Hypocalcemia

Background

• Low <8.5 (<2.0 ionized)
• Low! <6.5 (<1.5 ionized)

• Correct for hypoalbumimia
  • Corrected Ca = (0.8 * (Normal Alb - Pt's Alb)) + Serum Ca

Causes

• Misc
  • Shock
  • Sepsis
  • Pancreatitis
  • Hypomag
  • Rhabdo (phosphate overload)
  • Massive transfusion
  • Systemic Hydrofluoric Acid toxicity
• Decreased absorption
  • Vit D deficiency
• Increased excretion
  • Alcoholism
  • Renal Failure
  • Diuretics
• Endocrine
  • Hypoparathyroidism
• Drugs
  • Cimetidine
  • Phenytoin
  • Lasix

Clinical Features

• Paresthesias (mouth, fingertips)
• ↑ DTRs
• Cramps
• Weakness
• Confusion
• Seizures
• Chvostek/Trousseau signs, Tetany
• Hallucinations

Differential Diagnosis

Jaw Spasms

• Acute tetanus
• Akathisia
• Conversion disorder
• Drug toxicity (anticholinergic, phenytoin, valproate, carbamazepine)
• Dystonic reaction
• Electrolyte abnormality
  • Hypocalcemic tetany
  • Magnesium
• Mandible dislocation
• Meningitis
• Peritonsillar abscess
• Rabies
• Seizure
• Strychnine poisoning
• Stroke
• Temporomandibular disorder
• Torticollis

Diagnosis

• ECG
  • QT Prolongation

• Trousseau's Sign (Mod to high SN and SP)
  • Inflate BP cuff for 2-3 mins
  • Positive = Muscle contractions of the hand and wrist

• Chvostek's Sign (Low SN and SP)
  • Tapping on the face just anterior to the ear and just below the zygomatic bone
  • Positive = Ipsilateral facial twitching

Treatment

Avoid empiric treatment in patients taking digoxin due to risk for Stone Heart

• Asymptomatic
  • Calcium gluconate 1 gm PO Q6hrs
  • Vitamin D (calcitriol) 0.2 mcg BID
• Symptomatic
  • Calcium gluconate/chloride 10mL of 10% soln IV over 10min
• Correct hypomag at same time (otherwise PTH is inhibited)

See Also

• Electrolyte Abnormalities (Main)