American Board of Internal Medicine (ABIM) Certification Practice Exam

In metabolic alkalosis, a high urine chloride level (>15 mEq/L) may suggest which condition?

1. Saline-responsive metabolic alkalosis

2. Renal tubular disorders

3. Chronic kidney disease

4. Saline-resistant metabolic alkalosis

The correct answer is: Saline-resistant metabolic alkalosis

In metabolic alkalosis, a high urine chloride level greater than 15 mEq/L typically indicates a saline-resistant form of the condition. This is significant because saline-resistant metabolic alkalosis suggests that the body is unable to adequately compensate for the alkalosis through the use of saline or isotonic fluids, leading to sustained elevation of bicarbonate levels in the blood. The presence of elevated urine chloride can help differentiate between various causes of metabolic alkalosis. In saline-responsive metabolic alkalosis (often due to vomiting or diuretic use), you would typically see low urine chloride levels as the body retains chloride and sodium to correct the alkalosis when saline is administered. Conversely, high urine chloride levels signify that there is an underlying renal mechanism at play that prevents proper compensation through typical means. When considering renal tubular disorders or chronic kidney disease, these conditions may contribute to metabolic alkalosis but are not specifically associated with the high urine chloride levels that define a saline-resistant scenario. Instead, they may present with varied urine electrolytes depending on the specific tubular functions affected or the overall state of the kidneys. Therefore, a high urine chloride level in the context of metabolic alkalosis points toward a saline-resistant condition, which implies that the metabolic disturbance is maintained despite attempts to correct it with