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Test ID CAI Calcium, Ionized, Serum

Useful For

Assessing calcium states during liver transplantation surgery, cardiopulmonary bypass, or any procedure requiring rapid transfusion of whole blood in neonates and in critically ill patients

 

Second-order test in the evaluation of patients with abnormal calcium values

Method Name

Ion-Selective Electrode (ISE)

Reporting Name

Calcium, Ionized, S

Specimen Type

Serum SST

Container/Tube: Serum gel or serum gel Microtainer

Specimen Volume: Full tube

Collection Instructions:

1. Allow blood to clot for 30 minutes.

2. Centrifuge with stopper in place for 10 minutes at 3,000 rpm to ensure that the gel barrier separates the serum and cells.

3. Keep specimen anaerobic (do not transfer).

4. Serum gel tube/Microtainer must be centrifuged within 1 hour of draw time.

Specimen Minimum Volume

1.75 mL in a 3.5 mL serum gel tube or 1 full serum gel MICROTAINER

Specimen Stability Information

Specimen Type Temperature Time
Serum SST Refrigerated 5 days

Clinical Information

Ionized calcium, which accounts for 50% to 55% of total calcium, is the physiologically active form of calcium.

 

Low ionized calcium values are often seen in renal disease, critically ill patients, or patients receiving rapid transfusion of citrated whole blood or blood products.

 

Increased serum ionized calcium concentrations may be seen with primary hyperparathyroidism, ectopic parathyroid hormone-producing tumors, excess intake of vitamin D, or various malignancies.

 

Nomograms have been used to calculate ionized calcium from total calcium, albumin, and pH values. However, calculated ionized calcium results have proven to be unsatisfactory. A Mayo study of 114 patients found significant differences between ionized and total calcium in 26% of patients.

Reference Values

Males

1-19 years: 5.1-5.9 mg/dL

≥20 years: 4.8-5.7 mg/dL

Reference values have not been established for patients that are <12 months of age.

Females

1-17 years: 5.1-5.9 mg/dL

≥18 years: 4.8-5.7 mg/dL

Reference values have not been established for patients that are <12 months of age.

 

Pediatric ranges derived for GEM method from analytic comparison to reference method in: Snell J, Greeley C, Colaco A, et al: Pediatric reference ranges for arterial pH, whole blood electrolytes and glucose. Clin Chem 1993;39:1173.

Cautions

Proper specimen handling is necessary to ensure accurate results.

Day(s) Performed

Monday through Sunday; Continuously

Report Available

Same day/1 day

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

82330

NY State Approved

Yes