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Official Description

Calcium; ionized

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 82330 refers to the measurement of ionized calcium in a blood sample. Ionized calcium, also known as free calcium, is the form of calcium that circulates in the bloodstream without being bound to proteins. This measurement is crucial because ionized calcium plays a vital role in several physiological processes, including the regulation of heart function, muscle contraction, central nervous system activity, and the blood clotting mechanism. The assessment of ionized calcium levels is particularly important in specific clinical scenarios, such as prior to major surgical procedures, in patients who are critically ill, or when there are abnormalities in protein levels that may affect calcium binding. The testing for ionized calcium is typically performed using ion-selective electrode (ISE) or pH electrode methodologies, which provide accurate and reliable results for clinical decision-making.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The measurement of ionized calcium is indicated in various clinical situations where accurate assessment of calcium levels is critical for patient management. The following are specific indications for performing this test:

  • Preoperative Assessment Ionized calcium levels may be measured prior to major surgical procedures to ensure that the patient’s calcium status is within normal limits, which is essential for minimizing the risk of complications during and after surgery.
  • Critically Ill Patients In critically ill patients, monitoring ionized calcium is vital as fluctuations in calcium levels can significantly impact cardiac function and overall metabolic stability.
  • Abnormal Protein Levels When protein levels are abnormal, ionized calcium testing is necessary because total calcium measurements may not accurately reflect the biologically active calcium available in the bloodstream.

2. Procedure

The procedure for measuring ionized calcium involves several key steps to ensure accurate results. The following outlines the procedural steps:

  • Step 1: Sample Collection A blood sample is collected from the patient, typically via venipuncture. It is essential to use appropriate collection techniques to avoid contamination and ensure the integrity of the sample.
  • Step 2: Sample Handling The collected blood sample must be handled carefully to prevent changes in calcium levels. This may involve using specific tubes that prevent calcium binding and ensuring that the sample is processed promptly.
  • Step 3: Measurement Methodology The ionized calcium level is measured using ion-selective electrode (ISE) or pH electrode methodologies. These techniques allow for the precise determination of the free calcium concentration in the blood sample.
  • Step 4: Result Interpretation Once the measurement is complete, the results are interpreted in the context of the patient's clinical condition, taking into account any factors that may influence calcium levels.

3. Post-Procedure

After the ionized calcium measurement, the results should be reviewed and interpreted by a qualified healthcare professional. Depending on the findings, further clinical action may be required, such as additional testing or treatment interventions. It is important to monitor the patient for any symptoms related to calcium imbalances, especially in cases where ionized calcium levels are found to be abnormal. Follow-up care may include re-evaluation of calcium levels and addressing any underlying conditions that may have contributed to the abnormal results.

Short Descr ASSAY OF CALCIUM
Medium Descr CALCIUM IONIZED
Long Descr Calcium; ionized
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) Yes
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE 2
CCS Clinical Classification 233 - Laboratory - Chemistry and Hematology
90 Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
QW Clia waived test
CR Catastrophe/disaster related
26 Professional component: certain procedures are a combination of a physician or other qualified health care professional component and a technical component. when the physician or other qualified health care professional component is reported separately, the service may be identified by adding modifier 26 to the usual procedure number.
GA Waiver of liability statement issued as required by payer policy, individual case
GZ Item or service expected to be denied as not reasonable and necessary
59 Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25.
76 Repeat procedure or service by same physician or other qualified health care professional: it may be necessary to indicate that a procedure or service was repeated by the same physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 76 to the repeated procedure or service. note: this modifier should not be appended to an e/m service.
77 Repeat procedure by another physician or other qualified health care professional: it may be necessary to indicate that a basic procedure or service was repeated by another physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 77 to the repeated procedure or service. note: this modifier should not be appended to an e/m service.
91 Repeat clinical diagnostic laboratory test: in the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results. under these circumstances, the laboratory test performed can be identified by its usual procedure number and the addition of modifier 91. note: this modifier may not be used when tests are rerun to confirm initial results; due to testing problems with specimens or equipment; or for any other reason when a normal, one-time, reportable result is all that is required. this modifier may not be used when other code(s) describe a series of test results (eg, glucose tolerance tests, evocative/suppression testing). this modifier may only be used for laboratory test(s) performed more than once on the same day on the same patient.
AY Item or service furnished to an esrd patient that is not for the treatment of esrd
GV Attending physician not employed or paid under arrangement by the patient's hospice provider
GW Service not related to the hospice patient's terminal condition
GY Item or service statutorily excluded, does not meet the definition of any medicare benefit or, for non-medicare insurers, is not a contract benefit
Q1 Routine clinical service provided in a clinical research study that is in an approved clinical research study
Q4 Service for ordering/referring physician qualifies as a service exemption
XE Separate encounter, a service that is distinct because it occurred during a separate encounter
XU Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service
Date
Action
Notes
Pre-1990 Added Code added.
Code
Description
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