TY - CHAP M1 - Book, Section TI - Calcium A1 - Smith, Silas W. A1 - Ann Howland, Mary A2 - Nelson, Lewis S. A2 - Howland, Mary Ann A2 - Lewin, Neal A. A2 - Smith, Silas W. A2 - Goldfrank, Lewis R. A2 - Hoffman, Robert S. Y1 - 2019 N1 - T2 - Goldfrank's Toxicologic Emergencies, 11e AB - Calcium is a divalent cation that is essential to maintain the normal function of the heart, vascular smooth muscle, the skeletal system, the nervous system, and intracellular signaling. It is vital in enzymatic reactions, neurohormonal transmission, blood coagulation, and the maintenance of cellular integrity.12 The endocrine system maintains calcium homeostasis. Hypercalcemia raises the threshold for nerve and muscle excitation, resulting in muscle weakness, lethargy, cardiac conduction disturbances, and coma. Hypocalcemia can result in hyperreflexia, muscle spasms, tetany, seizures, and QT interval prolongation (Chaps. 12 and 15).12 SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessemergencymedicine.mhmedical.com/content.aspx?aid=1163003336 ER -