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Platelets are the tiny cells that stop you bleeding. Your count came back outside the normal range — here's what that means, what causes it, and when it actually requires action.
Clinical Pathology, Hematology ·
The essentials — before you read the full guide below.
When a blood vessel is damaged, platelets rush to the site and clump together to form the initial plug that stops bleeding. They also trigger the coagulation cascade.
150–400 × 10⁹/L. Mild variations are common and usually benign. A single mildly abnormal result rarely requires action without symptoms.
Below 150 × 10⁹/L. Risk of spontaneous bleeding starts below 50 × 10⁹/L. Below 10–20 × 10⁹/L is a medical emergency.
Above 400 × 10⁹/L. Reactive thrombocytosis (from infection or iron deficiency) is common and benign. Essential thrombocythaemia is rare.
Reference Ranges
Use the interactive slider below, or read the range cards for a full clinical breakdown.
Drag to see what your Platelet Count (Thrombocyte Count) means
The Science
Haemostasis — stopping bleeding — happens in two overlapping phases. Primary haemostasis is platelet-driven: platelet adhesion, activation, and aggregation form the initial plug within seconds. Secondary haemostasis is the coagulation cascade that reinforces this plug with fibrin. Platelet count affects the first phase — but platelet function tests are needed to assess the second.
Platelets circulate for 7–10 days before being cleared by the spleen. They have no nucleus — they're fragments of megakaryocytes from the bone marrow.
Platelets stick to damaged vessel walls via von Willebrand factor (vWF). Deficiency of vWF (von Willebrand disease) causes bleeding even with a normal platelet count.
Mean platelet volume (MPV), also on your CBC, measures platelet size. High MPV with low count suggests platelet destruction (ITP). Low MPV with low count suggests underproduction.
When to Test
These are the most common reasons a Platelet Count (Thrombocyte Count) test is requested — from symptoms to routine screening.
Unexplained bruises appearing without injury, particularly over the legs and trunk, are a classic sign of low platelet count.
Key symptomIf a small cut takes more than 5 minutes to stop bleeding, platelet count or function may be impaired.
Key symptomAspirin, clopidogrel, and NSAIDs impair platelet function. Heparin can cause HIT — a dangerous drop in platelets.
Drug causeViral infections — especially Epstein–Barr, dengue, and HIV — transiently lower platelet counts. Recovery is usually spontaneous.
Common causePetechiae — tiny red or purple dots on the skin — appear when platelets fall below 30–50 × 10⁹/L. They don't blanch when pressed.
Urgent signPlatelet count is included in every standard CBC and is routinely checked before surgical procedures.
ScreeningTesting Schedule
Frequency depends on your current health status and your doctor's guidance.
Checked as part of the standard annual CBC.
Required before all elective surgical procedures to ensure safe haemostasis.
Heparin-induced thrombocytopenia (HIT) is a dangerous platelet drop — counts monitored every 2–3 days for the first 14 days.
ITP, CLL, and myelosuppressive drug therapy require regular monitoring — frequency depends on severity.
If Your Result Is Abnormal
The required action depends heavily on the count level, trend, and clinical symptoms.
A mildly low platelet count (100–150 × 10⁹/L) without symptoms should be repeated in 1–4 weeks. EDTA-dependent pseudothrombocytopenia is a common laboratory artefact.
Rule out lab error firstMean platelet volume and a blood film help distinguish ITP (destruction) from marrow underproduction and pseudothrombocytopenia.
MPV + film reviewMany drugs cause thrombocytopenia — heparin, sulfonamides, quinine, valproate, and chemotherapy agents. A medication review is mandatory for new-onset low platelets.
Drug-induced firstPlatelet count consistently below 50 × 10⁹/L, or any count with active bleeding, petechiae, or suspected ITP requires urgent specialist assessment.
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