Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (702 page)

   Supplement to laboratory quality control, along with its components

   Interpretation

Increased In

   Organic (e.g., lactic acidosis, ketoacidosis)

   Inorganic (e.g., administration of phosphate, sulfate)

   Protein (e.g., hyperalbuminemia, transient)

   Exogenous (e.g., salicylate, formate, paraldehyde, nitrate, penicillin, carbenicillin)

   Not completely identified (e.g., hyperosmolar hyperglycemic nonketotic coma, uremia, poisoning by ethylene glycol, methanol)

   Artifactual

   Falsely increased serum sodium

   Falsely decreased serum chloride or bicarbonate

   When AG >12–14 mmol/L, diabetic ketoacidosis is the most common cause, uremic acidosis is the second most common cause, and drug ingestion (e.g., salicylates, methyl alcohol, ethylene glycol, ethyl alcohol) is the third most common cause; lactic acidosis should always be considered when these three causes are ruled out. In small children, rule out inborn errors of metabolism.

Decreased In

   Hypoalbuminemia (most common cause), hypocalcemia, hypomagnesemia.

   Artifactual (laboratory error, most frequent cause).