Sodium, Plasma or Serum

Sodium Serum/NA - NOCO

Note: This test is included in the BMP-Basic Metabolic Panel, CMP-Comprehensive Metabolic Panel, LYTES-Electrolytes, Plasma or Serum, Delta Osmolality-Osmolality, Delta, Serum, and RFP-Renal Function Panel.

1 mL plasma from Green top (Lithium Heparin)

1 ml serum from Serum Gel or Red Top

Specimen Type	Temperature	Time
Plasma Li Hep	Refrigerated	48 hours
Serum SST	Refrigerated	48 hours
Red Top – Separated*	Refrigerated	48 hours

 
*Centrifuge and aliquot into a plastic vial.

Gross hemolysis

Monday through Sunday; Continuously

Same day

Physiological significance: Electrolytes are involved in most major metabolic functions in the body. Sodium, potassium and chloride are amongst the most important physiological ions and the most often assayed electrolytes. They are supplied primarily through the diet, absorbed in the gastrointestinal tract, and excreted via the kidneys. Sodium is the major extracellular cation and functions to maintain fluid distribution and osmotic pressure. Some causes of decreased levels of sodium include prolonged vomiting or diarrhea, diminished reabsorption in the kidney and excessive fluid retention. Common causes of increased sodium include excessive fluid loss, high salt intake and increased kidney reabsorption. Potassium is the major intracellular cation and is critical to neural and muscle cell activity. Some causes of decreased potassium levels include reduced intake of dietary potassium or excessive loss of potassium from the body due to diarrhea, prolonged vomiting or increased renal excretion. Increased potassium levels may be caused by dehydration or shock, severe burns, diabetic ketoacidosis, and retention of potassium by the kidney. Chloride is the major extracellular anion and serves to regulate the balance of extracellular fluid distribution. Similarly to the other ions, common causes of decreased chloride include reduced dietary intake, prolonged vomiting and reduced renal reabsorption as well as some forms of acidosis and alkalosis. Increased chloride values are found in dehydration, kidney failure, some forms of acidosis, high dietary or parenteral chloride intake, and salicylate poisoning.