Calcium, Ionized (whole blood)

For Specimen Integrity during Extreme Weather see the “Lockbox Usage in Extreme Weather” document at the top of this page.

Specimen must be collected at Miami Valley Hospital PSC or Miami Valley Hospital South PSC due to specimen handling ans short specimen stability window.

Test Code

Alias/See Also

CPT Codes

Preferred Specimen
3 mL whole blood Sodium Heparin (dark green top) tube.

Minimum Volume
1 mL

After specimen collected invert tubes 8 - 10 times, then transport tube on wet ice slurry to MVH or MVHSouth laboratory within 2 hours.

Transport Container
Sodium Heparin (dark green top) tube

Transport Temperature
Transport on ice slurry to laboratory within 1 hour.

Specimen Stability
2 hours on ice slurry
Room Temperature = n/a
Refrigerated = n/a
Frozen = n/a

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis, Lipemia, incorrect specimen type, insufficient sample volume, improper storage conditions, exceeds specimen stability guidelines, contaminated sample.

ion selective electrode

Setup Schedule

Report Available
1 hour from receipt

Reference Range
SEX AGE Report Normals Units
N/M/F 1000Y 1.12 - 1.30 MMOL/L 

Clinical Significance
The ionized calcium is determined by an ion selective electrode methodology. The result that is generated is pH adjusted. The result is empirically based on a measured pH and ionized calcium concentration normalized to a pH of 7.40. This calculation compensates for in vitro changes in pH due to loss of CO 2 through specimen handling. Ionized calcium represents the true "bioavailable" calcium in the circulation. In situations where the total calcium is normal but does not fit the clinical picture, e.g., hyperparathyroidism, a determination of the ionized calcium will, many times, show an elevation in the "bioavailable" calcium component. This may be due to alterations in protein concentrations, especially albumin, that binds most of the calcium in the circulation.

Performing Laboratory
CompuNet Clinical Laboratories, LLC
2308 Sandridge Drive
Moraine, OH 45439

Last Updated: November 19, 2021

The CPT Codes provided in this document 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 payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.