Ionised Calcium Test

The ionised calcium test is usually done when the levels of total calcium are suspected to be abnormal. An abnormal total calcium level basically indicates an imbalance between the bound and free (ionised) calcium which are ideally present in equal amounts. This imbalance indicates a serious health concern which needs to be diagnosed. It is also done in critically ill patients, those requiring blood transfusions and in cases of abnormal protein levels.

Ionised calcium test measures the free or unbound calcium in the blood.

During a ionised calcium test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Low ionised calcium levels may lead to muscle cramps, numbness in hands, feet and around the mouth, and cardiac irregularities. In severe cases it may even lead to coma. Low ionised calcium levels (hypocalcemia) may occur due to hypoparathyroidism, kidney conditions, malnutrition and pancreatitis, and viatmin D deficiency. 
High ionised calcium levels (hypercalcemia) may indicate hyperparathyroidism (overactive parathyroid gland), certain cancers, bone disorders like Paget's disease or high vitamin D levels. It may lead to frequent urination, thirst, fatigue, bone pains, headache, nausea, vomiting and loss of appetite