Caution of overdependence on formulas while treating hyponatremia

Use of online formulas to treat hyponatremia is a common practice. We report here that while using the same goal of correction and type of infusate to treat a patient with hyponatremia, a large discrepancy in infusion rate is obtained from using the 2 commonly available online equations. When the therapy fluid is less concentrated saline (0.9%), Adrogue's formula poses the risk of large amount of volume being administered for only a small change in serum sodium concentration. This may be detrimental especially in patients with congestive heart failure. When the therapy fluid is hypertonic saline (3%), these formulas may result in overly rapid correction. We should, thus, never use these formulas blindly in the management of patients with hyponatremia.