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Test Code CRT Ca Ion Circuit Calcium Ionized

Clinical System Name

Circuit Calcium Ionized

Sample Requirements

Specimen: Whole Blood

Container(s): Heparinized Syringe, Capillary Blood Gas Tube

Preferred Vol: 0.5 mL in a Heparinized Syringe, or 2 Capillary Blood Gas Tubes

Minimum Vol:  2 Heparinized Capillary Blood Gas Tubes. (EPOC capillary tubes are not acceptable).


Note: Use only Arterial Blood Sample syringe with dry Lithium Heparin for gases and electrolytes or heparinized capillary blood gas tubes. Sample can be shared with a CBG if capillary blood gas tubes are collected. Send to the lab immediately. Avoid air bubbles. Expel air from syringe and cap it immediately after obtaining the sample. Capillary blood gas tubes must be filled completely and mixed thoroughly to dissolve and disperse the heparin. EPOC capillary tubes are not acceptable.  Ideally, whole blood specimens should be analyzed within 15 minutes of blood draw.

Processing Instructions

Reject due to: Inadequately filled specimens, air bubbles, visible clots, age of specimen

Spin: N

Aliquot: N


Off-site collection: Samples collected outside Children's may be drawn in a balanced heparin syringe and sent at 0-4o C within 4 hours.



Specimen Type Temperature Time
Heparinized Syringe, Heparinized Capillary Blood Gas Tube RT 30 M
Heparinized Syringe, Heparinized Capillary Blood Gas Tube 0-4o C 4 H
Heparinized Syringe, Heparinized Capillary Blood Gas Tube -20o C or -70oC No



STAT Performed TAT
Y 24/7 15 M


Performing Laboratory

Seattle Children's Laboratory    


Department:  Chemistry - Core

Phone Number: 206-987-2617

Reference Range


 Age mMol/L
<1 Y 1.16 - 1.45
1 - 4 Y 1.17 - 1.35
4 - 14 Y 1.18 - 1.30
> 14 Y 1.18 - 1.27



Method: Potentiometric method by SIEMENS RAPIDPOINT 405


Analytical Volume:

0-2 Y  0.2 mL Heparinized Capillary Blood Gas Tube
> 2 Y 0.5 mL Heparinized Syringe


CPT Codes


Critical Values

≤ 0.75 mMol/L


≥ 1.75 mMol/L