Which of the following is not associated with potassium?

• A. Has no renal threshold
• B. Increased serum level in acidosis
• C. Hemolysis causes false increase in serum levels
• D. Major anion of intracellular fluid

Answer: (D)

Potassium is the major intracellular cation and is tightly regulated by the kidneys; it is not an anion. This means you wouldn’t describe potassium as the major anion of intracellular fluid.

Other true associations about potassium: the body has no sharp renal threshold for potassium—the kidneys excrete it to match intake and maintain balance rather than spilling it at a specific plasma level; serum potassium rises in acidosis because hydrogen ions enter cells and potassium exits to maintain electroneutrality; and hemolysis releases intracellular potassium into the serum, falsely elevating the measured level.

So the statement that potassium is the major anion of intracellular fluid is not correct, making it the one that does not fit potassium’s properties.