What can cause “pseudohyperkalemia” and when should we suspect its presence?

One of our Members had a female patient in her 40s who had obesity and was being verbally abusive, loud, and disruptive. She had an elevated serum potassium level—around 5.5 [mmol/ L]. This is not rare, is it? Sometimes we get laboratory test results back and, unexpectedly, the serum potassium level is high. We are…