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CALCIUM, IONIZED, whole blood (8000100139)
Test Mnemonic:

AC CA2+         

Specimen Requirements:

1 mL of blood in syringe or vacutainer containing balanced/titrated heparin. Care should be taken to avoid drawing air into the syringe. Remove any bubbles from the syringe immediately. Venous blood should be collected with the tourniquet in place. Do not release the tourniquet before collecting the ionized calcium sample. Immediately place the specimen on ice.  "DO NOT OPEN the specimen."

Minimum Volume:

0.5mL of blood


Delivered to Sample Management within 10  minutes of collection

Specimen Preparation:


Keep specimen at room temperature as long as the analysis is completed within 30 minutes of collection. (If ordered without ABG, analysis must be completed within 2 hours of collection).

Causes for Rejection:

Clotted; blood leaking from syringe; large air space or bubbles in syringe; syringes with needles attached; and specimens not delivered to the lab within allotted time; incomplete and/or incorrect sample identification, improper storage/transport.             

Reference Range:

By report (reports may vary based on instrumentation, patient age and sex)

Turnaround Time:

STAT: 10 minutes; CODE: 5 minutes


Clinical Chemistry                      

CPT 4 Code:



The sample must be collected and kept anaerobic. Do not use anticoagulants containing citrate, EDTA, fluoride, or oxalate.   Green-stoppered tubes are also not acceptable. Heparin sources other than balanced/titrated heparin may influence the ionized calcium significantly and unpredictably.

When ordering tests for which Medicare or Medicaid reimbursement will be sought, physicians should only order tests that are medically necessary for the diagnosis or treatment of the patient. Components of the organ or disease panels may be ordered individually. The diagnostic information must substantiate all tests ordered and must be in the form of an ICD-10 code or its verbal equivalent.
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