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Calcium (Ca)

Serum Calcium
Interpreting Results

Overview of Ca

What is Ca?

Ca refers to Calcium. Calcium (Ca) plays vital role in the formation and maintenance of healthy bones of proper density. Calcium is also essential in the process of cell signaling (communication between cells to coordinate cellular activities in a tissue and interaction with other tissues), blood clotting, and in the proper functioning of muscles, heart, and nerves. The Calcium Test (Total) measures the total amount of calcium in the blood.

Why is Ca done?

  • As a part of regular metabolic panel health checkups 
  • Upon the appearance of symptoms indicating excess or shortfall of calcium
  • To check for diseases causing abnormalities in calcium level in blood like thyroid or parathyroid disorders, heart diseases, kidney diseases, neurological diseases, pancreatitis (inflammation of the pancreas) and bone and teeth diseases
  • At regular intervals to monitor treatment efficacy of calcium supplements or Vitamin D supplements
  • To monitor critically ill patients
  • To monitor the progress of the condition and the efficacy of treatment after the kidney transplant, and in certain types of cancer
  • To monitor calcium levels during and after large-volume blood transfusions

What does Ca Measure?

Calcium (Ca) Test measures the levels of calcium in blood. Calcium is essential for body processes including cell signaling, blood clotting, contraction of muscles, and functioning of nerves. It plays a crucial role in the formation and maintenance of healthy bones. Deficiency of calcium results in Osteoporosis, a disease in which the bones lose their density and become soft and fragile, causing them to fracture very easily.

About 99% of the total amount of calcium received by the body is bound as calcium complex in bones, and the remaining 1% lies in blood circulation. Of the amount of calcium circulating in the blood, about half remains bound to albumin protein or other ions and are metabolically inactive, while the remaining half remains free and metabolically active. Blood Calcium tests can be of two types: Total Calcium Test used to measure the total calcium concentration in blood including both the free and bound forms, and Ionized Calcium Test used to measure the concentration of only the metabolically active form.

Calcium levels in the blood are maintained within a very narrow range by a number of mechanisms. Deviation from the normal range of calcium concentration causes Hypocalcemia (low levels of calcium), or Hypercalcemia (excess of calcium). Both these conditions impact normal body processes in the short term and may give rise to other conditions in the long term.

A blood calcium test cannot be used to check for a lack of calcium in your diet or for osteoporosis (loss of calcium from bones) as the body can have normal calcium levels even in case of dietary deficiency of Calcium. The body can augment mild calcium deficiency by releasing the calcium stored in bones.

Preparation for Ca

  • Do not eat or drink anything other than water for 8-12 hours before the test.

Sample Type for Ca

The sample type collected for Calcium is: Blood

Interpreting Ca results


Normal range: 8.5 to 10.5 mg/dL (2.2 to 2.7 mmol/L approx.)

Hypocalcemia: Below 8.5 mg/dL (Below 2.2 mmol/L approx.)

Hypercalcemia: Above 10.5 mg/dL (Above 2.7 mmol/L approx.)

Calcium concentration in the body is maintained within a narrow normal range between 8.5mg/dL and 10.5mg/dL.

Hypocalcemia or low blood calcium is indicated if calcium concentration lies below the normal range.

Hypercalcemia or high blood calcium is indicated if calcium concentration lies above the normal range.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Ca

