Pseudo…

So a couple of weeks ago we got a lovely gentleman through our doors who had a medical problem.  He was mid 60s and had a pneumonia, but was tolerating it pretty well.  He had HTN, and CLL.

 What irked our collective team noodle was his K+ of 8.9, his ECG was normal, and he wasn’t in renal failure.

No tenting, sineing, PR prolongation, or P wave abnormality, or weird block.

“No, the sample isn’t haemolysed” the lab told us.

The repeat came back 8.7. – not haemolysed (this time written in block capitals).

The VBG we did, and ran to ICU to analyse gave us a value of 8.2.

So we turned to google, pubmed, and litfl, and all learnt about pseudohyperkalaemia:

The commonest cause is sloppy venepuncture, but it can also occur in patients with thrombocytosis, or leucocytosis.  Effectively it is a measurement error that occurs if you have tonne of cells in the sample all gently, slowly lysing.

Our gentleman’s WCC was 200

Pseudohypokalaemia has also been reported with leucocytosis as well.  As always I suppose we should always interpret lab results in light of what the patient looks like in front of us.

 

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