Electrolytes

What do all these things mean?

Cl  (chloride) is an electrolyte that is often lost when vomiting occurs or with Addison's disease, elevations typically indicate dehydration
K (potassium) is lost with vomiting, diarrhea or excessive urination.  Increases can indicate kidney failure, Addison's disease, dehydration or urethral obstruction, high levels may lead to cardiac arrest
Na (sodium) is lost with vomiting, diarrhea, kidney disease, and Addison's disease.  This helps to indicate hydration status.