A patient may take an ionized calcium blood test to detect any problems with his kidneys or parathyroid glands, to check for certain types of bone defects and cancers, or to check for pancreatitis. He may also undergo the test to check whether he has too little or too much calcium in the body, to find the cause of an abnormal electrocardiogram test, or as part of a scheduled blood test, says WebMD.
An ionized calcium test is used to check the amount of active calcium in a patient’s blood. Normally, the body carefully regulates the amount of calcium in the blood. When blood calcium levels plummet, the bones release calcium to regulate it. Conversely, when the levels get too high, the extra calcium is excreted in urine and stool or stored in the bones, according to WebMD. If the blood calcium levels are abnormal, it can indicate problems with the parathyroid gland, mineral and vitamin deficiencies, certain types of cancers, kidney disease, or the effects of certain medications, states Healthline.
To perform the test, the technician obtains a blood sample from the patient via venipuncture, where a needle is inserted through the skin into a vein to draw blood. The patient may experience complications such as lightheadedness or fainting, ongoing bleeding, hematoma, and blood infection, after undergoing the procedure, notes Healthline. However, the test results may not be reliable if the patient has taken any calcium or vitamin D supplements, taken medications such as diuretics, undergone dialysis, or eaten a large amount of blood in a short period of time, explains WebMD.
The patient should refrain from taking calcium supplements for at least eight hours before the test, states WebMD. The patient should also fast for at least six hours prior to the test, recommends Healthline.