Paramedics bring a lethargic 45-year-old male patient to the acute care unit. According to his brother, the patient has consumed heavy amounts of alcohol daily for the past two weeks while completely abstaining from solid foods. Over the last 96 hours, he has suffered from intractable emesis. Physical examination reveals a deeply furrowed tongue, delayed capillary refill, and a loss of skin elasticity.
Laboratory evaluations reveal the following:
| Parameter | Result |
|---|---|
| Sodium () | 140 mEq/L |
| Potassium () | 3.2 mEq/L |
| Chloride () | 89 mEq/L |
| Bicarbonate () | 18 mEq/L |
| Blood urea nitrogen | 42 mg/dL |
| Serum creatinine | 1.6 mg/dL |
| Plasma glucose | 70 mg/dL |
Urinalysis is strongly positive for ketones.
Assume a baseline normal serum anion gap of 12 mEq/L and a normal serum bicarbonate of 24 mEq/L. What is the calculated delta ratio () for this patient?
Answer: 3.5
Answer
The calculated delta ratio is 3.5.
The patient's anion gap is calculated as mEq/L. The change in anion gap () is mEq/L. The change in bicarbonate () is mEq/L. The delta ratio is . A ratio greater than 2.0 reveals that the drop in bicarbonate is much less than expected for the degree of anion gap elevation, which is characteristic of a concurrent metabolic alkalosis (in this case, from severe volume depletion and intractable emesis superimposed on alcoholic ketoacidosis).
Step-by-Step Solution
Key Concept
The delta ratio () is used in high anion gap metabolic acidosis to identify mixed acid-base disorders; a ratio significantly greater than 2.0 indicates a concurrent metabolic alkalosis.