A patient with type 1 diabetes reports nausea, vomiting, and abdominal pain. The nurse suspects diabetic ketoacidosis (DKA). Which lab result most strongly supports this diagnosis?

Rationale: A. Liver enzyme elevations (AST, ALT) are not characteristic of DKA. They may appear in other conditions such as hepatitis, medication effects, or fatty liver, but they do not indicate the metabolic derangements of DKA. Relying on liver enzymes could delay the correct diagnosis. B. Diabetic ketoacidosis occurs when insulin deficiency prevents glucose from entering cells, prompting the body to metabolize fat for energy. This fat metabolism produces ketone bodies (acetoacetate, β-hydroxybutyrate, acetone), which accumulate in the blood and spill into the urine. Ketonuria or positive serum ketones is a defining lab finding in DKA, especially when paired with hyperglycemia and metabolic acidosis. Detecting ketones allows for prompt fluid, insulin, and electrolyte management, which is critical to prevent life-threatening complications. C. Hyponatremia may appear in DKA due to osmotic dilution caused by hyperglycemia, sometimes called “pseudohyponatremia.” However, low sodium is secondary to the hyperglycemic state and does not directly indicate ketone production or acidosis. While it is important to monitor and correct electrolytes, hyponatremia alone cannot confirm DKA. D. Elevated creatinine may result from dehydration and reduced kidney perfusion in DKA. Though it signals renal involvement or pre-renal azotemia, it is nonspecific. Creatinine elevation does not differentiate DKA from other conditions causing vomiting, dehydration, or hyperglycemia.