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Hypocalcemia (Low Level of Calcium in the Blood)

By

James L. Lewis III

, MD, Brookwood Baptist Health and Saint Vincent’s Ascension Health, Birmingham

Last full review/revision Sep 2021| Content last modified Oct 2021
CLICK HERE FOR THE PROFESSONAL VERSION

In hypocalcemia, the calcium level in blood is too low.

  • A low calcium level may result from a problem with the parathyroid glands, as well as from diet, kidney disorders, or certain drugs.

  • As hypocalcemia progresses, muscle cramps are common, and people may become confused, depressed, and forgetful and have tingling in their lips, fingers, and feet as well as stiff, achy muscles.

  • Usually, the disorder is detected by routine blood tests.

  • Calcium and vitamin D supplements may be used to treat hypocalcemia.

Calcium is one of the body's electrolytes Overview of Electrolytes Well over half of the body's weight is made up of water. Doctors think about the body's water as being restricted to various spaces, called fluid compartments. The three main compartments are... read more , which are minerals Overview of Minerals Minerals are necessary for the normal functioning of the body’s cells. The body needs relatively large quantities of Calcium Chloride Magnesium Phosphate read more that carry an electric charge when dissolved in body fluids such as blood (but most of the body's calcium is uncharged). Although most of the body's calcium Overview of Calcium's Role in the Body Calcium is one of the body's electrolytes, which are minerals that carry an electric charge when dissolved in body fluids such as blood, but most of the body's calcium is uncharged. (See also... read more is stored in bones, some circulates in the blood. About 40% of the calcium in blood is attached (bound) to proteins in blood, mainly albumin. Protein-bound calcium acts as a reserve source of calcium for the cells but has no active function in the body. Only unbound calcium affects the body’s functions. Thus, hypocalcemia causes problems only when the level of unbound calcium is low. Unbound calcium has an electrical (ionic) charge, so it is also called ionized calcium.

Causes of Hypocalcemia

Hypocalcemia most commonly results when too much calcium is lost in urine or when not enough calcium is moved from bones into the blood. Causes of hypocalcemia include the following:

Symptoms of Hypocalcemia

The calcium level in blood can be moderately low without causing any symptoms. If levels of calcium are low for long periods, people may develop dry scaly skin, brittle nails, and coarse hair. Muscle cramps involving the back and legs are common. Over time, hypocalcemia can affect the brain and cause neurologic or psychologic symptoms, such as confusion, memory loss, delirium, depression, and hallucinations. These symptoms disappear if the calcium level is restored.

Diagnosis of Hypocalcemia

  • Measurement of calcium level in the blood

Hypocalcemia is often detected by routine blood tests before symptoms become obvious. Doctors measure the total calcium level (which includes calcium bound to albumin) and the albumin level in blood to determine whether the level of unbound calcium is low.

Blood tests are done to evaluate kidney function and to measure magnesium, phosphate, parathyroid hormone, and vitamin D levels. Other substances in blood may be measured to help determine the cause.

Treatment of Hypocalcemia

  • Calcium supplements

  • Sometimes vitamin D

Calcium supplements, given by mouth, are often all that is needed to treat hypocalcemia. If a cause is identified, treating the disorder causing hypocalcemia or changing drugs may restore the calcium level.

Once symptoms appear, calcium is usually given intravenously. Taking vitamin D supplements helps increase the absorption of calcium from the digestive tract.

Sometimes people with hypoparathyroidism are given a synthetic form of parathyroid hormone.

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