What could cause my potassium in my blood test to be a level 8?

Potassium of 8: Unless you are a dialysis patient, a potassium (k) of 8 would kill you by stopping your heart from pumping. Most likely, you had a elevated k due to some leaking of k from the intracellular space during the drawing of blood from your vein. This is called "factitious hyperkalemia". Elevated k levels are also seen with increased platelets in your blood or some destruction of rbc's in the test tube.