Calcium, Ionized, Whole Blood
Ordering Recommendation

Assess calcium status.

Ion-Selective Electrode/pH Electrode
Within 24 hours
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Time SensitiveTime Sensitive
UUHSC Testing OnlyUUHSC Testing Only
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Testing available to UUHC clients only.
Green (sodium or lithium heparin). Collect on ice.
Pediatric Collect: 2 full heparinized capillary tubes (call lab for tube). 
Specimen Preparation
Do not freeze. Transport minimum 0.5 mL specimen.
Pediatric Specimen Preparation: Transport 2 full heparinized capillary tubes. 
Storage/Transport Temperature
Deliver to lab within 10 minutes on wet ice. 
Unacceptable Conditions
Frozen or room temperature specimens. 
Ambient: Unacceptable; Refrigerated: 4 hours; 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
Interpretive Data

Differences between the ionized calcium result and the ionized calcium normalized to pH 7.4 are due to the specimen 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.
Hotline History
Component Test Code*Component Chart NameLOINC
0020141Ca Ionized Whole Blood1994-3
0020143Ca Ion pH7.4WB1994-3
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • CA ionized, whole blood
  • Free calcium, whole blood
  • ionized calcium, whole blood