Calcium, Ionized, Serum
Use
This test is useful for assessing calcium states during procedures like liver transplantation surgery, cardiopulmonary bypass, or rapid transfusion of whole blood in neonates and critically ill patients. It serves as a second-order test in the evaluation of patients with abnormal calcium values. Ionized calcium, which comprises 50% to 55% of total calcium, is the physiologically active form. Low ionized calcium values can occur in kidney disease, critically ill patients, or those receiving rapid transfusion of citrated blood products, while increased levels may indicate primary hyperparathyroidism, ectopic parathyroid hormone-producing tumors, excess vitamin D intake, or various malignancies.
Special Instructions
Proper specimen handling is necessary to ensure accurate results. Keep specimen anaerobic and do not aliquot. Test cannot be combined with other tests and requires separate specimens if multiple tests are ordered. If not ordering electronically, complete and send a Kidney Transplant Test Request or Renal Diagnostics Test Request form with the specimen.
Limitations
The test's performance characteristics were determined by Mayo Clinic consistent with CLIA requirements, although it is not FDA cleared or approved. Calculated ionized calcium from total calcium, albumin, and pH values have been proven unsatisfactory. Half-normal ionized calcium concentrations can severely reduce cardiac stroke work, affecting left ventricular function, which may be profoundly depressed in moderate to severe hypocalcemia. Accuracy in results depends on appropriate specimen handling and collection.
New York Approved
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 57333-7
- 57333-7
- 2753-2
Result Turnaround Time
0-1 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
Full tube
Minimum Volume
1.75 mL
Container
Serum gel or serum gel microtainer
Collection Instructions
Allow blood to clot for 30 minutes. Serum gel tube/microtainer must be centrifuged within 1 hour of collection with stopper in place for 7 minutes at 3000 rpm. Keep specimen anaerobic; do not aliquot. Test cannot be combined with other testing; separate specimens must be submitted when multiple tests are ordered.
Causes for Rejection
Gross hemolysis, tubes less than 50% full, specimens that have been aliquoted, opened, or poorly centrifuged.
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 7 days |