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Test Code CAION Calcium, Ionized, Blood, Plasma or Serum, LAB54

Important Note

Medlabs POL's and Outreach Clinics should collect plasma or serum separator tubes and follow specimen requirements.


Potentiometric sensor

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements


Preferred: 0.5mL Syringe with anaerobic heparinized whole blood.

Acceptable: Dark Green Tube with anaerobic heparinized blood, anaerobic mint-green PST, anaerobic serum SST (gold-top). If specimen is drawn in a vacutainer it must be full.



Whole Blood stability is 30 minutes at ambient temperature or up to 4 hours at 4°C.

Plasma or serum stability is 4 hours at ambient temperature or up to 70 hours at 4°C.


Collection Instructions:  Patient should be in a relaxed state and tourniquet application as brief as possible.  Specimen must be kept as anaerobic as possible. Vacutainer must be properly filled and remain sealed until analysis is performed.



Whole Blood Syringe or Dark Green:  Use of ice bath or ice block is recommended for specimen transportation if >30 minutes.

Plasma or Serum:  Keep sealed in tube after centrifugation.  Transport at ambient temperature.  If specimen delayed >4 hours, use of ice bath or ice block is recommended.


Reference Values

1.15-1.35 mmol/L

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding


Useful For

Ionized calcium is useful in the monitoring of calcium levels in patients receiving blood transfusion, undergoing hemodialysis, or in patients with thermal burns, and in neonates when hypocalcemia is suspected.