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Test Code CAI Calcium, Ionized, Serum

Reporting Name

Calcium, Ionized, S

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

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Serum SST


Specimen Required


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 7 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 7 days

Reference Values

IONIZED CALCIUM

≤13 days old: not established

14 days-<1 year: 5.21-5.99 mg/dL

1-<2 years: 5.04-5.84 mg/dL

2-<3 years: 4.87-5.67 mg/dL

3-<24 years: 4.83-5.52 mg/dL

24-≤97 years: 4.57-5.43 mg/dL

≥98 years: not established

 

pH

≤13 days old: not established

14 days-97 years old: 7.35-7.48

≥98 years old: not established

Day(s) and Time(s) Performed

Monday through Sunday; Continuously

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82330

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CAI Calcium, Ionized, S In Process

 

Result ID Test Result Name Result LOINC Value
CAIS Calcium, Ionized, S 17864-0
PHCC pH 2753-2

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.

Interpretation

Serum ionized calcium concentrations 50% below normal will result in severely reduced cardiac stroke work. With moderate to severe hypocalcemia, left ventricular function may be profoundly depressed.

 

Ionized calcium values are higher in children and young adults.

 

Ionized calcium result has been adjusted to pH 7.40 to account for changes in specimen pH that may occur during transport. Ionized calcium concentration increases approximately 0.2 mg/dL per 0.1 pH unit decrease.

Clinical Reference

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Edited by Carl A Burtis, Edward R Ashwood, David E Bruns. St. Louis, MO, Elsevier Saunders, 2012

Analytic Time

Same day/1 day

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

NA

Icterus

NA

Other

NA

 

Method Name

Ion-Selective Electrode (ISE)

Secondary ID

8378

Disease States

  • Hyperparathyroidism