Definition and Characteristics
Hypocalcemia is defined as a low serum calcium concentration. Since most laboratories measure total serum calcium, the level at which a patient is hypocalcemic is approximately 9 mg/dL (less than 2.25 mmol/L). Three different fractions comprise the measured serum calcium: ionized (accounting for 50% of total serum calcium), protein-bound (40%), and complexed to anions (10%). Ionized calcium is the biologically active form and is the critical fraction when evaluating hypocalcemia. Levels of ionized calcium below 4.5 mg/dL (1mmol/L) are considered hypocalcemia.
Prevalence
Hypocalcemia, defined by low levels of ionized calcium, is a rare condition. Prevalence data on hypocalcemia is not available in the general population. It occurs under certain pathophysiological conditions discussed in the following sections.
Genes
The human calcium-sensing receptor (CSR), encoded by six exons of the CSR gene located on chromosome 3q13.3-21, is a 1,070-amino acid...
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References
Brown EM, Pollack, Seidman CE et al. (1995) Calcium-ion-sensing cell surface receptors. N Engl J Med 333:234–340
Janicic N, Soliman E, Pausova Z et al. (1995) Mapping of the calcium-sensing receptor gene (CASR) to human chromosome 3q13.3-21 by fluorescence in situ hybridization, and localization to rat chromosome 11 and mouse chromosome 16. Mamm Genome 6:798–801
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Paparello, J.J., Klemmer, P.J., Kshirsagar, A.V. (2009). Hypocalcemia. In: Lang, F. (eds) Encyclopedia of Molecular Mechanisms of Disease. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-29676-8_887
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DOI: https://doi.org/10.1007/978-3-540-29676-8_887
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