Doctor's Assessment Included
Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
Platelet count: what does it tell you about your blood clotting?
Platelets, also called thrombocytes, play a central role in blood clotting. They form a plug at the site of a damaged blood vessel, preventing excessive blood loss. A low platelet count (thrombocytopenia) increases the risk of bleeding, while a high count (thrombocytosis) can increase the risk of blood clots.
Reference Ranges
Low
150
Normal
400
High
Low
150
Normal
400
High
Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.
What It Measures
This test counts the number of platelets in your blood, expressed in × 10⁹/L (billions per litre). The normal range is 150–400 × 10⁹/L. Platelets are produced in the bone marrow and have a lifespan of eight to ten days, after which they are broken down in the spleen.
The count is a standard component of the blood count. With an abnormal result, further investigation into the cause may be needed, such as a blood smear or bone marrow examination.
The count is a standard component of the blood count. With an abnormal result, further investigation into the cause may be needed, such as a blood smear or bone marrow examination.
Why It Matters
A normal platelet count is essential for properly functioning blood clotting. With thrombocytopenia (too few), bruising, gum bleeding, or nosebleeds occur more easily. At severely decreased levels (below 50 × 10⁹/L), the risk of spontaneous bleeding increases, and below 20 × 10⁹/L the risk of life-threatening bleeding.
Thrombocytosis (too many) can be reactive — as a result of inflammation, infection, or iron deficiency — or primary, due to a bone marrow disorder. In the reactive form, the count normalises once the underlying cause is treated.
Thrombocytosis (too many) can be reactive — as a result of inflammation, infection, or iron deficiency — or primary, due to a bone marrow disorder. In the reactive form, the count normalises once the underlying cause is treated.
When to Test
Platelets are routinely included in the blood count. It is particularly useful for unexplained bruising, frequent nosebleeds, prolonged bleeding after a cut, or when using blood thinners. Fasting is not required.
Symptoms
Low Levels
With a decreased platelet count (below 150 × 10⁹/L), unexplained bruising may occur, small red pinpoint bleeds in the skin (petechiae), gum bleeding, prolonged nosebleeds, and in women heavier menstrual bleeding. With severely decreased levels, spontaneous bleeding can occur.
High Levels
An elevated platelet count (above 400 × 10⁹/L) often causes no direct symptoms. In reactive thrombocytosis, the symptoms of the underlying cause are prominent. In primary thrombocytosis (bone marrow disorder), the risk of thrombosis or paradoxically also bleeding may be increased. Symptoms may then include headaches, dizziness, visual disturbances, and warmth in hands and feet.
Lifestyle Tips
There is limited direct lifestyle influence on platelet count. In reactive thrombocytosis, treating the underlying cause (infection, inflammation, iron deficiency) is most important. A varied diet with sufficient iron, vitamin B12, and folate supports healthy blood cell production, including platelets. When using blood thinners, it is important not to eat large quantities of vitamin K-rich foods (kale, spinach) at once, as this affects clotting balance.
Frequently Asked Questions
What is a normal platelet count?
The normal range is 150–400 × 10⁹/L. Values below 150 (thrombocytopenia) or above 400 (thrombocytosis) require attention and possibly further investigation.
What does a low platelet count mean?
A low count (thrombocytopenia) can result from reduced production in the bone marrow, increased breakdown in the spleen, or autoimmune reactions. It increases the risk of bleeding.
What does a high platelet count mean?
A high count (thrombocytosis) is usually reactive — as a result of inflammation, infection, or iron deficiency — and normalises after treatment of the cause. More rarely, it is a sign of a bone marrow disorder.
Do I need to fast before a platelet test?
No, fasting is not required. The test is part of the standard blood count.
Can stress affect my platelets?
Yes, acute physical or emotional stress can temporarily raise the platelet count. This is a normal reaction and typically normalises quickly.
When is a low platelet count dangerous?
A platelet count below 50 × 10⁹/L increases bleeding risk during procedures. Below 20 × 10⁹/L, there is risk of spontaneous bleeding. At such levels, medical supervision is necessary.