Calcium, Ionized

Cleveland HeartLab C, Test

CPT Code: 82330
Order Code: C2383
ABN Requirement: No
Synonyms: Ionized Calcium; Free Calcium
Specimen: Serum
Volume:  2.0 mL
Minimum Volume:  0.3 mL
Container: Gel-barrier tube (SST, Tiger Top)


  1. Collect and label sample according to standard protocols.
  2. Gently invert tube 5 times immediately after draw. DO NOT SHAKE.
  3. Allow blood to clot 30 minutes.
  4. Centrifuge for 10 minutes.

Special Instructions: Fill tube completely and allow to clot for 30 minutes. Do not open the tube once specimen is centrifuged. Collect a separate sample if other tests are required.

Transport:   Store serum at 2°C to 8°C after collection and ship the same day per packaging instructions provided with the Cleveland HeartLab shipping box.


Ambient (15-25°C): 1 day
Refrigerated (2-8°C): 7 days
Frozen (-20°C): not acceptable
Deep Frozen (-70°C): not acceptable

Causes for Rejection: Specimens other than centrifuged serum in an unopened SST; samples received frozen; grossly hemolyzed or lipemic sample; improper labeling; samples not stored properly; samples older than stability limits

Methodology: Ion Specific Electrode (ISE)

Turn Around Time: 4 days

Reference Range:

Component Age mmol/L
Calcium Normalized All Ages 1.08-1.30
Calcium Ionized All Ages 1.08-1.30


Urgent Values:

Age (Low) Urgent Low Value (mmol/L) Age (High) Urgent High Value
All Ages <0.90 All Ages >1.50

Use: Evaluation of calcium metabolism. The ionized calcium test is frequently used as a follow-up test for the evaluation of abnormal calcium levels. Ionized calcium testing is also used to evaluate calcium levels in individuals undergoing liver transplantation and in situations where critically ill individuals receive rapid transfusion of whole blood.

Additional Information: Ionized calcium is a measure of the “bioavailable” calcium. Individuals with a disorder associated with elevated calcium levels, such as hyperparathyroidism, but normal total calcium levels may have elevated ionized calcium levels upon further investigation. Ionized calcium levels are higher in infants and children.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.