Clinical signs: Rare signs of hypocalcaemia

A. Peroneal sign consists of dorsiflexion of foot and abduction of the toes on tapping the peroneal nerve on the lateral surface of the fibula just below the knee.

B. Erb's sign, or increased electrical excitability of the peripheral nerves to the galvanic current, was the most reliable proof of tetany in the days before blood chemical analyses were available. The procurement of electrical reactions is such a time consuming procedure that they are seldom sought for now.

C. Involvement of the autonomic nervous system has not been stressed in recent years as a manifestation of tetany but was well known to the older writers. They recognized as part of the picture of spasmophilia of infants disturbances of respiration; irregularity, tachypnea, an asthmatic type of breathing apparently due to bronchial spasm and even respiratory arrest as well as the better known laryngeal stridor.

D. Bradycardia, or more rarely tachycardia, and cardiac murmurs were noted.

E. Disturbance of the tonus of the gastrointestinal tract, manifested by abdominal distention, constipation or diarrhea, pylorospasm and vomiting were seen.

F. Pallor, erythema and urticaria were attributed to spasm of the capillaries of the skin. As a further possible sign of tetany, hemorrhages producing bloody vomitus, melena and hematuria should be mentioned.

References
1. J Stokes Jr. and K Dodd et al; Pediatrics, Dec 1948, 737-743, Vol 2, No. 6