Calcium, Ionized, Whole Blood
UUHSC Testing OnlyUUHSC Testing Only
Time SensitiveTime Sensitive
Ordering Recommendation
Ion-Selective Electrode/pH Electrode
Within 24 hours
New York DOH Approval Status
This test is New York DOH approved.
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.
CPT Code(s)
Component Test Code*Component Chart Name
0020141Ca Ionized Whole Blood
0020143Ca Ion pH7.4WB
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, contact interface support at
Cross References
  • CA ionized, whole blood
  • Free calcium, whole blood
  • ionized calcium, whole blood