HYPOCALCEMIA   = ionized Ca  < 2.0mEq/L 

 

Etiology:

  1. During trauma, shock, sepsis, fat embolism Ca tends to move into the cell
     
  2. Pancreatitis - fatty acids combine with Ca and form soaps.
     
  3. Drugs (cimetidine, phosphate containing enemas)
     
  4. HypoPTH
     
  5. Renal Failure 2ry to  production of 125-(OH)-vitamin D. Also 2ry to phosphate.
     
  6. HypoMg
     
  7. vitamin D
     
  8. Respiratory alkalosis (decreases ionized Ca)

What is important is the amount of ionized Ca and not the total amount of Ca. As a matter of fact during hypoalbuminemic state total Ca is low but ionized Ca is normal.

S & S :

  1. Weakness, N/V, fatigue
     
  2. CNS -tetany, Chvosteck's, Trousseau's, perioral numbness, psychosis.
     
  3. CV -heart failure, dysrhythmia
     
  4. ENDOCRIN - increase in PTH (negative feedback)

DX :

  1. S&S are helpful
     
  2. EKG shows > QT, possible TW inversion
     
  3. BUN, Mg, PO4,

Treatment:

  1. If pt shows no S&S, give oral Ca
     
  2. If symptoms present, give Ca gluconate (10ml amp contains 4.6mEq/L of Ca) or CaCl (10ml amp contains 13mEq/L Ca). Both are given IV over 20-30min.
     
  3. If albumin or Mg are low, supplementing these may suffice
     
  4. Due to prolonged QT and possibility of V.Tach pts should be on monitor
    and admitted to monitored bed. Hypercalcemia conversely gives shortening
    in QT which is not associated with arrhythmias