ARUP's Laboratory Test Directory

Calcium, Ionized, Serum : 0020135

Mnemonic: IONCA-S

Methodology: Ion-Selective Electrode/pH Electrode
Performed: Sun-Sat
Reported: Within 24 hours
Specimen Required: Collect: Serum separator tube.

Specimen Preparation: Do not open the tube or split the specimen. Do not freeze separator tube. Do not expose specimen to air at any time during collection or transport process. Centrifuge with stopper in place within one hour of collection. Transport 5 mL serum in original serum separator tube. (Min: 0.5 mL)

Storage/Transport Temperature: Refrigerated. Ship upright in original serum separator collection tube and transport in the ARUP shipping rack. Do not ship on dry ice.

Stability (collection to initiation of testing): Ambient: 24 hours; Refrigerated: 1 week; Frozen: Unacceptable
Reference Interval:
Ionized calcium (ISE):
Birth up to 1 month: 1.10-1.35 mmol/L
1 month-adult: 1.11-1.30 mmol/L

Ionized calcium (calculation at pH 7.4):
Birth up to 1 month: 1.10-1.35 mmol/L
1 month-adult: 1.11-1.30 mmol/L
Note: Differences between the ionized calcium result and the ionized calcium normalized to pH 7.4 are due to the sample having a pH significantly different from pH 7.4.  Specimen pH may be artificially decreased due to delayed processing and may be increased when the specimen is exposed to air.  Due to these factors, it is recommended that the ionized calcium normalized to pH 7.4 be interpreted with caution and only used when the clinician has knowledge of the patient's acid/base status.  Accurate determination of in vivo pH is best determined by arterial blood gas testing.
CPT Code(s): 82330
Cross References: Free Calcium (Calcium, Ionized, Serum), Ionized Calcium (Calcium, Ionized, Serum)