What It Measures
A serum potassium test measures the concentration of potassium ions in the blood. Since 98% of the body's potassium is inside cells, the serum level reflects a tightly regulated balance maintained by the kidneys, sodium-potassium ATPase pumps, and hormones like aldosterone and insulin.
Potassium is an essential electrolyte that plays a critical role in nerve signaling, muscle contraction, and heart rhythm regulation. It is the most abundant intracellular cation, and even small deviations in serum levels can have life-threatening consequences, particularly for cardiac function.
Current Value
What High Means
Elevated potassium (hyperkalemia, >5.0 mEq/L) can result from kidney disease (reduced excretion), medications (ACE inhibitors, ARBs, potassium-sparing diuretics, NSAIDs), acidosis (shifts potassium out of cells), adrenal insufficiency, rhabdomyolysis, or excessive supplementation. Hyperkalemia is dangerous because it disrupts cardiac electrical conduction, potentially causing fatal arrhythmias. Pseudohyperkalemia from hemolyzed blood samples is a common lab artifact.
Possible Symptoms
Muscle weakness, fatigue, nausea, heart palpitations, chest pain, irregular heartbeat, numbness or tingling, difficulty breathing. Severe hyperkalemia (>6.5 mEq/L) can cause cardiac arrest.
What Low Means
Low potassium (hypokalemia, <3.5 mEq/L) is commonly caused by diuretic use, vomiting, diarrhea, excessive sweating, low dietary intake, hyperaldosteronism, or magnesium deficiency (which impairs potassium retention). Hypokalemia increases the risk of cardiac arrhythmias, muscle weakness, and can worsen insulin resistance and blood pressure.
Possible Symptoms
Muscle cramps, weakness, fatigue, constipation, heart palpitations, abnormal heart rhythms, increased urination, excessive thirst, tingling or numbness. Severe hypokalemia (<2.5 mEq/L) can cause paralysis and respiratory failure.
Risk Factors
Chronic kidney disease, heart failure, cardiac arrhythmias, hypertension, metabolic acidosis, type 2 diabetes, adrenal disorders (Addison's disease, hyperaldosteronism), muscle disorders (rhabdomyolysis), medication interactions (ACE inhibitors, ARBs, diuretics, digoxin toxicity).
Actionable Advice
Supplements
- •Potassium citrate
- •Potassium bicarbonate
- •Potassium chloride
- •Magnesium glycinate (supports potassium retention)
- •Electrolyte supplements
Diet & Lifestyle
- •Eat potassium-rich foods daily: avocados, bananas, sweet potatoes, spinach, salmon, white beans, and coconut water
- •Aim for 3,500–4,700 mg of dietary potassium per day (most adults get only ~2,500 mg)
- •Ensure adequate magnesium intake — magnesium deficiency causes renal potassium wasting
- •Limit excessive sodium intake, which increases potassium excretion
- •Stay hydrated but avoid excessive water intake that dilutes electrolytes
- •Review medications with your doctor — diuretics and laxatives are common causes of low potassium
- •If supplementing, use potassium with meals and avoid exceeding 99 mg per single dose without medical supervision
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Historical Trend
Resources & Studies
All Readings
| Date | Value | Change |
|---|---|---|
| 2025-08-25 | 4.3 mmol/L | +0.3 |
| 2025-06-27 | 4 mmol/L | — |