American Board of Internal Medicine (ABIM) Certification Practice Exam

Which of the following describes the urine chloride cutoff for low urine chloride?

1. Less than 20 mEq/L

2. More than 25 mEq/L

3. Less than 15 mEq/L

4. Exactly 10 mEq/L

The correct answer is: Less than 15 mEq/L

The correct choice is based on established clinical guidelines for interpreting urine chloride levels. A urine chloride level of less than 15 mEq/L is typically considered indicative of low urine chloride. This threshold is significant in the evaluation of various clinical conditions, particularly in differentiating between causes of metabolic alkalosis or assessing volume status in patients with suspected gastroenteritis or other gastrointestinal losses. Evaluating urine chloride levels can help determine whether a patient's metabolic alkalosis is due to excessive vomiting, where chloride loss occurs, versus other conditions where chloride levels might be normal. The cutoff helps clinicians identify patients who may require further investigation or management related to electrolyte imbalances. In clinical practice, values below this threshold suggest that the kidneys are likely conserving chloride due to either low dietary intake or excessive loss from another source. A precise understanding of these levels plays a critical role in guiding appropriate treatment and diagnostic measures.