Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (802 page)

   Use

   With sodium, potassium, and carbon dioxide to assess electrolyte, acid–base, and water balance. Chloride usually changes in the same direction as sodium except in metabolic acidosis with bicarbonate depletion and metabolic alkalosis with bicarbonate excess, when serum sodium levels may be normal.

   Interpretation

Increased In

   Metabolic acidosis associated with prolonged diarrhea with loss of sodium bicarbonate

   Renal tubular diseases with decreased excretion of hydrogen ions and decreased reabsorption of bicarbonate (“hyperchloremic metabolic acidosis”)

   Respiratory alkalosis (e.g., hyperventilation, severe CNS damage)

   Drugs

   Excessive administration of certain drugs (e.g., ammonium chloride, IV saline, salicylate intoxication, acetazolamide therapy)

   False (methodologic) increase due to bromides or other halogens

   Retention of salt and water (e.g., corticosteroids, guanethidine, phenylbutazone)

   Some cases of hyperparathyroidism

   Diabetes insipidus, dehydration

   Sodium loss > chloride loss (e.g., diarrhea, intestinal fistulas)