How can a patient’s clenched fist affect test results, and what should you instruct?

How can a patient’s clenched fist affect test results, and what should you instruct?

• A. Decrease potassium
• B. No effect
• C. Elevate potassium and glucose
• D. Increase potassium

Answer: (C)

Clenching or pumping a fist during venipuncture causes muscle activity that releases potassium from muscle cells into the bloodstream and can trigger a stress response that raises glucose levels. That combination can elevate both potassium and glucose in the collected sample. To prevent this, tell the patient to stop squeezing, relax the hand, and keep the arm supported with the hand open and at ease during the draw. After the collection, avoid further fist pumping; if results are affected, a redraw with a relaxed hand may be needed.

Clenching or pumping a fist during venipuncture causes muscle activity that releases potassium from muscle cells into the bloodstream and can trigger a stress response that raises glucose levels. That combination can elevate both potassium and glucose in the collected sample. To prevent this, tell the patient to stop squeezing, relax the hand, and keep the arm supported with the hand open and at ease during the draw. After the collection, avoid further fist pumping; if results are affected, a redraw with a relaxed hand may be needed.