Calcium
Definition
Measures calcium in the blood in two forms:
| Measurement | What it covers |
|---|---|
| Total calcium | All of the bound (attached to proteins) + free/ionized (unbound) calcium |
| Ionized calcium | Only the unbound calcium. Ordered when total calcium is abnormal or in special situations |
Normally your body tightly controls the balance between bound and ionized calcium, so a total calcium test gives a good estimate of how much ionized calcium you have.
Purpose
Routine metabolic panel screening; diagnosis of conditions affecting the bones, kidneys, thyroid and parathyroid glands; evaluation of symptoms of abnormal calcium; monitoring of known diseases (kidney/thyroid disease, malnutrition, cancer).
Results
- High (hypercalcemia), hyperparathyroidism, certain cancers, Paget's disease or excess vitamin D
- Low (hypocalcemia), low blood protein, hypoparathyroidism, inadequate calcium intake, vitamin D or magnesium deficiency, pancreatitis, kidney disease
Normal Values
Laboratory specific.
Risks and Limitations
A frequently confused point:
This test does not tell you how much calcium is in your bones.
Bone health requires a bone density measurement (DEXA). Someone with normal blood calcium can have osteoporosis.