Potassium

Blood potassium levels reveal how well your body maintains heart, nerve, and muscle function. Low potassium can cause muscle weakness, cramps, twitching, constipation, and dangerous heart rhythm disturbances, while high potassium can lead to muscle weakness, tingling, nausea, and potentially fatal heart rhythm problems. Monitoring potassium and supporting balance through a diet rich in fruits, vegetables, and legumes, along with kidney and cardiovascular health, helps prevent life-threatening imbalances.

Most adults benefit from checking potassium once a year as part of standard electrolyte screening. If you take ACE inhibitors, ARBs, potassium-sparing diuretics, or have reduced kidney function, retest every three to six months. After starting one of these medications, retest at 1 to 2 weeks.

At baseline / for screening: Once every 12 months from age 30 as part of a comprehensive metabolic panel. More frequently, every 3 to 6 months, if you take diuretics, ACE inhibitors, ARBs, or have a condition affecting fluid balance.

When monitoring an intervention or change: Retest 1 to 2 weeks after starting or adjusting medication that affects potassium balance (ACE inhibitor, ARB, potassium-sparing diuretic, loop or thiazide diuretic). If your reading is unexpectedly high, retest before acting on it, since a clenched fist during the draw or delayed sample processing can artifactually raise potassium (pseudohyperkalemia).

Note: A clenched fist during the draw or sample processing delay can falsely elevate potassium (pseudohyperkalemia). If unexpectedly high, retest immediately before acting on it; after potassium-shifting events (intense exercise, illness), wait 48 hours.