Laboratory Medicine Program

Calcium ionized
(Ionized Calcium)

Clinical Decription:
Ninety nine percent of the total body calcium exists as crystalline hydroxyapatite in bone. Calcium in plasma exists in three states: protein-bound (45%), complexes with small anions such as phosphate (10)% and ionized (45%). Ionized calcium, Ca++, is the physiologically active form. Ca++ concentration is regulated and is affected by plasma pH and protein concentration. Alkalosis favours the formation of bound calcium and acidosis favours the formation of Ca++. Ca++ activates the contraction of striated muscle, diminishes neuromuscular excitability and plays a vital role in blood coagulation. Causes of hypercalcemia include hyperparathyroidism and malignancy resulting in bone resorption. Hypocalcemia can be the result in hyperparathyroidism or vitamin D deficiency. Acute or chronic hypocalcemia can result in tetany.

Method: Ionic Selective Electrode; Siemens Rapidpoint/Rapidlab

Component Tests Used: n/a

Reference Ranges Used:
Ionized calcium: 1.12 - 1.32 mmol/LNormalized ionized calcium (to pH 7.4): 1.12 - 1.32 mmol/L

Specimen Type: serum
Volume: 3 mL (minimum: 1 mL)

Shipping: 4C

Special Instructions: Sample must be collected in it's own primary container and remain closed until testing. Opening of the tube and exposure to air will comprimise the sample integrity.

Testing Schedule(s): Daily.

Turnaround Time: 1 day

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