In persistent vomiting, urine chloride is typically low.

• A. High
• B. Low
• C. Normal
• D. Variable

Answer: (B)

In metabolic alkalosis, the urine chloride level shows how the kidneys are handling chloride given the patient's volume status. Vomiting removes gastric HCl, causing extracellular fluid volume depletion and a net loss of chloride. The kidneys conserve chloride to correct this deficit, so urinary chloride falls to a low level, typically under 20 mEq/L. This low urine chloride is characteristic of chloride-responsive metabolic alkalosis from extrarenal chloride loss like persistent vomiting. If urine chloride were high, it would point toward renal chloride loss or mineralocorticoid excess rather than vomiting, while normal or variable values are less typical for this scenario.