Serum Calcium (Total)

Why test for Serum Calcium (Total) at Symbion VIP Diagnostics, Ahmedabad ?

Usually Serum Calcium Level is checked as part of a routine metabolic panel; when you have symptoms of a disorder, or known presence of one, affecting your kidneys, bones, thyroid, parathyroid, or nerves or when symptoms of significantly increased or decreased calcium concentrations are present; when someone is critically ill, to monitor ionized calcium levels; when someone has certain types of cancer; when someone is being treated for abnormal calcium levels, to evaluate the effectiveness of treatment

Blood calcium levels do not indicate levels of bone calcium but rather how much calcium is circulating in the blood.

Calcium absorption, use, and excretion are regulated and stabilized by a feedback loop involving PTH and vitamin D. Conditions and diseases that disrupt calcium regulation can cause inappropriate acute or chronic elevations or decreases in calcium and lead to symptoms of hypercalcemia or hypocalcemia.

In most cases, total calcium is measured because the test is more easily performed than the ionized calcium test and requires no special handling of the blood sample. Total calcium is usually a good reflection of free calcium since the free and bound forms are typically each about half of the total. However, because about half of the calcium in blood is bound to protein, total calcium test results can be affected by high or low levels of protein. In such cases, it is more useful to measure free calcium directly using an ionized calcium test.

Normal calcium
A normal total or ionized calcium result together with other normal laboratory results generally means that a person's calcium metabolism is normal and blood levels are being appropriately regulated.

High total calcium (hypercalcemia)

Two of the more common causes of high blood calcium are:

• Hyperparathyroidism, an increase in parathyroid gland function: this condition is usually caused by a benign tumor of the parathyroid gland. This form of hypercalcemia is usually mild and can be present for many years before being noticed.
• Cancer: cancer can cause hypercalcemia when it spreads to the bones and causes the release of calcium from the bone into the blood or when a cancer produces a hormone similar to PTH, resulting in increased calcium levels.

Some other causes of high blood calcium include:

• Hyperthyroidism
• Sarcoidosis
• Tuberculosis
• Prolonged immobilization
• Excess vitamin D intake
• Thiazide diuretics
• Kidney transplant
• HIV/AIDS

Low total calcium (hypocalcemia)

The most common cause of low total calcium is:

• Low blood protein levels, especially a low level of albumin, which can result from liver disease or malnutrition, both of which may result from alcoholism or other illnesses. Low albumin is also very common in people who are acutely ill. With low albumin, only the bound calcium is low. Ionized calcium remains normal, and calcium metabolism is being regulated appropriately.

Some other causes of low calcium include:

• Underactive parathyroid gland (hypoparathyroidism)
• Inherited resistance to the effects of parathyroid hormone
• Extreme deficiency in dietary calcium
• Decreased levels of vitamin D
• Magnesium deficiency
• Increased levels of phosphorus
• Acute inflammation of the pancreas (pancreatitis)
• Renal failure

Urinary calcium levels may be affected by the same conditions and diseases that affect blood levels (listed above). A high level of calcium in the urine (hypercalciuria) may lead to the formation of crystals or calculi (stones) in the kidneys. About 75% of kidney stones contain calcium.