Of the crystalloids discussed so far, only Hartmann's solution routinely contains potassium at 5 mmol/L.

0.9% NaCl also comes with added potassium if specified. Potassium is added to give a solution containing 3 g/L, i.e. 40 mmol/L.

5% glucose and 0.18 % NaCl + 4% glucose is also produced with added potassium, i.e. 3 g/L or 40 mmol/L.

If fluid without potassium is all that is available, it is possible to add concentrated KCl solution to intravenous fluid bags using a sterile technique. KCl 15%, i.e. 150 mg/ml, is available in 10 ml ampoules. Each ampoule contains 1.5 g of KCl, which is equivalent to 20 mmol each of K⁺ and Cl^-.

15% KCl must be kept away from other small fluid ampoules since it is very toxic if administered undiluted, cardiac standstill can be induced.

The daily requirement for potassium is approximately 80 mmol, which is 6 g. If there is no pre-existing potassium deficit, then 2 litres of a solution containing 3 g/L should provide sufficient daily potassium. Hartmann's solution alone does not adequately replace potassium loss.