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Calcium - ionized

Free calcium; Ionized calcium

 

Ionized calcium is calcium in your blood that is not attached to proteins. It is also called free calcium.

All cells need calcium in order to work. Calcium helps build strong bones and teeth. It is important for heart function. It also helps with muscle contraction, nerve signaling, and blood clotting.

This article discusses the test used to measure the amount of ionized calcium in blood.

How the Test is Performed

 

A blood sample is needed. Most of the time blood is drawn from a vein located on the inside of the elbow or the back of the hand.

 

How to Prepare for the Test

 

You should not eat or drink for at least 6 hours before the test.

Many medicines can interfere with blood test results.

  • Your health care provider will tell you if you need to stop taking any medicines before you have this test.
  • DO NOT stop or change your medicines without talking to your provider first.

 

Why the Test is Performed

 

Your provider may order this test if you have signs of kidney or parathyroid disease. The test may also be done to monitor progress and treatment of these diseases.

Most of the time, blood tests measure your total calcium level. This looks at both ionized calcium and calcium attached to proteins. You may need to have a separate ionized calcium test if you have factors that increase or decrease total calcium levels. These may include abnormal blood levels of albumin or immunoglobulins.

 

Normal Results

 

  • Children: 4.8 to 5.3 milligrams per deciliter (mg/dL) or 1.20 to 1.32 millimoles per liter (millimol/L)
  • Adults: 4.8 to 5.6 mg/dL or 1.20 to 1.40 millimol/L

Normal value ranges may vary slightly among different laboratories. Talk to your health care provider about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

 

What Abnormal Results Mean

 

Higher-than-normal levels of ionized calcium may be due to:

  • Decreased levels of calcium in the urine from an unknown cause
  • Hyperparathyroidism
  • Hyperthyroidism
  • Milk-alkali syndrome
  • Multiple myeloma
  • Paget disease
  • Sarcoidosis
  • Thiazide diuretics
  • Thrombocytosis (high platelet count)
  • Tumors
  • Vitamin A excess
  • Vitamin D excess

Lower-than-normal levels may be due to:

  • Hypoparathyroidism
  • Malabsorption
  • Osteomalacia
  • Pancreatitis
  • Renal failure
  • Rickets
  • Vitamin D deficiency

 

 

References

Thakker RV. The parathyroid glands, hypercalcemia, and hypocalcemia. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 245.

 
  • Blood test - illustration

    Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.

    Blood test

    illustration

    • Blood test - illustration

      Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.

      Blood test

      illustration

    A Closer Look

     

      Self Care

       

        Tests for Calcium - ionized

         

         

        Review Date: 5/4/2015

        Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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