Among the six major plasma electrolytes, which one is NOT normally excreted in urine but instead conserved by the kidneys?

1. Sodium, potassium, and chloride are all routinely excreted in urine and measured in routine urine samples. 2. Bicarbonate behaves differently because the body needs it for its buffering systems. 3. Bicarbonate is the one ion not normally excreted in urine, instead being conserved by the kidneys. 4. So bicarbonate is correct. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 26 "Fluid, Electrolyte, and Acid-Base Balance", p.1259-1260 §Electrolyte Balance_