Calcium Protein Binding (CALCIUM)

  • D. John Doyle


Calcium in plasma is in two main forms: as free ions and as calcium bound to plasma proteins. It is the level of free calcium ions that is important in the regulation of neuromuscular irritability and other cellular functions; the protein-bound fraction is biologically inert. In plasma, in normal adults, the reference range of total plasma calcium concentration is about 8.8 to 10.4mg/dl. However, hyperproteinemia (eg, due to hyperglobulinemia in myelomatosis) can increase total plasma calcium without changing ionized calcium levels, and hypoalbuminemia (eg, due to liver cirrhosis or nephritis) can decrease plasma calcium while keeping ionized calcium normal. Consequently, in examining a total plasma calcium concentration it is helpful to also know the percent of protein-bound calcium so that free ionized calcium can be determined by subtracting protein-bound from total calcium.


Liver Cirrhosis Calcium Protein Binding Total Calcium Plasma Calcium Ionize Calcium Level 
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  1. 1.
    Petersdorf, RG, et al: Harrison’s Principles of Internal Medicine, ed 10. New York, McGraw-Hill Book Co, 1983, p 1923.Google Scholar

Copyright information

© Springer-Verlag New York Inc. 1989

Authors and Affiliations

  • D. John Doyle
    • 1
  1. 1.Institute of Biomedical Engineering and Department of AnaesthesiaUniversity of TorontoTorontoCanada

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