Question

Mr. Oliver arrived early for his blood draw one Monday morning. The medical assistant was running late that day, and seemed to be a bit distracted as the preparation for the blood draw. Mr. Oliver's physician had ordered a CBC (to be collected in a potassium EDTA tube) and a potassium level (to be collected in a green top heparinized tube) The MA completed the blood draw, and thanked Mr. Oliver for his time.

The next day, the physician's office called Mr. Oliver and asked him to come in to have his potassium level rechecked, as it was elevated on the test from the day before. This was not an expected result, as usually Mr. Oliver's potassium level was decreased below the reference range. The specimen was drawn and checked on a STAT basis, and the result was in the low end of the reference range. The physician told Mr. Oliver that the previous result was elevated because of a laboratory error.

1. What are two sources of error that could cause the potassium result to be erroneously elevated in this scenario?

Answer 1

ANSWER :

1)Two sources of error are :

As the medical assistant was running late and bit distracted during the preparation of blood draw can lead to :

• Mechanical errors : a) Application of tourniquet for more than 1 min can cause hemoconcentration, altered water balance , hemolysis ----> elevates potassium levels. b) Clenching of fist of patient can release potassium locally from forearm muscles. c)Traumatic venipuncture , excessive force while drawing blood-----> hemolysis ----> elevated potassium levels
• Contaminants : Due to distraction of the medical assistant he might have collected blood in potassium EDTA tube(for potassium levels) instead of heparinized tube , backflow of potassium salts occur from the tube additive EDTA , can elevate potassium levels.

answered by: anonymous