TY - CHAP M1 - Book, Section TI - Hypercalcemia and Hypocalcemia A1 - Khosla, Sundeep A2 - Jameson, J. Larry PY - 2017 T2 - Harrison's Endocrinology, 4e AB - The calcium ion plays a critical role in normal cellular function and signaling, regulating diverse physiologic processes such as neuromuscular signaling, cardiac contractility, hormone secretion, and blood coagulation. Thus, extracellular calcium concentrations are maintained within an exquisitely narrow range through a series of feedback mechanisms that involve parathyroid hormone (PTH) and the active vitamin D metabolite 1,25-dihydroxyvitmin D [1,25(OH)2D]. These feedback mechanisms are orchestrated by integrating signals between the parathyroid glands, kidney, intestine, and bone (Fig. 33-1; Chap. 32). Disorders of serum calcium concentration are relatively common and often serve as a harbinger of underlying disease. This chapter provides a brief summary of the approach to patients with altered serum calcium levels. See Chap. 34 for a detailed discussion of this topic. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - accessbiomedicalscience.mhmedical.com/content.aspx?aid=1141276568 ER -