
- very heavy periods that are new for you,
- a sudden severe headache, weakness on one side, or chest pain.
What the doctor may do
The doctor will look at the whole CBC, ask about symptoms, medicines and recent illness, and may repeat the test or look at a blood film. Further tests depend on what is found.
For a clear explanation of your own count, you can book a new consultation. In an emergency, go to the nearest emergency department.
Frequently asked questions
Is a slightly low platelet count dangerous?
Small changes are often found by chance and may be temporary, for example during or after a viral illness. The right next step depends on how low the count is, your symptoms and your history, so ask your doctor.
Can a platelet count be wrong?
Sometimes a laboratory machine counts platelets as lower than they truly are, for example if they clump in the sample. A doctor may ask for a repeat test or a blood film to check.