Chvostek’s sign is momentary contraction of the nose and/or lips in response to tapping the facial nerve at the angle of the jaw.  Associated with hypocalcemia, it has been found to be poorly sensitive and specific.  It is seen in 10-25% of healthy individuals with normal calcium levels (as demonstrated by two of our own EM residents below), whereas approximately one third of patients with hypocalcemia will not demonstrate this sign^1-3. 

 Hypocalcemia – Brief Review

 v*Normal range of serum (total) calcium: 8.5-10.5 mg/dL

• 50 % is ionized
• 40% is bound to proteins (90% of which binds to albumin)
• 10% circulates bound to anions (phosphate, carbonate, citrate, lactate, sulfate, etc)

v*Normal range of ionized calcium: 4.8-5.7 mg/dL

v A value presented in mEq/L is equivalent to ONE HALF of the value in mg/dL

v Definition of hypocalcemia: ionized calcium <4.0 mg/dL or <2.0 mEq/L

v Remember that serum (total) calcium level is dependent upon albumin level.  As a guideline, if albumin is low, add 0.8mg/dL to the calcium level for every 1.0g/dL drop in albumin below 4.0g/dL.  The opposite is true for high levels of albumin – subtract 0.8mg/dL from the measured calcium level for every 1.0 g/dL above 4.0g/dL of albumin.

v Symptoms: 

Ø  Mild: peri-oral numbness, paresthesias, cramping, fatigue, anxiety, Chvostek and Trousseau’s sign

Ø  Severe:  Tetany, laryngospasm, bronchospasm, seizures, and cardiac arrhythmias

v Hypocalcemia may be evident in patients with sepsis, after blood transfusion, status-post traumatic injury, and in pancreatitis, as well as in patients with nutritional deficiencies (vitamin D) and in alcoholics.

v Drugs that decrease levels of calcium include but are not limited to: norepinephrine, glucagon, loop diuretics (ie furosemide), glucocorticoids, magnesium sulfate, sodium nitroprusside

v Life threatening cases that may be encountered in the emergency department are more commonly seen in patients with end-stage renal disease.  High levels of phosphate (due to decreased renal excretion) complex with ionized calcium, and the kidney is no longer producing sufficient levels of calcitriol to increase GI absorption of calcium.  Life threatening cases of hypocalcemia may also be seen in patients with recent thyroidectomy. 

v Treatment:

Ø  Mild cases: for asymptomatic or mildly symptomatic patients, oral supplementation is adequate, ranging from 500-3000 mg of elemental calcium daily, with or without vitamin D.

Ø  Moderate cases: IV calcium gluconate is preferred to calcium chloride as it has lower rates of extravasation and complication during administration.

Ø  Severe cases: 10ml of 10% CaCl₂ may be given IV over 10-20 minutes and repeated every 60 minutes until symptoms resolve.  Calcium chloride can also be provided as an infusion of 10% CaCl₂ at 0.02-0.08 mL/kg/hour.  Calcium chloride must be infused using central access given it’s potentially caustic effects on peripheral vasculature.

*Normal range may depend on institution/lab

References

1)    Jesus JE, Landry A.  Images in clinical medicine.  Chvostek’s and Trousseau’s signs.  New England Journal of Medicine 2012.  367(11):e15

2)    Méneret A, Guey S, Degos,B. Chvostek sign, frequently found in healthy subjects, is not a useful clinical sign. Neurology. 2013 Mar 12;80(11):1067

3)    Hoffman E. The Chvostek sign: a clinical study. Am J Surg 1958;96:33–37

4)    Tintinalli et al.  Tintinalli’s Emergency Medicine: A Comprehensive Study Guide.  7^th Ed. New York: McGraw Hill Education, 2011. Print.

5)  Suneja, Manish.  Hypocalcemia.  (2016, July 26).  eMedicine.  Retrieved February 28, 2017, from http://emedicine.medscape.com/article/241893-overview