What is the difference between normal saline and half-normal saline use in DKA fluid resuscitation?

• A. Normal saline is used initially for dehydration; half-normal saline is used when corrected sodium is high or after initial resuscitation; adjust.
• B. Half-normal saline is used initially; normal saline later.
• C. Both are used randomly without consideration of sodium.
• D. Only dextrose-containing fluids should be used.

Answer: (A)

In DKA, fluid choices are guided by volume status and the effect of high glucose on measured sodium. You start with normal saline (0.9% NaCl) to restore intravascular volume and perfusion. After the initial resuscitation, you look at the corrected serum sodium (accounting for hyperglycemia, since high glucose makes sodium look low). If the corrected sodium is low, you switch to half-normal saline (0.45% NaCl) to provide some sodium but with less overall tonicity, helping to raise sodium modestly without driving it too fast. If the corrected sodium is normal or high, you continue with normal saline to maintain volume and sodium until glucose starts to fall, then you transition to dextrose-containing fluids when appropriate (usually when glucose drops toward ~200 mg/dL) to prevent hypoglycemia while continuing insulin and electrolyte correction. This approach balances vascular rehydration, careful sodium correction, and safe glucose reduction.