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Test Name:
Sodium, Serum or Plasma

• SBMF No:
  29028
• Performance Lab Name:
  Automated Lab
• Test Mnemonic:
  NA
• ABN:
  Not required
• CPT Code:
  84295
• LOINC Code:
  2951-2
• Also Known As:
  Na
• Also See:
  23058 Electrolyte Panel
• Spec Type:
  Serum or plasma
• Spec Container:
  Gold top (SST), Red top (serum), Light green top (PST), or Green top (lithium heparin) tube
• Pref Vol:
  1.0 mL
• Min Vol:
  0.3 mL
• Fasting:
  No
• Spec Collect:
  Routine venipuncture
• Spec Process:
  Serum sample tubes, clot 30 minutes
  Promptly centrifuge 15 minutes
  Immediately transfer serum or plasma to separate plastic tube
  Properly centrifuged gel barrier tube sample does not require transfer of specimen to separate tube
• Spec Store Transport:
  Refrigerated
• Spec Stability:
  2 weeks refrigerated (2-8°C)
• Spec Reject:
  Hemolyzed specimen
• Methodology:
  Ion-selective Electrode (ISE)
• Clinical Significance:
  Sodium (NA+) is the major positive ion of the extracellular (outside of the cell) fluids. The concentration of sodium inside cells is only about 5 mEq/L compared to 140 outside. Sodium is the major determinant of extracellular osmolality. The sodium content of the blood is a result of a balance between dietary intake and renal excretion (only a small percent is lost through the stool or sweat). Many factors affect sodium levels, including the steroid hormone aldosterone which decreases loss of sodium in the urine. Atrial natriuretic protein (ANP) is a hormone secreted from the heart that increases sodium loss from the body. Water and sodium are interrelated in that, for example, retention of increased sodium is followed by retention of fluid and vice versa. However, the blody is able to regulate sodium and water separately if necessary, controlling sodium by means of aldosterone and ANP and water by ADH (antidiuretic hormone).

  Increased Na+ levels (hypernatremia) may indicate:
   • Cushing's syndrome (rare)
   • Dehydration
   • Diabetes insipidus
   • Extensive thermal burns
   • Hyperaldosteronism (very rare)
   • Osmotic diuresis

  Decreased Na+ levels (hyponatremia) may indicate:
   • Addison's disease (rare)
   • Ascites (leakage of fluid into the peritoneum and commonly seen in cirrhosis of the liver)
   • Congestive heart failure
   • Diarrhea
   • Excessive sweating
   • Intraluminal bowel loss (ileus or mechanical obstruction)
   • Ketoacidosis
   • Kidney disease
   • Osmotic dilution
   • Peripheral edema
   • Pleural effusion
   • Syndrome of inappropriate antidiuretic hormone secretion
   • Vomiting or nasogastric aspiration
   • Use of diuretics

  Additional conditions under which Na+ testing may be performed:
   • Acute adrenal crisis
   • Diabetic hyperglycemic hyperosmolar coma
   • Drug-induced hypothyroidism
   • Hepatorenal syndrome
   • Hypopituitarism
   • Hypothyroidism
   • Hypothyroidism; primary
   • Hypothyroidism; secondary

• Reference Range:
  134-145 mEq/L
• Critical Low Value:
  124 mEq/L
• Critical High Value:
  161 mEq/L
• Additional Test Info:
  
• Day Run:
  Sun-Sat (daily)
• Time Run:
  As received
• Time Reported:
  4 hours
• Test Type:
  GAS-LYTE