Cases corner – 50 years old with thrombocytosis

2nd November 2020

Mr D, a 50 year old man, attends for his annual health check. He is currently fit and well and his examination is unremarkable. A urine dipstick is negative. You perform routine bloods as part of your assessment. The results of this show an abnormal platelet count of 620 x10⁹/L. His previous blood test 6 months ago, was normal. A repeat 2 weeks later is also raised at 624 x10⁹/L.

What would you do next?

  1. Reassure, as patient is asymptomatic, and safety net if symptoms arise to comeback
  2. Re-book patient for a repeat platelet count in 3 months
  3. Refer for a chest x-ray
  4. Refer under a 2-week-wait pathway to haematology for further investigation


Thrombocytosis is a new risk factor for cancer, identified by the NICE NG12 Guidelines. Thrombocytosis is not a feature of haematological cancer. A raised platelet count is a non-specific marker of inflammation which features in a number of different tumour types as well as benign inflammatory diseases. Within the NICE Guidelines thrombocytosis features in 4 cancer pathways, Lung, endometrial, Gastric (stomach) and Oesophageal, known as the LEGO cancers. There is also mounting evidence to support thrombocytosis as a marker of colorectal cancer as well; however, this has yet to be included in guidelines to date.

For Mr D the most appropriate next step would be an urgent chest x-ray (CXR) to be performed within 2 weeks. The guidelines recommend a CXR for any patient ages 40 or over with the following:

  • Persistent or recurrent chest infection
  • Finger clubbing
  • Supraclavicular lymphadenopathy or persistent cervical lymphadenopathy
  • Chest signs consistent with lung cancer
  • Thrombocytosis

Knowing how to investigate a patient with a raised platelet count can be exceptionally difficult, especially knowing where to start. There are currently no specific pathways for asymptomatic patients with thrombocytosis. It can be useful to consider direct access tests or investigations, to be able to rule in or out the LEGO cancers. This may be an trans-vaginal ultrasound scan, an endoscopy and CXR until further information can be gathered.