What is the definition of hypocalcemia?

Hypocalcemia is a state of having a low blood calcium levels. According to most laboratories this would be a calcium level that is below the normal range of 8.4 to 10.2 mg/dl.

How is calcium regulated?

The two hormones which control calcium balance are parathyroid hormone (PTH) and the activated form of vitamin D called 1,25 vitamin D. PTH is produced by the parathyroid glands which are located in the neck, usually behind the thyroid gland. Vitamin D comes from food and production in the skin related to the amount of sun exposure you receive.

What are the major causes of hypocalcemia?

There are five major categories of conditions which cause hypocalcemia: 1) hypoparathyroidism, 2) failure to produce 1,25 vitamin D normally, 3) resistance to PTH action, 4) resistance to 1,25 vitamin D, or 5) acute complexation or deposition of calcium. The first two categories are the most commonly encountered conditions. Hypoparathyroidism occurs when there is injury to the parathyroid glands and can be temporary or permanent. This damage may be surgical, autoimmune, familial, or idiopathic. Hypocalcemia may also occur if there is vitamin D deficiency. Vitamin D is necessary for adequate absorption of calcium from the gastrointestinal tract. Vitamin D deficiency is a very common condition due to avoidance of sun exposure, remaining indoors, and the use of sunscreens.

How is surgical hypoparathyroidism (hypocalcemia) treated?

After a neck surgery, temporary hypocalcemia may develop. Calcium and vitamin D supplementation may be needed in the hospital and after you are discharged. Sometimes magnesium supplementation is also required to maintain adequate blood levels of magnesium and calcium. Your blood may be drawn and tested once a week or every few days to adjust your therapy. You may be asked to obtain a 24-hour urine collection to determine how much calcium you are eliminating through your kidneys. Your doctor may prescribe an additional medication, called hydrochlorothiazide, to try to prevent excessive elimination of calcium.

It is important to take your medication as prescribed and to contact your doctor if you develop any signs of low or high calcium, as described in the “Signs and Symptoms” section. If you develop any of the symptoms of low calcium listed below, take an additional dose of calcium. Your symptoms should go away within thirty minutes. If symptoms persist, particularly hand cramping, please contact your doctor or go to the nearest hospital emergency center to assess your calcium levels.

Permanent damage to the parathyroid glands usually requires lifelong calcium and vitamin D (calcitriol) replacement therapy. In permanent hypoparathyroidism, you must take both calcium and vitamin D to maintain normal calcium levels. The goal is to maintain your calcium level in the range of 8.0 to 8.5 mg/dl. This range is slightly lower than the normal range to prevent your kidneys from excreting too much calcium.

Signs and Symptoms of Hypocalcemia (Low Calcium)

• Muscle cramps, including spasms of the hands and feet

• Numbness and tingling around the lips and the tips of your fingers and toes

• Mental changes (e.g. confusion, irritability)

• Drowsiness, anxiety

Signs and Symptoms of Hypercalcemia (High Calcium)

Overtreatment with calcium treatmentscan lead to hypercalcemia (high calcium) if you take more calcium or vitamin D than what you need. If the symptoms below occur, go to the nearest hospital emergency center.

• Sluggishness

• Mental changes (e.g. confusion, irritability)

• Loss of appetite, nausea, constipation

• Frequent urination or kidney stones

• Pain in your joints or muscles, weakness

Always take your medication exactly as prescribed. Do not change your medications unless directed to by your endocrine health care provider. If you do not know what to do, please always call to clarify the instructions.

Contact Information

If you develop signs and symptoms of hypocalcemia or hypercalcemia, contact your Houston Thyroid and Endocrine nurse or doctor, Monday through Friday, 9 a.m. to 430 p.m. at (713) 795-0770. On weekdays after normal business hours and on weekends and holidays, please call the Houston Thyroid and Endocrine operator at 713-795-0770 and leave a message for the physician on call. If your symptoms are severe and you are in the Houston area, go to the St Lukes Hospital Emergency Room. If you are outside the Houston area, go to the nearest hospital emergency center.

Special Instructions that you may be given while in the hospital:

The name and dose of your calcium supplement is:


The name and dose of your vitamin D supplement is:


The name and dose of your magnesium supplement is:


You have received a lab requisition to check your calcium level in _____ days.

Please make sure that your lab faxes us the results as indicated on the prescription, and call your doctor’s nurse to make sure the results have been received.

We will check your calcium level in ______ days during a clinic appointment.