A 24-year-old woman with a history of type 1 diabetes mellitus presents to the emergency department with nausea, vomiting, and diffuse abdominal pain. She reports missing her insulin doses for the past two days due to illness. On physical examination, she appears lethargic. Her blood pressure is 105/65 mm Hg, heart rate is 118/min, and respiratory rate is 26/min with deep, rapid breaths. Laboratory studies show the following:
| Laboratory test | Result |
|---|---|
| Serum sodium | 140 mEq/L |
| Serum potassium | 5.2 mEq/L |
| Serum chloride | 98 mEq/L |
| Serum bicarbonate | 12 mEq/L |
| Blood glucose | 485 mg/dL |
| Serum creatinine | 1.1 mg/dL |
What is the patient's calculated serum anion gap? (Provide the numerical value in mEq/L).
Answer: 30 mEq/L
Answer
30
The serum anion gap is calculated using the standard formula: . In this patient, substituting the given laboratory values yields: mEq/L. A normal anion gap is typically between 8 and 12 mEq/L. This patient has a significantly elevated anion gap of 30 mEq/L, which, in the context of her hyperglycemia and missed insulin doses, is highly consistent with diabetic ketoacidosis, a classic cause of high anion gap metabolic acidosis.
Step-by-Step Solution
Key Concept
Calculation of the serum anion gap is a fundamental step in evaluating a patient with metabolic acidosis, utilizing the formula: Anion Gap = .