From the Guidelines
A safe potassium level for discharge is generally between 3.5 and 5.0 mEq/L (or mmol/L). Patients with potassium levels within this range can typically be safely discharged from the hospital, assuming other discharge criteria are met. If a patient's potassium level is slightly outside this range but stable (for example, 3.3-3.4 mEq/L or 5.1-5.2 mEq/L), discharge might still be appropriate with a clear follow-up plan.
Key Considerations
- For patients discharged with borderline low potassium, oral potassium supplements such as potassium chloride 20-40 mEq daily may be prescribed, with instructions to follow up within 1-2 weeks for repeat testing 1.
- For those with borderline high potassium, dietary counseling to limit potassium intake and possibly adjustment of medications that can raise potassium (such as ACE inhibitors, ARBs, or potassium-sparing diuretics) should be considered.
- Potassium is critical for proper nerve and muscle function, particularly for cardiac muscle, which is why maintaining appropriate levels is essential.
- Levels below 3.0 mEq/L or above 5.5 mEq/L generally warrant correction before discharge due to increased risk of cardiac arrhythmias and other complications.
Rationale
The rationale behind these recommendations is based on the importance of maintaining potassium levels within a safe range to prevent cardiac arrhythmias and other complications.
- A study published in the European Journal of Heart Failure in 2018 found that serum potassium levels outside the range of 3.9-4.5 mmol/L were associated with higher mortality in patients receiving loop diuretics after their first episode of myocardial infarction 1.
- Another report examined 44,799 hypertensive patients and found that serum potassium levels outside 4.1-4.7 mmol/L were associated with higher mortality 1.
- The 2009 focused update incorporated into the ACC/AHA 2005 guidelines for the diagnosis and management of heart failure in adults recommends targeting serum potassium concentrations in the 4.0 to 5.0 mmol per liter range 1.
From the FDA Drug Label
The normal adult plasma concentration is 3.5 to 5 mEq per liter. The safe level for discharge on potassium is between 3.5 to 5 mEq per liter 2.
From the Research
Safe Potassium Levels for Discharge
The safe level for discharge on potassium is a crucial consideration in patient care. According to the available evidence:
- A study published in 2020 3 found that the optimal range of serum potassium at hospital discharge is between 4.0-4.4 mEq/L, with a U-shaped association between discharge serum potassium and one-year mortality.
- Another study from 2019 4 also found that the lowest one-year mortality was associated with an admission serum potassium of 4.0-4.4 mEq/L.
- A 2016 study 5 found that patients with "normal-very high" potassium levels (4.45-5.2 mEq/L) experienced increased risk for 30-day and 1-year all-cause mortality.
Potassium Level Ranges and Associated Risks
The following potassium level ranges have been associated with increased risks:
- Hypokalemia (≤3.9 mEq/L): associated with increased one-year mortality 3, 4
- Hyperkalemia (≥5.0 mEq/L): associated with increased one-year mortality 3, 4
- High-normal potassium levels (5.0-5.5 mEq/L): may be associated with improved outcomes in patients with heart failure 6
Clinical Considerations
When considering discharge potassium levels, clinicians should be aware of the potential risks associated with abnormal potassium levels, including: