Calcium Test

About this test

This test measures the level of calcium in your blood. Calcium is the most abundant mineral in your body and plays essential roles in bone strength, muscle contraction, nerve signaling, and blood clotting.

Blood calcium is tightly controlled by the parathyroid hormone and vitamin D, so an abnormal result is usually a signal to investigate further — not a direct measure of bone density. High calcium (hypercalcemia) can cause fatigue, confusion, and kidney stones; low calcium (hypocalcemia) can cause muscle cramps, tingling, and in severe cases, heart rhythm changes. A clinician will typically look at PTH and vitamin D levels together when results are outside the normal range.

Components

• Calcium (serum): Reflects the amount of calcium circulating in your bloodstream. Roughly half is bound to proteins (mainly albumin); the other half is free (ionized) and biologically active. If your albumin is abnormally low, your clinician may calculate a corrected calcium value.

Who is this test for?

A standalone calcium test is most useful for people being monitored for parathyroid disorders, kidney disease, or certain cancers that affect calcium levels. It is also used to follow up on symptoms like muscle cramps, numbness, excessive thirst, or frequent urination that may signal calcium imbalance.