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Test Code IOCA Ionized Calcium

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Li-Heparin Mint Green Top

Other Acceptable specimens: Serum/Gold Top, Serum/Red Top

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 30 minutes of collection.
  • Centrifuge specimens with stopper in place for 7 minutes at 3000 rpm to ensure gel barrier separates serum/plasma from cells
  • Keep specimen anaerobic; Do NOT aliquot or expose serum/plasma to air.
  • Samples must be sent room temperature at 15-25oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimen collection tubes that are less than 50% full
  • Specimen that have been aliquoted, opened or poorly centrifuged
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours.

Reference Values

 

Test

Age

Sex

Reference Range

IOCA

All

All

1.15 - 1.35 mmol/L

Critical Values

Analyte

Unit

Low

High

Age

N/A

N/A

N/A

N/A

N/A

CPT Codes

82330

LOINC Codes

57333-7

Volume

Preferred Volume: 100% Full Tube - Volume is dependent on specimen tube size

Minimum Volume: 50% Full Tube - Volume is dependent on specimen tube size

Specimen Stability

Storage Temperature

Stability

Room temperature

Unopened - 24 hours

Opened/Exposed to Air - 2 hours after exposure

Refrigerated

Unopened - 24 hours

Opened/Exposed to Air - 2 hours after exposure

Frozen

Not Acceptable

 

*Due to the inherent instability of Ionized Calcium once a specimen is collected and processed, testing CANNOT be added on to previously collected specimen

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Test Components

Ionized Calcium
 

Clinical Indications

  • The relative proportions of calcium that exist in the ionized, protein bound, and complexed forms can change drastically with the blood pH, changes in the concentration and composition of the plasma proteins and changes in concentration of calcium binding anions.
  • The following are some of the clinical conditions in which the measurement of ionized calcium is helpful or essential:
    • Primary hyperparathyroidism
    • Massive tranfusions with blood containing citrate phosphate or heparin, or infusion of buffered saline containing lactate.
    • Plasma protein disorders.
    • Symptomatic hypocalcemia in neonates.
  • Second-order test in the evaluation of patients with abnormal calcium values.

Methodology

Ion Specific Electrode (ISE), (ABL 800 FLX Analyzer)

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • Heparninzed plasma may give slightly lower results due to binding by the heparin.
  • The binding of calcium by protein is influenced by the pH both in vivo and in vitro. Increasing the pH, increases the amount of protein boung calcium and decreases the amount of ionized calcium. Decreasing the pH, decreases the amount of protein bound calcium and increases the amount of ionized calcium.
  • Specimens exposed for prolonged periods of time to metabolizing red and white blood cells which produce acids will have decreased pH and therefore increased the ionized calcium. Serum specimens should also be analyzed as soon as possible to prevent cellular metabolism from altering serum pH.
  • Specimens exposed to air lose carbon dioxide and become more alkaline thereby resulting in decreased ionized calcium. Whenever possible, specimens for ionized calcium should be collected and maintained anaerobically to prevent loss of carbon dioxide.

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour

Routine Turnaround Time: 4 hours

Testing Schedule: 24/7

Synonyms/Keyword Search

Free Calcium, CA Ionized, Calcium Ionized

Last Review Date

1/26/23