Frequently Asked Questions about Calcium

Q. How is this test performed?
This test is performed on a blood sample. A syringe with a fine needle is used to withdraw blood sample from a blood vessel in your arm, generally from the inner side of the elbow area. The doctor, nurse or the phlebotomist will tie an elastic band around your arm which will help the blood vessels to swell with blood. This makes it easier to withdraw blood. You may be asked to tightly clench your fist. Once the veins are clearly visible, the area is cleaned with an antiseptic solution. The needle is then inserted into the blood vessel to collect the sample. You may feel a tiny pinprick during the procedure. Blood sample, once collected, is then sent to the laboratory.
Q. Is there any risk associated with this test?
There is no risk associated with the test. However, since this test involves a needle prick to withdraw the blood sample, in very rare cases, a patient may experience increased bleeding, hematoma formation (blood collection under the skin), bruising or infection at the site of needle prick.
Q. What is Hypocalcemia?
Hypocalcemia is a condition where the blood calcium levels are below the normal range. This may occur due to: · Low levels of blood protein, especially albumin · Hypoparathyroidism or reduced secretion of parathyroid hormones · Genetic resistance to parathyroid hormones · Dietary deficiency of calcium · Intolerance of dietary calcium · Vitamin D deficiency · Magnesium deficiency · High phosphorus concentration in blood · Acute pancreatitis (inflammation of pancreas) · Hormonal changes in women after menopause · Renal failure · Alcoholism
Q. What are the symptoms of Hypocalcemia?
Short term or mild deficiency of calcium usually produces very little symptoms. This happens because the body can augment mild calcium deficiency by releasing the calcium stored in bones. Symptoms appear in case of chronic or long term calcium deficiency. Symptoms of Hypocalcemia include: · Weak and brittle hairs · Brittle nails · Thin and brittle bones which fracture easily · Confusion · Memory loss · Numbness and tingling sensation · Muscle spasms and cramps · Depression · Hallucinations · Seizures
Q. What is Hypercalcemia?
Hypercalcemia is the condition where blood calcium levels rise higher than the normal range. This may occur due to: · Hyperparathyroidism or increased secretion of parathyroid hormones · Hyperthyroidism or increased secretion of thyroid hormones · Prolonged period of immobility as in bed rest · Sarcoidosis, a condition that produces nodules in different organs · Tuberculosis · Overconsumption of Vitamin D · Treatment by thiazide diuretics · Kidney transplant · HIV/AIDS · Cancer
Q. What are the symptoms of Hypercalcemia?
Symptoms of Hypercalcemia include: · Headache · Weakness and fatigue · Excessive urination and thirst · Nausea · Pain in abdomen · Constipation · Abnormal heartbeat or cardiac arrhythmia · Weak and brittle bones · Muscular cramps · Depression and irritability · Confusion · Coma
Q. Is there any preparation required before the Calcium test?
Inform the doctor about any medications you may be taking. Some medications like antacids, diuretics, lithium, Vitamin D supplements, etc. can affect the test results and may have to be stopped before testing. No other preparations are required unless specified by your doctor.
Q. When can false results appear in the Calcium Test?
False results may appear in newborns, showing hypocalcemia. This is usually due to immature parathyroid gland. False results may also appear after a large volume blood transfusion. Some medications can elevate or lower blood calcium levels.
Q. What other tests can be prescribed by your doctor in case Calcium test result is not normal?
Others tests that may be prescribed upon the appearance of an abnormal result in the blood Calcium test include: · Ionized Calcium Test · Urine Calcium Test · Vitamin D Test · Electrolyte Panel Test · Kidney Function Test · Parathyroid Hormone (PTH) Test · PTH Related Peptide Test (PTHrH) · Electrocardiography (ECG)
Q. Which food items are good source of calcium?
Dietary sources form the principal source of calcium. Some very commonly available food items rich in calcium are: · Seeds and nuts · Milk and dairy products · Beans · Lentils · Green leafy vegetables
Q. What is Osteoporosis and how is it related to calcium deficiency?
Osteoporosis is a disease where the bone density is drastically reduced, making them very weak, brittle, and easily susceptible to fracture. Symptoms do not usually appear until there is a fracture. Osteoporosis occurs mostly due to a continuous loss of calcium and insufficient dietary replacement. Calcium is required for nerve and muscle functioning, hence any shortage of it in blood is made up by supplying calcium from the bones. This loss of bone calcium causes the bones to lose bone mass and density, making them soft and brittle.
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We at CORE Diagnostics are a renowned pathology testing laboratory & a premier institute in the country capable of providing varied diagnostic tests & facilities in the field of laboratory medicine and have established state-of-art testing facilities in Gurgaon. We are a Clinical laboratory focused on Next Generation Diagnostics for disease stratification and therapy selection. We are focused on bringing the most advanced testing techniques and expertise to India and aim to become the destination for all your high-end diagnostic needs.

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