ionized Ca+2 in blood

Reference interval

• whole blood
  • adults: 4.60-5.08 mg/dL (1.15-1.27 nmol/L)

Clinical significance

• determines free or biologically active Ca+2, thus determines 'true' hypercalcemia or 'true' hypocalcemia

Increases

• clinical disorders
  • decreased plasma pH (acidemia)
  • primary hyperparathyroidism
  • PTH producing tumors (hypercalcemia of malignancy)
  • excess intake of vitamin D
• pharmaceutical agents
  • in vivo effects
    • hydrochlorothiazide (chronic use), lithium

Decreases

• clinical disorders
  • increased plasma pH (alkalemia)
  • increased plasma ionic strength
  • primary hypoparathyroidism
  • pseudohypoparathyroidism
  • vitamin D deficiency
  • magnesium deficiency
  • major surgery
  • trauma
  • sepsis
  • burns
  • pancreatitis
  • multiple organ failure
  • hemodialysis with low calcium diasylate
• pharmaceutical agents
  • in vivo effects
    • anticonvulsants, danazol, foscarnet, furosemide (initial effect), transfusion with citrate- containing products
  • chemical interferences
    • Ca+2-binding agents (EDTA, citrate, oxalate, heparin)

Methods

ion-specific electrode

Specimen

• whole blood or plasma (heparin)
• collect blood anaerobically
• place on ice & deliver to lab immediately

More general terms

• ionized Ca+2 in serum/plasma/blood

Additional terms

• Ca+2
• hypercalcemia
• hypocalcemia