Which risk is commonly associated with hypotonic crystalloids?

• A. Cellular lysis
• B. Pulmonary edema
• C. Hypernatremia
• D. Thrombocytopenia

Answer: (A)

When you infuse hypotonic crystalloids, their osmolality is lower than that of plasma, so the extracellular fluid becomes hypotonic relative to the intracellular environment. Water then shifts from outside the cells into the cells to balance the osmotic gradient. This influx causes cells to swell, and in extreme cases the swelling can rupture cell membranes, leading to cellular lysis. This osmotic risk is the most characteristic concern with hypotonic fluids. By contrast, pulmonary edema is more about fluid overload and heart-lung dynamics, hypernatremia arises from too much sodium or too little free water, and thrombocytopenia is a blood cell count issue unrelated to the tonicity of the IV fluid.