Serum Calcium Test

Your doctor may want to know about the levels of your free/ionised calcium if you have abnormal levels of albumin or immunoglobins in your blood. You may also need to know your ionised calcium levels if:

• You need blood transfusions
• You are critically ill and need intravenous (IV) fluids
• You are having a major surgery
• You are having abnormal blood protein levels

In these cases, your doctor may want to know the exact amount of free calcium available in your body.

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 appetit

Higher than normal levels of calcium might indicate one or more of the following conditions:

• Overactivity of the parathyroid glands (hyperparathyroidism) leads to the increased production of parathyroid hormone by the parathyroid glands
• Certain types of cancer, including the ones spreading to the bone
• Bone disorders
• Consistent and prolonged intake of high levels of Vitamin D

Lower than normal levels of calcium might indicate one or more of the following conditions:

• Lower levels of blood protein often caused due to liver disease
• Underactivity of the parathyroid glands (hypoparathyroidism) leads to the decreased production of parathyroid hormone by the parathyroid glands
• Calcium deficiency in your diet
• Vitamin D or magnesium deficiency
• Pancreatitis
• Kidney disorder

There are some very rare risks involved in taking a blood sample. These include:

• Lightheadedness or fainting
• Hematoma. It occurs when blood accumulates under your skin
• Infection
• Excessive bleeding

Bleeding for a long period after the procedure may indicate a more serious bleeding condition.

If you have high levels of calcium the symptoms may include:

• Increased thirst
• Confusion
• Loss of appetite
• Frequent urination
• Abdominal pain
• Constipation
• Nausea and vomiting

If you have low levels of calcium the symptoms may include:

• Dry skin, coarse hair, and brittle nails
• Muscle spasms, or stiffness
• Tingling sensation in the lips, tongue, fingers, and feet
• Irregular heartbeat

An ionised calcium serum blood test cannot predict the levels of calcium in your bones. If you need to measure your bone health, it can be done by a bone density scan or a DEXA scan. It is a type of X-ray. It can predict the mineral content in your bones.

• Performing a test of ionized calcium is harder than a serum calcium test.
• Special handling of the blood sample is very essential.
• In most cases, your healthcare provider will ask you to fast for six to eight hours before your blood is drawn for an ionised calcium test. During this fasting time, you are required to abstain from eating or drinking anything except water.
• It is essential to discuss your history and current medications with your doctor. There are certain medicines like calcium salts, hydralazine, lithium, thyroxine, thiazide and diuretics. These might interfere with the test results of ionized calcium levels.
• Please do not stop taking your medications without consulting your doctor.

• An ionized calcium serum test requires a small amount of your blood as a sample.
• Your healthcare provider will obtain the blood sample by venipuncture.
• They will identify an area on your arm for the venipuncture. Then clean/disinfect the area. They will insert a sterile needle into your vein. They will then draw a small amount of blood into a syringe.
• This procedure hardly takes five minutes. You will most likely feel a mild pinching during the insertion of the needle. This often goes away quickly.
• You will be instructed to apply pressure to the site where the needle entered your skin. Once the blood is drawn, your healthcare provider will put a bandage on the site of the injection. This is done to minimise any discomfort.

The normal levels of ionised calcium vary between adults and children. In general, a level of 4.64 to 5.28 mg/dL is considered normal in the case of adults. In children, a normal ionized calcium level varies between 4.8 and 5.52 mg/dL.

Ionised calcium

Ionized calcium

Free Calcium

A positive result, indicating high or low ionized calcium levels, may suggest conditions such as hyperparathyroidism, certain cancers, kidney disease, or other disorders affecting calcium metabolism. Discuss the results with your healthcare provider to determine the underlying cause.

Benefits include accurate diagnosis of calcium-related disorders, monitoring treatment effectiveness, and assessing the biological availability of calcium for critical bodily functions.

The ionized calcium test helps diagnose conditions such as hyperparathyroidism, hypoparathyroidism, certain cancers (e.g., multiple myeloma), kidney disease, liver disease, and disorders affecting nutrient absorption from the intestines.

Yes, certain medications like calcium salts, vitamin D supplements, lithium, thiazide diuretics, and levothyroxine can affect ionized calcium levels. Inform your healthcare provider about any medications you are taking.

Fasting is generally not required for a ionized calcium test. However, if other tests are being done alongside it, your healthcare provider will inform you of any specific preparations needed.

Factors that can affect the results include certain medications, dietary intake of calcium and vitamin D, kidney or liver function, and the presence of specific medical conditions. Errors in sample collection, transport, or processing can also influence the results.

Ionized calcium test results are typically available within 24 hours, depending on when the sample was collected and processed.