Calcium

Serum calcium is a simple blood test that helps measure the amount of calcium in the blood

Other names: Calcium, Total calcium, Ca 

Calcium is one of the most important minerals needed for the normal functioning of the body. Its role in maintenance of bones, teeth and muscles is well known. Calcium is also needed for blood clotting.

99% of the calcium in our body is found in bones and only 1% is circulating in the blood. When calcium levels in the blood fall (due to inadequacy in diet or inadequate absorption or excel loss through kidney), calcium is taken from the bones to maintain optimum levels in the blood.

Even in the calcium that is freely circulating in the blood, there are two forms. One which is free and the other is connected to mostly albumins and to some extent to globulins. The total calcium serum test measures both the free and bound forms. Calcium is also sometimes excreted in the urine and is sometimes measured to diagnose specific conditions through a Calcium urine test. 

Apart from checking for normal calcium levels, doctors prefer a DEXA scan test to assess bone health and bone density, especially as one gets older and to estimate the risk for osteoporosis.

Why Calcium test?

A calcium test is included as part of routine wellness testing. Thyroid disorders, kidney disorders, malnutrition, malabsorption, vitamin D deficiencies or excess vitamin D intake are all related to calcium levels and hence is ordered both during diagnosis and treatment monitoring of these conditions.

Who should get tested?

Calcium test is frequently ordered if a person has symptoms relating to:

1. Kidney Stones or kidney failure – low calcium is often recorded in those with kidney failure
2. Bone Diseases
3. Neurological Disorders

Thyroid disease or parathyroid disorder that may lead to a deficiency in calcium

Reference values for Calcium: 8.6 - 10 mg/dL

Interpretation:

Normal levels indicate that the blood calcium levels are normal and controlled.

Low levels may be recorded in liver disorders or malnutrition. During illness or with liver disorders, the levels of albumin in the blood fall and can lead to low levels of calcium (in such cases, the level of the bound calcium falls and ionized calcium remains normal).

Low calcium levels in the blood can also be a result of underactive thyroid, deficiency in dietary supplement, low levels of vitamin D, magnesium deficiency, pancreatic disorders or kidney failure.

High blood calcium is noted in hyperthyroidism, diseases such as tuberculosis and HIV, excess vitamin D intake or being immobile for a long time.