Department of Emergency Medicine

UMEM Educational Pearls

Title: Hypocalcemia

Category: Critical Care

Posted: 2/3/2010 by Evadne Marcolini, MD (Updated: 12/26/2024)
Click here to contact Evadne Marcolini, MD

  • Total body calcium consists of about half biologically active (ionized) and half inactive (80% bound to albumin and 20% to other ions)
  • hypocalcemia caused by hypoalbuminemia is physiologically insignificant, and correction factors are not accurate or reliable
  • The best way to measure true active calcium is to order an ionized calcium level

There are several conditions that alter ionized calcium levels, including:

  • alkalosis (increases binding to albumin)
  • gas bubbles in the sample (false lowering of calcium)
  • anticoagulants (must be collected in a red top tube)
  • blood transfusions (binding to citrate)
  • cardiopulmonary bypass
  • drugs (aminoglycosides, cimetidine, heparin, theophylline)
  • fat embolism
  • hypomagnesemia (correcting mg levels may preclude need for Ca repletion)
  • pancreatitis (several mechanisms, poor prognosis)
  • renal insufficiency (impaired phosphate retention)
  • sepsis

The bottom line is to measure ionized calcium, and consider all other factors that can be contributing to hypocalcemia in addition to repleting it. 

 

Download the UMEM Pearls App!

UMEM Daily Pearls

Subscribe to daily UMEM Pearls (FREE!) via:

Email Mailing List

Browse a Pearl Category:

Browse a Pearl Author:

Search Pearls