A few hours later a lab technician calls in a flat spin. The patient’s Potassium is dangerously high. The doctors immediately commence potassium-lowering therapy.
However, a short while later the patient deteriorates. By some miracle, the patient survives when it is noted on a follow-up specimen that the patient’s Potassium is now dangerously low. Yet the therapy given would not have been able to lower Potassium so drastically.
When the Little (Inexperienced) Med Student drew blood, he/she accidentally allowed the vacuum purple top tube to guzzle all the blood. Not wanting to poke another hole in the sick patient, Med Student unscrewed the purple top tube and poured some blood into the yellow top tube (SST: Serum Separator Tube), which is used to test U&E, such as Potassium. And because the EDTA tube contained Potassium, the blood now has a false high potassium.
This apparently happens regularly. To be honest, the thought had never occurred to me before.