Platelets

Platelets are tiny cell fragments that stop bleeding: when a blood vessel is damaged, they stick together at the injury and help form a clot. The test shows how many are in your blood. It is performed when you bruise easily or bleed frequently, before procedures, and to monitor diseases and medicines that may change platelet counts.

Who is this test for

• people who bruise easily or develop tiny red spots on the skin;
• for frequent nosebleeds or bleeding gums and heavy periods;
• before surgery and other procedures;
• people taking medicines that may affect platelet counts, such as heparin or chemotherapy;
• in liver or autoimmune disease;
• for monitoring when a doctor has previously found a low or high platelet count.

What the test reveals

Platelets form in the bone marrow and survive in blood for around ten days, so they are constantly renewed. The test measures their number per litre of blood. In adults, normal counts are usually around 158 to 424 billion per litre (158–424 × 10⁹/L); the exact reference interval is printed on the report.

If there are too few, blood clots less easily and bruising and bleeding occur more readily. If there are too many, this is most often a temporary bodily reaction and less commonly a sign of bone marrow disease. Platelet counts are part of a complete blood count, which also shows red and white blood cells from the same sample.

The test and preparation

The sample is venous blood, and collection takes a few minutes. Fasting is not required unless glucose or blood lipids are also tested from the same sample. Avoid intense physical exertion the day before and drink enough fluid. Tell your doctor which medicines you take.

What your results mean

• A low platelet count (thrombocytopenia) is often temporary, for example after a viral infection or with some medicines. It may also occur with liver disease, excessive alcohol consumption, vitamin B12 or folic acid deficiency, in pregnancy, and when the immune system destroys platelets. Serious bleeding is usually a risk only when counts are extremely low.
• A falsely low count: in some people, platelets clump together after blood collection, so the reported count is lower than the actual blood count. The doctor then requests a repeat test.
• A high platelet count (thrombocytosis) is most often a temporary reaction to inflammation, infection, bleeding, iron deficiency or surgery. If counts are persistently and markedly high without a clear cause, the doctor refers for haematological investigation.

A doctor interprets the result alongside blood count, symptoms and medicines. Bleeding that does not stop, blood in stools or vomiting blood, and tiny red skin spots with high fever and a poor general condition are emergencies: call 194 or 112.

How to arrange testing

You can come for blood collection without an appointment or referral at one of our branches throughout Croatia (listed on the Contactpage). Prices for all tests and panels are listed in the price list. If this is your first test, it is worth choosing a complete blood count, which shows anaemia and signs of infection alongside platelets.

Frequently asked questions

Is the platelet count part of a blood count?

Yes. A complete blood count shows red blood cells, haemoglobin and white blood cells as well as platelets. A separate platelet test is mainly used for monitoring when a doctor has previously identified a change.

Does the platelet count show how my blood clots?

Only partly. The count does not show how well platelets work or how clotting proteins act. Clotting proteins are checked by the Coagulation Panel with PT, APTT and fibrinogen.

Do medicines affect platelet counts?

Acetylsalicylic acid and clopidogrel change platelet function, not their number. Heparin, some antibiotics, epilepsy medicines and chemotherapy may lower counts, so tell your doctor which medicines you take.

Should slightly low platelets be a cause for concern?

A mildly low count is common and usually harmless, for example after a viral infection. The doctor usually repeats the test after several weeks and assesses whether further investigations are needed.