Update Type: Specimen collection or handling and/or storage changed
Test Updated: 06/17/2026
Test Overview
Test Methodology

ISE

Test Usage

Ionized calcium is the physiologically active form of calcium and a better indicator than total calcium of the functional status of calcium metabolism.

Reference Range *

1.12 - 1.30 mmol/L

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details
Days Set Up
Daily, 24 hours
Analytic Time

2 hours

Soft Order Code
ICAL
MiChart Code
Calcium, Ionized
Synonyms
  • Free Calcium
  • Ionized Calcium
Laboratory
Clinical Core Laboratory
Section
Clinical Chemistry
STAT Availability

STAT requests for this test will be performed on a STAT basis (supervisory staff approval is not required).

Specimen Requirements
Collection Instructions

Collect specimen in Lithium Heparin green top tube. Do not centrifuge, or aliquot or remove stopper for any reason. Because this analyte is sensitive to air exposure and pH changes, specimens sent for Ionized Calcium require a dedicated sample and cannot be shared for other tests ordered and add-on requests cannot be accepted for samples sent for other testing.  Samples that are clotted will be rejected and canceled. 

Alternate Specimen

None

Normal Volume

2 mL

Minimum Volume

0.3 mL

Rejection Criteria
Other Rejected Containers: Open Containers, EDTA plasma (lavender)

Samples that are clotted will be rejected and canceled.
Billing
CPT Code
82330
Fee Code
22194
LOINC
1994-3
NY State Approved
No