Unexpected Thrombocytosis

 

Created 8 July 2018,

Updated 3 June 2021 (Added another case)

Last update 4 May 2026 (Added another case)

 

Overview

I’ll take it as read that we all know what platelets are and what they do…

 

Here’s an interesting case. I walked in to a night shift to be told about an amazing unexpected thrombocythaemia. The platelet count had shot up from just under two hundred to nearly two thousand in just two weeks. The age of the patient was young enough to give serious alarm. Would I pass it on to the consultant haematologist immediately

 

I thought “No” (I knew what was going on) but I said nothing. I was also told that not only had we got this rather unusual thrombocythaemia, we also had two other almost identical cases. Perfectly normal within the last month; platelet counts in the thousands today.

 

I put a blood film from one of these worrying cases under the microscope knowing full well what I expected to see:

 

 

So…. What did I see?

 

The photo from my phone doesn’t really do the case justice. But what we had wasn’t thrombocythaemia at all. There was massive red cell anisocytosis and poikilocytosis and *lots* of red cell fragments seen. It was these red cell fragments that were causing the erroneously high platelet count

But the red cell fragments weren’t pathological in origin.  

…Now at this point I feel I should give the wider picture. Where I live in the UK was having an unprecedented heatwave at the time. The blood samples had been cooked.

Somehow or other during their transport from patient to lab they had been left in the heat of the day.

 

This is not uncommon on very hot days. Bear it in mind when faced with multiple cases of unexpected thrombocytosis on a hot day. The red cells break down and the analysers mistake red cell fragments for platelets.

 

 

And Here’s Another One…

 

Much the same could be said in this case. The country was going through a heatwave, and again the sample had cooked.

 

 

 

 

 

 

And Another One…

 

 

I was sitting in the garden on a May Bank Holiday enjoying the sunshine when I had a Whatsapp message. A sample had come in from a patient in the community. All normal a couple of weeks ago; a platelet count in the thousands today…

 

 

Some More Expert Opinion…

 

I seem to be unable to find any reference to this in the literature…. I can’t be the only person who has found this ?