Calcium (Ca) in Blood
Normal blood calcium values are lower in older people. Normal blood calcium values are higher in children
because their bones are growing quickly.
An ionized calcium test checks the amount of calcium
that is not attached to protein in the blood. The level of ionized calcium in
the blood is not affected by the amount of protein in the blood.
4.65–5.28 mg/dL or 1.16–1.32 mmol/L
4.80–5.52 mg/dL or 1.20–1.38 mmol/L
High values of calcium may be caused by:
Low values of calcium may be caused by:
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
Taking calcium or
vitamin D in any form including milk, antacids, or supplements right before the test. Taking medicines, such as
diuretics. Many medicines can affect calcium levels in the blood. Having
dialysis. Having a high volume blood transfusion or many blood transfusions in a short period of time.
What To Think About
More than one blood test may be needed to see if blood calcium
levels are not normal.
Low blood levels of calcium may be caused by low levels of
protein (albumin) in the blood, because about half of all calcium in the blood
is attached to albumin. For this reason, an ionized calcium level (which is not
attached to albumin) and a blood albumin level may also be measured. To learn more, see the topic
Total Serum Protein. Other tests that may be done to find the cause of abnormal blood
calcium levels include blood tests for
parathyroid hormone (PTH), chloride, acid phosphatase,
alkaline phosphatase, and vitamin D. Calcium levels can also be checked in the urine. To learn more, see the topic
Calcium (Ca) in Urine.
WebMD Medical Reference from Healthwise
September 24, 2012
This information is not intended to replace the advice of a doctor.
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