[Vecuronium-induced neuromuscular blockade in two patients with hyperparathyroidism and a patient with hypoparathyroidism].

Vecuronium-induced neuromuscular blockade was evaluated in two patients with primary hyperparathyroidism and in a patient with hypoparathyroidism. A 39 year old male with typical primary hyperparathyroidism was scheduled for surgical removal of the parathyroid adenoma. Serum levels of calcium and ionized calcium were 15.0 mg.dl-1 and 1.95 mmol.l-1, respectively. A 44 year old female suffering from primary hyperparathyroidism was also scheduled for surgical removal of the adenoma. Serum levels of calcium and ionized calcium were 12.5 mg.dl-1 and 1.51 mmol.l-1, respectively. A 63 year old male, suffering from postoperative secondary hypoparathyroidism and treated with calcium, was scheduled for surgical removal of the recurrent pharyngeal cancer. Serum levels of calcium and ionized calcium were 9.0 mg.dl-1 and 1.15 mmol.l-1, respectively. Anesthesia was induced with thiamylal 4-5 mg.kg-1 and vecuronium 0.08 mg.kg-1 and was maintained with 70% nitrous oxide in oxygen and fentanyl in all three patients. Neuromuscular blockade following the administration of vecuronium was measured by a big toe abduction evoked by supramaximal stimulation of the tibial nerve (Myograph 2000, Biometer, Denmark). In order to evaluate the effect of serum calcium level on vecuronium neuromuscular blockade, ten patients with normal serum levels of calcium, were examined in the same fashion. In only one patient with hyperparathyroidism, whose serum calcium was 15.0 mg.dl-1, the onset and the duration of vecuronium were later and shorter than those of other patients with normal serum levels of calcium. In conclusion, we should pay attention to the antagonistic responses to vecuronium in patients with severely high levels of serum calcium.