Audience

• Highland HSCP 

The normal platelet count is 150 to 450 × 10⁹/L. It would be unusual to get any bleeding symptoms with a platelet count above 50 × 10⁹/L. Spontaneous bleeding is more common when the platelet count is below 30 × 10⁹/L.

Causes

• Artifact e.g. platelet clumping
• Medications – check BNF
• Infections including HIV and hepatitis, Helicobacter pylori and other viral infections
• Liver disease and alcohol
•  Hypersplenism
• Vitamin B12 or folate deficiency
• Autoimmune diseases
• Pregnancy
• Thyroid dysfunction
• Sepsis
• Major haemorrhage
•  Disseminated intravascular coagulation
• Immune thrombocytopenia (ITP)
•  Anti-phospholipid syndrome
•  Inherited bleeding disorders
• Thrombotic thrombocytopenic purpura (TTP) – very rare but an emergency
• Bone marrow failure e.g. myelodysplasia or aplastic anaemia
• Bone marrow infiltration e.g. acute leukaemia
• Post-transfusion purpura

History and examination 

Think about asking questions to rule out above causes. Ask about bleeding symptoms, alcohol and a family history. Examine for hepatosplenomegaly, signs of liver disease, signs of autoimmune disease and any bruises. Review older blood tests and take a medication history.

Suggested investigations
These may depend on the history and examination.

• Blood film
• Vitamin B12 and folate
• Liver function tests
• HIV, hepatitis B and C
• TSH
• Coagulation screen
• Pregnancy test
• Consider autoimmune screen if history or examination suggestive
• Abdominal ultrasound if concerned about liver disease or palpable splenomegaly

Management

• Repeat the full blood count in case of artifact (unless deep symptomatic thrombocytopenia in which please refer in to hospital for urgent evaluation)
• Asymptomatic patients with a stable platelet count above 80 × 10⁹/L should be evaluated for the above conditions and have the above investigations but do not need to be seen by a haematologist. Discuss via Clinical Dialogue if further information or help required in first instance. Repeat the blood count in four to six weeks and if stable monitor every four months for 12 months and then annually. Patients with a stable platelet count over 80 × 10⁹/L for over a year and who are not on an anticoagulant do not generally require routine monitoring but should be advised to report any bleeding symptoms and get a full blood count prior to any invasive procedure.
• If there is another cytopenia or blood film abnormality or concern about haematological malignancy then please discuss or refer.
• Please refer to haematology if the platelet count is persistently greater than 30 but under 50 × 10⁹/L for over four months or if the platelet count is under 50 × 10⁹/L and the patient is awaiting surgery.
• If the platelet count is below 30 × 10⁹/L or there are bleeding concerns arrange urgent repeat and urgent referral
• Anticoagulation or antiplatelet drugs are usually avoided when the platelet count is below 50 × 10⁹/L and are safe when the platelet count is above 80 × 10⁹/L. For most patients with a platelet count between 50 and 80 × 10⁹/L anticoagulation is safe but at the lower end of this range a risk verses benefit decision is required. Bleeding risks are influenced by the stability and aetiology of the thrombocytopenia. In the absence of bleeding symptoms serial monitoring over the first 12 months to confirm stability should be
• If the platelet count is low due to liver disease then discuss with hepatology in first instance.