Calcium (Ionized), Serum

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General Information

Lab Name
Ionized Calcium, Serum
Lab Code
SRICG
Epic Ordering
Ionized Calcium, Serum
Description

If LIME GREEN PST tube is collected/received, see Ionized Calcium, Plasma [PLIC].

Direct vs. Reflexive Ionized Calcium Testing

Calcium testing is useful for investigating disorders involving the parathryoid-vitamin D-calcium endocrine system. Testing is indicated for patients with documented or suspected derangements in this system, but there is little evidence to suggest that screening unselected patients with calcium testing is useful, even in critically ill patients. Standing orders for monitoring ionized or total calcium and replacing with calcium gluconate in patients WITHOUT documented or suspected calcium disorders is unlikely to be of benefit, and may lead to poorer outcomes (see references below).

In order to detect clinically-significant hypo- and hyper-calcemia in hospitalized patients, please use Calcium (Reflexive Ionized) [ICAR], Basic Metabolic Panel with Reflexive Ionized Calcium [BMPICR], or Comprehensive Metabolic Panel with Reflexive Ionized Ca [COMPIC]. In these test panels, a patient receives a total calcium test first, and if the result is <8 mg/dL or >10.2mg/dL, an ionized calcium test is performed on the same plasma sample. The test panel was developed as an alternative to daily ionized calcium testing in patients hospitalized at UW and Harborview Medical Centers, a largely unnecessary practice that was associated with excessive calcium therapy.

Calcium (Ionized), Whole Blood [WIC] is intended for patients in whom a calcium metabolic derangement has ALREADY been detected and in whom the calcium concentration needs to be followed, i.e. in post-surgical hypoparathyroidism. Additionally, nonreflexive ionized calcium testing is useful when the total calcium is not expected to correlate well with ionized calcium concentrations, i.e. hypo- or hyper- proteinemia or albuminemia, altered pH, and high concentrations of calcium binding substances like citrate anticoagulants.

Synonyms
Components

Interpretation

Method

Ion Selective Electrode (ISE)

Reference Range
See individual components
Ref. Range Notes

0-11m 1.16 - 1.45

1yr 1.18-1.38

Ordering & Collection

Specimen Type
Serum
Collection

All Locations:
Preferred: 4 mL blood in GOLD SST tube
Also Acceptable: 4 mL blood in ORANGE RST or RED TOP tube
Unacceptable: SARSTEDT, GREEN TOP or MICROTAINER

Handling Instructions

Note: For addons see specimen stability listed below.

Quantity
requested: 1 mL serum
minimum: 0.5 mL serum

Processing

Processing

Allow tube to clot at Room Temperature
Centrifuge with stopper on within 1 1/2hr of collection.
SST may go directly to bench without aliquotting unless shared specimen. If shared, aliquot SRIC into 1 mL syringe, allowing minimal air contact with serum. Tap syringe to expel air bubbles & cap with Leur cap.
Serum is stoppered & re-spun and aliquots made for other tests requested.

Stability: Centrifuged, unopened SST stable 24 hr @ 4°C. Once tube is uncapped (both SST and Red tops), serum sample is stable for 60 minutes.

Performance

LIS Dept Code
Chemistry (CH)
Performing Location(s)
HMC Chemistry, Automated
206-520-4600

325 9th Ave, Rm # GWH-47, Seattle, WA 98104-2420
UW-NW Main Lab
206-668-1344

UW Medical Center – Northwest
1550 N 115th Street, A200
Seattle, WA 98133
UW-MT Chemistry, Special
206-520-4600

Clinical Lab, Room NW220,
University of Washington Medical Center,
1959 NE Pacific street, Seattle, WA 98195
Frequency
Daily
Available STAT?
Yes

Billing & Coding

CPT codes
82330
LOINC
12180-6
Interfaced Order Code
UOW1268