Platelets
Cell fragments that help blood clot. Too few raises bleeding risk; too many can raise clotting risk.
Typical reference range
| Range | Unit |
|---|---|
| 150–360 | E9/l |
What Platelets measures
Platelets are tiny cell fragments that circulate in the blood and play a central role in clotting. When a blood vessel is injured, platelets gather at the site, stick together, and help form a plug that stops bleeding. They are produced in the bone marrow from large parent cells and are constantly replaced as older ones are cleared.
Your platelet count is reported as part of the complete blood count (CBC), alongside red blood cells, which carry oxygen, and white blood cells, which support immune defence. Reading platelets together with these other lines helps build a fuller picture of how the blood-forming system is working. As with any single value, the count is best interpreted in context and discussed with a clinician rather than viewed on its own.
What a high Platelets can mean
A high platelet count, sometimes called thrombocytosis, is most often reactive, meaning it reflects the body responding to something else rather than a problem with the platelets themselves. Common triggers can include infection, inflammation, iron deficiency, recovery from recent surgery or bleeding, and even vigorous exercise. In these situations the count usually settles once the underlying trigger resolves.
Less commonly, a persistently raised count can suggest a condition affecting the bone marrow itself, where platelets are overproduced. Because so many everyday factors can nudge the number upward, a single high reading rarely means much on its own. A clinician will typically look at the surrounding results, ask about recent illness or activity, and often recheck the count later to see whether it is temporary or sustained before drawing conclusions.
What a low Platelets can mean
A low platelet count, known as thrombocytopenia, can arise through several different routes. It may reflect reduced production in the bone marrow, which some medications, alcohol, or viral infections can influence. It can also stem from increased destruction, including immune-related causes where the body clears platelets too quickly, or from platelets pooling in an enlarged spleen rather than circulating freely.
Very low counts can raise the risk of easy bruising or bleeding, so a markedly reduced value is usually taken seriously and followed up. It is also worth knowing that platelets can occasionally clump together in the sample tube, which can produce a falsely low reading that does not reflect the true count. For this reason a low result is often confirmed before it is acted on. Any low count is best reviewed with a clinician in the context of your other results.
Track your Platelets over time in Quanome — it reads your lab reports (PDF or photo) on your device, charts each marker against its range, and an AI coach explains what your trends mean alongside your Apple Health and DNA.