Investigating elevated potassium values.

Continues on page 26 One of the most frequently asked questions regarding phlebotomy is, why are the potassiums high? The answer involves a variety of factors, which can have a significant impact on the care of a patient. When an abnormally high value exists, it frequently sets off a train of investigations looking for such severe diseases as: renal failure; adrenocortical hypofunction; and diabetes. A falsely elevated potassium value (pseudohyperkalemia) discovered in a pre-surgical work-up can unnecessarily delay surgery and result in additional time in the hospital. Conversely, pseudohyperkalemia can elevate an abnormally low potassium, masking a real illness such as: adrenocortical hyperfunction or tumor; renal failure (potassium-losing phase); and metabolic alkalosis secondary to obstructive lung disease.