Potassium Content in D5NM Fluid
D5NM (Dextrose 5% in Normal Saline, also written as D5NS or D5 0.9% NaCl) contains 0 mEq/L of potassium in its standard formulation.
Standard Composition of D5NM
D5NM is a crystalloid solution consisting of:
- 5% dextrose (50 grams per liter)
- 0.9% sodium chloride (normal saline)
- Sodium: 154 mEq/L 1
- Chloride: 154 mEq/L 1
- Potassium: 0 mEq/L (no potassium in standard formulation) 1
Comparison with Balanced Crystalloids
Unlike balanced crystalloid solutions such as Ringer's lactate, Plasmalyte, or Isofundine which contain 4-5 mEq/L of potassium, standard normal saline-based solutions (including D5NS) do not contain any potassium 1.
Clinical Implications
When Potassium Supplementation is Needed
- If potassium replacement is required, it must be added separately to D5NS, as the base solution contains none 1
- For maintenance therapy requiring electrolyte replacement, guidelines recommend adding 20 mEq/L potassium chloride to dextrose-containing saline solutions 1
- In pediatric DKA management, potassium monitoring is essential as insulin therapy drives potassium intracellularly, and supplementation is typically needed despite the absence of potassium in the base fluid 1
Risk of Hypokalemia
- Prolonged administration of D5NS without potassium supplementation can lead to hypokalemia, particularly in patients with ongoing losses or increased cellular uptake 1, 2
- Loop diuretics administered with potassium-free fluids significantly increase hypokalemia risk 1
When to Consider Balanced Solutions Instead
- For severe dehydration or shock requiring large-volume resuscitation, consider using balanced crystalloids (Ringer's lactate, Plasmalyte) which contain physiologic potassium concentrations of 4-5 mEq/L 1
- Balanced solutions more closely approximate normal plasma electrolyte composition and may reduce the need for separate potassium supplementation 1
Important Caveats
- The presence of dextrose in D5NS does not affect potassium content but does provide 170 calories per liter and can cause transient hyperglycemia 3
- Always verify the specific product formulation, as some institutions may add potassium to create custom maintenance solutions, but this would be clearly labeled as "D5NS with KCl" 1
- Monitor serum potassium levels when administering any maintenance fluid, especially D5NS, as it provides no potassium replacement 1, 2