Calcium, Ionized

Test Code
306

CPT Codes
82330

Preferred Specimen
2 mL serum collected in a: serum separator tube

Minimum Volume
0.6 mL

Instructions
Instructions: Collect blood (2 mL serum) in a gel barrier tube. Let clot and spin immediately with cap on. Do not open tube. Ship the unopened gel barrier tube at room temperature. Do not freeze.

Transport Container
Serum Separator Tube

Transport Temperature
Room temperature

Specimen Stability
Room temperature: 7 days

Refrigerated: 7 days

Frozen: Unacceptable

Methodology
Ion Specific Electrode (ISE)

Reference Range
<8 Months  Not established
8 Months-10 Years 4.9-5.4 mg/dL
11-17 Years 4.8-5.3 mg/dL
Adult 4.8-5.6 mg/dL


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 CO2 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.

Performed By
Quest Diagnostics Nichols Institute



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.