Serum Calcium (Ionized)

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Test

Serum calcium (ionized) testing is usually performed to evaluate calcium levels in the blood in people with symptoms of calcium imbalance, such as muscle cramps, numbness or tingling in the fingers or toes, weakness, or bone pain. It can also be used to monitor the effectiveness of treatment for calcium-related conditions.

When this test is required

This test may be requested when an individual has symptoms of calcium imbalance or a medical condition that can affect calcium levels in the body.

What the Test Detects

This test measures the amount of ionized calcium in the blood. Ionized calcium is the active form of calcium that is available for use by the body’s cells and tissues.

Preparation for the Test

There is usually no special preparation needed for this test. However, certain medications, such as diuretics or those containing lithium, may affect calcium levels and should be discussed with a healthcare provider before the test.

Sample Requirements

A blood sample is required to measure serum calcium (ionized) levels.

Additional Notes

In addition to measuring ionized calcium levels, a healthcare provider may also order other tests to evaluate calcium and vitamin D levels in the body, such as total calcium, serum vitamin D, and parathyroid hormone (PTH) levels.

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