Case study
Case Study: Diabetic Ketoacidosis in a Newly Diagnosed Adolescent
A graduate-level case analysis of DKA management, integrating pathophysiology, fluid and insulin protocols, and prioritized nursing diagnoses.
Presentation and Pathophysiology
A 15-year-old female presented to the emergency department with a two-day history of polyuria, polydipsia, abdominal pain, and vomiting. Her parents reported an unintentional 4 kg weight loss over three weeks. On arrival she was tachypneic with deep, sighing (Kussmaul) respirations, and her breath carried a fruity, acetone odor. Point-of-care testing showed a blood glucose of 486 mg/dL, and venous blood gas revealed a pH of 7.14 with a bicarbonate of 9 mEq/L and a positive serum ketone screen — findings diagnostic of diabetic ketoacidosis (DKA).
The underlying mechanism is an absolute insulin deficiency. Without insulin, glucose cannot enter cells, so the body shifts to lipolysis for fuel; the resulting free fatty acids are converted in the liver to ketone bodies, producing a high anion-gap metabolic acidosis. Osmotic diuresis from glucosuria drives profound dehydration and electrolyte depletion, most dangerously of potassium (Wolfsdorf et al., 2018).
7.14
Arterial pH on admission — severe DKA (< 7.15)
Priority Nursing Diagnoses
Two NANDA-I diagnoses take priority. First, Deficient Fluid Volume related to osmotic diuresis, evidenced by dry mucous membranes, tachycardia, and a capillary refill of three seconds. Second, Risk for Electrolyte Imbalance, given the predictable potassium shift that accompanies insulin therapy and acidosis correction.
Analytic excerpt
The paradox junior clinicians miss: the initial serum potassium may be normal or high even though total-body potassium is severely depleted. As insulin drives potassium intracellularly and acidosis resolves, serum levels can fall precipitously — so potassium is replaced before it looks low.
Evidence-Based Management
Management follows a sequenced protocol: fluid resuscitation first, then insulin, with continuous electrolyte surveillance. Guidelines recommend restoring circulating volume with isotonic saline before initiating a continuous insulin infusion, and delaying or moderating insulin until serum potassium is confirmed above 3.3 mEq/L to avoid life-threatening hypokalemia (Wolfsdorf et al., 2018). Glucose is lowered gradually to reduce the risk of cerebral edema, the most feared pediatric complication.