Order Code: 306
ABN Requirement: No
Synonyms: Ionized Calcium; Free Calcium
Specimen: Serum
Volume: 2.0 mL
Minimum Volume: 0.6 mL
Container: Gel-barrier tube (SST, Tiger Top)
Collection:
- Collect and label sample according to standard protocols.
- Gently invert tube 5 times immediately after draw. DO NOT SHAKE.
- See Special Instructions.
Special Instructions: Allow blood to clot and then centrifuge immediately for 10 minutes with the cap on. Do not open the tube. If submitting with any other assay, please submit a separate tube for this test.
Transport: Store serum at 2°C to 8°C after collection and ship the same day per packaging instructions included with the provided shipping box.
Stability:
Ambient (15-25°C): 7 days
Refrigerated (2-8°C): 7 days
Frozen (-20°C): Not Acceptable
Causes for Rejection: Specimens other than unopened SST tube; samples received frozen; improper labeling; samples not stored properly; samples older than stability limits; gross hemolysis; gross lipemia; Red-Top Tube (without gel barrier)
Methodology: Ion Selective Electrode (ISE)
Turn Around Time: 2 to 3 days
Reference Range:
| Age | mg/dL |
|---|---|
| <8 Months | 5.3-6.3 |
| 8 - 11 Months | 5.2-6.1 |
| 1 Year | 5.1-6.0 |
| 2 Years | 4.9-5.8 |
| 3 Years | 4.9-5.7 |
| 4 - 6 Years | 4.8-5.7 |
| 7 - 12 Years | 4.8-5.6 |
| 13 - 17 Years | 4.8-5.5 |
| 18 - 89 Years | 4.7-5.5 |
| ≥90 Years | 4.5-5.5 |
Priority Value:
| Age | Priority 1 Value (mg/dL) | Priority 1 Value (mg/dL) |
|---|---|---|
| All Ages | ≤3.2 | >6.9 |
Clinical Significance: Ionized calcium represents the true “bioavailable” calcium in the circulation. In situations where the total calcium is normal but does not fit the clinical picture, e.g., hyperparathyroidism, a determination of the ionized calcium will, many times, show an elevation in the “bioavailable” calcium component. This may be due to alterations in protein concentrations, especially albumin, that binds most of the calcium in the circulation.
The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.