Calcium, Ionized
Also known as: Calcium Filterable, Calcium Unbound, Ionized Calcium
Use
Evaluate nonbound calcium, calcium metabolism, physiologically active calcium fraction, hyperparathyroidism, ectopic hyperparathyroidism. Occasionally useful when hypercalcemia coexists with abnormal protein state such as myeloma. Useful in assessing active calcium fraction in hypoproteinemia and acidosis when calcium is low.
Special Instructions
Not provided.
Limitations
While ionized calcium provides valuable insight, total calcium remains the primary test for evaluating calcium abnormalities. It is important to note that ionized calcium measurement is influenced by proteins and albumin levels. Additionally, women may exhibit greater circadian variation of ionized calcium and intact parathyroid hormone levels compared to men.
Methodology
Other
Biomarkers
Ionized Calcium
Analyte
LOINC Codes
- 17864-0 - Ca-I SerPl ISE-mCnc
- 17864-0 - Ca-I SerPl ISE-mCnc
Result Turnaround Time
1-2 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
Not provided
Container
Gel-barrier tube
Collection Instructions
Centrifuge and send unopened gel-barrier tube with vacuum intact. It is critical that the vacuum not be disrupted. Exposure of the serum to room air causes a loss of carbon dioxide to the atmosphere. This changes the sample pH and can prevent the lab from measuring the ionized calcium. To ensure that testing can be performed, send a separate tube for ionized calcium and adhere a piece of labeling tape over the top of the tube with the following written on it 'Ionized Calcium − DO NOT OPEN.'
Storage Instructions
Room temperature. Do not freeze.
Causes for Rejection
Hemolysis; opened gel-barrier tube; gel-barrier not completely sealing the clot; plasma specimen; gross lipemia
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
Other tests from different labs that may be relevant