1. Should I be concerned if my doctor only orders a total calcium test and not free or ionized calcium?
No. Measuring total calcium is usually sufficient for screening purposes. The total calcium test is more easily performed than the ionized calcium test since it requires no special handling of the blood sample.
The ionized calcium test requires specialized handling and expedited delivery of the blood sample to the laboratory for prompt analysis. The necessary handling and delivery is difficult to achieve outside of a hospital setting.
In most cases, total calcium is a good substitute for free calcium since the free and bound forms are usually each about half of the total.
The direct measurement of ionized calcium is particularly important during surgery as well as in severely ill patients, when changes in total calcium do not reliably tell how abnormal the ionized calcium level is.
Dairy products are the main source of calcium, but lesser amounts are found in eggs, green leafy vegetables, broccoli, legumes, nuts, and whole grains. Many fruit juices are now fortified with calcium.
3. If I consume foods fortified with calcium, would it change my laboratory results?
In general, consuming fortified foods will not directly affect your calcium test results. Talk to your health care provider about your calcium requirements to help determine whether you should be taking calcium and/or vitamin supplements.
5. My doctor ordered a test for albumin-corrected calcium. What is it?
Since about half of calcium in the blood is bound to albumin, an abnormally high or low level of albumin may affect the interpretation of calcium results and "free" or "ionized calcium" must be measured. (See "What is being tested?") Sometimes, however, laboratories do not have the resources to measure free, biologically active calcium directly. In these cases, some laboratories calculate an albumin-corrected calcium or adjusted calcium with a formula that uses the results of total calcium and albumin tests. This is sometimes used, for example, with patients who have liver disease or kidney failure.
However, some studies have questioned the usefulness of this practice. There is some uncertainty whether corrected calcium results provide a better evaluation of the amount of free calcium present in the blood compared to a standard total calcium test.
This article was last reviewed on March 7, 2014. | This article was last modified on May 13, 2015.
The review date indicates when the article was last reviewed from beginning to end to ensure that it reflects the most current science. A review may not require any modifications to the article, so the two dates may not always agree.
The modified date indicates that one or more changes were made to the article. Such changes may or may not result from a full review of the article, so the two dates may not always agree.