A nurse is caring for a child in diabetic ketoacidosis (DKA). The nurse knows she needs to specifically look at what blood level that will initially be elevated but then shift into the cells once insulin is given.

A. In diabetic ketoacidosis (DKA), serum potassium is often elevated initially due to the shift of potassium from inside the cells to the bloodstream caused by insulin deficiency and acidosis. However, once insulin therapy is started, potassium shifts back into the cells, which can rapidly cause hypokalemia if not carefully monitored. Therefore, frequent monitoring and appropriate potassium replacement are critical during DKA management to prevent cardiac arrhythmias and other complications. B. Calcium levels are not directly affected by insulin therapy in DKA. While acid-base changes can influence ionized calcium, calcium does not typically exhibit the same rapid intracellular shift seen with potassium during insulin administration. C. Magnesium levels may fluctuate in DKA due to osmotic diuresis and electrolyte losses, but it is not the primary electrolyte that shifts intracellularly in response to insulin therapy. Monitoring is important but less immediately critical than potassium. D. Bicarbonate is low in DKA due to metabolic acidosis from ketone accumulation. It does not shift into cells with insulin; instead, bicarbonate levels gradually normalize as ketoacidosis resolves and pH improves. Bicarbonate therapy is rarely indicated unless severe acidosis is present.